Optimum criteria of an irreversible quantum Brayton refrigeration cycle with an ideal Bose gas
NASA Astrophysics Data System (ADS)
Wang, Hao; Liu, Sanqiu; He, Jizhou
2008-11-01
An irreversible cycle model of the quantum Brayton refrigeration cycle is established, in which finite-time processes and irreversibility in the two adiabatic processes are taken into account. On the basis of the thermodynamic properties of an ideal Bose gas, by using the optimal control-theory, the mathematical expressions for several important performance parameters, such as the coefficient of performance, power input and cooling load, are derived and some important performance parameters, e.g., the temperatures of the working substance at several important state-points, are optimized. By means of numerical predictions, the optimal performance characteristic curves of a Bose-Brayton refrigeration cycle are obtained and analyzed. Furthermore, some optimal operating regions including those for the cooling load, coefficient of performance and the temperatures of the cyclic working substance at the two important state-points are determined and evaluated. Finally, several special cases are discussed in detail.
Yang, Jaw-Yen; Yan, Chih-Yuan; Diaz, Manuel; Huang, Juan-Chen; Li, Zhihui; Zhang, Hanxin
2014-01-01
The ideal quantum gas dynamics as manifested by the semiclassical ellipsoidal-statistical (ES) equilibrium distribution derived in Wu et al. (Wu et al. 2012 Proc. R. Soc. A 468, 1799-1823 (doi:10.1098/rspa.2011.0673)) is numerically studied for particles of three statistics. This anisotropic ES equilibrium distribution was derived using the maximum entropy principle and conserves the mass, momentum and energy, but differs from the standard Fermi-Dirac or Bose-Einstein distribution. The present numerical method combines the discrete velocity (or momentum) ordinate method in momentum space and the high-resolution shock-capturing method in physical space. A decoding procedure to obtain the necessary parameters for determining the ES distribution is also devised. Computations of two-dimensional Riemann problems are presented, and various contours of the quantities unique to this ES model are illustrated. The main flow features, such as shock waves, expansion waves and slip lines and their complex nonlinear interactions, are depicted and found to be consistent with existing calculations for a classical gas. PMID:24399919
Yang, Jaw-Yen; Yan, Chih-Yuan; Diaz, Manuel; Huang, Juan-Chen; Li, Zhihui; Zhang, Hanxin
2014-01-01
The ideal quantum gas dynamics as manifested by the semiclassical ellipsoidal-statistical (ES) equilibrium distribution derived in Wu et al. (Wu et al. 2012 Proc. R. Soc. A 468, 1799–1823 (doi:10.1098/rspa.2011.0673)) is numerically studied for particles of three statistics. This anisotropic ES equilibrium distribution was derived using the maximum entropy principle and conserves the mass, momentum and energy, but differs from the standard Fermi–Dirac or Bose–Einstein distribution. The present numerical method combines the discrete velocity (or momentum) ordinate method in momentum space and the high-resolution shock-capturing method in physical space. A decoding procedure to obtain the necessary parameters for determining the ES distribution is also devised. Computations of two-dimensional Riemann problems are presented, and various contours of the quantities unique to this ES model are illustrated. The main flow features, such as shock waves, expansion waves and slip lines and their complex nonlinear interactions, are depicted and found to be consistent with existing calculations for a classical gas. PMID:24399919
Wakefield, C.B.
1996-12-31
For a closed Thermodynamic System in equilibrium, the internal energy of the system (U) is a function of two variables. The equilibrium states of a closed system, for example, described by means of 3 thermodynamic coordinates P, V, and T are completely determined by only two, since the third is fixed by the equation of state. For this reason the internal energy (U) may be considered as a function of only two (any two) of the other thermodynamic coordinates. If we use the two variable chain rule with U = f(T,V), we get the following: dU = ({partial_derivative}U/{partial_derivative}T) {sub v} dT + ({partial_derivative}U/{partial_derivative}V){sub T} dV. The first partial derivative is the heat capacity at constant volume. The second partial derivative is zero for an ideal gas, since interactions between the gas molecules is neglected the internal energy does not change with a change in volume at constant T. The purpose of this paper is to evaluate this second partial derivative for several non ideal equations of state, using mathematics and a software package {open_quotes}Mathematica.{close_quotes} The results (graphics and tables) illustrate the conditions where forces of attraction become significant. Next we see where the forces of repulsion becomes important.
Ideal quantum gas in expanding cavity: nature of non-adiabatic force
K. Nakamura; S. K. Avazbaev; Z. A. Sobirov; D. U. Matrasulov; T. Monnai
2011-05-21
We consider a quantum gas of non-interacting particles confined in the expanding cavity, and investigate the nature of the non-adiabatic force which is generated from the gas and acts on the cavity wall. Firstly, with use of the time-dependent canonical transformation which transforms the expanding cavity to the non-expanding one, we can define the force operator. Secondly, applying the perturbative theory which works when the cavity wall begins to move at time origin, we find that the non-adiabatic force is quadratic in the wall velocity and thereby does not break the time-reversal symmetry, in contrast with the general belief. Finally, using an assembly of the transitionless quantum states, we obtain the nonadiabatic force exactly. The exact result justifies the validity of both the definition of force operator and the issue of the perturbative theory. The mysterious mechanism of nonadiabatic transition with use of transitionless quantum states is also explained. The study is done on both cases of the hard-wall and soft-wall confinement with the time-dependent confining length.
Optimization criteria for an irreversible quantum Brayton engine with an ideal Bose gas
NASA Astrophysics Data System (ADS)
Wu, Feng; Chen, Lingen; Sun, Fengrui; Wu, Chih; Guo, Fangzhong
2006-03-01
The purpose of this paper is to study the optimal performance for an irreversible quantum Brayton engine consisting of two constant-frequency branches connected by two irreversible adiabatic branches. The solution of the generalized quantum master equation of a thermal system is obtained in the Heisenberg picture. The optimization region (or criteria) for an irreversible quantum Brayton engine is obtained. The relationship between the dimensionless power output P* versus efficiency ? for the irreversible quantum Brayton engine with heat leakage and other irreversible losses are derived.
ERIC Educational Resources Information Center
Daisley, R. E.
1973-01-01
Presents some organized ideas in thermodynamics which are suitable for use with high school (GCE A level or ONC) students. Emphases are placed upon macroscopic observations and intimate connection of the modern definition of temperature with the concept of ideal gas. (CC)
NASA Astrophysics Data System (ADS)
Wang, Jianhui; Ma, Yongli; He, Jizhou
2015-07-01
Based on quantum thermodynamic processes, we make a quantum-mechanical (QM) extension of the typical heat engine cycles, such as the Carnot, Brayton, Otto, Diesel cycles, etc., with no introduction of the concept of temperature. When these QM engine cycles are implemented by an ideal gas confined in an arbitrary power-law trap, a relation between the quantum adiabatic exponent and trap exponent is found. The differences and similarities between the efficiency of a given QM engine cycle and its classical counterpart are revealed and discussed.
Yu. E. Kuzovlev
2013-11-13
Statistics of classical Hamiltonian random walk of particle colliding with atoms of ideal gas is considered from viewpoint of earlier suggested exact pseudo-quantum path integral representation of the problem, and qualitative agreement is demostrated between results of an naturally arising simple approximation of this integral and results obtained by formally different methods, thus in a new fashion showing inevitability of scaleless 1/f-type fluctuations in rates of molecular Brownian motions and other dynamical transport and evolution processes.
ERIC Educational Resources Information Center
Sevilla, F. J.; Olivares-Quiroz, L.
2012-01-01
In this work, we address the concept of the chemical potential [mu] in classical and quantum gases towards the calculation of the equation of state [mu] = [mu](n, T) where n is the particle density and "T" the absolute temperature using the methods of equilibrium statistical mechanics. Two cases seldom discussed in elementary textbooks are…
Quantum noise in ideal operational amplifiers
Jean-Michel Courty; Francesca Grassia; Serge Reynaud
1998-11-24
We consider a model of quantum measurement built on an ideal operational amplifier operating in the limit of infinite gain, infinite input impedance and null output impedance and with a feddback loop. We evaluate the intensity and voltage noises which have to be added to the classical amplification equations in order to fulfill the requirements of quantum mechanics. We give a description of this measurement device as a quantum network scattering quantum fluctuations from input to output ports.
Derivation of the Ideal Gas Law
ERIC Educational Resources Information Center
Laugier, Alexander; Garai, Jozsef
2007-01-01
Undergraduate and graduate physics and chemistry books usually state that combining the gas laws results in the ideal gas law. Leaving the derivation to the students implies that this should be a simple task, most likely a substitution. Boyle's law, Charles's law, and the Avogadro's principle are given under certain conditions; therefore, direct…
How Is the Ideal Gas Law Explanatory?
ERIC Educational Resources Information Center
Woody, Andrea I.
2013-01-01
Using the ideal gas law as a comparative example, this essay reviews contemporary research in philosophy of science concerning scientific explanation. It outlines the inferential, causal, unification, and erotetic conceptions of explanation and discusses an alternative project, the functional perspective. In each case, the aim is to highlight…
Statistical theory of ideal quantum measurement processes
Armen E. Allahverdyan; Roger Balian; Theo M. Nieuwenhuizen
2015-02-24
A minimalist theory of ideal quantum measurements is presented. The tested system S and the apparatus A are treated as a compound, isolated system, and the process is identified with the establishment of a generalised thermodynamic equilibrium. The results can be found on the level of thermodynamics, with a qualitative account of the relaxation mechanisms, but they can also be derived through detailed dynamic calculations based on standard quantum statistical mechanics. A quantum formalism without interpretation is used, where density operators encode knowledge about properties of a statistical ensemble, and also of its subensembles. The analysis of the measurement involves three steps. The first one deals with the dynamics of the density matrix of S+A associated with a large set of runs; it involves both the disappearance of the off-diagonal blocks (by decoherence or dephasing)and the establishment of correlations between S and the pointer of A in the diagonal blocks. The desired form for this density matrix at the end of the process is thus obtained, under some specified conditions to be fulfilled by the Hamiltonian. However, due to a quantum ambiguity, this is not sufficient to account for the occurrence of a well defined outcome for each individual run of the ensemble. Therefore, in a second step, a stronger result is established, concerning all possible subensembles of runs. Their associated density operators are shown to relax towards the required structure owing to a specific mechanism that acts near the end of the process. In the third step, the equations thus formally obtained are interpreted by means of postulates which relate macrophysics to microphysics and pertain more to A than to S. The properties currently attributed to ideal measurements are thereby recovered most economically, and the status of Born's rule is re-evaluated.
Generalized Ideal Gas Equations for Structureful Universe
Shahid N. Afridi; Khalid Khan
2006-09-04
We have derived generalized ideal gas equations for a structureful universe consisting of all forms of matters. We have assumed a universe that contains superclusters. Superclusters are then made of clusters. Each cluster can be further divided into smaller ones and so on. We have derived an expression for the entropy of such a universe. Our model is rather independent of the geometry of the intermediate clusters. Our calculations are valid for a non-interacting universe within non-relativistic limits. We suggest that structure formation can reduce the expansion rate of the universe.
Thermodynamics of Ideal Gas in Cosmology
Ying-Qiu Gu
2009-10-04
The equation of state and the state functions for the gravitational source are necessary conditions for solving cosmological model and stellar structure. The usual treatments are directly based on the laws of thermodynamics, and the physical meanings of some concepts are obscure. This letter show that, we can actually derive all explicit fundamental state functions for the ideal gas in the context of cosmology via rigorous dynamical and statistical calculation. These relations have clear physical meanings, and are valid in both non-relativistic and ultra-relativistic cases. Some features of the equation of state are important for a stable structure of a star with huge mass.
How is the Ideal Gas Law Explanatory?
NASA Astrophysics Data System (ADS)
Woody, Andrea I.
2013-07-01
Using the ideal gas law as a comparative example, this essay reviews contemporary research in philosophy of science concerning scientific explanation. It outlines the inferential, causal, unification, and erotetic conceptions of explanation and discusses an alternative project, the functional perspective. In each case, the aim is to highlight insights from these investigations that are salient for pedagogical concerns. Perhaps most importantly, this essay argues that science teachers should be mindful of the normative and prescriptive components of explanatory discourse both in the classroom and in science more generally. Giving attention to this dimension of explanation not only will do justice to the nature of explanatory activity in science but also will support the development of robust reasoning skills in science students while helping them understand an important respect in which science is more than a straightforward collection of empirical facts, and consequently, science education involves more than simply learning them.
WINDING-INVARIANT PRIME IDEALS IN QUANTUM 3 3 MATRICES
Lenagan, Tom
WINDING-INVARIANT PRIME IDEALS IN QUANTUM 3 Ã? 3 MATRICES K. R. Goodearl and T. H. Lenagan Â¢Â¡Â¤Â£Â¦Â¥Â¨Â§Â¤Â©Â¨Â¥ A complete determination of the prime ideals invariant under winding auto- morphisms in the generic 3 Ã? 3 heavily on certain tensor product decompositions for winding-invariant prime ideals, developed
Pauli paramagnetism of an ideal Fermi gas
Lee, Ye-Ryoung
We show how to use trapped ultracold atoms to measure the magnetic susceptibility of a two-component Fermi gas. The method is illustrated for a noninteracting gas of [superscript 6]Li, using the tunability of interactions ...
Irreversibility and decoherence in an ideal gas
Janos Polonyi
2015-02-13
Different models are described where non-interacting particles generate dissipative effective forces by the mixing of infinitely many soft normal modes. The effective action is calculated for these models within the Closed Time Path formalism. This is a well known scheme for quantum systems but its application in classical mechanics presents a new, more unified derivation and treatment of dissipative forces within classical and quantum physics.
The modified ASEP as a model of ideal gas
NASA Astrophysics Data System (ADS)
Mironov, D.; Sossinsky, A.
2015-01-01
A modified version of the ASEP model is interpreted as a two-dimensional model of ideal gas. Its properties are studied by simulating its behavior in different situations, using an animation program designed for that purpose.
2/2015 ideal gas 1/8 IDEAL AND NON-IDEAL GASES
Gustafsson, Torgny
molecule, b 1 2 No 4 3 2r 3 , (3) where No is Avogadro's number, the number of molecules in a mole calculations remember that R is = 8314 J/(kmol).K. Avogadro's number is 6.02 x 1023 molecules per mole of a gas varies with temperature when no change is made in either the volume V or the number of moles
Viscosity of an ideal relativistic quantum fluid: A perturbative study
Giorgio Torrieri
2012-02-14
We show that a quantized ideal fluid will generally exhibit a small but non-zero viscosity due to the backreaction of quantum soundwaves on the background. We use an effective field theory expansion to estimate this viscosity to first order in perturbation theory. We discuss our results, and whether this estimate can be used to obtain a more model-independent estimate of the "quantum bound" on the viscosity of physical systems
Efficient quantum processing of ideals in finite rings
Pawel M. Wocjan; Stephen P. Jordan; Hamed Ahmadi; Joseph P. Brennan
2009-07-31
Suppose we are given black-box access to a finite ring R, and a list of generators for an ideal I in R. We show how to find an additive basis representation for I in poly(log |R|) time. This generalizes a recent quantum algorithm of Arvind et al. which finds a basis representation for R itself. We then show that our algorithm is a useful primitive allowing quantum computers to rapidly solve a wide variety of problems regarding finite rings. In particular we show how to test whether two ideals are identical, find their intersection, find their quotient, prove whether a given ring element belongs to a given ideal, prove whether a given element is a unit, and if so find its inverse, find the additive and multiplicative identities, compute the order of an ideal, solve linear equations over rings, decide whether an ideal is maximal, find annihilators, and test the injectivity and surjectivity of ring homomorphisms. These problems appear to be hard classically.
Thermal transport through non-ideal Andreev quantum dots
Pedro Vidal
2015-01-07
We consider the scenario of thermal transport through two types of Andreev quantum dots which are coupled to two leads, belonging to the Class D and Class C symmetry classes. Using the random matrix description we derive the joint probability density function (j.p.d.f.) in term of Hypergeometric Function of Matrix Arguments when we consider one lead to be attached ideally and one lead non ideally. For the class C ensemble we derive a more explicit representation of the j.p.d.f. which results in a new type of random matrix model.
Thermodynamics of Ideal Gas in Doubly Special Relativity
Nitin Chandra; Sandeep Chatterjee
2012-02-22
We study thermodynamics of an ideal gas in Doubly Special Relativity. New type of special functions (which we call Incomplete Modified Bessel functions) emerge. We obtain a series solution for the partition function and derive thermodynamic quantities. We observe that DSR thermodynamics is non-perturbative in the SR and massless limits. A stiffer equation of state is found.
From Free Expansion to Abrupt Compression of an Ideal Gas
ERIC Educational Resources Information Center
Anacleto, Joaquim; Pereira, Mario G.
2009-01-01
Using macroscopic thermodynamics, the general law for adiabatic processes carried out by an ideal gas was studied. It was shown that the process reversibility is characterized by the adiabatic reversibility coefficient r, in the range 0 [less than or equal] r [less than or equal] 1 for expansions and r [greater than or equal] 1 for compressions.…
Experimental Verification of Boyle's Law and the Ideal Gas Law
ERIC Educational Resources Information Center
Ivanov, Dragia Trifonov
2007-01-01
Two new experiments are offered concerning the experimental verification of Boyle's law and the ideal gas law. To carry out the experiments, glass tubes, water, a syringe and a metal manometer are used. The pressure of the saturated water vapour is taken into consideration. For educational purposes, the experiments are characterized by their…
A Demonstration of Ideal Gas Principles Using a Football.
ERIC Educational Resources Information Center
Bare, William D.; Andrews, Lester
1999-01-01
Uses a true-to-life story of accusations made against a college football team to illustrate ideal gas laws. Students are asked to decide whether helium-filled footballs would increase punt distances and how to determine whether a football contained air or helium. (WRM)
Kåre Olaussen; Asle Sudbø
2015-02-04
The virial expansion of ideal quantum gases reveals some interesting and amusing properties when considered as a function of dimensionality $d$. In particular, the convergence radius $\\rho_c(d)$ of the expansion is particulary large at {\\em exactly\\/} $d=3$ dimensions, $\\rho_c(3) = 7.1068\\ldots \\times \\lim_{d\\to3} \\rho_c(d)$. The same phenomenon occurs in a few other special (non-integer) dimensions. We explain the origin of these facts, and discuss more generally the structure of singularities governing the asymptotic behavior of the ideal gas virial expansion.
Ideal Gas Resonance Scattering Kernel Routine for the NJOY Code
Rothenstein , W.
1999-11-14
In a recent publication an expression for the temperature-dependent double-differential ideal gas scattering kernel is derived for the case of scattering cross sections that are energy dependent. Some tabulations and graphical representations of the characteristics of these kernels are presented in Ref. 2. They demonstrate the increased probability that neutron scattering by a heavy nuclide near one of its pronounced resonances will bring the neutron energy nearer to the resonance peak. This enhances upscattering, when a neutron with energy just below that of the resonance peak collides with such a nuclide. A routine for using the new kernel has now been introduced into the NJOY code. Here, its principal features are described, followed by comparisons between scattering data obtained by the new kernel, and the standard ideal gas kernel, when such comparisons are meaningful (i.e., for constant values of the scattering cross section a 0 K). The new ideal gas kernel for variable {sigma}{sub s}{sup 0}(E) at 0 K leads to the correct Doppler-broadened {sigma}{sub s}{sup T}(E) at temperature T.
Quantum Algorithms for Unit Group and principal ideal problem
Hong Wang; Zhi Ma
2010-09-01
Computing the unit group and solving the principal ideal problem for a number field are two of the main tasks in computational algebraic number theory. This paper proposes efficient quantum algorithms for these two problems when the number field has constant degree. We improve these algorithms proposed by Hallgren by using a period function which is not one-to-one on its fundamental period. Furthermore, given access to a function which encodes the lattice, a new method to compute the basis of an unknown real-valued lattice is presented.
Cabbolet, Marcoen J T F
2015-01-01
This note shows that orthodox quantum mechanics (OQM) entails a Berkelian idealism regarding properties (BIRP): a quantum only `has' a quantitative property upon observation of that property. It is argued that this BIRP poses an issue for the development of a theory of gravitation in the framework of OQM, for how can a quantum curve space-time if it doesn't have the property energy in absence of observation to begin with?
Microeconomics of the ideal gas like market models
NASA Astrophysics Data System (ADS)
Chakrabarti, Anindya S.; Chakrabarti, Bikas K.
2009-10-01
We develop a framework based on microeconomic theory from which the ideal gas like market models can be addressed. A kinetic exchange model based on that framework is proposed and its distributional features have been studied by considering its moments. Next, we derive the moments of the CC model (Eur. Phys. J. B 17 (2000) 167) as well. Some precise solutions are obtained which conform with the solutions obtained earlier. Finally, an output market is introduced with global price determination in the model with some necessary modifications.
CHAPTER 5 -SYSTEMS UNDER PRESSURE 5.1 Ideal gas law
Boal, David
CHAPTER 5 - SYSTEMS UNDER PRESSURE 5.1 Ideal gas law The quantitative study of gases goes back more as it is heated. These two observations are combined into an expression known as the ideal gas law, which weB is Boltzmann's constant (see Chap. 4). It is more conventional to express the ideal gas law in terms
Suppression of Density Fluctuations in a Quantum Degenerate Fermi Gas
Sanner, Christian Burkhard
We study density profiles of an ideal Fermi gas and observe Pauli suppression of density fluctuations (atom shot noise) for cold clouds deep in the quantum degenerate regime. Strong suppression is observed for probe volumes ...
Exact solutions of Einstein's equations with ideal gas sources
NASA Astrophysics Data System (ADS)
Sussman, R. A.; Triginer, J.
1999-01-01
We derive a new class of exact solutions characterized by the Szekeres-Szafron metrics (of class I), admitting in general no isometries. The source is a fluid with viscosity but zero heat flux (adiabatic but irreversible evolution) whose equilibrium state variables satisfy the equations of state of: (a) an ultra-relativistic ideal gas; (b) a non-relativistic ideal gas; (c) a mixture of (a) and (b). Einstein's field equations reduce to a quadrature that is integrable in terms of elementary functions (cases (a) and (c)) and elliptic integrals (case (b)). Necessary and sufficient conditions are provided for the viscous dissipative stress and equilibrium variables to be consistent with the theoretical framework of extended irreversible thermodynamics and kinetic theory of the Maxwell-Boltzmann and radiative gases. Energy and regularity conditions are discussed. We prove that a smooth matching can be performed along a spherical boundary with a Friedmann-Lemaître-Robertson-Walker (FLRW) cosmology or with a Vaidya exterior solution. Possible applications are briefly outlined.
Finite size effect on classical ideal gas revisited
NASA Astrophysics Data System (ADS)
Ghosh, P.; Ghosh, S.; Mitra, J.; Bera, N.
2015-09-01
Finite size effects on classical ideal gas are revisited. The micro-canonical partition function for a collection of ideal particles confined in a box is evaluated using Euler-Maclaurin’s as well as Poisson's summation formula. In Poisson's summation formula there are some exponential terms which are absent in Euler-Maclaurin’s formula. In the thermodynamic limit the exponential correction is negligibly small but in the macro/nano dimensions and at low temperatures they may have a great significance. The consequences of finite size effects have been illustrated by redoing the calculations in one and three dimensions keeping the exponential corrections. Global and local thermodynamic properties, diffusion driven by the finite size effect, and effect on speed of sound have been discussed. Thermo-size effects, similar to thermoelectric effects, have been described in detail and may be a theoretical basis with which to design nano-scaled devices. This paper can also be very helpful for undergraduate and graduate students in physics and chemistry as an instructive exercise for a good course in statistical mechanics.
Identifying and addressing student difficulties with the ideal gas law
NASA Astrophysics Data System (ADS)
Kautz, Christian Hans
This dissertation reports on an in-depth investigation of student understanding of the ideal gas law. The research and curriculum development were mostly conducted in the context of algebra- and calculus-based introductory physics courses and a sophomore-level thermal physics course. Research methods included individual demonstration interviews and written questions. Student difficulties with the quantities: pressure, volume, temperature, and the number of moles were identified. Data suggest that students' incorrect and incomplete microscopic models about gases contribute to the difficulties they have in answering questions posed in macroscopic terms. In addition, evidence for general reasoning difficulties is presented. These research results have guided the development of curriculum to address the student difficulties that have been identified.
Quantum arrival and dwell times via idealized clocks
Yearsley, J. M.; Downs, D. A.; Halliwell, J. J.; Hashagen, A. K.
2011-08-15
A number of approaches to the problem of defining arrival- and dwell-time probabilities in quantum theory makes use of idealized models of clocks. An interesting question is the extent to which the probabilities obtained in this way are related to standard semiclassical results. In this paper, we explore this question using a reasonably general clock model, solved using path-integral methods. We find that, in the weak-coupling regime, where the energy of the clock is much less than the energy of the particle it is measuring, the probability for the clock pointer can be expressed in terms of the probability current in the case of arrival times, and the dwell-time operator in the case of dwell times, the expected semiclassical results. In the regime of strong system-clock coupling, we find that the arrival-time probability is proportional to the kinetic-energy density, consistent with an earlier model involving a complex potential. We argue that, properly normalized, this may be the generically expected result in this regime. We show that these conclusions are largely independent of the form of the clock Hamiltonian.
Suppression of Density Fluctuations in a Quantum Degenerate Fermi Gas
Sanner, Christian; Su, Edward J.; Keshet, Aviv; Gommers, Ralf; Shin, Yong-il; Huang Wujie; Ketterle, Wolfgang
2010-07-23
We study density profiles of an ideal Fermi gas and observe Pauli suppression of density fluctuations (atom shot noise) for cold clouds deep in the quantum degenerate regime. Strong suppression is observed for probe volumes containing more than 10 000 atoms. Measuring the level of suppression provides sensitive thermometry at low temperatures. After this method of sensitive noise measurements has been validated with an ideal Fermi gas, it can now be applied to characterize phase transitions in strongly correlated many-body systems.
High School Forum. The Solution: "Derivation of the Ideal Gas Law."
ERIC Educational Resources Information Center
Herron, J. Dudley, Ed.
1980-01-01
Presents responses to an earlier report concerning a procedure for the derivation of the Ideal Gas Law from Charles', Boyle's, and other gas laws. Logic errors and solutions that work are discussed. (CS)
Ideal gas thermodynamic properties for the phenyl, phenoxy, and o-biphenyl radicals
NASA Technical Reports Server (NTRS)
Burcat, A.; Zeleznik, F. J.; Mcbride, B. J.
1985-01-01
Ideal gas thermodynamic properties of the phenyl and o-biphenyl radicals, their deuterated analogs and the phenoxy radical were calculated to 5000 K using estimated vibrational frequencies and structures. The ideal gas thermodynamic properties of benzene, biphenyl, their deuterated analogs and phenyl were also calculated.
Optimal performance of an irreversible quantum Brayton refrigerator with ideal Bose gases
NASA Astrophysics Data System (ADS)
Wu, Feng; Chen, Lingen; Sun, Fengrui; Wu, Chih; Guo, Fangzhong
2006-05-01
This paper presents a model of an irreversible quantum Brayton refrigerator (IQBR) using ideal Bose gases as working fluid. The optimal relationship between the dimensionless cooling rate and the coefficient of performance, and the optimization region (or criteria) for an IQBR is obtained. The effects of heat leakage, irreversibility in two adiabatic processes and the quantum characteristic of the working fluid are discussed.
PHYSICAL REVIEW A 87, 043629 (2013) Pauli paramagnetism of an ideal Fermi gas
2013-01-01
PHYSICAL REVIEW A 87, 043629 (2013) Pauli paramagnetism of an ideal Fermi gas Ye-Ryoung Lee,1 Tout T. Wang,1,2 Timur M. Rvachov,1 Jae-Hoon Choi,1 Wolfgang Ketterle,1 and Myoung-Sun Heo1,* 1 MIT, such as ideal, noninteracting gases that do not exist in nature. For example, several phenomena related to Pauli
Distance measures to compare real and ideal quantum processes
Alexei Gilchrist; Nathan K. Langford; Michael A. Nielsen
2009-01-27
With growing success in experimental implementations it is critical to identify a "gold standard" for quantum information processing, a single measure of distance that can be used to compare and contrast different experiments. We enumerate a set of criteria such a distance measure must satisfy to be both experimentally and theoretically meaningful. We then assess a wide range of possible measures against these criteria, before making a recommendation as to the best measures to use in characterizing quantum information processing.
Reynolds and Favre-averaged rapid distortion theory for compressible, ideal-gas turbulence
Lavin, Tucker Alan
2007-09-17
Compressible ideal-gas turbulence subjected to homogeneous shear is investigated at the rapid distortion limit. Specific issues addressed are (i) the interaction between kinetic and internal energies and role of pressure-dilatation; (ii...
40 CFR 1065.645 - Amount of water in an ideal gas.
Code of Federal Regulations, 2011 CFR
2011-07-01
...measure humidity as a relative humidity, RH %, determine the amount of water in an... = amount of water in an ideal gas. RH % = relative humidity. p H20...relative humidity measurement. Example: RH % = 50.77% p abs = 99.980...
40 CFR 1065.645 - Amount of water in an ideal gas.
Code of Federal Regulations, 2010 CFR
2010-07-01
...measure humidity as a relative humidity, RH %, determine the amount of water in an... = amount of water in an ideal gas. RH % = relative humidity. p H20...relative humidity measurement. Example: RH % = 50.77% p abs = 99.980...
40 CFR 1065.645 - Amount of water in an ideal gas.
Code of Federal Regulations, 2012 CFR
2012-07-01
...measure humidity as a relative humidity, RH %, determine the amount of water in an... = amount of water in an ideal gas. RH % = relative humidity. p H20...relative humidity measurement. Example: RH % = 50.77% p abs = 99.980...
40 CFR 1065.645 - Amount of water in an ideal gas.
Code of Federal Regulations, 2013 CFR
2013-07-01
...measure humidity as a relative humidity, RH %, determine the amount of water in an... = amount of water in an ideal gas. RH % = relative humidity. p H20...relative humidity measurement. Example: RH % = 50.77% p abs = 99.980...
Ideal quantum glass transitions: Many-body localization without quenched disorder
Schiulaz, M.; Müller, M.
2014-08-20
We explore the possibility for translationally invariant quantum many-body systems to undergo a dynamical glass transition, at which ergodicity and translational invariance break down spontaneously, driven entirely by quantum effects. In contrast to analogous classical systems, where the existence of such an ideal glass transition remains a controversial issue, a genuine phase transition is predicted in the quantum regime. This ideal quantum glass transition can be regarded as a many-body localization transition due to self-generated disorder. Despite their lack of thermalization, these disorder-free quantum glasses do not possess an extensive set of local conserved operators, unlike what is conjectured for many-body localized systems with strong quenched disorder.
Jump relations across a shock in non-ideal gas flow
Anand, R K
2012-01-01
Generalized forms of jump relations are obtained for one dimensional shock waves propagating in a non-ideal gas which reduce to Rankine-Hugoniot conditions for shocks in idea gas when non-idealness parameter becomes zero. The equation of state for non-ideal gas is considered as given by Landau and Lifshitz. The jump relations for pressure, density, temperature, particle velocity, and change in entropy across the shock are derived in terms of upstream Mach number. Finally, the useful forms of the shock jump relations for weak and strong shocks, respectively, are obtained in terms of the non-idealness parameter. It is observed that the shock waves may arise in flow of real fluids where upstream Mach number is less than unity.
A Unified Theory of Non-Ideal Gas Lattice Boltzmann Models
NASA Technical Reports Server (NTRS)
Luo, Li-Shi
1998-01-01
A non-ideal gas lattice Boltzmann model is directly derived, in an a priori fashion, from the Enskog equation for dense gases. The model is rigorously obtained by a systematic procedure to discretize the Enskog equation (in the presence of an external force) in both phase space and time. The lattice Boltzmann model derived here is thermodynamically consistent and is free of the defects which exist in previous lattice Boltzmann models for non-ideal gases. The existing lattice Boltzmann models for non-ideal gases are analyzed and compared with the model derived here.
WINDING-INVARIANT PRIME IDEALS IN QUANTUM 3 x 3 MATRICES
Bigelow, Stephen
WINDING-INVARIANT PRIME IDEALS IN QUANTUM 3 x 3. The result relies heavily on certa* *in tensor product decompositions for winding-invariant prime.1). There is a natural action of the torus H = (kx )n x (* *kx )n on A by winding automorphisms, which we recall in (1
A Quantum Gas Microscope for Ultracold Fermions
NASA Astrophysics Data System (ADS)
Cheuk, Lawrence; Nichols, Matthew; Okan, Melih; Lompe, Thomas; Zwierlein, Martin
2015-05-01
Ultracold atoms in optical lattices are ideal systems to study model quantum many-body physics in a clean and well-controlled environment. Experiments at Harvard and MPQ Munich using bosonic 87Rb atoms in optical lattices have demonstrated the ability to detect and address atoms at the single-site level, revealing microscopic density distributions and correlations difficult to extract from bulk measurements. The goal of our experiment is to achieve such single-site control for a quantum gas of fermions. This allows for exploring physics that arise in strongly-correlated fermionic systems. In this talk, we present results of site-resolved fluorescent imaging of fermionic 40K with high fidelity.
Suppression of Density Fluctuations in a Quantum Degenerate Fermi Gas
Sanner, Christian; Keshet, Aviv; Gommers, Ralf; Shin, Yong-il; Huang, Wujie; Ketterle, Wolfgang
2010-01-01
We study density profiles of an ideal Fermi gas and observe Pauli suppression of density fluctuations for cold clouds deep in the quantum degenerate regime. Strong suppression of shot noise was observed for probe volumes containing more than 10,000 atoms. Atom noise provides sensitive thermometry at low temperatures. The Poissonian noise of a hot cloud provides a direct and accurate calibration of the optical resolution and absorption cross section. After this method of sensitive noise measurements has been validated with an ideal Fermi gas, it can now be applied to characterize phase transitions in strongly correlated many-body systems.
Quantum degenerate dipolar Fermi gas.
Lu, Mingwu; Burdick, Nathaniel Q; Lev, Benjamin L
2012-05-25
We report the first quantum degenerate dipolar Fermi gas, the realization of which opens a new frontier for exploring strongly correlated physics and, in particular, quantum liquid crystalline phases. A quantum degenerate Fermi gas of the most magnetic atom 161Dy is produced by laser cooling to 10 ?K before sympathetically cooling with ultracold, bosonic 162Dy. The temperature of the spin-polarized 161Dy is a factor T/T(F)=0.2 below the Fermi temperature T(F)=300 nK. The cotrapped 162Dy concomitantly cools to approximately T(c) for Bose-Einstein condensation, thus realizing a novel, nearly quantum degenerate dipolar Bose-Fermi gas mixture. Additionally, we achieve the forced evaporative cooling of spin-polarized 161Dy without 162Dy to T/T(F)=0.7. That such a low temperature ratio is achieved may be a first signature of universal dipolar scattering. PMID:23003275
Statistical relativistic temperature transformation for ideal gas of bradyons, luxons and tachyons
Felipe Asenjo; Cristian A. Farías; Pablo S. Moya
2009-03-05
Starting from a microcanonical statistical approach and special relativity, the relativistic transformations for temperature and pressure for an ideal gas of bradyons, luxons or tachyons is found. These transformations are in agreement with the three laws of thermodynamic and our temperature transformation is the same as Ott's. Besides, it is shown that the thermodynamic $dS$ element is Lorentz-invariant.
How Incorrect Is the Classical Partition Function for the Ideal Gas?
ERIC Educational Resources Information Center
Kroemer, Herbert
1980-01-01
Discussed is the classical partition function for the ideal gas and how it differs from the exact value for bosons or fermions in the classical regime. The differences in the two values are negligible hence the classical treatment leads in the end to correct answers for all observables. (Author/DS)
Fluctuation theorem for entropy production during effusion of a relativistic ideal gas.
Cleuren, B; Willaert, K; Engel, A; Van den Broeck, C
2008-02-01
The probability distribution of the entropy production for the effusion of a relativistic ideal gas is calculated explicitly. This result is then extended to include particle and antiparticle pair production and annihilation. In both cases, the fluctuation theorem is verified. PMID:18352067
Cooking under Pressure: Applying the Ideal Gas Law in the Kitchen
ERIC Educational Resources Information Center
Chen, Ling; Anderson, Jennifer Y.; Wang, Diane R.
2010-01-01
This case study uses a daily cooking scenario to demonstrate how the boiling point of water is directly related to the external pressures in order to reinforce the concepts of boiling and boiling point, apply ideal gas law, and relate chemical reaction rates with temperatures. It also extends its teaching to autoclaves used to destroy…
40 CFR 1065.645 - Amount of water in an ideal gas.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Amount of water in an ideal gas. 1065.645 Section 1065.645 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.645 Amount of...
40 CFR 1065.645 - Amount of water in an ideal gas.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Amount of water in an ideal gas. 1065.645 Section 1065.645 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.645 Amount of...
Complete Quantum Thermodynamics of the Black Body Photon Gas
Pankovic, Vladan
2011-01-01
Kelly and Leff demonstrated and discussed formal and conceptual similarities between basic thermodynamic formulas for the classical ideal gas and black body photon gas. Leff pointed out that thermodynamic formulas for the photon gas cannot be deduced completely by thermodynamic methods since these formulas hold two characteristic parameters, {\\it r} and {\\it b}, whose accurate values can be obtained exclusively by accurate methods of the quantum statistics (by explicit use of the Planck's or Bose-Einstein distribution). In this work we prove that the complete quantum thermodynamics of the black body photon gas can be done by simple, thermodynamic (non-statistical) methods. We prove that both mentioned parameters and corresponding variables (photons number and pressure) can be obtained very simply and practically exactly (with relative error about few percent), by non-statistical (without any use of the Planck's or Bose-Einstein distribution), quantum thermodynamic methods. Corner-stone of these methods repres...
ERIC Educational Resources Information Center
Smith, Brent
2002-01-01
Describes equations of state as a supplement to an introductory thermodynamics undergraduate course. Uses rubber-elastic materials (REM) which have strong analogies to the concept of an ideal gas and explains the molar basis of REM. Provides examples of the analogies between ideal gas and REM and mathematical analogies. (Contains 22 references.)…
ERIC Educational Resources Information Center
Smith, Brent
2002-01-01
Describes the laws of thermodynamics as a supplement to an introductory thermodynamics undergraduate course. Uses rubber-elastic materials (REM) which have strong analogies to the concept of ideal gas. Provides examples of the analogies between ideal gas and REM and mathematical analogies. (YDS)
Boal, David
to the ideal gas law. Because it is more common to Chapter 6 - Periodic boundaries 78 Â©1997 by David BoalCHAPTER 6 - PERIODIC BOUNDARIES In considering an ideal gas, we didn't worry about whether our is the use of periodic boundaries, in which a given sample is surrounded by replicas of itself
NASA Astrophysics Data System (ADS)
Kreis, K.; Fogarty, A. C.; Kremer, K.; Potestio, R.
2015-09-01
In adaptive resolution simulations, molecular fluids are modeled employing different levels of resolution in different subregions of the system. When traveling from one region to the other, particles change their resolution on the fly. One of the main advantages of such approaches is the computational efficiency gained in the coarse-grained region. In this respect the best coarse-grained system to employ in the low resolution region would be the ideal gas, making intermolecular force calculations in the coarse-grained subdomain redundant. In this case, however, a smooth coupling is challenging due to the high energetic imbalance between typical liquids and a system of non-interacting particles. In the present work, we investigate this approach, using as a test case the most biologically relevant fluid, water. We demonstrate that a successful coupling of water to the ideal gas can be achieved with current adaptive resolution methods, and discuss the issues that remain to be addressed.
Characteristic decomposition of compressible Euler equations for a non-ideal gas in two-dimensions
NASA Astrophysics Data System (ADS)
Zafar, M.; Sharma, V. D.
2014-09-01
We consider a two-dimensional compressible Euler system for a non-ideal gas, and use the characteristic decomposition to establish that any pseudo-steady isentropic irrotational flow, adjacent to a constant state, must be a simple wave. Further, the constancy of the entropy and vorticity along the pseudo-flow characteristics extends the foregoing conclusion to full Euler system. An attention is drawn to the fact that the result is also applicable to the shallow water system as it bears a close structural resemblance with the system under study. These results are generalization of the well-known theorem on reducible equations by Courant and Friedrichs [Supersonic Flow and Shock Waves (Springer-Verlag, New York, 1999)] and a recent result on compressible Euler system for an ideal gas by Li et al. ["Simple waves and a characteristic decomposition of the two-dimensional compressible Euler equations," Commun. Math. Phys. 267, 1-12 (2006)
Complete Quantum Thermodynamics of the Black Body Photon Gas
Vladan Pankovic; Darko V. Kapor
2011-03-16
Kelly and Leff demonstrated and discussed formal and conceptual similarities between basic thermodynamic formulas for the classical ideal gas and black body photon gas. Leff pointed out that thermodynamic formulas for the photon gas cannot be deduced completely by thermodynamic methods since these formulas hold two characteristic parameters, {\\it r} and {\\it b}, whose accurate values can be obtained exclusively by accurate methods of the quantum statistics (by explicit use of the Planck's or Bose-Einstein distribution). In this work we prove that the complete quantum thermodynamics of the black body photon gas can be done by simple, thermodynamic (non-statistical) methods. We prove that both mentioned parameters and corresponding variables (photons number and pressure) can be obtained very simply and practically exactly (with relative error about few percent), by non-statistical (without any use of the Planck's or Bose-Einstein distribution), quantum thermodynamic methods. Corner-stone of these methods represents a quantum thermodynamic stability condition that is, in some degree, very similar to quantum stability condition in the Bohr quantum atomic theory (de Broglie's interpretation of the Bohr quantization postulate). Finally, we discuss conceptual similarities between black body photon gas entropy and Bekenstein-Hawking black hole entropy.
NASA Astrophysics Data System (ADS)
Shech, Elay
2015-09-01
This paper looks at the nature of idealizations and representational structures appealed to in the context of the fractional quantum Hall effect, specifically, with respect to the emergence of anyons and fractional statistics. Drawing on an analogy with the Aharonov-Bohm effect, it is suggested that the standard approach to the effects—(what we may call) the topological approach to fractional statistics—relies essentially on problematic idealizations that need to be revised in order for the theory to be explanatory. An alternative geometric approach is outlined and endorsed. Roles for idealizations in science, as well as consequences for the debate revolving around so-called essential idealizations, are discussed.
Ideal Negative Measurements in Quantum Walks Disprove Theories Based on Classical Trajectories
NASA Astrophysics Data System (ADS)
Robens, Carsten; Alt, Wolfgang; Meschede, Dieter; Emary, Clive; Alberti, Andrea
2015-01-01
We report on a stringent test of the nonclassicality of the motion of a massive quantum particle, which propagates on a discrete lattice. Measuring temporal correlations of the position of single atoms performing a quantum walk, we observe a 6 ? violation of the Leggett-Garg inequality. Our results rigorously excludes (i.e., falsifies) any explanation of quantum transport based on classical, well-defined trajectories. We use so-called ideal negative measurements—an essential requisite for any genuine Leggett-Garg test—to acquire information about the atom's position, yet avoiding any direct interaction with it. The interaction-free measurement is based on a novel atom transport system, which allows us to directly probe the absence rather than the presence of atoms at a chosen lattice site. Beyond the fundamental aspect of this test, we demonstrate the application of the Leggett-Garg correlation function as a witness of quantum superposition. Here, we employ the witness to discriminate different types of walks spanning from merely classical to wholly quantum dynamics.
Dynamics of the electric current in an ideal electron gas: A sound mode inside the quasiparticles
NASA Astrophysics Data System (ADS)
Grozdanov, Sašo; Polonyi, Janos
2015-09-01
We study the equation of motion for the Noether current in an electron gas within the framework of the Schwinger-Keldysh closed-time-path formalism. The equation is shown to be highly nonlinear and irreversible even for a noninteracting, ideal gas of electrons at nonzero density. We truncate the linearized equation of motion, written as the Laurent series in Fourier space, so that the resulting expressions are local in time, both at zero and at small finite temperatures. Furthermore, we show that the one-loop Coulomb interactions only alter the physical picture quantitatively, while preserving the characteristics of the dynamics that the electric current exhibits in the absence of interactions. As a result of the composite nature of the Noether current, composite sound waves are found to be the dominant IR collective excitations at length scales between the inverse Fermi momentum and the mean free path that would exist in an interacting electron gas. We also discuss the difference and the transition between the hydrodynamical regime of an ideal gas, defined in this work, and the hydrodynamical regime in phenomenological hydrodynamics, which is normally used for the description of interacting gases.
A Quantum Gas Microscope for Ultracold Fermions
NASA Astrophysics Data System (ADS)
Nichols, Matthew; Cheuk, Lawrence; Okan, Melih; Lompe, Thomas; Zwierlein, Martin
2015-05-01
In the past decade ultracold atoms in optical lattices have been established as an ideal model system to study quantum many body physics in a clean and well-controlled environment. Recently, experiments at Harvard and MPQ Munich using bosonic 87Rb atoms have made these systems even more powerful by demonstrating the ability to observe and address atoms in optical lattices with single-site resolution. The goal of our experiment is to achieve such single-site resolution for a quantum gas of fermionic atoms. Such local probing would reveal microscopic density or spin correlations which are difficult to extract from bulk measurements. This technique could for example be used to directly observe antiferromagnetic ordering in a fermionic Mott insulator. As the starting point for our experiments we cool fermionic potassium atoms with bosonic sodium as a sympathetic coolant. The atoms are then loaded into an optical lattice located seven microns below a solid immersion microscope for high-resolution imaging. In this poster we describe how we perform single-site resolved fluorescence imaging of 40K atoms in an optical lattice with high detection fidelity.
A complete theory for the magnetism of an ideal gas of electrons
Biswas, Shyamal; Jana, Debnarayan; Sen, Swati
2013-05-15
We have explored Pauli paramagnetism, Landau diamagnetism, and de Haas-van Alphen effect in a single framework, and unified these three effects for all temperatures as well as for all strengths of magnetic field. Our result goes beyond Pauli-Landau result on the magnetism of the 3-D ideal gas of electrons, and is able to describe crossover of the de Haas-van Alphen oscillation to the saturation of magnetization. We also have obtained a novel asymptotic series expansion for the low temperature properties of the system.
Gas-Kinetic Theory Based Flux Splitting Method for Ideal Magnetohydrodynamics
NASA Technical Reports Server (NTRS)
Xu, Kun
1998-01-01
A gas-kinetic solver is developed for the ideal magnetohydrodynamics (MHD) equations. The new scheme is based on the direct splitting of the flux function of the MHD equations with the inclusion of "particle" collisions in the transport process. Consequently, the artificial dissipation in the new scheme is much reduced in comparison with the MHD Flux Vector Splitting Scheme. At the same time, the new scheme is compared with the well-developed Roe-type MHD solver. It is concluded that the kinetic MHD scheme is more robust and efficient than the Roe- type method, and the accuracy is competitive. In this paper the general principle of splitting the macroscopic flux function based on the gas-kinetic theory is presented. The flux construction strategy may shed some light on the possible modification of AUSM- and CUSP-type schemes for the compressible Euler equations, as well as to the development of new schemes for a non-strictly hyperbolic system.
NASA Astrophysics Data System (ADS)
Kaehler, G.; Wagner, A. J.
2013-06-01
Current implementations of fluctuating ideal-gas descriptions with the lattice Boltzmann methods are based on a fluctuation dissipation theorem, which, while greatly simplifying the implementation, strictly holds only for zero mean velocity and small fluctuations. We show how to derive the fluctuation dissipation theorem for all k, which was done only for k=0 in previous derivations. The consistent derivation requires, in principle, locally velocity-dependent multirelaxation time transforms. Such an implementation is computationally prohibitively expensive but, with a small computational trick, it is feasible to reproduce the correct FDT without overhead in computation time. It is then shown that the previous standard implementations perform poorly for non vanishing mean velocity as indicated by violations of Galilean invariance of measured structure factors. Results obtained with the method introduced here show a significant reduction of the Galilean invariance violations.
Generic features of the wealth distribution in ideal-gas-like markets
P. K. Mohanty
2006-07-10
We provide an exact solution to the ideal-gas-like models studied in econophysics to understand the microscopic origin of Pareto-law. In these class of models the key ingredient necessary for having a self-organized scale-free steady-state distribution is the trading or collision rule where agents or particles save a definite fraction of their wealth or energy and invests the rest for trading. Using a Gibbs ensemble approach we could obtain the exact distribution of wealth in this model. Moreover we show that in this model (a) good savers are always rich and (b) every agent poor or rich invests the same amount for trading. Nonlinear trading rules could alter the generic scenario observed here.
Isobars of an ideal Bose gas within the grand canonical ensemble
NASA Astrophysics Data System (ADS)
Jeon, Imtak; Kim, Sang-Woo; Park, Jeong-Hyuck
2011-08-01
We investigate the isobar of an ideal Bose gas confined in a cubic box within the grand canonical ensemble for a large yet finite number of particles, N. After solving the equation of the spinodal curve, we derive precise formulas for the supercooling and the superheating temperatures that reveal an N-1/3 or N-1/4 power correction to the known Bose-Einstein condensation temperature in the thermodynamic limit. Numerical computations confirm the accuracy of our analytical approximation, and further show that the isobar zigzags on the temperature-volume plane if N?14393. In particular, for the Avogadro’s number of particles, the volume expands discretely about 105 times. Our results quantitatively agree with a previous study on the canonical ensemble within 0.1% error.
Isobars of an ideal Bose gas within the grand canonical ensemble
Jeon, Imtak; Park, Jeong-Hyuck; Kim, Sang-Woo
2011-08-15
We investigate the isobar of an ideal Bose gas confined in a cubic box within the grand canonical ensemble for a large yet finite number of particles, N. After solving the equation of the spinodal curve, we derive precise formulas for the supercooling and the superheating temperatures that reveal an N{sup -1/3} or N{sup -1/4} power correction to the known Bose-Einstein condensation temperature in the thermodynamic limit. Numerical computations confirm the accuracy of our analytical approximation, and further show that the isobar zigzags on the temperature-volume plane if N{>=}14 393. In particular, for the Avogadro's number of particles, the volume expands discretely about 10{sup 5} times. Our results quantitatively agree with a previous study on the canonical ensemble within 0.1% error.
Generic features of the wealth distribution in ideal-gas-like markets
NASA Astrophysics Data System (ADS)
Mohanty, P. K.
2006-07-01
We provide an exact solution to the ideal-gas-like models studied in econophysics to understand the microscopic origin of Pareto law. In these classes of models the key ingredient necessary for having a self-organized scale-free steady-state distribution is the trading or collision rule where agents or particles save a definite fraction of their wealth or energy and invest the rest for trading. Using a Gibbs ensemble approach we could obtain the exact distribution of wealth in this model. Moreover we show that in this model (a) good savers are always rich and (b) every agent poor or rich invests the same amount for trading. Nonlinear trading rules could alter the generic scenario observed here.
Boyd, Robert W.
Quantum noise properties of non-ideal optical amplifiers and attenuators This article has been properties of non-ideal optical amplifiers and attenuators Zhimin Shi1 , Ksenia Dolgaleva1,2 and Robert W 26 1817) of the noise properties of ideal linear amplifiers to include the possibility of non
ERIC Educational Resources Information Center
Leinonen, Risto; Asikainen, Mervi A.; Hirvonen, Pekka E.
2012-01-01
This study focuses on second-year university students' explanations and reasoning related to adiabatic compression of an ideal gas. The phenomenon was new to the students, but it was one which they should have been capable of explaining using their previous upper secondary school knowledge. The students' explanations and reasoning were…
Determination of ideal-gas enthalpies of formation for key compounds:
Steele, W.V.; Chirico, R.D.; Nguyen, A.; Hossenlopp, I.A.; Smith, N.K.
1991-10-01
The results of a study aimed at improvement of group-contribution methodology for estimation of thermodynamic properties of organic and organosilicon substances are reported. Specific weaknesses where particular group-contribution terms were unknown, or estimated because of lack of experimental data, are addressed by experimental studies of enthalpies of combustion in the condensed phase, vapor-pressure measurements, and differential scanning calorimetric (d.s.c.) heat-capacity measurements. Ideal-gas enthalpies of formation of ({plus minus})-butan-2-ol, tetradecan-1-ol, hexan-1,6-diol, methacrylamide, benzoyl formic acid, naphthalene-2,6-dicarboxylic acid dimethyl ester, and tetraethylsilane are reported. A crystalline-phase enthalpy of formation at 298.15 K was determined for naphthalene-2,6-dicarboxylic acid, which decomposed at 695 K before melting. The combustion calorimetry of tetraethylsilane used the proven fluorine-additivity methodology. Critical temperature and critical density were determined for tetraethylsilane with differential scanning calorimeter and the critical pressure was derived. Group-additivity parameters useful in the application of group- contribution correlations are derived. 112 refs., 13 figs., 19 tabs.
Quantum learning in a quantum lattice gas computer
NASA Astrophysics Data System (ADS)
Behrman, Elizabeth; Steck, James
2015-04-01
Quantum lattice gas is the logical generalization of quantum cellular automata. At low energy the dynamics are well described by the Gross-Pitaevskii equation in the mean field limit, which is an effective nonlinear interaction model of a Bose-Einstein condensate. In previous work, we have shown in simulation that both spatial and temporal models of quantum learning computers can be used to ``design'' non-trivial quantum algorithms. The advantages of quantum learning over the usual practice of using quantum gate building blocks are, first, the rapidity with which the problem can be solved, without having to decompose the problem; second, the fact that our technique can be used readily even when the problem, or the operator, is not well understood; and, third, that because the interactions are a natural part of the physical system, connectivity is automatic. The advantage to quantum learning obviously grows with the size and the complexity of the problem. We develop and present our learning algorithm as applied to the mean field lattice gas equation, and present a few preliminary results.
Quantum learning for a quantum lattice gas computer
NASA Astrophysics Data System (ADS)
Behrman, Elizabeth; Steck, James
2015-03-01
Quantum lattice gas is the logical generalization of quantum cellular automata. In low energy the dynamics are well described by the Gross-Pitaevskii equation in the mean field limit, which is an effective nonlinear interaction model of a Bose-Einstein condensate. In previous work, we have shown in simulation that both spatial and temporal models of quantum learning computers can be used to ``design'' non-trivial quantum algorithms. The advantages of quantum learning over the usual practice of using quantum gate building blocks are, first, the rapidity with which the problem can be solved, without having to decompose the problem; second, the fact that our technique can be used readily even when the problem, or the operator, is not well understood; and, third, that because the interactions are a natural part of the physical system, connectivity is automatic. The advantage to quantum learning obviously grows with the size and the complexity of the problem. We develop and present our learning algorithm as applied to the mean field lattice gas equation, and present a few preliminary results.
[Development and application of quantum cascade laser based gas sensing system].
Wen, Zhi-yu; Wang, Ling-fang; Chen, Gang
2010-08-01
Quantum cascade laser (QCL) is an ideal mid-infrared source for gas sensing in the wavelength range from 2.5 to 25 microm, due to its fast response, high sensitivity and selectivity for gas detecting. Prototypes of gas sensing system based on QCL have been developed by worldwide research groups. They have great potential in many applications, such as environment monitoring, space exploration, anti-terrorism and so on. The present paper gives a broad review of QCL gas sensing system, including the basic working principle, existing systems, and its application and future development. PMID:20939303
On the Equipartition of Kinetic Energy in an Ideal Gas Mixture
ERIC Educational Resources Information Center
Peliti, L.
2007-01-01
A refinement of an argument due to Maxwell for the equipartition of translational kinetic energy in a mixture of ideal gases with different masses is proposed. The argument is elementary, yet it may work as an illustration of the role of symmetry and independence postulates in kinetic theory. (Contains 1 figure.)
Dynamics of the electric current in an ideal electron gas: a sound mode inside the quasi-particles
Sašo Grozdanov; Janos Polonyi
2015-09-03
We study the equation of motion for the Noether current in an electron gas within the framework of the Schwinger-Keldysh Closed-Time-Path formalism. The equation is shown to be highly non-linear and irreversible even for a non-interacting, ideal gas of electrons at non-zero density. We truncate the linearised equation of motion, written as the Laurent series in Fourier space, so that the resulting expressions are local in time, both at zero and at small finite temperatures. Furthermore, we show that the one-loop Coulomb interactions only alter the physical picture quantitatively, while preserving the characteristics of the dynamics that the electric current exhibits in the absence of interactions. As a result of the composite nature of the Noether current, {\\it composite sound} waves are found to be the dominant IR collective excitations at length scales between the inverse Fermi momentum and the mean free path that would exist in an interacting electron gas. We also discuss the difference and the transition between the hydrodynamical regime of an ideal gas, defined in this work, and the hydrodynamical regime in phenomenological hydrodynamics, which is normally used for the description of interacting gases.
The Heat Capacity of Ideal Gases
ERIC Educational Resources Information Center
Scott, Robert L.
2006-01-01
The heat capacity of an ideal gas has been shown to be calculable directly by statistical mechanics if the energies of the quantum states are known. However, unless one makes careful calculations, it is not easy for a student to understand the qualitative results. Why there are maxima (and occasionally minima) in heat capacity-temperature curves…
Internal energy The internal (total) energy for an ideal gas is the total
Bertulani, Carlos A. - Department of Physics and Astronomy, Texas A&M University
Twater+mleadcleadTlead mwatercwater+mleadclead #12;10 Phase Change GAS(high T) liquid (medium T) Solid (low T)Q=cgasmT Q=cliquidmT Q=csolidmT Gas liquid liquid solid #12;11 Phase changeGas liquid When heat is added to a liquid, potential LIQUID TO GAS, THE KINETIC ENERGY DOES NOT CHANGE AND SO THE TEMPERATURE DOES NOT CHANGE. ALL ADDED HEAT
Mesoscopic Effects in Bose-Einstein Condensate Fluctuations of an Ideal Gas in a Box
Dorfman, Konstantin Evgenievich
2009-05-15
of BEC; however, they could be observed also above and below the critical temperature. Here I study the quantum and thermal fluctuations of the Bose-Einstein condensate (BEC) in a box with the periodic boundary conditions under a particle...
History dependent quantum random walks as quantum lattice gas automata
Shakeel, Asif E-mail: dmeyer@math.ucsd.edu Love, Peter J. E-mail: dmeyer@math.ucsd.edu; Meyer, David A. E-mail: dmeyer@math.ucsd.edu
2014-12-15
Quantum Random Walks (QRW) were first defined as one-particle sectors of Quantum Lattice Gas Automata (QLGA). Recently, they have been generalized to include history dependence, either on previous coin (internal, i.e., spin or velocity) states or on previous position states. These models have the goal of studying the transition to classicality, or more generally, changes in the performance of quantum walks in algorithmic applications. We show that several history dependent QRW can be identified as one-particle sectors of QLGA. This provides a unifying conceptual framework for these models in which the extra degrees of freedom required to store the history information arise naturally as geometrical degrees of freedom on the lattice.
Quantum noise of non-ideal Sagnac speed meter interferometer with asymmetries
NASA Astrophysics Data System (ADS)
Danilishin, S. L.; Gräf, C.; Leavey, S. S.; Hennig, J.; Houston, E. A.; Pascucci, D.; Steinlechner, S.; Wright, J.; Hild, S.
2015-04-01
The speed meter concept has been identified as a technique that can potentially provide laser-interferometric measurements at a sensitivity level which surpasses the standard quantum limit (SQL) over a broad frequency range. As with other sub-SQL measurement techniques, losses play a central role in speed meter interferometers and they ultimately determine the quantum noise limited sensitivity that can be achieved. So far in the literature, the quantum noise limited sensitivity has only been derived for lossless or lossy cases using certain approximations (for instance that the arm cavity round trip loss is small compared to the arm cavity mirror transmission). In this article we present a generalized, analytical treatment of losses in speed meters that allows accurate calculation of the quantum noise limited sensitivity of Sagnac speed meters with arm cavities. In addition, our analysis allows us to take into account potential imperfections in the interferometer such as an asymmetric beam splitter or differences of the reflectivities of the two arm cavity input mirrors. Finally, we use the examples of the proof-of-concept Sagnac speed meter currently under construction in Glasgow and a potential implementation of a Sagnac speed meter in the Einstein Telescope to illustrate how our findings affect Sagnac speed meters with metre- and kilometre-long baselines.
Towards a Quantum Gas Microscope for Ultracold Fermions
NASA Astrophysics Data System (ADS)
Nichols, Matthew; Cheuk, Lawrence; Okan, Melih; Ramasesh, Vinay; Bakr, Waseem; Lompe, Thomas; Zwierlein, Martin
2014-05-01
In the past decade ultracold atoms in optical lattices have been established as an ideal model system to study quantum many body physics in a clean and well-controlled environment. Recently, experiments at Harvard and MPQ Munich using bosonic 87Rb atoms have made these systems even more powerful by demonstrating the ability to observe and address atoms in optical lattices with single-site resolution. The goal of our experiment is to achieve such single-site resolution for a quantum gas of fermionic atoms. Such local probing would reveal microscopic density or spin correlations which are difficult to extract from bulk measurements. This technique could for example be used to directly observe antiferromagnetic ordering in a fermionic Mott insulator. As the starting point for our experiments we cool fermionic potassium atoms with bosonic sodium as a sympathetic coolant. The atoms are then magnetically transported to an optical trap located ten microns below a solid immersion microscope for high-resolution imaging. In this poster we give a description of our experimental setup and report on our progress towards performing single-site resolved fluorescence imaging of 40K atoms trapped in a deep optical lattice. Currently at University of California, Berkeley.
NASA Technical Reports Server (NTRS)
Hall, R. M.; Adcock, J. B.
1981-01-01
The real gas behavior of nitrogen, the gas normally used in transonic cryogenic tunnels, is reported for the following flow processes: isentropic expansion, normal shocks, boundary layers, and interactions between shock waves and boundary layers. The only difference in predicted pressure ratio between nitrogen and an ideal gas which may limit the minimum operating temperature of transonic cryogenic wind tunnels occur at total pressures approaching 9 atm and total temperatures 10 K below the corresponding saturation temperature. These pressure differences approach 1 percent for both isentropic expansions and normal shocks. Alternative cryogenic test gases were also analyzed. Differences between air and an ideal diatomic gas are similar in magnitude to those for nitrogen and should present no difficulty. However, differences for helium and hydrogen are over an order of magnitude greater than those for nitrogen or air. It is concluded that helium and cryogenic hydrogen would not approximate the compressible flow of an ideal diatomic gas.
Dynamics of a Massive Piston in an Ideal Gas: Oscillatory Motion and Approach to Equilibrium
Chernov, Nikolai
across the piston from the hot side to the cold side which are at equal pressure but different birthday Abstract We study numerically and theoretically (on a heuristic level) the time evolution of a gas questions remain. Not surprisingly the microscopic motion of the piston, and thus the time evolution
Dynamics of a Massive Piston in an Ideal Gas: Oscillatory Motion and Approach to Equilibrium
of energy transport across the piston from the hot side to the cold side which are at equal pressure but di birthday Abstract We study numerically and theoretically (on a heuristic level) the time evolution of a gas questions remain. Not surprisingly the microscopic motion of the piston, and thus the time evolution
First Law of Thermodynamics Two closed thermodynamic cycles for an ideal gas
Winokur, Michael
positive because W is negative and U = W + Q = 0 Demo:steam engine #12;2 A cylinder with initial volume V convertible has an eight-cylinder engine. At the beginning of its compression stroke, one of the cylinders.72 x 106 Pa. What is the final temperature of the gas in an engine cylinder after the compression
Approaching the ideal quantum key distribution with two-intensity decoy states
NASA Astrophysics Data System (ADS)
Zhang, Chun-Hui; Luo, Sun-Long; Guo, Guang-Can; Wang, Qin
2015-08-01
We present a scheme for the practical decoy-state quantum key distribution with heralded single-photon source. In this scheme, only two-intensity decoy states are employed. However, its performance can approach the asymptotic case of using infinite decoy states. We compare it with the standard three-intensity decoy-state method, and through numerical simulations, we demonstrate its significant improvement over the three-intensity method in both the final key rate and the secure transmission distance. Furthermore, when taking statistical fluctuations into account, a very high key generation rate can still be obtained even at a long transmission distance.
Thermodynamics and kinetics of binary nucleation in ideal-gas mixtures.
Alekseechkin, Nikolay V
2015-08-01
The nonisothermal single-component theory of droplet nucleation [N. V. Alekseechkin, Physica A 412, 186 (2014)] is extended to binary case; the droplet volume V, composition x, and temperature T are the variables of the theory. An approach based on macroscopic kinetics (in contrast to the standard microscopic model of nucleation operating with the probabilities of monomer attachment and detachment) is developed for the droplet evolution and results in the derived droplet motion equations in the space (V, x, T)—equations for V??dV/dt, ?, and ?. The work W(V, x, T) of the droplet formation is obtained in the vicinity of the saddle point as a quadratic form with diagonal matrix. Also, the problem of generalizing the single-component Kelvin equation for the equilibrium vapor pressure to binary case is solved; it is presented here as a problem of integrability of a Pfaffian equation. The equation for ? is shown to be the first law of thermodynamics for the droplet, which is a consequence of Onsager's reciprocal relations and the linked-fluxes concept. As an example of ideal solution for demonstrative numerical calculations, the o-xylene-m-xylene system is employed. Both nonisothermal and enrichment effects are shown to exist; the mean steady-state overheat of droplets and their mean steady-state enrichment are calculated with the help of the 3D distribution function. Some qualitative peculiarities of the nucleation thermodynamics and kinetics in the water-sulfuric acid system are considered in the model of regular solution. It is shown that there is a small kinetic parameter in the theory due to the small amount of the acid in the vapor and, as a consequence, the nucleation process is isothermal. PMID:26254656
Thermodynamics and kinetics of binary nucleation in ideal-gas mixtures
NASA Astrophysics Data System (ADS)
Alekseechkin, Nikolay V.
2015-08-01
The nonisothermal single-component theory of droplet nucleation [N. V. Alekseechkin, Physica A 412, 186 (2014)] is extended to binary case; the droplet volume V, composition x, and temperature T are the variables of the theory. An approach based on macroscopic kinetics (in contrast to the standard microscopic model of nucleation operating with the probabilities of monomer attachment and detachment) is developed for the droplet evolution and results in the derived droplet motion equations in the space (V, x, T)—equations for V ? ? d V / d t , x ? , and T ? . The work W(V, x, T) of the droplet formation is obtained in the vicinity of the saddle point as a quadratic form with diagonal matrix. Also, the problem of generalizing the single-component Kelvin equation for the equilibrium vapor pressure to binary case is solved; it is presented here as a problem of integrability of a Pfaffian equation. The equation for T ? is shown to be the first law of thermodynamics for the droplet, which is a consequence of Onsager's reciprocal relations and the linked-fluxes concept. As an example of ideal solution for demonstrative numerical calculations, the o-xylene-m-xylene system is employed. Both nonisothermal and enrichment effects are shown to exist; the mean steady-state overheat of droplets and their mean steady-state enrichment are calculated with the help of the 3D distribution function. Some qualitative peculiarities of the nucleation thermodynamics and kinetics in the water-sulfuric acid system are considered in the model of regular solution. It is shown that there is a small kinetic parameter in the theory due to the small amount of the acid in the vapor and, as a consequence, the nucleation process is isothermal.
Idealized gas turbine combustor for performance research and validation of large eddy simulations.
Williams, Timothy C; Schefer, Robert W; Oefelein, Joseph C; Shaddix, Christopher R
2007-03-01
This paper details the design of a premixed, swirl-stabilized combustor that was designed and built for the express purpose of obtaining validation-quality data for the development of large eddy simulations (LES) of gas turbine combustors. The combustor features nonambiguous boundary conditions, a geometrically simple design that retains the essential fluid dynamics and thermochemical processes that occur in actual gas turbine combustors, and unrestrictive access for laser and optical diagnostic measurements. After discussing the design detail, a preliminary investigation of the performance and operating envelope of the combustor is presented. With the combustor operating on premixed methane/air, both the equivalence ratio and the inlet velocity were systematically varied and the flame structure was recorded via digital photography. Interesting lean flame blowout and resonance characteristics were observed. In addition, the combustor exhibited a large region of stable, acoustically clean combustion that is suitable for preliminary validation of LES models. PMID:17411224
Anomalous Heat Conduction in a Di-atomic One-Dimensional Ideal Gas
Giulio Casati; Tomaz Prosen
2002-04-02
We provide firm convincing evidence that the energy transport in a one-dimensional gas of elastically colliding free particles of unequal masses is anomalous, i.e. the Fourier Law does not hold. Our conclusions are based on the analysis of the dependence of the heat current on the number of particles, of the internal temperature profile and on the Green-Kubo formalism.
Ideal-Modified Bosonic Gas Trapped in an Arbitrary Three Dimensional Power-Law Potential
E. Castellanos; C. Laemmerzahl
2012-10-22
We analyze the effects caused by an anomalous single-particle dispersion relation suggested in several quantum-gravity models, upon the thermodynamics of a Bose-Einstein condensate trapped in a generic 3-dimensional power-law potential. We prove that the shift in the condensation temperature, caused by a deformed dispersion relation, described as a non-trivial function of the number of particles and the shape associated to the corresponding trap, could provide bounds for the parameters associated to such deformation. Additionally, we calculate the fluctuations in the number of particles as a criterium of thermodynamic stability for these systems. We show that the apparent instability caused by the anomalous fluctuations in the thermodynamic limit can be suppressed considering the lowest energy associated to the system in question.
Quantum Phase Transition and Protected Ideal Transport in a Kondo Chain
NASA Astrophysics Data System (ADS)
Tsvelik, A. M.; Yevtushenko, O. M.
2015-11-01
We study the low energy physics of a Kondo chain where electrons from a one-dimensional band interact with magnetic moments via an anisotropic exchange interaction. It is demonstrated that the anisotropy gives rise to two different phases which are separated by a quantum phase transition. In the phase with easy plane anisotropy, Z2 symmetry between sectors with different helicity of the electrons is broken. As a result, localization effects are suppressed and the dc transport acquires (partial) symmetry protection. This effect is similar to the protection of the edge transport in time-reversal invariant topological insulators. The phase with easy axis anisotropy corresponds to the Tomonaga-Luttinger liquid with a pronounced spin-charge separation. The slow charge density wave modes have no protection against localization.
Quantum phase transition and protected ideal transport in a Kondo chain
Tsvelik, A. M.; Yevtushenko, O. M.
2015-11-30
We study the low energy physics of a Kondo chain where electrons from a one-dimensional band interact with magnetic moments via an anisotropic exchange interaction. It is demonstrated that the anisotropy gives rise to two different phases which are separated by a quantum phase transition. In the phase with easy plane anisotropy, Z2 symmetry between sectors with different helicity of the electrons is broken. As a result, localization effects are suppressed and the dc transport acquires (partial) symmetry protection. This effect is similar to the protection of the edge transport in time-reversal invariant topological insulators. The phase with easy axis anisotropy corresponds to the Tomonaga-Luttinger liquid with a pronounced spin-charge separation. The slow charge density wave modes have no protection against localizatioin.
Quantum phase transition and protected ideal transport in a Kondo chain
Tsvelik, A. M.; Yevtushenko, O. M.
2015-11-30
We study the low energy physics of a Kondo chain where electrons from a one-dimensional band interact with magnetic moments via an anisotropic exchange interaction. It is demonstrated that the anisotropy gives rise to two different phases which are separated by a quantum phase transition. In the phase with easy plane anisotropy, Z2 symmetry between sectors with different helicity of the electrons is broken. As a result, localization effects are suppressed and the dc transport acquires (partial) symmetry protection. This effect is similar to the protection of the edge transport in time-reversal invariant topological insulators. The phase with easy axismore »anisotropy corresponds to the Tomonaga-Luttinger liquid with a pronounced spin-charge separation. The slow charge density wave modes have no protection against localizatioin.« less
NASA Technical Reports Server (NTRS)
Lee, Jeffrey M.
1999-01-01
This study establishes a consistent set of differential equations for use in describing the steady secondary flows generated by periodic compression and expansion of an ideal gas in pulse tubes. Also considered is heat transfer between the gas and the tube wall of finite thickness. A small-amplitude series expansion solution in the inverse Strouhal number is proposed for the two-dimensional axisymmetric mass, momentum and energy equations. The anelastic approach applies when shock and acoustic energies are small compared with the energy needed to compress and expand the gas. An analytic solution to the ordered series is obtained in the strong temperature limit where the zeroth-order temperature is constant. The solution shows steady velocities increase linearly for small Valensi number and can be of order I for large Valensi number. A conversion of steady work flow to heat flow occurs whenever temperature, velocity or phase angle gradients are present. Steady enthalpy flow is reduced by heat transfer and is scaled by the Prandtl times Valensi numbers. Particle velocities from a smoke-wire experiment were compared with predictions for the basic and orifice pulse tube configurations. The theory accurately predicted the observed steady streaming.
Dynamics of the electric current in an ideal electron gas: a sound mode inside the quasi-particles
Grozdanov, Sašo
2015-01-01
We study the equation of motion for the Noether current in an electron gas within the framework of the Schwinger-Keldysh Closed-Time-Path formalism. The equation is shown to be highly non-linear and irreversible even for a non-interacting, ideal gas of electrons at non-zero density. We truncate the linearised equation of motion, written as the Laurent series in Fourier space, so that the resulting expressions are local in time, both at zero and at small finite temperatures. Furthermore, we show that the one-loop Coulomb interactions only alter the physical picture quantitatively, while preserving the characteristics of the dynamics that the electric current exhibits in the absence of interactions. As a result of the composite nature of the Noether current, composite sound waves are found to be the dominant IR collective excitations at length scales between the inverse Fermi momentum and the mean free path that would exist in an interacting electron gas. We also discuss the difference and the transition betwee...
Mechanics of liquid and gas, or mechanics of the inertless mass I. Ideal liquid
I. Z. Shkurchenko
2007-01-11
This monograph is a theoretical work. Its title shows that the theory states a novel view of the mechanical motion of liquids and gases to explain phenomena connected with mechanical motion of continuous medium. The second part of the monograph (II. Real liquids and gases) is placed in the same archive. It takes into account features of the real liquids and gases to give a practical direction for the theory. Both these parts are connected and have no practical meaning if separated. They were published in Russia in 2003 (after the death of the author) under the title "Mechanics of liquids and gas, or mechanics of the inertless mass (mechanics of media)" by the daughter of the author under her editing. This monograph is the last editing of the author's manuscript, which was made by the same editor in 2006. The editor plans to place two applied works of the author of the monograph in the same archive soon. The monograph contains information about both these manuscripts. The monograph is addressed to specialists in the field of theoretical and practical hydrodynamics and adjacent sciences.
Quantum-gas microscope for fermionic atoms.
Cheuk, Lawrence W; Nichols, Matthew A; Okan, Melih; Gersdorf, Thomas; Ramasesh, Vinay V; Bakr, Waseem S; Lompe, Thomas; Zwierlein, Martin W
2015-05-15
We realize a quantum-gas microscope for fermionic ^{40}K atoms trapped in an optical lattice, which allows one to probe strongly correlated fermions at the single-atom level. We combine 3D Raman sideband cooling with high-resolution optics to simultaneously cool and image individual atoms with single-lattice-site resolution at a detection fidelity above 95%. The imaging process leaves the atoms predominantly in the 3D motional ground state of their respective lattice sites, inviting the implementation of a Maxwell's demon to assemble low-entropy many-body states. Single-site-resolved imaging of fermions enables the direct observation of magnetic order, time-resolved measurements of the spread of particle correlations, and the detection of many-fermion entanglement. PMID:26024169
Quantum-Gas Microscope for Fermionic Atoms
NASA Astrophysics Data System (ADS)
Cheuk, Lawrence W.; Nichols, Matthew A.; Okan, Melih; Gersdorf, Thomas; Ramasesh, Vinay V.; Bakr, Waseem S.; Lompe, Thomas; Zwierlein, Martin W.
2015-05-01
We realize a quantum-gas microscope for fermionic 40K atoms trapped in an optical lattice, which allows one to probe strongly correlated fermions at the single-atom level. We combine 3D Raman sideband cooling with high-resolution optics to simultaneously cool and image individual atoms with single-lattice-site resolution at a detection fidelity above 95%. The imaging process leaves the atoms predominantly in the 3D motional ground state of their respective lattice sites, inviting the implementation of a Maxwell's demon to assemble low-entropy many-body states. Single-site-resolved imaging of fermions enables the direct observation of magnetic order, time-resolved measurements of the spread of particle correlations, and the detection of many-fermion entanglement.
Beau, Mathieu; Savoie, Baptiste
2014-05-15
In this paper, we rigorously investigate the reduced density matrix (RDM) associated to the ideal Bose gas in harmonic traps. We present a method based on a sum-decomposition of the RDM allowing to treat not only the isotropic trap, but also general anisotropic traps. When focusing on the isotropic trap, the method is analogous to the loop-gas approach developed by Mullin [“The loop-gas approach to Bose-Einstein condensation for trapped particles,” Am. J. Phys. 68(2), 120 (2000)]. Turning to the case of anisotropic traps, we examine the RDM for some anisotropic trap models corresponding to some quasi-1D and quasi-2D regimes. For such models, we bring out an additional contribution in the local density of particles which arises from the mesoscopic loops. The close connection with the occurrence of generalized-Bose-Einstein condensation is discussed. Our loop-gas-like approach provides relevant information which can help guide numerical investigations on highly anisotropic systems based on the Path Integral Monte Carlo method.
ERIC Educational Resources Information Center
Yu, Anne
2010-01-01
The gasometric analysis of nitrogen produced in a reaction between sodium nitrite, NaNO[superscript 2], and sulfamic acid, H(NH[superscript 2])SO[superscript 3], provides an alternative to more common general chemistry experiments used to study the ideal gas law, such as the experiment in which magnesium is reacted with hydrochloric acid. This…
NASA Astrophysics Data System (ADS)
Yang, Kesong; Nazir, Safdar; Behtash, Maziar
2015-03-01
The two-dimensional electron gas (2DEG) in LaAlO3/SrTiO3 perovskite-oxide heterostructure has attracted much attention because of its potential applications in nanoelectronic devices. A 2DEG has two landmark characters: strong charge confinement in the third dimension and high electron conductivity in two dimensions. In an ideal 2DEG system, electrons can move freely along the interface but are tightly confined in the c-axis that is perpendicular to the interface. Nevertheless, the actual electron gas in the SrTiO3-based perovskite heterostructures is extended a few nanometers along the c-axis into the SrTiO3 substrate, and thus they are also called as quasi-2DEG. Actually, it is a problem of both fundamental and practical interest to achieve an ideal 2DEG via enhancing the lateral quantum confinement effects. By using first-principles electronic structure calculations, herein we proposed two possible approaches to enhance the quantum charge confinement effects by confining the electron gas within one single atomic layer in the perovskite oxide heterostructure. This work is supported by start-up funds at the University of California, San Diego.
NASA Astrophysics Data System (ADS)
Lee, Jeffrey Marshall
1997-11-01
This study establishes a consistent set of differential equations for use in describing the steady secondary flows generated by periodic compression and expansion of an ideal gas in pulse tubes. A small amplitude series expansion solution in the inverse Strouhal number at the anelastic limit is proposed for the two-dimensional axisymmetric mass, momentum and energy equations. The anelastic approach applies when shock and acoustic energies are small compared to the energy needed to compress and expand the gas, such as for pulse tubes. Seven independent dimensionless numbers are used to scale the system. The reciprocal Strouhal number and Valensi number are used to linearize the mass and momentum equations. The Fourier number is used to characterize heat transfer within the tube wall. The Mach number, the Prandtl number, the velocity amplitude and the velocity phase angle at the tube ends complete the dimensionless scales. The ordered equations show that the zeroth-, first- and second-order equations, are coupled through the zeroth- order temperature. An analytic solution is obtained in the strong temperature limit where the zeroth-order temperature is constant. The solution shows that periodic heat transfer between the gas and tube, characterized by the complex Nusselt number, is independent of axial velocity boundary conditions and Fourier number. Steady velocities increase linearly for small Valensi number and can be of order 1 for large Valensi number. Decreasing heat transfer between the gas and the tube decreases steady velocities for orifice pulse tubes. The opposite is true for basic pulse tubes. A conversion of steady work flow to heat flow occurs whenever temperature, velocity or phase angle gradients are present. Steady enthalpy flow is reduced by heat transfer and is scaled by the Prandtl times Valensi numbers. Particle velocities from a smoke-wire experiment were compared to predictions for basic and orifice pulse tube configurations. The theory predicted the observed mass streaming and flow reversals between the centerline and diffusion layers. The results indicate that the theory is valid for pulse tubes and can be used to solve for the zeroth-order temperature, to compute enthalpy flows, and to determine losses associated with steady secondary streaming.
Field Theory of Anisotropic Quantum Hall Gas: Metrology and a Novel Quantum Hall Regime
K. Ishikawa; T. Aoyama; Y. Ishizuka; N. Maeda
2003-09-06
The von Neumann lattice representation is a convenient representation for studying several intriguing physics of quantum Hall systems. In this formalism, electrons are mapped to lattice fermions. A topological invariant expression of the Hall conductance is derived and is used for the proof of the integer quantum Hall effect in the realistic situation. Anisotropic quantum Hall gas is investigated based on the Hartree-Fock approximation in the same formalism. Thermodynamic properties, transport properties, and unusual response under external modulations are found. Implications for the integer quantum Hall effect in the finite systems are also studied and a new quantum Hall regime with non-zero longitudinal resistance is shown to exist.
Simulating an Interacting Quantum Gas with Superconducting Circuits
NASA Astrophysics Data System (ADS)
Eichler, Christopher; Mlynek, Jonas; Butscher, Jonas; Kurpiers, Philipp; Osborne, Tobias; Wallraff, Andreas
2015-03-01
The high level of control achievable over quantized degrees of freedom have turned superconducting circuits into one of the prime physical architectures for quantum computing and simulation. While conventional approaches towards quantum information processing mostly rely on unitary time evolution, more recently open-system dynamics are considered for quantum simulations. In this talk, I will present experiments in which we use an open cavity QED system with tunable interactions to simulate the ground state of an interacting Bose gas confined in one dimension. These experiments rely on the ability to efficiently measure higher order photon correlations of the cavity output field. For this purpose we have developed a quantum limited amplifier achieving phase-preserving amplification at large bandwidth and high dynamic range. Our results explore a different path towards the simulation of complex quantum many-body physics based on the controlled generation and detection of nonclassical radiation in an open quantum system.
Kheruntsyan, Karen
2012-01-01
) and ^ (r) are the bosonic creation and annihilation field operators, respectively, allow us to reformulate of quantum statistical mechanics [27] (for a comprehensive review, see Ref. [8]). The epithet catastrophe, Villetaneuse, France 4 Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, 1020 Vienna
Heraty, Kevin B; Laffey, John G; Quinlan, Nathan J
2008-11-01
The objective of this work is to develop understanding of the local fluid dynamic mechanisms that underpin gas exchange in high-frequency oscillatory ventilation (HFOV). The flow field during HFOV was investigated experimentally using particle image velocimetry in idealized and realistic models of a single bifurcation. Results show that inspiratory and expiratory fluid streams coexist in the airway at flow reversal, and mixing between them is enhanced by secondary flow and by vortices associated with shear layers. Unsteady flow separation and recirculation occurs in both geometries. The magnitude of secondary flow is greater in the realistic model than in the idealized model, and the structure of secondary flow is quite different. However, other flow structures are qualitatively similar. PMID:18785010
Quantum chemical studies of trace gas adsorption on ice nanoparticles
NASA Astrophysics Data System (ADS)
Schrems, Otto; Ignatov, Stanislav K.; Gadzhiev, Oleg B.; Masunov, Artem E.
2013-04-01
We have investigated the interaction of atmospheric trace gases with crystalline water ice particles of nanoscale size by modern quantum chemical methods. Small ice particles which can be formed in different altitudes play an important role in chemistry and physics of the Earth atmosphere. Knowledge about the uptake and incorporation of atmospheric trace gases in ice particles as well as their interactions with water molecules is very important for the understanding of processes at the air/ice interface. The interaction of the atmospheric trace gases with atmospheric ice nanoparticles is also an important issue for the development of modern physicochemical models. Usually, the interactions between trace gases and small particles considered theoretically apply small-size model complexes or the surface models representing only fragments of the ideal surface. Ice particles consisting of 48, 72, 216 and 270 water molecules with a distorted structure of hexagonal water ice Ih were studied using the new SCC-DFTBA method combining well the advantages of the DFT theory and semiempirical methods of quantum chemistry. The largest clusters correspond to the minimal nanoparticle size which are considered to be crystalline as determined experimentally. The clusters up to (H2O)72 were studied at the B3LYP/6-31++G(d,p) and B3LYP/6-311++G(2d,2p) levels. The larger clusters were studied using DFTBA and DFTB+ methods. Several adsorption complexes for the (H2O)270 water ice cluster were optimized at the RI-BLYP/6-31+G(d) theory level to verify the DFTB+ results. Trace gas molecules were coordinated on different sites of the nanoparticles corresponding to different ice Ih crystal planes: (0001), (10-10), (11-20). As atmospheric trace gases we have chosen CO, CO2, HCO*, HCOH*, HCHO, HCOOH and (HCO)2. which are the possible products and intermediates of the UV photolysis of organic molecules such as HCHCHO adsorbed on the ice surface. The structures of the corresponding coordination complexes, their vibrational frequencies, their adsorption energies and thermodynamic parameters (the enthalpy and the Gibbs free energy of adsorption) were evaluated using the full optimization followed by the frequency calculations. Additionally, the different modes of incorporation of trace gas molecules into the ice particles were considered and the corresponding structural and energetic parameters were evaluated. The transition states for the possible hydration were located and the influence of the water cluster surrounding on the barrier heights was studied as well. Acknowledgements: Financial support by the Russian Foundation for basic Research, project No. 11-03-00085 and German Academic Exchange Service (DAAD) within the Eastpartnership program is greatly acknowledged. O.B.G. and A.E.M. are grateful to DOE NERSC, I2lab, and Institute for Simulation and Training (IST) for making computer time available.
Quantum memory in warm rubidium vapor with buffer gas
Mark Bashkansky; Fredrik K. Fatemi; Igor Vurgaftman
2011-12-02
The realization of quantum memory using warm atomic vapor cells is appealing because of their commercial availability and the perceived reduction in experimental complexity. In spite of the ambiguous results reported in the literature, we demonstrate that quantum memory can be implemented in a single cell with buffer gas using the geometry where the write and read beams are nearly co-propagating. The emitted Stokes and anti-Stokes photons display cross-correlation values greater than 2, characteristic of quantum states, for delay times up to 4 microseconds.
Ideal clocks - a convenient fiction
Krzysztof Lorek; Jorma Louko; Andrzej Dragan
2015-08-24
We show that no device built according to the rules of quantum field theory can measure proper time along its path. Highly accelerated quantum clocks experience the Unruh effect, which inevitably influences their time rate. This contradicts the concept of an ideal clock, whose rate should only depend on the instantaneous velocity.
Quantum Dew Formation of quantum liquid in a nonequilibrium Bose gas
Khlebnikov, S Yu
2000-01-01
We consider phase separation in nonequilibrium Bose gas with an attractive interaction between the particles. Using numerical integrations on a lattice, we show that the system evolves into a state that contains drops of Bose-Einstein condensate suspended in uncondensed gas. When the initial gas is sufficiently rarefied, the rate of formation of this quantum dew scales with the initial density as expected for a process governed by two-particle collisions.
Quantum dew: Formation of quantum liquid in a nonequilibrium Bose gas
Khlebnikov, S.; Tkachev, I.; TH Division, CERN, CH-1211 Geneva 23, Switzerland,; Institute for Nuclear Research, Russian Academy of Sciences, Moscow 117312, Russia
2000-04-15
We consider phase separation in a nonequilibrium Bose gas with an attractive interaction between particles. Using numerical integrations on a lattice, we show that the system evolves into a state that contains drops of a Bose-Einstein condensate suspended in uncondensed gas. When the initial gas is sufficiently rarefied, the rate of formation of this quantum dew scales with the initial density as expected for a process governed by two-particle collisions. (c) 2000 The American Physical Society.
Quantum dew: Formation of quantum liquid in a nonequilibrium Bose gas
NASA Astrophysics Data System (ADS)
Khlebnikov, S.; Tkachev, I.
2000-04-01
We consider phase separation in a nonequilibrium Bose gas with an attractive interaction between particles. Using numerical integrations on a lattice, we show that the system evolves into a state that contains drops of a Bose-Einstein condensate suspended in uncondensed gas. When the initial gas is sufficiently rarefied, the rate of formation of this quantum dew scales with the initial density as expected for a process governed by two-particle collisions.
NASA Astrophysics Data System (ADS)
Wang, Jianhui; Zhuang, Bo; He, Jizhou
2013-01-01
Within an exact canonical-ensemble treatment, we investigate the thermodynamics for a finite number of ideal bosons confined in a three-dimensional quartic trap. We calculate several physical quantities including the specific heat C N , chemical potential ?, condensate fraction < n 0>/ N, root-mean-square fluctuations ?n 0 of the condensate population, and transition temperature T c . We discuss the particle-number dependence of T c through proposing three T c definitions, which are compared with ones derived in the grand canonical ensemble.
Quantum pump effect induced by a linearly polarized microwave in a two-dimensional electron gas.
Song, Juntao; Liu, Haiwen; Jiang, Hua
2012-05-30
A quantum pump effect is predicted in an ideal homogeneous two-dimensional electron gas (2DEG) that is normally irradiated by linearly polarized microwaves (MW). Without considering effects from spin-orbital coupling or the magnetic field, it is found that a polarized MW can continuously pump electrons from the longitudinal to the transverse direction, or from the transverse to the longitudinal direction, in the central irradiated region. The large pump current is obtained for both the low frequency limit and the high frequency case. Its magnitude depends on sample properties such as the size of the radiated region, the power and frequency of the MW, etc. Through the calculated results, the pump current should be attributed to the dominant photon-assisted tunneling processes as well as the asymmetry of the electron density of states with respect to the Fermi energy. PMID:22575800
A Non-destructive Quantum Gas Microscope for Fermions
NASA Astrophysics Data System (ADS)
Patil, Yogesh; Chakram, Srivatsan; Vengalattore, Mukund
2014-05-01
We have demonstrated a two photon fluorescence imaging technique which allows in situ imaging of a lattice gas of Rb atoms. We report progress on extending this technique to fermionic species, in our case, 6 Li . In contrast to demonstrated means of quantum gas microscopy using molasses cooling, our scheme is not restricted to atomic species amenable to polarization gradient cooling. Furthermore, our imaging scheme is nondestructive in the limit of zero duty cycle of using the Raman transition for imaging and cooling. This presents new opportunities for non-equilibrium many-body studies involving the continuous measurement of system dynamics, measurement based many-body control of the lattice gas and quantum zeno physics. We also describe progress towards augmenting our current system with single site resolution imaging. This work was supported by the NSF and DARPA QuASAR program through a grant from the ARO.
Knapp, Julia L A; Osenbrück, Karsten; Cirpka, Olaf A
2015-10-15
Estimating respiration and photosynthesis rates in streams usually requires good knowledge of reaeration at the given locations. For this purpose, gas-tracer tests can be conducted, and reaeration rate coefficients are determined from the decrease in gas concentration along the river stretch. The typical procedure for analysis of such tests is based on simplifying assumptions, as it neglects dispersion altogether and does not consider possible fluctuations and trends in the input signal. We mathematically derive the influence of these non-idealities on estimated reaeration rates and how they are propagated onto the evaluation of aerobic respiration and photosynthesis rates from oxygen monitoring. We apply the approach to field data obtained from a gas-tracer test using propane in a second-order stream in Southwest Germany. We calculate the reaeration rate coefficients accounting for dispersion as well as trends and uncertainty in the input signals and compare them to the standard approach. We show that neglecting dispersion significantly underestimates reaeration, and results between sections cannot be compared if trends in the input signal of the gas tracer are disregarded. Using time series of dissolved oxygen and the various estimates of reaeration, we infer respiration and photosynthesis rates for the same stream section, demonstrating that the bias and uncertainty of reaeration using the different approaches significantly affects the calculation of metabolic rates. PMID:26150069
Carlisle, TK; Wiesenauer, EF; Nicodemus, GD; Gin, DL; Noble, RD
2013-01-23
Six vinyl-based, imidazolium room-temperature ionic liquid (RTIL) monomers were synthesized and photopolymerized to form dense poly(RTIL) membranes. The effect of polymer backbone (i.e., poly(ethylene), poly(styrene), and poly(acrylate)) and functional cationic substituent (e.g., alkyl, fluoroalkyl, oligo(ethylene glycol), and disiloxane) on ideal CO2/N-2 and CO2/CH4 membrane separation performance was investigated. The vinyl-based poly(RTIL)s were found to be generally less CO2-selective compared to analogous styrene- and acrylate-based poly(RTIL)s. The CO2 permeability of n-hexyl-(69 barrers) and disiloxane- (130 barrers) substituted vinyl-based poly(RTIL)s were found to be exceptionally larger than that of previously studied styrene and acrylate poly(RTIL)s. The CO2 selectivity of oligo(ethylene glycol)-functionalized vinyl poly(RTIL)s was enhanced, and the CO2 permeability was reduced when compared to the n-hexyl-substituted vinyl-based poly(RTIL). Nominal improvement in CO2/CH4 selectivity was observed upon fluorination of the n-hexyl vinyl-based poly(RTIL), with no observed change in CO2 permeability. However, rather dramatic improvements in both CO2 permeability and selectivity were observed upon blending 20 mol % RTIL (emim Tf2N) into the n-hexyl- and disiloxane-functionalized vinyl poly(RTIL)s to form solid liquid composite films.
Shortcut to Adiabaticity for an Anisotropic Gas Containing Quantum Defects.
Papoular, D J; Stringari, S
2015-07-10
We present a shortcut to adiabaticity (STA) protocol applicable to 3D unitary Fermi gases and 2D weakly interacting Bose gases containing defects such as vortices or solitons. Our protocol relies on a new class of exact scaling solutions in the presence of anisotropic time-dependent harmonic traps. It connects stationary states in initial and final traps having the same frequency ratios. The resulting scaling laws exhibit a universal form and also apply to the classical Boltzmann gas. The duration of the STA can be made very short so as to realize a quantum quench from one stationary state to another. When applied to an anisotropically trapped superfluid gas, the STA conserves the shape of the quantum defects hosted by the cloud, thereby acting like a perfect microscope, which sharply contrasts with their strong distortion occurring during the free expansion of the cloud. PMID:26207476
Dual-wavelength quantum cascade laser for trace gas spectroscopy
Jágerská, J.; Tuzson, B.; Mangold, M.; Emmenegger, L.; Jouy, P.; Hugi, A.; Beck, M.; Faist, J.; Looser, H.
2014-10-20
We demonstrate a sequentially operating dual-wavelength quantum cascade laser with electrically separated laser sections, emitting single-mode at 5.25 and 6.25??m. Based on a single waveguide ridge, this laser represents a considerable asset to optical sensing and trace gas spectroscopy, as it allows probing multiple gas species with spectrally distant absorption features using conventional optical setups without any beam combining optics. The laser capability was demonstrated in simultaneous NO and NO{sub 2} detection, reaching sub-ppb detection limits and selectivity comparable to conventional high-end spectroscopic systems.
Interacting modified Chaplygin gas in loop quantum cosmology
Mubasher Jamil; Ujjal Debnath
2011-02-14
We investigate the background dynamics when dark energy is coupled to dark matter in the universe described by loop quantum cosmology. We consider dark energy of the form modified Chaplygin gas. The dynamical system of equations is solved numerically and a stable scaling solution is obtained. It henceforth resolves the famous cosmic coincidence problem in modern cosmology. The statefinder parameters are also calculated to classify this dark energy model.
NASA Astrophysics Data System (ADS)
Tarasov, S. V.; Kocharovsky, Vl. V.; Kocharovsky, V. V.
2015-11-01
We find a self-similar analytical solution for the grand-canonical-ensemble (GCE) statistics and thermodynamics in the critical region of Bose-Einstein condensation. It is valid for an arbitrary trap, loaded with an ideal gas, in the thermodynamic limit. We show that for the quantities, changing by a finite amount across the critical region, the exact GCE result differs from the corresponding canonical-ensemble result by a factor on the order of unity even in the thermodynamic limit. Thus, a widely used GCE approach does not describe correctly the critical phenomena at the phase transition for the actual systems with a fixed number of particles and yields only an asymptotics far outside the critical region.
Ravi Samtaney
2009-02-10
We present a numerical method to solve the linear stability of impulsively accelerated density interfaces in two dimensions such as those arising in the Richtmyer-Meshkov instability. The method uses an Eulerian approach, and is based on an unwind method to compute the temporally evolving base state and a flux vector splitting method for the perturbations. The method is applicable to either gas dynamics or magnetohydrodynamics. Numerical examples are presented for cases in which a hydrodynamic shock interacts with a single or double density interface, and a doubly shocked single density interface. Convergence tests show that the method is spatially second order accurate for smooth flows, and between first and second order accurate for flows with shocks.
External cavity tunable quantum cascade lasers and their applications to trace gas monitoring.
Rao, Gottipaty N; Karpf, Andreas
2011-02-01
Since the first quantum cascade laser (QCL) was demonstrated approximately 16 years ago, we have witnessed an explosion of interesting developments in QCL technology and QCL-based trace gas sensors. QCLs operate in the mid-IR region (3-24??m) and can directly access the rotational vibrational bands of most molecular species and, therefore, are ideally suited for trace gas detection with high specificity and sensitivity. These sensors have applications in a wide range of fields, including environmental monitoring, atmospheric chemistry, medical diagnostics, homeland security, detection of explosive compounds, and industrial process control, to name a few. Tunable external cavity (EC)-QCLs in particular offer narrow linewidths, wide ranges of tunability, and stable power outputs, which open up new possibilities for sensor development. These features allow for the simultaneous detection of multiple species and the study of large molecules, free radicals, ions, and reaction kinetics. In this article, we review the current status of EC-QCLs and sensor developments based on them and speculate on possible future developments. PMID:21283214
Ultrastable, Zerodur-based optical benches for quantum gas experiments.
Duncker, Hannes; Hellmig, Ortwin; Wenzlawski, André; Grote, Alexander; Rafipoor, Amir Jones; Rafipoor, Mona; Sengstock, Klaus; Windpassinger, Patrick
2014-07-10
Operating ultracold quantum gas experiments outside of a laboratory environment has so far been a challenging goal, largely due to the lack of sufficiently stable optical systems. In order to increase the thermal stability of free-space laser systems, the application of nonstandard materials such as glass ceramics is required. Here, we report on Zerodur-based optical systems which include single-mode fiber couplers consisting of multiple components jointed by light-curing adhesives. The thermal stability is thoroughly investigated, revealing excellent fiber-coupling efficiencies between 0.85 and 0.92 in the temperature range from 17°C to 36°C. In conjunction with successfully performed vibration tests, these findings qualify our highly compact systems for atom interferometry experiments aboard a sounding rocket as well as various other quantum information and sensing applications. PMID:25090066
A quantum-gas microscope for fermionic potassium
NASA Astrophysics Data System (ADS)
Cotta, Dylan; Hudson, James; Kelly, Andrew; Peaudecerf, Bruno; Haller, Elmar; Kuhr, Stefan; Single-atom imaging Team
2015-05-01
Recent experiments with single-site resolution and addressing of strongly correlated rubidium atoms in optical lattices have resulted in the direct observation of, e.g., bosonic Mott insulators, and out-of-equilibrium physics. Here we present a quantum-gas microscope for single-atom-resolved fluorescence detection of fermionic 40K. The atoms are held in a single layer of a 1064 nm optical lattice and observed by a high-resolution optical microscope with numerical aperture NA = 0.68. This setup will enable quantum simulation of the Fermi-Hubbard model with single-particle access, allowing for the direct observation and characterization of, e.g., fermionic Mott insulators, Band insulators, metallic phases or Néel antiferromagnets.
NASA Astrophysics Data System (ADS)
Mehedi Faruk, Mir
2015-09-01
The average energy per fermion in the case of a Fermi gas with any kinematic characteristic, trapped under the most general power law potential in d-dimension has been calculated at zero temperature. In a previous paper (Acharyya M 2010 Eur. J Phys. 31 L89) it was shown, in the case of a free ideal Fermi gas, as the dimension increases the average energy approaches the Fermi energy and in infinite dimension the average energy becomes equal to the Fermi energy at T = 0. In this letter it is shown that, for a trapped system at finite dimension the average energy depends on a power law exponent, but as the dimension tends to infinity the average energy coincides with the Fermi energy for any power law exponent. The result obtained in this manuscript is more general, as we can describe the free system as well as any trapped system with an appropriate choice of power law exponent, and is true for any kinematic parameter.
NASA Astrophysics Data System (ADS)
Klein, R.
2015-09-01
Kreis et al. (Eur. Phys. J. Special Topics, this issue, 2015, doi: 10.1140/epjst/e2015-02412-1) discuss the option of minimizing the complexity of the coarse-grained model in adaptive resolution molecular dynamics simulations (AdResS) by adopting a collisionless ideal gas model for this purpose. Here we discuss the technical detail of how an ideal gas model is implemented, the effective role in the simulation that is left to the coarse-grained model when it is drastically simplified as suggested, and relations between the force and potential interpolations adopted in different variants of AdResS.
Quintessence and (anti-)Chaplygin gas in loop quantum cosmology
Lamon, Raphael; Woehr, Andreas J.
2010-01-15
The concordance model of cosmology contains several unknown components such as dark matter and dark energy. Many proposals have been made to describe them by choosing an appropriate potential for a scalar field. We study four models in the realm of loop quantum cosmology: the Chaplygin gas, an inflationary and radiationlike potential, quintessence and an anti-Chaplygin gas. For the latter we show that all trajectories start and end with a type II singularity and, depending on the initial value, may go through a bounce. On the other hand the evolution under the influence of the first three scalar fields behaves classically at times far away from the big bang singularity and bounces as the energy density approaches the critical density.
Prime ideals in quantum algebras
Russell, Ewan
The central objects of study in this thesis are quantized coordinate algebras. These algebras originated in the 1980s in the work of Drinfeld and Jumbo and are noncommutative analogues of coordinate rings of algebraic ...
Cyclotron resonance photoconductivity of a two-dimensional electron gas in HgTe quantum wells
Ganichev, Sergey
Cyclotron resonance photoconductivity of a two-dimensional electron gas in HgTe quantum wells Ze-infrared cyclotron resonance photoconductivity (CRP) is investigated in HgTe quantum wells (QWs) of various widths that the transport time substantially exceeds the cyclotron resonance lifetime as well as the quantum lifetime which
Probing a quantum gas with single Rydberg atoms
Nguyen, Huan; Schlagmüller, Michael; Lochead, Graham; Westphal, Karl M; Löw, Robert; Hofferberth, Sebastian; Pfau, Tilman
2015-01-01
We present a novel spectroscopic method for probing the \\insitu~density of quantum gases. We exploit the density-dependent energy shift of highly excited {Rydberg} states, which is of the order $10$\\MHz\\,/\\,1E14\\,cm$^{\\text{-3}}$ for \\rubidium~for triplet s-wave scattering. The energy shift combined with a density gradient can be used to localize Rydberg atoms in density shells with a spatial resolution less than optical wavelengths, as demonstrated by scanning the excitation laser spatially across the density distribution. We use this Rydberg spectroscopy to measure the mean density addressed by the Rydberg excitation lasers, and to monitor the phase transition from a thermal gas to a Bose-Einstein condensate (BEC).
Quantum holographic encoding in a two-dimensional electron gas
Moon, Christopher
2010-05-26
The advent of bottom-up atomic manipulation heralded a new horizon for attainable information density, as it allowed a bit of information to be represented by a single atom. The discrete spacing between atoms in condensed matter has thus set a rigid limit on the maximum possible information density. While modern technologies are still far from this scale, all theoretical downscaling of devices terminates at this spatial limit. Here, however, we break this barrier with electronic quantum encoding scaled to subatomic densities. We use atomic manipulation to first construct open nanostructures - 'molecular holograms' - which in turn concentrate information into a medium free of lattice constraints: the quantum states of a two-dimensional degenerate Fermi gas of electrons. The information embedded in the holograms is transcoded at even smaller length scales into an atomically uniform area of a copper surface, where it is densely projected into both two spatial degrees of freedom and a third holographic dimension mapped to energy. In analogy to optical volume holography, this requires precise amplitude and phase engineering of electron wavefunctions to assemble pages of information volumetrically. This data is read out by mapping the energy-resolved electron density of states with a scanning tunnelling microscope. As the projection and readout are both extremely near-field, and because we use native quantum states rather than an external beam, we are not limited by lensing or collimation and can create electronically projected objects with features as small as {approx}0.3 nm. These techniques reach unprecedented densities exceeding 20 bits/nm{sup 2} and place tens of bits into a single fermionic state.
NASA Technical Reports Server (NTRS)
Frazier, D. O.; Hung, R. J.; Paley, M. S.; Penn, B. G.; Long, Y. T.
1996-01-01
A mathematical model has been developed to determine heat transfer during vapor deposition of source materials under a variety of orientations relative to gravitational accelerations. The model demonstrates that convection can occur at total pressures as low as 10-2 mm Hg. Through numerical computation, using physical material parameters of air, a series of time steps demonstrates the development of flow and temperature profiles during the course of vapor deposition. These computations show that in unit gravity vapor deposition occurs by transport through a fairly complicated circulating flow pattern when applying heat to the bottom of the vessel with parallel orientation with respect to the gravity vector. The model material parameters for air predict the effect of kinematic viscosity to be of the same order as thermal diffusivity, which is the case for Prandtl number approx. 1 fluids. Qualitative agreement between experiment and the model indicates that 6-(2-methyl-4-nitroanilino)-2,4-hexadiyn-l-ol (DAMNA) at these pressures indeed approximates an ideal gas at the experiment temperatures, and may validate the use of air physical constants. It is apparent that complicated nonuniform temperature distribution in the vapor could dramatically affect the homogeneity, orientation, and quality of deposited films. The experimental test i's a qualitative comparison of film thickness using ultraviolet-visible spectroscopy on films generated in appropriately oriented vapor deposition cells. In the case where heating of the reaction vessel occurs from the top, deposition of vapor does not normally occur by convection due to a stable stratified medium. When vapor deposition occurs in vessels heated at the bottom, but oriented relative to the gravity vector between these two extremes, horizontal thermal gradients induce a complex flow pattern. In the plane parallel to the tilt axis, the flow pattern is symmetrical and opposite in direction from that where the vessel is positioned vertically. The ground-based experiments are sufficient preliminary tests of theory and should be of significant interest regarding vapor deposited films in microgravity.
Teaching the photon gas in introductory physics Harvey S. Leffa)
Teaching the photon gas in introductory physics Harvey S. Leffa) Department of Physics, California characteris- tics. First, it is based on classical physics or the semiclassical limit of a quantum ideal gas, and hence does not provide insights on quantum or relativistic phenomena. Second, the internal energy
Ideal clocks—a convenient fiction
NASA Astrophysics Data System (ADS)
Lorek, Krzysztof; Louko, Jorma; Dragan, Andrzej
2015-09-01
We show that no device built according to the rules of quantum field theory can measure proper time along its path. Highly accelerated quantum clocks experience the Unruh effect, which inevitably influences their time rate. This contradicts the concept of an ideal clock, whose rate should only depend on the instantaneous velocity.
Measurement-based quantum lattice gas model of fluid dynamics in 2+1 dimensions.
Micci, Michael M; Yepez, Jeffrey
2015-09-01
Presented are quantum simulation results using a measurement-based quantum lattice gas algorithm for Navier-Stokes fluid dynamics in 2+1 dimensions. Numerical prediction of the kinematic viscosity was measured by the decay rate of an initial sinusoidal flow profile. Due to local quantum entanglement in the quantum lattice gas, the minimum kinematic viscosity in the measurement-based quantum lattice gas is lower than achievable in a classical lattice gas. The numerically predicted viscosities precisely match the theoretical predictions obtained with a mean field approximation. Uniform flow profile with double shear layers, on a 16K×8K lattice, leads to the Kelvin-Helmholtz instability, breaking up the shear layer into pairs of counter-rotating vortices that eventually merge via vortex fusion and dissipate because of the nonzero shear viscosity. PMID:26465581
K. Ishikawa; N. Maeda
2002-04-16
Physical properties of anisotropic compressible quantum Hall states and their implications to integer quantum Hall effect are studied based on a mean field theory on the von Neumann lattice. It is found that the Hall gas has unusual thermodynamic properties such as negative pressure and negative compressibility and unusual transport properties. Transport properties and density profile of Hall gas states at half fillings agree with those of anisotropic states discovered experimentally in higher Landau levels. Hall gas formed in the bulk does not spread but shrinks, owing to negative pressure, and a strip of Hall gas gives abnormal electric transport at finite temperature. Conductances at finite temperature and finite injected current agree with recent experiments on collapse and breakdown phenomena of the integer quantum Hall effect. As a byproduct, existence of new quantum Hall regime, dissipative quantum Hall regime, in which Hall resistance is quantized exactly even in the system of small longitudinal resistance is derived.
Suppression of the quantum-mechanical collapse by repulsive interactions in a quantum gas
Sakaguchi, Hidetsugu; Malomed, Boris A.
2011-01-15
The quantum-mechanical collapse (alias fall onto the center of particles attracted by potential -r{sup -2}) is a well-known issue in quantum theory. It is closely related to the quantum anomaly, i.e., breaking of the scaling invariance of the respective Hamiltonian by quantization. We demonstrate that the mean-field repulsive nonlinearity prevents the collapse and thus puts forward a solution to the quantum-anomaly problem that differs from that previously developed in the framework of the linear quantum-field theory. This solution may be realized in the 3D or 2D gas of dipolar bosons attracted by a central charge and in the 2D gas of magnetic dipoles attracted by a current filament. In the 3D setting, the dipole-dipole interactions are also taken into regard, in the mean-field approximation, resulting in a redefinition of the scattering length which accounts for the contact repulsion between the bosons. In lieu of the collapse, the cubic nonlinearity creates a 3D ground state (GS), which does not exist in the respective linear Schroedinger equation. The addition of the harmonic trap gives rise to a tristability, in the case when the Schroedinger equation still does not lead to the collapse. In the 2D setting, the cubic nonlinearity is not strong enough to prevent the collapse; however, the quintic term does it, creating the GS, as well as its counterparts carrying the angular momentum (vorticity). Counterintuitively, such self-trapped 2D modes exist even in the case of a weakly repulsive potential r{sup -2}. The 2D vortical modes avoid the phase singularity at the pivot (r=0) by having the amplitude diverging at r{yields}0 instead of the usual situation with the amplitude of the vortical mode vanishing at r{yields}0 (the norm of the mode converges despite of the singularity of the amplitude at r{yields}0). In the presence of the harmonic trap, the 2D quintic model with a weakly repulsive central potential r{sup -2} gives rise to three confined modes, the middle one being unstable, spontaneously developing into a breather. In both the 3D and 2D cases, the GS wave functions are found in a numerical form and in the form of an analytical approximation, which is asymptotically exact in the limit of the large norm.
Swihart, Mark T.
of atmospheric chemistry. The gas phase chemistry of many processes in high-temperature inorganic systems, from [16]. The gas phase chemistry of many processes in high- temperature inorganic systems, fromAssembling gas-phase reaction mechanisms for high temperature inorganic systems based on quantum
Thermodynamics of Quantum Ultra-cold Neutron Gas under Gravity of The Earth
Hiromi Kaneko; Akihiro Tohsaki; Atsushi Hosaka
2012-06-29
The stored ultra-cold neutrons have been developed. A high density ultra-cold neutron gas has been recently produced by using the nuclear spallation method. We investigate the thermodynamic properties of the quantum ultra-cold neutron gas in the Earth's gravitational field. We find that the quantum effects increase temperature dependence of the chemical potential and the internal energy in the low temperature region. The density distribution of quantum ultra-cold neutron gas is modified by the Earth's gravitational field.
Collective oscillations of a trapped quantum gas in low dimensions
NASA Astrophysics Data System (ADS)
De Rosi, Giulia; Stringari, Sandro
2015-11-01
We present a comprehensive study of the discretized modes of an atomic gas in different conditions of confinement. Starting from the equations of hydrodynamics we derive a closed equation for the velocity field, depending on the adiabatic and isothermal compressibilities and applicable to different dimensions and quantum statistics. At zero temperature the equation reproduces the irrotational behavior of superfluid hydrodynamics. It is also applicable above the critical temperature in the collisional regime, where the appearance of rotational components in the velocity field is caused by the external potential. In the presence of harmonic trapping, a general class of analytic solutions is obtained for systems exhibiting a polytropic equation of state, characterized by a power law isoentropic dependence of the pressure on the density. Explicit results for the compressional modes are derived for both Bose and Fermi gases in the pancake and cigar as well as in the deep two- and one-dimensional regimes. Our results agree with the analytical predictions available in the literature in some limiting cases. They are particularly relevant in one-dimensional configurations, where the study of the collective frequencies could provide a unique test of the achievement of the collisional regime at finite temperature.
NASA Astrophysics Data System (ADS)
Rahmani, Amir; Sadeghzadeh, Mohammad Ali; Khordad, Reza
2015-07-01
Low temperature transport and quantum lifetimes (?T,?Q) of two dimensional electron gas (2DEG) confined in the partially alloyed AlxGa1-xAs (with 0 < x < 0.01) quantum well have been explored. Scattering angle ? , 2DEG density ns , and alloy content x dependence of electron lifetimes due to screened short range (alloy disorder) and long range Coulomb interaction (remote and background charged impurities) scattering mechanisms have been evaluated. We explain how different components limit the total transport and quantum electron lifetimes. Finally, the theoretical lifetimes versus alloy content x has been exemplified with experimental results.
NASA Astrophysics Data System (ADS)
Li, Tianshu; Morris, J. W., Jr.; Nagasako, N.; Kuramoto, S.; Chrzan, D. C.
2007-03-01
A newly discovered group of alloys, called Gum Metals, approaches ideal strength in bulk form, exhibits significant plastic deformation prior to failure, and shows no indications of conventional-dislocation activity. Two conditions must be met for a material to exhibit this “ideal” behavior: (1) the stress required to trigger conventional-dislocation plasticity in the material must exceed its ideal strength, and (2) the material must be intrinsically ductile when stressed to ideal strength. Gum Metals satisfy both criteria, explaining their remarkable mechanical properties.
Master Equation for a Quantum Particle in a Gas
Hornberger, Klaus
2006-08-11
The equation for the quantum motion of a Brownian particle in a gaseous environment is derived by means of S-matrix theory. This quantum version of the linear Boltzmann equation accounts nonperturbatively for the quantum effects of the scattering dynamics and describes decoherence and dissipation in a unified framework. As a completely positive master equation it incorporates both the known equation for an infinitely massive Brownian particle and the classical linear Boltzmann equation as limiting cases.
Quantum lattice gas model of Fermi systems with relativistic energy relations
Jeffrey Yepez
2013-07-12
Presented are several example quantum computing representations of quantum systems with a relativistic energy relation. Basic unitary representations of free Dirac particles and BCS superconductivity are given. Then, these are combined into a novel unitary representation of a Fermi condensate superfluid. The modeling approach employs an operator splitting method that is an analytically closed-form product decomposition of the unitary evolution operator, applied in the high-energy limit. This allows the relativistic wave equations to be cast as unitary finite-difference equations. The split evolution operators (comprising separate kinetic and interaction energy evolution terms) serve as quantum lattice gas models useful for efficient quantum simulation.
Ideals and Category Typicality
ERIC Educational Resources Information Center
Kim, ShinWoo; Murphy, Gregory L.
2011-01-01
Barsalou (1985) argued that exemplars that serve category goals become more typical category members. Although this claim has received support, we investigated (a) whether categories have a single ideal, as negatively valenced categories (e.g., cigarette) often have conflicting goals, and (b) whether ideal items are in fact typical, as they often…
Construction of a quantum gas microscope for fermionic atoms
Ramasesh, Vinay (Vinay V.)
2013-01-01
This thesis reports the construction of a novel apparatus for experiments with ultracold atoms in optical lattices: the Fermi gas microscope. Improving upon similar designs for bosonic atoms, our Fermi gas microscope has ...
Single-atom imaging of fermions in a quantum-gas microscope
NASA Astrophysics Data System (ADS)
Haller, Elmar; Hudson, James; Kelly, Andrew; Cotta, Dylan A.; Peaudecerf, Bruno; Bruce, Graham D.; Kuhr, Stefan
2015-09-01
Single-atom-resolved detection in optical lattices using quantum-gas microscopes has enabled a new generation of experiments in the field of quantum simulation. Although such devices have been realized with bosonic species, a fermionic quantum-gas microscope has remained elusive. Here we demonstrate single-site- and single-atom-resolved fluorescence imaging of fermionic potassium-40 atoms in a quantum-gas microscope set-up, using electromagnetically-induced-transparency cooling. We detected on average 1,000 fluorescence photons from a single atom within 1.5 s, while keeping it close to the vibrational ground state of the optical lattice. A quantum simulator for fermions with single-particle access will be an excellent test bed to investigate phenomena and properties of strongly correlated fermionic quantum systems, allowing direct measurement of ordered quantum phases and out-of-equilibrium dynamics, with access to quantities ranging from spin-spin correlation functions to many-particle entanglement.
Single-atom imaging of fermions in a quantum-gas microscope
Haller, Elmar; Kelly, Andrew; Cotta, Dylan A; Peaudecerf, Bruno; Bruce, Graham D; Kuhr, Stefan
2015-01-01
Single-atom-resolved detection in optical lattices using quantum-gas microscopes has enabled a new generation of experiments in the field of quantum simulation. Fluorescence imaging of individual atoms has so far been achieved for bosonic species with optical molasses cooling, whereas detection of fermionic alkaline atoms in optical lattices by this method has proven more challenging. Here we demonstrate single-site- and single-atom-resolved fluorescence imaging of fermionic potassium-40 atoms in a quantum-gas microscope setup using electromagnetically-induced-transparency cooling. We detected on average 1000 fluorescence photons from a single atom within 1.5s, while keeping it close to the vibrational ground state of the optical lattice. Our results will enable the study of strongly correlated fermionic quantum systems in optical lattices with resolution at the single-atom level, and give access to observables such as the local entropy distribution and individual defects in fermionic Mott insulators or anti-...
Engineering Light: Quantum Cascade Lasers
Claire Gmachl
2010-09-01
Quantum cascade lasers are ideal for environmental sensing and medical diagnostic applications. Gmachl discusses how these lasers work, and their applications, including their use as chemical trace gas sensors. As examples of these applications, she briefly presents results from her field campaign at the Beijing Olympics, and ongoing campaigns in Texas, Maryland, and Ghana.
Engineering Light: Quantum Cascade Lasers
Claire Gmachl
2010-03-17
Quantum cascade lasers are ideal for environmental sensing and medical diagnostic applications. Gmachl discusses how these lasers work, and their applications, including their use as chemical trace gas sensors. As examples of these applications, she briefly presents results from her field campaign at the Beijing Olympics, and ongoing campaigns in Texas, Maryland, and Ghana.
Spin-Nematic Squeezed Vacuum in a Quantum Gas
C. D. Hamley; C. S. Gerving; T. M. Hoang; E. M. Bookjans; M. S. Chapman
2012-03-02
Using squeezed states it is possible to surpass the standard quantum limit of measurement uncertainty by reducing the measurement uncertainty of one property at the expense of another complementary property. Squeezed states were first demonstrated in optical fields and later with ensembles of pseudo spin-1/2 atoms using non-linear atom-light interactions. Recently, collisional interactions in ultracold atomic gases have been used to generate a large degree of quadrature spin squeezing in two-component Bose condensates. For pseudo spin-1/2 systems, the complementary properties are the different components of the total spin vector , which fully characterize the state on an SU(2) Bloch sphere. Here, we measure squeezing in a spin-1 Bose condensate, an SU(3) system, which requires measurement of the rank-2 nematic or quadrupole tensor as well to fully characterize the state. Following a quench through a nematic to ferromagnetic quantum phase transition, squeezing is observed in the variance of the quadratures up to -8.3(-0.7 +0.6) dB (-10.3(-0.9 +0.7) dB corrected for detection noise) below the standard quantum limit. This spin-nematic squeezing is observed for negligible occupation of the squeezed modes and is analogous to optical two-mode vacuum squeezing. This work has potential applications to continuous variable quantum information and quantum-enhanced magnetometry.
Quantum Control by Imaging: The Zeno Effect in an Ultracold Lattice Gas
NASA Astrophysics Data System (ADS)
Patil, Yogesh Sharad; Chakram, Srivatsan; Vengalattore, Mukund
2015-05-01
We demonstrate the control of quantum tunneling in an ultracold lattice gas by the measurement backaction imposed by an imaging process. A in situ imaging technique is used to acquire repeated images of an ultracold gas confined in a shallow optical lattice. The backaction induced by these position measurements modifies the coherent quantum tunneling of atoms within the lattice. By varying the rate at which atoms are imaged, we observe the crossover from the weak measurement regime, where the measurement has a negligible effect on coherent dynamics, to the strong measurement regime, where measurement-induced localization leads to a dramatic suppression of tunneling. The latter effect is a manifestation of the Quantum Zeno effect. We thereby demonstrate the paradigmatic Heisenberg microscope in a lattice gas, and shed light on the implications of quantum measurement on the coherent evolution of a mesoscopic quantum system. Our technique demonstrates a powerful tool for the control of an interacting many-body quantum system via spatially resolved measurement backaction. This work is supported by the ARO MURI on non-equilibrium dynamics.
Primary Components of Binomial Ideals
Eser, Zekiye
2014-07-11
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.3 Lattice Ideals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1.4 Primary Decomposition of Binomial Ideals . . . . . . . . . . . . . . . 15 1.5 Primary Decomposition of Lattice Ideals in Positive Characteristic . . 18 2... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 2.3 Codimension Two Lattice Basis Ideals . . . . . . . . . . . . . . . . . 40 2.4 Graphs Associated to Matrices . . . . . . . . . . . . . . . . . . . . . . 43 2.5 Codimension Two Lattice Basis Ideals in Three Variables . . . . . . . 54 3. CELLULAR...
Burnett, Russell C; Medin, Douglas L; Ross, Norbert O; Blok, Sergey V
2005-03-01
A well-established finding in research on concepts and categories is that some members are rated as better or more typical examples than others. It is generally thought that typicality reflects centrality, that is, that typical examples are those that are similar to many other members of the category. This interpretation of typicality is based on studies in which participants had little knowledge about the relevant categories. In the present study, experienced fishermen were asked to give goodness-of-example ratings to familiar freshwater fish. These fishermen were of two cultural groups with somewhat different goals and ideals. Typicality was well predicted by fishes' desirability and poorly predicted by their centrality. Further, the two cultural groups differed in their typicality ratings in ways that corresponded to their different goals and ideals. For knowledgeable reasoners typicality in natural taxonomic categories appears based on ideals rather than on centrality. PMID:15832626
Chemical Potential Jump during Evaporation of a Quantum Bose Gas
E. A. Bedrikova; A. V. Latyshev
2013-01-07
The dependence of the chemical potential jump coefficient on the evaporation coefficient is analyzed for the case in which the evaporating component is a Bose gas. The concentration of the evaporating component is assumed to be much lower than the concentration of the carrier gas. The expression for the chemical potential jump is derived from the analytic solution of the problem for the case in which the collision frequency of molecules of the evaporating component is constant.
Chemiresistive gas sensors employing solution-processed metal oxide quantum dot films
Liu, Huan Xu, Songman; Li, Min; Shao, Gang; Zhang, Wenkai; Wei, Wendian; He, Mingze; Song, Huaibing; Gao, Liang; Song, Haisheng; Tang, Jiang
2014-10-20
We report low-temperature chemiresistive gas sensors based on tin oxide colloidal quantum dots (CQDs), in which the benefits of CQDs such as extremely small crystal size, solution-processability, and tunable surface activity are exploited to enhance the gas-sensing effect. The sensor fabrication is simply employing spin-coating followed by a solid-state ligand exchange treatment at room temperature in air ambient. The optimal gas sensor exhibited rapid and significant decrease in resistance upon H{sub 2}S gas exposure when operated at 70?°C, and it was fully recoverable upon gas release. We observed a power law correlation between the sensor response and H{sub 2}S gas concentration, and the sensing mechanism was discussed using the completely depletion model with a flat band diagram.
Frequency Locking of a 3.5 Thz Quantum Cascade Laser Using a Gas Cell
Ren, Y.
We report a frequency locking experiment of a 3.5 THz third-order distributed feedback quantum cascade laser (QCL) by using a molecular absorption line of methanol (CH[subscript 3]OH) gas. With the help of the absorption ...
ERIC Educational Resources Information Center
Dosiere, M.
1985-01-01
Background information, procedures used, and typical results obtained are provided for an experiment in which gas chromatography is used to prove the application of quantum symmetry restrictions in homonuclear diatomic molecules. Comparisons between experimental results and theoretical computed values show good agreement, within one to two…
Creation of a low-entropy quantum gas of polar molecules in an optical lattice.
Moses, Steven A; Covey, Jacob P; Miecnikowski, Matthew T; Yan, Bo; Gadway, Bryce; Ye, Jun; Jin, Deborah S
2015-11-01
Ultracold polar molecules, with their long-range electric dipolar interactions, offer a unique platform for studying correlated quantum many-body phenomena. However, realizing a highly degenerate quantum gas of molecules with a low entropy per particle is challenging. We report the synthesis of a low-entropy quantum gas of potassium-rubidium molecules (KRb) in a three-dimensional optical lattice. We simultaneously load into the optical lattice a Mott insulator of bosonic Rb atoms and a single-band insulator of fermionic K atoms. Then, using magnetoassociation and optical state transfer, we efficiently produce ground-state molecules in the lattice at those sites that contain one Rb and one K atom. The achieved filling fraction of 25% should enable future studies of transport and entanglement propagation in a many-body system with long-range dipolar interactions. PMID:26542566
Creation of a low-entropy quantum gas of polar molecules in an optical lattice
NASA Astrophysics Data System (ADS)
Moses, Steven A.; Covey, Jacob P.; Miecnikowski, Matthew T.; Yan, Bo; Gadway, Bryce; Ye, Jun; Jin, Deborah S.
2015-11-01
Ultracold polar molecules, with their long-range electric dipolar interactions, offer a unique platform for studying correlated quantum many-body phenomena. However, realizing a highly degenerate quantum gas of molecules with a low entropy per particle is challenging. We report the synthesis of a low-entropy quantum gas of potassium-rubidium molecules (KRb) in a three-dimensional optical lattice. We simultaneously load into the optical lattice a Mott insulator of bosonic Rb atoms and a single-band insulator of fermionic K atoms. Then, using magnetoassociation and optical state transfer, we efficiently produce ground-state molecules in the lattice at those sites that contain one Rb and one K atom. The achieved filling fraction of 25% should enable future studies of transport and entanglement propagation in a many-body system with long-range dipolar interactions.
Creating a quantum degenerate gas of stable molecules via weak photoassociation
Mackie, Matt; Phou, Pierre
2010-07-15
Quantum degenerate molecules represent a new paradigm for fundamental studies and practical applications. Association of already quantum degenerate atoms into molecules provides a crucial shortcut around the difficulty of cooling molecules to ultracold temperatures. Whereas association can be induced with either laser or magnetic fields, photoassociation requires impractical laser intensity to overcome poor overlap between the atom pair and molecular wave functions, and experiments are currently restricted to magnetoassociation. Here we model realistic production of a quantum degenerate gas of stable molecules via two-photon photoassociation of Bose-condensed atoms. An adiabatic change of the laser frequency converts the initial atomic condensate almost entirely into stable molecular condensate, even for low-intensity lasers. Results for dipolar LiNa provide an upper bound on the necessary photoassociation laser intensity for alkali-metal atoms {approx}30 W/cm{sup 2}, indicating a feasible path to quantum degenerate molecules beyond magnetoassociation.
Creating a quantum degenerate gas of stable molecules via weak photoassociation
NASA Astrophysics Data System (ADS)
Mackie, Matt; Phou, Pierre
2010-07-01
Quantum degenerate molecules represent a new paradigm for fundamental studies and practical applications. Association of already quantum degenerate atoms into molecules provides a crucial shortcut around the difficulty of cooling molecules to ultracold temperatures. Whereas association can be induced with either laser or magnetic fields, photoassociation requires impractical laser intensity to overcome poor overlap between the atom pair and molecular wave functions, and experiments are currently restricted to magnetoassociation. Here we model realistic production of a quantum degenerate gas of stable molecules via two-photon photoassociation of Bose-condensed atoms. An adiabatic change of the laser frequency converts the initial atomic condensate almost entirely into stable molecular condensate, even for low-intensity lasers. Results for dipolar LiNa provide an upper bound on the necessary photoassociation laser intensity for alkali-metal atoms ~30 W/cm2, indicating a feasible path to quantum degenerate molecules beyond magnetoassociation.
NASA Astrophysics Data System (ADS)
Eshraghi, H.; Gibbon, J. D.
2008-08-01
After a review of some of the recent works by Holm and Gibbon on quaternions and their application to Lagrangian flows, particularly the incompressible Euler equations and the equations of ideal MHD, this paper investigates the compressible and relativistic Euler equations using these methods.
THE CONDUCTOR IDEAL KEITH CONRAD
Lozano-Robledo, Alvaro
THE CONDUCTOR IDEAL KEITH CONRAD 1. Introduction Let O be an order in the number field K. When O ideal in O, called the conductor, that is closely related to the noninvertible prime ideals in O. The nonzero ideals in O that are relatively prime to the conductor will be invertible and have unique
Quantum enhancement of spin drag in a Bose gas
NASA Astrophysics Data System (ADS)
Koller, S. B.; Groot, A.; Bons, P. C.; Duine, R. A.; Stoof, H. T. C.; van der Straten, P.
2015-11-01
In spintronics the active control and manipulation of spin currents is studied in solid-state systems. Opposed to charge currents, spin currents are strongly damped due to collisions between different spin carriers in addition to relaxation due to impurities and lattice vibrations. The phenomenon of relaxation of spin currents is called spin drag. Here we study spin drag in ultra-cold bosonic atoms deep in the hydrodynamic regime and show that spin drag is the dominant damping mechanism for spin currents in this system. By increasing the phase space density we find that spin drag is enhanced in the quantum regime by more than a factor of two due to Bose stimulation, which is in agreement with recent theoretical predictions and, surprisingly, already occurs considerably above the phase transition.
NASA Technical Reports Server (NTRS)
Kogut, A.; DiPirro, M.; Moseley, S. H.
2004-01-01
We describe a new "ideal integrator" bolometer as a prototype for a new generation of sensitive, flexible far-IR detectors suitable for use in large arrays. The combination of a non-dissipative sensor coupled with a fast heat switch provides breakthrough capabilities in both sensitivity and operation. The bolometer temperature varies linearly with the integrated infrared power incident on the detector, and may be sampled intermittently without loss of information between samples. The sample speed and consequent dynamic range depend only on the heat switch reset cycle and can be selected in software. Between samples, the device acts as an ideal integrator with noise significantly lower than resistive bolometers. Since there is no loss of information between samples, the device is well-suited for large arrays. A single SQUID readout could process an entire column of detectors, greatly reducing the complexity, power requirements, and cost of readout electronics for large pixel arrays.
C. W. Gardiner; P. Zoller
1996-11-25
A Quantum Kinetic Master Equation (QKME) for bosonic atoms is formulated. It is a quantum stochastic equation for the kinetics of a dilute quantum Bose gas, and describes the behavior and formation of Bose condensation. The key assumption in deriving the QKME is a Markov approximation for the atomic collision terms. In the present paper the basic structure of the theory is developed, and approximations are stated and justified to delineate the region of validity of the theory. Limiting cases of the QKME include the Quantum Boltzmann master equation and the Uehling-Uhlenbeck equation, as well as an equation analogous to the Gross-Pitaevskii equation.
Observation of scaling in the dynamics of a strongly quenched quantum gas
Nicklas, Eike; Höfer, Moritz; Johnson, Aisling; Muessel, Wolfgang; Strobel, Helmut; Tomkovi?, Ji?í; Gasenzer, Thomas; Oberthaler, Markus
2015-01-01
We report on the experimental observation of scaling in the time evolution following a sudden quench into the vicinity of a quantum critical point. The experimental system, a two-component Bose gas with coherent exchange between the constituents, allows for the necessary high level of control of parameters as well as the access to time-resolved spatial correlation functions. The theoretical analysis reveals that quenching the system close to the critical point, the energy introduced by the quench leads to a short-time evolution exhibiting crossover reminiscent of the finite-temperature critical properties in the system's universality class. Observing the time evolution after a quench represents a paradigm shift in accessing and probing experimentally universal properties close to a quantum critical point and allows in a new way benchmarking of quantum many-body theory with experiments.
Measuring the dynamic structure factor of a quantum gas undergoing a structural phase transition
NASA Astrophysics Data System (ADS)
Landig, Renate; Brennecke, Ferdinand; Mottl, Rafael; Donner, Tobias; Esslinger, Tilman
2015-05-01
The dynamic structure factor is a central quantity describing the physics of quantum many-body systems, capturing structure and collective excitations of a material. In condensed matter, it can be measured via inelastic neutron scattering, which is an energy-resolving probe for the density fluctuations. In ultracold atoms, a similar approach could so far not be applied because of the diluteness of the system. Here we report on a direct, real-time and nondestructive measurement of the dynamic structure factor of a quantum gas exhibiting cavity-mediated long-range interactions. The technique relies on inelastic scattering of photons, stimulated by the enhanced vacuum field inside a high finesse optical cavity. We extract the density fluctuations, their energy and lifetime while the system undergoes a structural phase transition. We observe an occupation of the relevant quasi-particle mode on the level of a few excitations, and provide a theoretical description of this dissipative quantum many-body system.
Observation of Scaling in the Dynamics of a Strongly Quenched Quantum Gas.
Nicklas, E; Karl, M; Höfer, M; Johnson, A; Muessel, W; Strobel, H; Tomkovi?, J; Gasenzer, T; Oberthaler, M K
2015-12-11
We report on the experimental observation of scaling in the time evolution following a sudden quench into the vicinity of a quantum critical point. The experimental system, a two-component Bose gas with coherent exchange between the constituents, allows for the necessary high level of control of parameters as well as the access to time-resolved spatial correlation functions. The theoretical analysis reveals that when quenching the system close to the critical point, the energy introduced by the quench leads to a short-time evolution exhibiting crossover reminiscent of the finite-temperature critical properties in the system's universality class. Observing the time evolution after a quench represents a paradigm shift in accessing and probing experimentally universal properties close to a quantum critical point and allows in a new way benchmarking of quantum many-body theory with experiments. PMID:26705638
Quantum gas microscopy with spin, atom-number, and multilayer readout
NASA Astrophysics Data System (ADS)
Preiss, Philipp M.; Ma, Ruichao; Tai, M. Eric; Simon, Jonathan; Greiner, Markus
2015-04-01
Atom- and site-resolved experiments with ultracold atoms in optical lattices provide a powerful platform for the simulation of strongly correlated materials. In this Rapid Communication, we present a toolbox for the preparation, control, and site-resolved detection of a tunnel-coupled bilayer degenerate quantum gas. Using a collisional blockade, we engineer occupation-dependent interplane transport which enables us to circumvent light-assisted pair loss during imaging and count n =0 to n =3 atoms per site. We obtain the first number- and site-resolved images of the Mott insulator "wedding cake" structure and observe the emergence of antiferromagnetic ordering across a magnetic quantum phase transition. We are further able to employ the bilayer system for spin-resolved readout of a mixture of two hyperfine states. This work opens the door to direct detection of entanglement and Kosterlitz-Thouless-type phase dynamics, as well as studies of coupled planar quantum materials.
Breakdown of a topological phase: Quantum phase transition in a loop gas model with tension
Simon Trebst; Philipp Werner; Matthias Troyer; Kirill Shtengel; Chetan Nayak
2006-09-03
We study the stability of topological order against local perturbations by considering the effect of a magnetic field on a spin model -- the toric code -- which is in a topological phase. The model can be mapped onto a quantum loop gas where the perturbation introduces a bare loop tension. When the loop tension is small, the topological order survives. When it is large, it drives a continuous quantum phase transition into a magnetic state. The transition can be understood as the condensation of `magnetic' vortices, leading to confinement of the elementary `charge' excitations. We also show how the topological order breaks down when the system is coupled to an Ohmic heat bath and discuss our results in the context of quantum computation applications.
Terahertz Plasma Waves in Two Dimensional Quantum Electron Gas with Electron Scattering
NASA Astrophysics Data System (ADS)
Zhang, Liping
2015-10-01
We investigate the Terahertz (THz) plasma waves in a two-dimensional (2D) electron gas in a nanometer field effect transistor (FET) with quantum effects, the electron scattering, the thermal motion of electrons and electron exchange-correlation. We find that, while the electron scattering, the wave number along y direction and the electron exchange-correlation suppress the radiation power, but the thermal motion of electrons and the quantum effects can amplify the radiation power. The radiation frequency decreases with electron exchange-correlation contributions, but increases with quantum effects, the wave number along y direction and thermal motion of electrons. It is worth mentioning that the electron scattering has scarce influence on the radiation frequency. These properties could be of great help to the realization of practical THz plasma oscillations in nanometer FET. supported by National Natural Science Foundation of China (No. 10975114)
Single-atom imaging of fermions in a quantum-gas microscope
Elmar Haller; James Hudson; Andrew Kelly; Dylan A. Cotta; Bruno Peaudecerf; Graham D. Bruce; Stefan Kuhr
2015-08-20
Single-atom-resolved detection in optical lattices using quantum-gas microscopes has enabled a new generation of experiments in the field of quantum simulation. Fluorescence imaging of individual atoms has so far been achieved for bosonic species with optical molasses cooling, whereas detection of fermionic alkaline atoms in optical lattices by this method has proven more challenging. Here we demonstrate single-site- and single-atom-resolved fluorescence imaging of fermionic potassium-40 atoms in a quantum-gas microscope setup using electromagnetically-induced-transparency cooling. We detected on average 1000 fluorescence photons from a single atom within 1.5s, while keeping it close to the vibrational ground state of the optical lattice. Our results will enable the study of strongly correlated fermionic quantum systems in optical lattices with resolution at the single-atom level, and give access to observables such as the local entropy distribution and individual defects in fermionic Mott insulators or anti-ferromagnetically ordered phases.
Theta Bodies for Polynomial Ideals
Parrilo, Pablo A.
Inspired by a question of Lovász, we introduce a hierarchy of nested semidefinite relaxations of the convex hull of real solutions to an arbitrary polynomial ideal called theta bodies of the ideal. These relaxations ...
Steele, W.V.
2002-07-01
Ideal-gas enthalpies of formation of methyl benzoate, ethyl benzoate, (R)-(+)-limonene, tert-amyl methyl ether, trans-crotonaldehyde, and diethylene glycol are reported. The standard energy of combustion and hence standard enthalpy of formation of each compound in the liquid phase has been measured using an oxygen rotating-bomb calorimeter without rotation. Vapor pressures were measured to a pressure limit of 270 kPa or the lower decomposition point for each of the six compounds using a twin ebulliometric apparatus. Liquid-phase densities along the saturation line were measured for each compound over a range of temperature (ambient to a maximum of 548 K). A differential scanning calorimeter was used to measure two-phase (liquid + vapor) heat capacities for each compound in the temperature region ambient to the critical temperature or lower decomposition point. For methyl benzoate and tert-amyl methyl ether, critical temperatures and critical densities were determined from the DSC results and corresponding critical pressures derived from the fitting procedures. Fitting procedures were used to derive critical temperatures, critical pressures, and critical densities for each of the remaining compounds. The results of the measurements were combined to derive a series of thermophysical properties including critical temperature, critical density, critical pressure, acentric factor, enthalpies of vaporization (restricted to within {+-}50 K of the temperature region of the experimentally determined vapor pressures), and heat capacities along the saturation line. Wagner-type vapor-pressure equations were derived for each compound. All measured and derived values were compared with those obtained in a search of the literature. Recommended critical parameters are listed for each of the compounds studied. Group-additivity parameters, useful in the application of the Benson gas-phase group-contribution correlations, were derived.
Trace-gas sensing using the compliance voltage of an external cavity quantum cascade laser
Phillips, Mark C.; Taubman, Matthew S.
2013-06-04
Quantum cascade lasers (QCLs) are increasingly being used to detect, identify, and measure levels of trace gases in the air. External cavity QCLs (ECQCLs) provide a broadly-tunable infrared source to measure absorption spectra of chemicals and provide high detection sensitivity and identification confidence. Applications include detecting chemical warfare agents and toxic industrial chemicals, monitoring building air quality, measuring greenhouse gases for atmospheric research, monitoring and controlling industrial processes, analyzing chemicals in exhaled breath for medical diagnostics, and many more. Compact, portable trace gas sensors enable in-field operation in a wide range of platforms, including handheld units for use by first responders, fixed installations for monitoring air quality, and lightweight sensors for deployment in unmanned aerial vehicles (UAVs). We present experimental demonstration of a new chemical sensing technique based on intracavity absorption in an external cavity quantum cascade laser (ECQCL). This new technique eliminates the need for an infrared photodetector and gas cell by detecting the intracavity absorption spectrum in the compliance voltage of the laser device itself. To demonstrate and characterize the technique, we measure infrared absorption spectra of chemicals including water vapor and Freon-134a. Sub-ppm detection limits in one second are achieved, with the potential for increased sensitivity after further optimization. The technique enables development of handheld, high-sensitivity, and high-accuracy trace gas sensors for in-field use.
NMR dynamics of quantum discord for spin-carrying gas molecules in a closed nanopore
Yurishchev, M. A.
2014-11-15
A local orthogonal transformation that transforms any centrosymmetric density matrix of a two-qubit system to the X form has been found. A piecewise-analytic-numerical formula Q = min(Q{sub ?/2}, Q{sub ?}, Q{sub 0}), where Q{sub ?/2} and Q{sub 0} are analytical expressions and the branch Q{sub 0?} can be obtained only by numerically searching for the optimal measurement angle ? ? (0, ?/2), is proposed to calculate the quantum discord Q of a general X state. The developed approaches have been applied for a quantitative description of the recently predicted flickering (periodic disappearance and reappearance) of the quantum-information pair correlation between nuclear 1/2 spins of atoms or molecules of a gas (for example, {sup 129}Xe) in a bounded volume in the presence of a strong magnetic field.
Recurrence Time in the Quantum Dynamics of the 1D Bose Gas
NASA Astrophysics Data System (ADS)
Kaminishi, Eriko; Sato, Jun; Deguchi, Tetsuo
2015-06-01
Recurrence time is evaluated for some initial quantum states in the one-dimensional Bose gas with repulsive short-range interactions. In the relatively strong and weak coupling cases some different types of initial states show almost complete recurrence and the estimates of recurrence time are proportional to some powers of the system size at least in some range of the system size. They are much longer than in the case of free particles such as 100 times. In the free-bosonic and free-fermionic regimes we evaluate the recurrence time rigorously, which is proportional to the square of the system size. The estimate of recurrence time is given by the order of ten milliseconds in the corresponding experimental systems of cold atoms trapped in one dimension of ten micrometers in length. It is much shorter than the estimate in a generic quantum many-body system, which may be as long as the age of the universe.
Chemical dynamics in the gas phase : quantum mechanics of chemical reactions.
Gray, S. K.
2006-01-01
This research program focuses on both the development and application of accurate quantum mechanical methods to describe gas phase chemical reactions and highly excited molecules. Emphasis is often placed on time-dependent or integrative approaches that, in addition to computational simplifications, yield useful mechanistic insights. Applications to systems of current experimental and theoretical interest are emphasized. The results of these calculations also allow one to gauge the quality of the underlying potential energy surfaces and the reliability of more approximate theoretical approaches such as classical trajectories and transition state theories.
From gauge transformations to topology computation in quantum lattice gas automata
David A. Meyer
2001-05-17
The evolution of a quantum lattice gas automaton (LGA) for a single charged particle is invariant under multiplication of the wave function by a global phase. Requiring invariance under the corresponding local gauge transformations determines the rule for minimal coupling to an arbitrary external electromagnetic field. We develop the Aharonov-Bohm effect in the resulting model into a constant time algorithm to distinguish a one dimensional periodic lattice from one with boundaries; any classical deterministic LGA algorithm distinguishing these two spatial topologies would have expected running time on the order of the cardinality of the lattice.
NASA Astrophysics Data System (ADS)
Popov, M.
Erwin Schrodinger suggested that " Scientific knowledge forms part of the idealistic background of human life", which exalted man from a nude and savage state to true humanity [Science and Humanism, Cambridge, 1961, p9]. Modern space sciences an space exploration are a brilliant demonstration of the validity of Schrodinger's thesis on Idealism. Moreover, Schrodingers thesis could be considered also as a basic principle for the New Educational Space Philosophical Project "TIMAEUS"."TIMAEUS" is not only an attempt to to start a new dialogue between Science, the Humanities and Religion; but also it is an origin of the cultural innovations of our so strange of globilisation. TIMAEUS, thus, can reveal Idealism as something more fundamental , more refined, more developed than is now accepted by the scientific community and the piblic. TIMAEUS has a significant cultural agenda, connected with the high orbital performance of the synthetic arts, combining a knowledge of the truly spiritual as well as the universal. In particular, classical ballet as a synthetic art can be a new and powerful perfector and re-creator of the real human, real idealistic, real complex culture in orbit. As is well known, Carlo Blasis, the most important dance theorist of the 19t h .century, made probably the first attempts to use the scientific ideas of Leonardo da Vinci and Isaac Newton for the understanding of the gravitational nature of balance and allegro in ballet. In particular Blasis's idea of the limited use of the legs in classical dance realised by the gifted pupils of Enrico Cecchetti - M.Fokine, A.Pavlova and V.Nijinsky, with thinkable purity and elegance of style. V.Nijinsky in his remarkable animation of the dance of two dimensional creatures of a Euclidean flat world (L'Apres Midi d'un Faune,1912) discovered that true classical dance has some gravitational limits. For example, Nijinsky's Faunes and Nymphs mut use running on the heels (In accordance with "Partitura" 1916); they cannot use a turn-out or epaulement for their pas-de-bra. In other words Nijinsky's dancers must live in weightlessness in order to perform what his "Partitura" (L'Apres Midi d'un Faune, version of 1916) describes. Diaghilev and Benois, platonised theorists of the Ballet Russe, suggested that the true idealised classical dance must be performed in Tiepolo's weightlessnessful manner of later Baroque. Anna Pavlova by her idiosyncrasy of parallel motion opened the New World of Aesthetics and brought it to its utmost perfection. Hence, it is natural to think that some findings of choreographers could be developed and tested in space environment. Moreover, we believe that classical ballet itself could be brought to perfection in space fter Diaghilev's reform. Correspondingly, we may await that such innovations can initiate a development of the New Grand Style in Arts, Music and Choreography free from contemporary religious and national prejudices.
Optically multiplexed multi-gas detection using quantum cascade laser photoacoustic spectroscopy.
Mukherjee, Anadi; Prasanna, Manu; Lane, Michael; Go, Rowel; Dunayevskiy, Ilya; Tsekoun, Alexei; Patel, C Kumar N
2008-09-20
We report high-throughput, nondispersive optical multiplexing of laser beams using a scanning galvanometer. We have utilized this technique for multispecies trace-gas detection using multiple quantum cascade laser photoacoustic spectroscopy. We demonstrate switching from one laser to another in less than 1 s, a performance level needed for a comprehensive multispecies sensor, and a high signal-to-noise ratio detection of five gaseous components, NH(3), NO(2), dimethyl methyl phosphonate (DMMP, a simulant for nerve agents), acetone, and ethylene glycol, in a room air gas mixture containing approximately 3 ppb of NH(3), approximately 8 ppb of NO(2), approximately 20 ppb of DMMP, approximately 30 ppb of acetone, and approximately 40 ppb of ethylene glycol. PMID:18806847
Quantum anomaly, universal relations, and breathing mode of a two-dimensional Fermi gas.
Hofmann, Johannes
2012-05-01
In this Letter, we show that the classical SO(2,1) symmetry of a harmonically trapped Fermi gas in two dimensions is broken by quantum effects. The anomalous correction to the symmetry algebra is given by a two-body operator that is well known as the contact. Taking into account this modification, we are able to derive the virial theorem for the system and a universal relation for the pressure of a homogeneous gas. The existence of an undamped breathing mode is associated with the classical symmetry. We provide an estimate for the anomalous frequency shift of this oscillation at zero temperature and compare the result with a recent experiment by [E. Vogt et al., Phys. Rev. Lett. 108, 070404 (2012)]. Discrepancies are attributed to finite temperature effects. PMID:22681087
NASA Astrophysics Data System (ADS)
Luo, Ercang
2012-06-01
This paper analyzes the thermodynamic cycle of oscillating-flow regenerative machines. Unlike the classical analysis of thermodynamic textbooks, the assumptions for pistons' movement limitations are not needed and only ideal flowing and heat transfer should be maintained in our present analysis. Under such simple assumptions, the meso-scale thermodynamic cycles of each gas parcel in typical locations of a regenerator are analyzed. It is observed that the gas parcels in the regenerator undergo Lorentz cycle in different temperature levels, whereas the locus of all gas parcels inside the regenerator is the Ericson-like thermodynamic cycle. Based on this new finding, the author argued that ideal oscillating-flow machines without heat transfer and flowing losses is not the Stirling cycle. However, this new thermodynamic cycle can still achieve the same efficiency of the Carnot heat engine and can be considered a new reversible thermodynamic cycle under two constant-temperature heat sinks.
FK-DLR properties of a quantum multi-type Bose-gas with a repulsive interaction
NASA Astrophysics Data System (ADS)
Suhov, Y.; Stuhl, I.
2014-08-01
The paper extends earlier results from Suhov and Kelbert ["FK-DLR states of a quantum Bose-gas with a hardcore interaction," arXiv:1304.0782] and Suhov et al. ["Shift-invariance for FK-DLR states of a 2D quantum Bose-gas," arXiv:1304.4177] about infinite-volume quantum bosonic states (FK-DLR states) to the case of multi-type particles with non-negative interactions. (An example is a quantum Widom-Rowlinson model.) Following the strategy from Suhov and Kelbert and Suhov et al., we establish that, for the values of fugacity z ? (0, 1) and inverse temperature ? > 0, finite-volume Gibbs states form a compact family in the thermodynamic limit. Next, in dimension two we show that any limit-point state (an FK-DLR state in the terminology adopted in Suhov and Kelbert and Suhov et al.) is translation-invariant.
Carbon Nanomaterials: The Ideal Interconnect
Carbon Nanomaterials: The Ideal Interconnect Technology for Next- Generation ICs Hong Li, Chuan Xu-generation ICs. In this research, carbon nanomaterials, with their many attractive properties, are emerging-a`-vis optical and RF interconnects, and we illustrate why carbon nanomaterials constitute the ideal intercon
Collective motions of a quantum gas confined in a harmonic trap
Song, Dae-Yup
2005-08-15
Single-component quantum gas confined in a harmonic potential, but otherwise isolated, is considered. From the invariance of the system of the gas under a displacement-type transformation, it is shown that the center of mass oscillates along a classical trajectory of a harmonic oscillator. It is also shown that this harmonic motion of the center has, in fact, been implied by Kohn's theorem. If there is no interaction between the atoms of the gas, the system in a time-independent isotropic potential of frequency {nu}{sub c} is invariant under a squeeze-type unitary transformation, which gives collective radial breathing motion of frequency 2{nu}{sub c} to the gas. The amplitudes of the oscillating and breathing motions from the exact invariances could be arbitrarily large. For a Fermi system, appearance of 2{nu}{sub c} mode of the large breathing motion indicates that there is no interaction between the atoms, except for a possible long-range interaction through the inverse-square-type potential.
Interacting Generalized Cosmic Chaplygin Gas in Loop Quantum Cosmology: A Singularity Free Universe
NASA Astrophysics Data System (ADS)
Chowdhury, Ratul; Rudra, Prabir
2013-02-01
In this work we investigate the background dynamics when dark energy is coupled to dark matter with a suitable interaction in the universe described by Loop quantum cosmology. Dark energy in the form of Generalized Cosmic Chaplygin gas is considered. A suitable interaction between dark energy and dark matter is taken into account in order to at least alleviate (if not solve) the cosmic coincidence problem. The dynamical system of equations is solved numerically and a stable scaling solution is obtained. A significant attempt towards the solution of the cosmic coincidence problem is taken. The statefinder parameters are also calculated to classify the dark energy model. Graphs and phase diagrams are drawn to study the variations of these parameters. It is seen that the background dynamics of Generalized Cosmic Chaplygin gas is completely consistent with the notion of an accelerated expansion in the late universe. From the graphs, generalized cosmic Chaplygin gas is identified as a dark fluid with a lesser negative pressure compared to Modified Chaplygin gas, thus supporting a `No Big Rip' cosmology. It has also been shown that in this model the universe follows the power law form of expansion around the critical point, which is consistent with the known results. Future singularities that may be formed in this model as an ultimate fate of the universe has been studied in detail. It was found that the model is completely free from any types of future singularities.
Measuring the dynamic structure factor of a quantum gas undergoing a structural phase transition
Landig, Renate; Brennecke, Ferdinand; Mottl, Rafael; Donner, Tobias; Esslinger, Tilman
2015-01-01
The dynamic structure factor is a central quantity describing the physics of quantum many-body systems, capturing structure and collective excitations of a material. In condensed matter, it can be measured via inelastic neutron scattering, which is an energy-resolving probe for the density fluctuations. In ultracold atoms, a similar approach could so far not be applied because of the diluteness of the system. Here we report on a direct, real-time and nondestructive measurement of the dynamic structure factor of a quantum gas exhibiting cavity-mediated long-range interactions. The technique relies on inelastic scattering of photons, stimulated by the enhanced vacuum field inside a high finesse optical cavity. We extract the density fluctuations, their energy and lifetime while the system undergoes a structural phase transition. We observe an occupation of the relevant quasi-particle mode on the level of a few excitations, and provide a theoretical description of this dissipative quantum many-body system. PMID:25944151
Common physical mechanism for integer and fractional quantum Hall effects
Jianhua wang; Kang Li; Shuming Long; Yi Yuan
2012-01-24
Integer and fractional quantum Hall effects were studied with different physics models and explained by different physical mechanisms. In this paper, the common physical mechanism for integer and fractional quantum Hall effects is studied, where a new unified formulation of integer and fractional quantum Hall effect is presented. Firstly, we introduce a 2-dimensional ideal electron gas model in the presence of strong magnetic field with symmetry gauge, and the transverse electric filed $\\varepsilon_2$ is also introduced to balance Lorentz force. Secondly, the Pauli equation is solved where the wave function and energy levels is given explicitly. Thirdly, after the calculation of the degeneracy density for 2-dimensional ideal electron gas system, the Hall resistance of the system is obtained, where the quantum Hall number $\
Schiemangk, Max; Lampmann, Kai; Dinkelaker, Aline; Kohfeldt, Anja; Krutzik, Markus; Kürbis, Christian; Sahm, Alexander; Spießberger, Stefan; Wicht, Andreas; Erbert, Götz; Tränkle, Günther; Peters, Achim
2015-06-10
We present micro-integrated diode laser modules operating at wavelengths of 767 and 780 nm for cold quantum gas experiments on potassium and rubidium. The master-oscillator-power-amplifier concept provides both narrow linewidth emission and high optical output power. With a linewidth (10 ?s) below 1 MHz and an output power of up to 3 W, these modules are specifically suited for quantum optics experiments and feature the robustness required for operation at a drop tower or on-board a sounding rocket. This technology development hence paves the way toward precision quantum optics experiments in space. PMID:26192832
Quantum linear Boltzmann equation with finite intercollision time
Diosi, Lajos
2009-12-15
Inconsistencies are pointed out in the usual quantum versions of the classical linear Boltzmann equation constructed for a quantized test particle in a gas. These are related to the incorrect formal treatment of momentum decoherence. We prove that ideal collisions with the molecules would result in complete momentum decoherence, the persistence of coherence is only due to the finite intercollision time. A corresponding quantum linear Boltzmann equation is proposed.
OBTAINING LAWS OF THERMODYNAMICS FOR IDEAL GASES USING ELASTIC COLLISIONS
Montgomery-Smith, Stephen
N molecules of gas B in the right half of the container. The molecules obey Newton's laws of motion that Newton's laws of motion are all that are needed to predict the ideal gas laws, and that the collisions Newtonian. For example, the motion is reversible, thus demonstrating that the second law of thermodynamics
COVER IMAGE An ideal amplifier has low noise,
Loss, Daniel
COVER IMAGE An ideal amplifier has low noise, operates over a broad frequency range and has large and can achieve a noise limit very close to that set by quantum mechanics. Letter p623 COVER IMAGE with individual atoms is now demonstrated. Atomic-resolution differential phase-contrast imaging using aberration
Stationary waves in a superfluid exciton gas in quantum Hall bilayers.
Pikalov, A A; Fil, D V
2011-07-01
Stationary waves in a superfluid magnetoexciton gas in ? = 1 quantum Hall bilayers are considered. The waves are induced by counterpropagating electrical currents that flow in a system with a point obstacle. It is shown that stationary waves can emerge only in imbalanced bilayers in a certain diapason of currents. It is found that the stationary wave pattern is modified qualitatively under a variation of the ratio of the interlayer distance to the magnetic length [Formula: see text]. The advantages of using graphene-dielectric-graphene sandwiches for the observation of stationary waves are discussed. We determine the range of parameters (the dielectric constant of the layer that separates two graphene layers and the ratio d/l) for which the state with superfluid magnetoexcitons can be realized in such sandwiches. Typical stationary wave patterns are presented as density plots. PMID:21666305
Ferromagnetism of a repulsive atomic Fermi gas in an optical lattice: a quantum Monte Carlo study.
Pilati, S; Zintchenko, I; Troyer, M
2014-01-10
Using continuous-space quantum Monte Carlo methods, we investigate the zero-temperature ferromagnetic behavior of a two-component repulsive Fermi gas under the influence of periodic potentials that describe the effect of a simple-cubic optical lattice. Simulations are performed with balanced and with imbalanced components, including the case of a single impurity immersed in a polarized Fermi sea (repulsive polaron). For an intermediate density below half filling, we locate the transitions between the paramagnetic, and the partially and fully ferromagnetic phases. As the intensity of the optical lattice increases, the ferromagnetic instability takes place at weaker interactions, indicating a possible route to observe ferromagnetism in experiments performed with ultracold atoms. We compare our findings with previous predictions based on the standard computational method used in material science, namely density functional theory, and with results based on tight-binding models. PMID:24483906
Quantum Recurrences in a One-Dimensional Gas of Impenetrable Bosons
E. Solano-Carrillo
2015-10-13
It is well-known that a dilute one-dimensional (1D) gas of bosons with infinitely strong repulsive interactions behaves like a gas of free fermions. Just as with conduction electrons in metals, we consider a single-particle picture of the resulting dynamics, when the gas is isolated by enclosing it into a box with hard walls and preparing it in a special initial state. We show, by solving the nonstationary problem of a free particle in a 1D hard-wall box, that the single-particle state recurs in time, signaling the intuitively expected back-and-forth motion of a free particle moving in a confined space. Under suitable conditions, the state of the whole gas can then be made to recur if all the particles are put in the same initial momentum superposition. We introduce this problem here as a modern instance of the discussions giving rise to the famous recurrence paradox in statistical mechanics: on one hand, our results may be used to develop a poor man's interpretation of the recurrence of the initial state observed [T. Kinoshita et al, Nature 440, 900 (2006)] in trapped 1D Bose gases of cold atoms, for which our estimated recurrence time is in fair agreement with the period of the oscillations observed; but this experiment, on the other hand, has been substantially influential on the belief that an isolated quantum many-body system can equilibrate as a consequence of its own unitary nonequilibrium dynamics. Some ideas regarding the latter are discussed.
Quantum recurrences in a one-dimensional gas of impenetrable bosons.
Solano-Carrillo, E
2015-10-01
It is well-known that a dilute one-dimensional (1D) gas of bosons with infinitely strong repulsive interactions behaves like a gas of free fermions. Just as with conduction electrons in metals, we consider a single-particle picture of the resulting dynamics, when the gas is isolated by enclosing it into a box with hard walls and preparing it in a special initial state. We show, by solving the nonstationary problem of a free particle in a 1D hard-wall box, that the single-particle state recurs in time, signaling the intuitively expected back-and-forth motion of a free particle moving in a confined space. Under suitable conditions, the state of the whole gas can then be made to recur if all the particles are put in the same initial momentum superposition. We introduce this problem here as a modern instance of the discussions giving rise to the famous recurrence paradox in statistical mechanics: on one hand, our results may be used to develop a poor man's interpretation of the recurrence of the initial state observed [T. Kinoshita et al., Nature 440, 900 (2006)NATUAS0028-083610.1038/nature04693] in trapped 1D Bose gases of cold atoms, for which our estimated recurrence time is in fair agreement with the period of the oscillations observed; but this experiment, on the other hand, has been substantially influential on the belief that an isolated quantum many-body system can equilibrate as a consequence of its own unitary nonequilibrium dynamics. Some ideas regarding the latter are discussed. PMID:26565225
Quantum recurrences in a one-dimensional gas of impenetrable bosons
NASA Astrophysics Data System (ADS)
Solano-Carrillo, E.
2015-10-01
It is well-known that a dilute one-dimensional (1D) gas of bosons with infinitely strong repulsive interactions behaves like a gas of free fermions. Just as with conduction electrons in metals, we consider a single-particle picture of the resulting dynamics, when the gas is isolated by enclosing it into a box with hard walls and preparing it in a special initial state. We show, by solving the nonstationary problem of a free particle in a 1D hard-wall box, that the single-particle state recurs in time, signaling the intuitively expected back-and-forth motion of a free particle moving in a confined space. Under suitable conditions, the state of the whole gas can then be made to recur if all the particles are put in the same initial momentum superposition. We introduce this problem here as a modern instance of the discussions giving rise to the famous recurrence paradox in statistical mechanics: on one hand, our results may be used to develop a poor man's interpretation of the recurrence of the initial state observed [T. Kinoshita et al., Nature 440, 900 (2006), 10.1038/nature04693] in trapped 1D Bose gases of cold atoms, for which our estimated recurrence time is in fair agreement with the period of the oscillations observed; but this experiment, on the other hand, has been substantially influential on the belief that an isolated quantum many-body system can equilibrate as a consequence of its own unitary nonequilibrium dynamics. Some ideas regarding the latter are discussed.
An ytterbium quantum gas microscope with narrow-line laser cooling
Yamamoto, Ryuta; Kuno, Takuma; Kato, Kohei; Takahashi, Yoshiro
2015-01-01
We demonstrate site-resolved imaging of individual bosonic $^{174}\\mathrm{Yb}$ atoms in a Hubbard-regime two-dimensional optical lattice with a short lattice constant of 266 nm. To suppress the heating by probe light with the $^1S_0$-$^1P_1$ transition of the wavelength $\\lambda$ = 399 nm for high-resolution imaging and preserve atoms at the same lattice sites during the fluorescence imaging, we simultaneously cool atoms by additionally applying narrow-line optical molasses with the $^1S_0$-$^3P_1$ transition of the wavelength $\\lambda$ = 556 nm. We achieve a low temperature of $T = 7.4(1.3)\\ \\mu\\mathrm{K}$, corresponding to a mean oscillation quantum number along the horizontal axes of 0.22(4) during imaging process. We detect on average 200 fluorescence photons from a single atom within 400 ms exposure time, and estimate the detection fidelity of 87(2)%. The realization of a quantum gas microscope with enough fidelity for Yb atoms in a Hubbard-regime optical lattice opens up the possibilities for studying v...
Multi-species trace gas analysis with dual-wavelength quantum cascade laser
NASA Astrophysics Data System (ADS)
Jágerská, Jana; Tuzson, Béla; Looser, Herbert; Jouy, Pierre; Hugi, Andreas; Mangold, Markus; Soltic, Patrik; Faist, Jérôme; Emmenegger, Lukas
2015-04-01
Simultaneous detection of multiple gas species using mid-IR laser spectroscopy is highly appealing for a large variety of applications ranging from air quality monitoring, medical breath analysis to industrial process control. However, state-of-the-art distributed-feedback (DFB) mid-IR lasers are usually tunable only within a narrow spectral range, which generally leads to one-laser-one-compound measurement strategy. Thus, multi-species detection involves several lasers and elaborate beam combining solutions [1]. This makes them bulky, costly, and highly sensitive to optical alignment, which limits their field deployment. In this paper, we explore an alternative measurement concept based on a dual-wavelength quantum cascade laser (DW-QCL) [2]. Such a laser can emit at two spectrally distinct wavelengths using a succession of two DFB gratings with different periodicities and a common waveguide to produce one output beam. The laser design was optimized for NOx measurements and correspondingly emits single-mode at 5.26 and 6.25 ?m. Electrical separation of the respective laser sections makes it possible to address each wavelength independently. Thereby, it is possible to detect NO and NO2 species with one laser using the same optical path, without any beam combining optics, i.e. in a compact and cost-efficient single-path optical setup. Operated in a time-division multiplexed mode, the spectrometer reaches detection limits at 100 s averaging of 0.5 and 1.5 ppb for NO2 and NO, respectively. The performance of the system was validated against the well-established chemiluminescence detection while measuring the NOx emissions on an automotive test-bench, as well as monitoring the pollution at a suburban site. [1] B. Tuzson, K. Zeyer, M. Steinbacher, J. B. McManus, D. D. Nelson, M. S. Zahniser, and L. Emmenegger, 'Selective measurements of NO, NO2 and NOy in the free troposphere using quantum cascade laser spectroscopy,' Atmospheric Measurement Techniques 6, 927-936 (2013). [2] J. Jágerská, P. Jouy, A. Hugi, B. Tuzson, H. Looser, M. Mangold, M. Beck, L. Emmenegger, and J. Faist, 'Dual-wavelength quantum cascade laser for trace gas spectroscopy,' Applied Physics Letters 105, 161109-161109-4 (2014).
Ideal near-field thermophotovoltaic cells
NASA Astrophysics Data System (ADS)
Molesky, Sean; Jacob, Zubin
2015-05-01
We ask the question, what are the ideal characteristics of a near-field thermophotovoltaic cell? Our search leads us to a reformulation of near-field radiative heat transfer in terms of the joint density of electronic states of the emitter-absorber pair in the thermophotovoltaic system. This form reveals that semiconducting materials with narrowband absorption spectra are critical to the energy-conversion efficiency. This essential feature is unavailable in conventional bulk semiconductor cells but can be obtained using low-dimensional materials. Our results show that the presence of matched van Hove singularities resulting from quantum confinement in the emitter and absorber of a thermophotovoltaic cell boosts both the magnitude and spectral selectivity of radiative heat transfer, dramatically improving energy-conversion efficiency. We provide a model near-field thermophotovoltaic system design making use of this idea by employing the van Hove singularities present in carbon nanotubes. Shockley-Queisser analysis shows that the predicted heat transfer characteristics of this model device are fundamentally better than existing thermophotovoltaic designs. Our work paves the way for the use of quantum dots, quantum wells, two-dimensional semiconductors, semiconductor nanowires, and carbon nanotubes as future materials for thermophotovoltaic cells.
Quantum theory Bohrification: topos theory and quantum theory
Spitters, Bas
Quantum theory Bohrification: topos theory and quantum theory Bas Spitters Domains XI, 9/9/2014 Bas Spitters Bohrification: topos theory and quantum theory #12;Quantum theory Point-free Topology The axiom and quantum theory #12;Quantum theory Point-free Topology The axiom of choice is used to construct ideal
Elementary Excitations in Quantum Fermi Liquid
Nodar L. Tsintsadze; Levan N. Tsintsadze
2010-06-02
Landau's theory of Fermi liquids is generalized by incorporating the de Broglie waves diffraction. A newly derived kinetic equation of the Fermi particles is used to derive a general dispersion relation and the excitation of zero sound is studied. A new mode is found due to the quantum correction. It is shown that the zero sound can exist even in an ideal Fermi gas. We also disclose a new branch of frequency spectrum due to the weak interaction.
Chemical Laws, Idealization and Approximation
ERIC Educational Resources Information Center
Tobin, Emma
2013-01-01
This paper examines the notion of laws in chemistry. Vihalemm ("Found Chem" 5(1):7-22, 2003) argues that the laws of chemistry are fundamentally the same as the laws of physics they are all "ceteris paribus" laws which are true "in ideal conditions". In contrast, Scerri (2000) contends that the laws of chemistry are…
Collider performance with ideal collisions
Month, M.
1985-06-01
Performance is estimated for head-on bunch collisions. The luminosity is written as a distribution in time and length along the collision path, using a Gaussian distribution in all space dimensions. Computations are made for the Tevatron. Sources of luminosity reduction are listed in the case of non-ideal conditions.
. Su, Aviv Keshet, Ralf Gommers, Yong-il Shin, Wujie Huang, and Wolfgang Ketterle MIT-Harvard Center profiles of an ideal Fermi gas and observe Pauli suppression of density fluctuations (atom shot noise.1103/PhysRevLett.105.040402 PACS numbers: 03.75.Ss, 05.30.Fk, 67.85.Lm Systems of fermions obey the Pauli
Ideal mixture approximation of cluster size distributions at low density
S. Jansen; W. König
2011-12-20
We consider an interacting particle system in continuous configuration space. The pair interaction has an attractive part. We show that, at low density, the system behaves approximately like an ideal mixture of clusters (droplets): we prove rigorous bounds (a) for the constrained free energy associated with a given cluster size distribution, considered as an order parameter, (b) for the free energy, obtained by minimising over the order parameter, and (c) for the minimising cluster size distributions. It is known that, under suitable assumptions, the ideal mixture has a transition from a gas phase to a condensed phase as the density is varied; our bounds hold both in the gas phase and in the coexistence region of the ideal mixture. The present paper improves our earlier results by taking into account the mixing entropy.
Quantum chaos in ultracold collisions of gas-phase erbium atoms.
Frisch, Albert; Mark, Michael; Aikawa, Kiyotaka; Ferlaino, Francesca; Bohn, John L; Makrides, Constantinos; Petrov, Alexander; Kotochigova, Svetlana
2014-03-27
Atomic and molecular samples reduced to temperatures below one microkelvin, yet still in the gas phase, afford unprecedented energy resolution in probing and manipulating the interactions between their constituent particles. As a result of this resolution, atoms can be made to scatter resonantly on demand, through the precise control of a magnetic field. For simple atoms, such as alkalis, scattering resonances are extremely well characterized. However, ultracold physics is now poised to enter a new regime, where much more complex species can be cooled and studied, including magnetic lanthanide atoms and even molecules. For molecules, it has been speculated that a dense set of resonances in ultracold collision cross-sections will probably exhibit essentially random fluctuations, much as the observed energy spectra of nuclear scattering do. According to the Bohigas-Giannoni-Schmit conjecture, such fluctuations would imply chaotic dynamics of the underlying classical motion driving the collision. This would necessitate new ways of looking at the fundamental interactions in ultracold atomic and molecular systems, as well as perhaps new chaos-driven states of ultracold matter. Here we describe the experimental demonstration that random spectra are indeed found at ultralow temperatures. In the experiment, an ultracold gas of erbium atoms is shown to exhibit many Fano-Feshbach resonances, of the order of three per gauss for bosons. Analysis of their statistics verifies that their distribution of nearest-neighbour spacings is what one would expect from random matrix theory. The density and statistics of these resonances are explained by fully quantum mechanical scattering calculations that locate their origin in the anisotropy of the atoms' potential energy surface. Our results therefore reveal chaotic behaviour in the native interaction between ultracold atoms. PMID:24670766
A new quantum gas apparatus for ultracold mixtures of K and Cs and KCs ground-state molecules
Gröbner, Michael; Meinert, Florian; Lauber, Katharina; Kirilov, Emil; Nägerl, Hanns-Christoph
2015-01-01
We present a new quantum gas apparatus for ultracold mixtures of K and Cs atoms and ultracold samples of KCs ground-state molecules. We demonstrate the apparatus' capabilities by producing Bose-Einstein condensates (BEC) of 39K and 133Cs in a manner that will eventually allow sequential condensation within one experimental cycle, precise sample overlap, and magnetic association of atoms into KCs molecules. The condensates are created independently without relying on sympathetic cooling. Our approach is universal and applicable to other species combinations when the two species show dramatically different behavior in terms of loss mechanisms and post laser cooling temperatures, i.e. species combinations that make parallel generation of quantum degenerate samples challenging. We give an outlook over the next experiments involving e.g. sample mixing, molecule formation, and transport into a science chamber for high-resolution spatial imaging of novel quantum-many body phases based on K-Cs.
Gas-Phase Reactivity of Cesium-Containing Species by Quantum Chemistry.
Šulková, Katarína; Cantrel, Laurent; Louis, Florent
2015-09-01
Thermodynamics and kinetics of cesium species reactions have been studied by using high-level quantum chemical tools. A systematic theoretical study has been done to find suitable methodology for calculation of reliable thermodynamic properties, allowing us to determine bimolecular rate constants with appropriate kinetic theories of gas-phase reactions. Four different reactions have been studied in this work: CsO + H2 = CsOH + H (R1), Cs + HI = CsI + H (R2), CsI + H2O = CsOH + HI (R3), and CsI + OH = CsOH + I (R4). All reactions involve steam, hydrogen, and iodine in addition of cesium. Most of the reactions are fast and (R3) and (R4) proceed even without energetic barrier. In terms of chemical reactivity in the reactor coolant system (RCS) in the case of severe accident, it can be expected that there will be no kinetic limitations for main cesium species (CsOH and CsI) transported along the RCS. Cs chemical speciation inside the RCS should be governed by the thermodynamics. PMID:26237575
Quantum molecular dynamics study of the pressure dependence of the ammonia inversion transition
I. M. Herbauts; D. J. Dunstan
2007-04-15
The mechanism of the shift, broadening and quenching of the ammonia inversion frequency with gas pressure has been a problem of lively interest for over seventy years. A simple quantum model of the ammonia molecule perturbed by collisions with ideal gas molecules displays the essential features of the experimental data for NH3 and for ND3. The model does not display the behaviour expected from theories of quantum localisation such as quantum state diffusion and decoherence. On the other hand, models of perturbed classical oscillators do display similar behaviour to our model. The quenching of the ammonia inversion transition cannot therefore be interpreted as spatial localisation of the wavefunction.
Size-controlled synthesis of SnO2 quantum dots and their gas-sensing performance
NASA Astrophysics Data System (ADS)
Du, Jianping; Zhao, Ruihua; Xie, Yajuan; Li, Jinping
2015-08-01
Tin dioxide quantum dots (TQDs) with controllable size were synthesized by changing the amount of alkaline reagent in the hydrothermal process. The gas-sensing properties were investigated by operating chemoresistor type sensor. The morphology and structure were characterized by X-ray diffraction, scanning/transmission electron microscopy, UV-vis and Raman spectrometry. The as-synthesized SnO2 shows the characteristics of quantum dots and the narrowest size distribution is about 2-3 nm. The gas-sensing results indicate that the responses are strongly dependent on the size of quantum dots. TQDs with different sizes exhibit different sensitivities and selectivities to volatile toxic chemicals such as aldehyde, acetone, methanol, ethanol and amine. Especially, when the sensors are exposed to 100 ppm triethylamine (TEA), the sensing response value of TQDs with small size is two times higher than that of the large-size TQDs. The maximum response values of TQDs to 1 ppm and 100 ppm TEA are 15 and 153, respectively. The response time is 1 s and the recovery time is 47 s upon exposure to 1 ppm TEA. The results suggest that it is an effective method by regulating the size of SnO2 quantum dots to detect low-concentration hazardous volatile compounds.
FK-DLR properties of a quantum multi-type Bose-gas with a repulsive interaction
Suhov, Y.; Stuhl, I.
2014-08-01
The paper extends earlier results from Suhov and Kelbert [“FK-DLR states of a quantum Bose-gas with a hardcore interaction,” http://arxiv.org/abs/arXiv:1304.0782 ] and Suhov et al. [“Shift-invariance for FK-DLR states of a 2D quantum Bose-gas,” http://arxiv.org/abs/arXiv:1304.4177 ] about infinite-volume quantum bosonic states (FK-DLR states) to the case of multi-type particles with non-negative interactions. (An example is a quantum Widom–Rowlinson model.) Following the strategy from Suhov and Kelbert and Suhov et al., we establish that, for the values of fugacity z?(0, 1) and inverse temperature ? > 0, finite-volume Gibbs states form a compact family in the thermodynamic limit. Next, in dimension two we show that any limit-point state (an FK-DLR state in the terminology adopted in Suhov and Kelbert and Suhov et al.) is translation-invariant.
Ujjal Debnath; Mubasher Jamil
2015-01-03
In this work, we focus on the collapse of a spherically symmetric perturbation, with a classical top-hat profile, to study the nonlinear evolution of only viscous modified Chaplygin gas (VMCG) perturbations in Einstein's gravity as well as in loop quantum Cosmology (LQC). In the perturbed region, we have investigated the natures of equation of state parameter, square speed of sound and another perturbed quantities. The results have been analyzed by numerical and graphical investigations.
Phillips, Mark C.; Craig, Ian M.
2013-11-03
We analyze the long-term performance and stability of a trace-gas sensor based on an external cavity quantum cascade laser using data collected over a one-year period in a building air monitoring application.
Representation of Ideal Magnetohydrodynamic Modes
Roscoe B. White
2013-01-15
One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through ? ? = ? X (xi X B) ensures that ? B • ? ? = 0 at a resonance, with ? labelling an equilibrium flux surface. Also useful for the analysis of guiding center orbits in a perturbed field is the representation ? ? = ? X ?B. These two representations are equivalent, but the vanishing of ? B • ?? at a resonance is necessary but not sufficient for the preservation of field line topology, and a indiscriminate use of either perturbation in fact destroys the original equilibrium flux topology. It is necessary to find the perturbed field to all orders in xi to conserve the original topology. The effect of using linearized perturbations on stability and growth rate calculations is discussed
Obese people's perceptions of the thin ideal.
Couch, Danielle; Thomas, Samantha L; Lewis, Sophie; Blood, R Warwick; Holland, Kate; Komesaroff, Paul
2016-01-01
The media play a key role in promoting the thin ideal. A qualitative study, in which we used in depth interviews and thematic analysis, was undertaken to explore the attitudes of 142 obese individuals toward media portrayals of the thin ideal. Participants discussed the thin ideal as a social norm that is also supported through the exclusion of positive media portrayals of obese people. They perceived the thin ideal as an 'unhealthy' mode of social control, reflecting on their personal experiences and their concerns for others. Participants' perceptions highlighted the intersections between the thin ideal and gender, grooming and consumerism. Participants' personal responses to the thin ideal were nuanced - some were in support of the thin ideal and some were able to critically reflect and reject the thin ideal. We consider how the thin ideal may act as a form of synoptical social control, working in tandem with wider public health panoptical surveillance of body weight. PMID:26685706
Positron kinetics in an idealized PET environment.
Robson, R E; Brunger, M J; Buckman, S J; Garcia, G; Petrovi?, Z Lj; White, R D
2015-01-01
The kinetic theory of non-relativistic positrons in an idealized positron emission tomography PET environment is developed by solving the Boltzmann equation, allowing for coherent and incoherent elastic, inelastic, ionizing and annihilating collisions through positronium formation. An analytic expression is obtained for the positronium formation rate, as a function of distance from a spherical source, in terms of the solutions of the general kinetic eigenvalue problem. Numerical estimates of the positron range - a fundamental limitation on the accuracy of PET, are given for positrons in a model of liquid water, a surrogate for human tissue. Comparisons are made with the 'gas-phase' assumption used in current models in which coherent scattering is suppressed. Our results show that this assumption leads to an error of the order of a factor of approximately 2, emphasizing the need to accurately account for the structure of the medium in PET simulations. PMID:26246002
Positron kinetics in an idealized PET environment
Robson, R. E.; Brunger, M. J.; Buckman, S. J.; Garcia, G.; Petrovi?, Z. Lj.; White, R. D.
2015-01-01
The kinetic theory of non-relativistic positrons in an idealized positron emission tomography PET environment is developed by solving the Boltzmann equation, allowing for coherent and incoherent elastic, inelastic, ionizing and annihilating collisions through positronium formation. An analytic expression is obtained for the positronium formation rate, as a function of distance from a spherical source, in terms of the solutions of the general kinetic eigenvalue problem. Numerical estimates of the positron range - a fundamental limitation on the accuracy of PET, are given for positrons in a model of liquid water, a surrogate for human tissue. Comparisons are made with the ‘gas-phase’ assumption used in current models in which coherent scattering is suppressed. Our results show that this assumption leads to an error of the order of a factor of approximately 2, emphasizing the need to accurately account for the structure of the medium in PET simulations. PMID:26246002
Positron kinetics in an idealized PET environment
NASA Astrophysics Data System (ADS)
Robson, R. E.; Brunger, M. J.; Buckman, S. J.; Garcia, G.; Petrovi?, Z. Lj.; White, R. D.
2015-08-01
The kinetic theory of non-relativistic positrons in an idealized positron emission tomography PET environment is developed by solving the Boltzmann equation, allowing for coherent and incoherent elastic, inelastic, ionizing and annihilating collisions through positronium formation. An analytic expression is obtained for the positronium formation rate, as a function of distance from a spherical source, in terms of the solutions of the general kinetic eigenvalue problem. Numerical estimates of the positron range - a fundamental limitation on the accuracy of PET, are given for positrons in a model of liquid water, a surrogate for human tissue. Comparisons are made with the ‘gas-phase’ assumption used in current models in which coherent scattering is suppressed. Our results show that this assumption leads to an error of the order of a factor of approximately 2, emphasizing the need to accurately account for the structure of the medium in PET simulations.
that leverages the unique current injection mechanism in the form of quantum-mechanical band-to-band tunneling-to-band-tunneling current- injection mechanism of Tunnel-FET813 to achieve signifi- cantly superior performance under to sense hydrogen.2,3 The transduction mechanism involves dissociation and adsorption of hydrogen molecules
Nanowire Waveguides Launching Single Photons in a Gaussian Mode for Ideal Fiber Coupling
Nanowire Waveguides Launching Single Photons in a Gaussian Mode for Ideal Fiber Coupling Gabriele by embedding a semiconductor quantum dot in a tapered nanowire waveguide. Owing to the deterministic photonic technologies. KEYWORDS: Quantum dot, nanowire, single photon emission, waveguide modes, Fourier
Quantum lattice gas model of Dirac particles in 1+1 dimensions
Jeffrey Yepez
2013-07-12
Presented is a quantum computing representation of Dirac particle dynamics. The approach employs an operator splitting method that is an analytically closed-form product decomposition of the unitary evolution operator. This allows the Dirac equation to be cast as a unitary finite-difference equation in a high-energy limit. The split evolution operator (with separate kinetic and interaction terms) is useful for efficient quantum simulation. For pedagogical purposes, here we restrict the treatment to Dirac particle dynamics in 1+1 spacetime dimensions. Independent derivations of the quantum algorithm are presented and the model's validity is tested in several quantum simulations by comparing the numerical results against analytical predictions. Using the relativistic quantum algorithm in the case when mc^2 >> pc, quantum simulations of a nonrelativistic particle in an external scalar square well and parabolic potential is presented.
Experimentally efficient methods for estimating the performance of quantum measurements
Magesan, Easwar
Efficient methods for characterizing the performance of quantum measurements are important in the experimental quantum sciences. Ideally, one requires both a physically relevant distinguishability measure between measurement ...
Chemical Laws, Idealization and Approximation
NASA Astrophysics Data System (ADS)
Tobin, Emma
2013-07-01
This paper examines the notion of laws in chemistry. Vihalemm ( Found Chem 5(1):7-22, 2003) argues that the laws of chemistry are fundamentally the same as the laws of physics they are all ceteris paribus laws which are true "in ideal conditions". In contrast, Scerri (2000) contends that the laws of chemistry are fundamentally different to the laws of physics, because they involve approximations. Christie ( Stud Hist Philos Sci 25:613-629, 1994) and Christie and Christie ( Of minds and molecules. Oxford University Press, New York, pp. 34-50, 2000) agree that the laws of chemistry are operationally different to the laws of physics, but claim that the distinction between exact and approximate laws is too simplistic to taxonomise them. Approximations in chemistry involve diverse kinds of activity and often what counts as a scientific law in chemistry is dictated by the context of its use in scientific practice. This paper addresses the question of what makes chemical laws distinctive independently of the separate question as to how they are related to the laws of physics. From an analysis of some candidate ceteris paribus laws in chemistry, this paper argues that there are two distinct kinds of ceteris paribus laws in chemistry; idealized and approximate chemical laws. Thus, while Christie ( Stud Hist Philos Sci 25:613-629, 1994) and Christie and Christie ( Of minds and molecules. Oxford University Press, New York, pp. 34--50, 2000) are correct to point out that the candidate generalisations in chemistry are diverse and heterogeneous, a distinction between idealizations and approximations can nevertheless be used to successfully taxonomise them.
FAITHFUL IDEAL MODELS FOR RECURSIVE POLYMORPHIC TYPES
Abadi, Martin; Pierce, Benjamin; Plotkin, Gordon
2003-11-03
We explore ideal models for a programming language with recursive polymorphic types, variants of the model studied by MacQueen, Plotkin, and Sethi. The use of suitable ideals yields a close fit between models and programming ...
Deviation magnification: Revealing departures from ideal geometries
Wadhwa, Neal
Structures and objects are often supposed to have idealized geometries such as straight lines or circles. Although not always visible to the naked eye, in reality, these objects deviate from their idealized models. Our ...
Homological Invariants of Monomial and Binomial Ideals
Kummini, Neelakandhan Manoj
2008-08-19
In this dissertation, we study numerical invariants of minimal graded free resolutions of homogeneous ideals in a polynomial ring R. Chapters 2, 3 and 4 deal with homological invariants of edge ideals of bipartite graphs. First, in Chapter 2, we...
(Fuzzy) Ideals of BN-Algebras.
Dymek, Grzegorz; Walendziak, Andrzej
2015-01-01
The notions of an ideal and a fuzzy ideal in BN-algebras are introduced. The properties and characterizations of them are investigated. The concepts of normal ideals and normal congruences of a BN-algebra are also studied, the properties of them are displayed, and a one-to-one correspondence between them is presented. Conditions for a fuzzy set to be a fuzzy ideal are given. The relationships between ideals and fuzzy ideals of a BN-algebra are established. The homomorphic properties of fuzzy ideals of a BN-algebra are provided. Finally, characterizations of Noetherian BN-algebras and Artinian BN-algebras via fuzzy ideals are obtained. PMID:26125050
Numerical simulation of oscillatory flow in an idealized thermoacoustic refrigerator
NASA Astrophysics Data System (ADS)
Besnoin, Etienne; Knio, Omar
1998-11-01
A vorticity-based computational model of an idealized thermoacoustic refrigerator is developed. The refrigerator consists of a stack of rectangular parallel plates and of heat exchangers on both sides of the stack. The heat exchangers are assumed to have a geometry similar to that of the stack and are separated from it by gaps whose widths can be varied. The evolution of the flow within the idealized refrigerator is described in terms of a low-Mach-number formulation of the compressible mass, momentum and energy conservation equations for an ideal gas mixture. The governing equations are simulated using a finite-difference solver which combines a domain-decomposition/boundary Green's function technique with fast Poisson solvers. The scheme is used to compute the response of the device to low-amplitude acoustic oscillations, and to analyze the evolution of the vorticity and temperature fields in the neighborhood of the stack and heat exchangers. * Supported by the Office of Naval Research
Representation of ideal magnetohydrodynamic modes
White, R. B.
2013-02-15
One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through {delta}B(vector sign)={nabla} Multiplication-Sign ({xi}(vector sign) Multiplication-Sign B(vector sign)) ensures that {delta}B(vector sign){center_dot}{nabla}{psi}=0 at a resonance, with {psi} labelling an equilibrium flux surface. Also useful for the analysis of guiding center orbits in a perturbed field is the representation {delta}B(vector sign)={nabla} Multiplication-Sign {alpha}B(vector sign). These two representations are equivalent, but the vanishing of {delta}B(vector sign){center_dot}{nabla}{psi} at a resonance is necessary but not sufficient for the preservation of field line topology, and a indiscriminate use of either perturbation in fact destroys the original equilibrium flux topology. It is necessary to find the perturbed field to all orders in {xi}(vector sign) to conserve the original topology. The effect of using linearized perturbations on stability and growth rate calculations is discussed.
Life's Solutions are Not Ideal
Bob Eisenberg
2011-05-01
Life occurs in ionic solutions, not pure water. The ionic mixtures of these solutions are very different from water and have dramatic effects on the cells and molecules of biological systems, yet theories and simulations cannot calculate their properties. I suggest the reason is that existing theories stem from the classical theory of ideal or simple gases in which (to a first approximation) atoms do not interact. Even the law of mass action describes reactants as if they were ideal. I propose that theories of ionic solutions should start with the theory of complex fluids because that theory is designed to deal with interactions from the beginning. The variational theory of complex fluids is particularly well suited to describe mixtures like the solutions in and outside biological cells. When a component or force is added to a solution, the theory derives - by mathematics alone - a set of partial differential equations that captures the resulting interactions self-consistently. Such a theory has been implemented and shown to be computable in biologically relevant systems but it has not yet been thoroughly tested in equilibrium or flow.
Fashion dolls: representations of ideals of beauty.
Pedersen, E L; Markee, N L
1991-08-01
To study the ideal of beauty that fashion dolls portray, a sample of 15 dolls (one of each type available by manufacturer) was collected. In comparison with both the fashion model ideal and the Greek model of beauty the dolls were observed to be short waisted and to have longer legs than either ideal. PMID:1945727
Recharging Our Sense of Idealism: Concluding Thoughts
ERIC Educational Resources Information Center
D'Andrea, Michael; Dollarhide, Colette T.
2011-01-01
In this article, the authors aim to recharge one's sense of idealism. They argue that idealism is the Vitamin C that sustains one's commitment to implementing humanistic principles and social justice practices in the work of counselors and educators. The idealism that characterizes counselors and educators who are humanistic and social justice…
A quantum lattice-gas model for the many-particle Schrödinger equation in d dimensions
Boghosian, B M
1996-01-01
We consider a general class of discrete unitary dynamical models on the lattice. We show that generically such models give rise to a wavefunction satisfying a Schroedinger equation in the continuum limit, in any number of dimensions. We find a simple mathematical relationship between the mass of the Schroedinger particle and the eigenvalues of a unitary matrix describing the local evolution of the model. An arbitrary potential is easily incorporated into these systems. Quantum versions of these unitary models can be defined, describing in the continuum limit the evolution of a nonrelativistic quantum many-body theory. These discrete quantum systems fall in the recently considered class of quantum lattice gases. As such, these models are particularly well suited for simulation on a quantum computer.
Goswami, Srijit; Aamir, Mohammed Ali; Shamim, Saquib; Ghosh, Arindam; Siegert, Christoph; Farrer, Ian; Ritchie, David A.; Pepper, Michael
2013-12-04
We use a dual gated device structure to introduce a gate-tuneable periodic potential in a GaAs/AlGaAs two dimensional electron gas (2DEG). Using only a suitable choice of gate voltages we can controllably alter the potential landscape of the bare 2DEG, inducing either a periodic array of antidots or quantum dots. Antidots are artificial scattering centers, and therefore allow for a study of electron dynamics. In particular, we show that the thermovoltage of an antidot lattice is particularly sensitive to the relative positions of the Fermi level and the antidot potential. A quantum dot lattice, on the other hand, provides the opportunity to study correlated electron physics. We find that its current-voltage characteristics display a voltage threshold, as well as a power law scaling, indicative of collective Coulomb blockade in a disordered background.
The Quantum Field Theory of the Ensemble Operator
NASA Astrophysics Data System (ADS)
Porter, Richard N.
2009-03-01
Quantum field theory (QFT) provides a systematic investigative tool for ensembles of molecules. The grand-canonical ensemble operator (GCEO) for an ideal gas is presented in terms of the Fock creation and annihilation operators. The ideal GCEO can be shown to obey a simple equation which facilitates calculation of quantum-statistical properties of bosonic and fermionic molecules. Examples are linked-cluster QFT derivations of the grand-canonical partition function and the Poisson distribution for non-interacting molecules. The Boltzmann limit is achieved by omitting exchange diagrams. Summations of Feynman diagrams for long- and short-range interactions to infinite order lead to a useful model of the pair-correlation function and a new avenue for the study of dynamics near the critical point for gas-liquid phase transitions.
The Quantum Field Theory of the Ensemble Operator
Porter, Richard N.
2009-03-09
Quantum field theory (QFT) provides a systematic investigative tool for ensembles of molecules. The grand-canonical ensemble operator (GCEO) for an ideal gas is presented in terms of the Fock creation and annihilation operators. The ideal GCEO can be shown to obey a simple equation which facilitates calculation of quantum-statistical properties of bosonic and fermionic molecules. Examples are linked-cluster QFT derivations of the grand-canonical partition function and the Poisson distribution for non-interacting molecules. The Boltzmann limit is achieved by omitting exchange diagrams. Summations of Feynman diagrams for long- and short-range interactions to infinite order lead to a useful model of the pair-correlation function and a new avenue for the study of dynamics near the critical point for gas-liquid phase transitions.
Jianming Zhan; Wies?aw A. Dudek
2006-05-28
A characterization of an $h$-hemiregular hemiring in terms of a fuzzy $h$-ideal is provided. Some properties of prime fuzzy $h$-ideals of $h$-hemiregular hemirings are investigated. It is proved that a fuzzy subset $\\zeta$ of a hemiring $S$ is a prime fuzzy left (right) $h$-ideal of $S$ if and only if $\\zeta$ is two-valued, $\\zeta(0) = 1$, and the set of all $x$ in $S$ such that $\\zeta(x) = 1$ is a prime (left) right $h$-ideal of $S$. Finally, the similar properties for maximal fuzzy left (right) $h$-ideals of hemirings are considered.
Duxbury, Geoffrey; Langford, Nigel; McCulloch, Michael T; Wright, Stephen
2005-11-01
The Quantum cascade (QC) laser is an entirely new type of semiconductor device in which the laser wavelength depends on the band-gap engineering. It can be made to operate over a much larger range than lead salt lasers, covering significant parts of both the infrared and submillimetre regions, and with higher output power. In this tutorial review we survey some of the applications of these new lasers, which range from trace gas detection for atmospheric or medical purposes to sub-Doppler and time dependent non-linear spectroscopy. PMID:16239994
NASA Astrophysics Data System (ADS)
Bai, C.; Yang, Y.-L.; Zhang, X.-D.
2008-09-01
Based on the extended Blonder-Tinkham-Klapwijk (BTK) approach, we have investigated the coherent quantum transport in two-dimensional electron gas/superconductor (2DEG/SC) double tunneling junctions in the presence of the Rashba spin-orbit coupling (RSOC). It is found that all the reflection coefficients in BTK theory as well as conductance spectra oscillate with the external voltage and energy. The oscillation feature of conductance can be tuned largely by the RSOC for low insulating barriers, while for high insulating barriers it is almost independent of the RSOC. These phenomena are essentially different from those found in ferromagnet/superconductor double tunneling junctions.
Analysis of Trace Gas Mixtures Using an External Cavity Quantum Cascade Laser Sensor
Phillips, Mark C.; Taubman, Matthew S.; Brumfield, Brian E.; Kriesel, Jason M.
2015-07-01
We measure and analyze mixtures of trace gases at ppb-ppm levels using an external cavity quantum cascade laser sensor with a 1-second response time. Accurate spectral fits are obtained in the presence of overlapping spectra.
Two-dimensional electron gas in monolayer InN quantum wells
Pan, W. E-mail: e.dimakis@hzdr.de; Wang, G. T.; Dimakis, E. E-mail: e.dimakis@hzdr.de; Moustakas, T. D.; Tsui, D. C.
2014-11-24
We report in this letter experimental results that confirm the two-dimensional nature of the electron systems in a superlattice structure of 40 InN quantum wells consisting of one monolayer of InN embedded between 10?nm GaN barriers. The electron density and mobility of the two-dimensional electron system (2DES) in these InN quantum wells are 5?×?10{sup 15?}cm{sup ?2} (or 1.25?×?10{sup 14?}cm{sup ?2} per InN quantum well, assuming all the quantum wells are connected by diffused indium contacts) and 420?cm{sup 2}/Vs, respectively. Moreover, the diagonal resistance of the 2DES shows virtually no temperature dependence in a wide temperature range, indicating the topological nature of the 2DES.
NASA Astrophysics Data System (ADS)
Phillips, Mark C.; Taubman, Matthew S.; Kriesel, Jason
2015-01-01
We describe a prototype trace gas sensor designed for real-time detection of multiple chemicals. The sensor uses an external cavity quantum cascade laser (ECQCL) swept over its tuning range of 940-1075 cm-1 (9.30-10.7 ?m) at a 10 Hz repetition rate. The sensor was designed for operation in multiple modes, including gas sensing within a multi-pass Heriott cell and intracavity absorption sensing using the ECQCL compliance voltage. In addition, the ECQCL compliance voltage was used to reduce effects of long-term drifts in the ECQCL output power. The sensor was characterized for noise, drift, and detection of chemicals including ammonia, methanol, ethanol, isopropanol, Freon- 134a, Freon-152a, and diisopropyl methylphosphonate (DIMP). We also present use of the sensor for mobile detection of ammonia downwind of cattle facilities, in which concentrations were recorded at 1-s intervals.
Barmettler, Peter; Kollath, Corinna
2011-10-15
We study the complex dynamics of a one-dimensional Bose gas subjected to a dissipative local defect which induces one-body atom losses. In experiments these atom losses occur, for example, when a focused electron or light beam or a single trapped ion is brought into contact with a quantum gas. We discuss how within such setups one can measure or manipulate densities locally and specify the excitations that are induced by the defect. In certain situations the defect can be used to generate entanglement in a controlled way despite its dissipative nature. The careful examination of the interplay between hole excitations and the collapse of the wave function due to nondetection of loss is crucial for the understanding of the dynamics we observe.
Li, Yongqiang; Dong, Wenpu; Zeng, Jiaolong; Yuan, Jianmin
2015-01-01
We develop a large scale quantum master equation approach to describe dynamical processes of practical open quantum systems driven by both coherent and stochastic interactions by including more than one thousand true states of the systems, motivated by the development of highly bright and fully coherent lasers in the X-ray wavelength regime. The method combines the processes of coherent dynamics induced by the X-ray laser and incoherent relaxations due to spontaneous emissions, Auger decays, and electronic collisions. As examples, theoretical investigation of {\\it real} coherent dynamics of inner-shell electrons of a neon gas, irradiated by a high-intensity X-ray laser with a full temporal coherence, is carried out with the approach. In contrast to the rate equation treatment, we find that coherence can suppress the multiphoton absorptions of a neon gas in the ultra-intense X-ray pulse, due to coherence-induced Rabi oscillations and power broadening effects. We study the influence of coherence on ionization p...
Huseyin Cakalli; Bipan Hazarika
2012-03-09
An ideal $I$ is a family of subsets of positive integers $\\textbf{N}$ which is closed under taking finite unions and subsets of its elements. A sequence $(x_n)$ of real numbers is said to be $I$-convergent to a real number $L$, if for each \\;$ \\varepsilon> 0$ the set $\\{n:|x_{n}-L|\\geq \\varepsilon\\}$ belongs to $I$. We introduce $I$-ward compactness of a subset of $\\textbf{R}$, the set of real numbers, and $I$-ward continuity of a real function in the senses that a subset $E$ of $\\textbf{R}$ is $I$-ward compact if any sequence $(x_{n})$ of points in $E$ has an $I$-quasi-Cauchy subsequence, and a real function is $I$-ward continuous if it preserves $I$-quasi-Cauchy sequences where a sequence $(x_{n})$ is called to be $I$-quasi-Cauchy when $(\\Delta x_{n})$ is $I$-convergent to 0. We obtain results related to $I$-ward continuity, $I$-ward compactness, ward continuity, ward compactness, ordinary compactness, ordinary continuity, $\\delta$-ward continuity, and slowly oscillating continuity.
Chemical dynamics in the gas phase: Time-dependent quantum mechanics of chemical reactions
Gray, S.K.
1993-12-01
A major goal of this research is to obtain an understanding of the molecular reaction dynamics of three and four atom chemical reactions using numerically accurate quantum dynamics. This work involves: (i) the development and/or improvement of accurate quantum mechanical methods for the calculation and analysis of the properties of chemical reactions (e.g., rate constants and product distributions), and (ii) the determination of accurate dynamical results for selected chemical systems, which allow one to compare directly with experiment, determine the reliability of the underlying potential energy surfaces, and test the validity of approximate theories. This research emphasizes the use of recently developed time-dependent quantum mechanical methods, i.e. wave packet methods.
Two-dimensional electron gas in monolayer InN quantum wells
Pan, Wei; Dimakis, Emmanouil; Wang, George T.; Moustakas, Theodore D.; Tsui, Daniel C.
2014-11-24
We report in this letter experimental results that confirm the two-dimensional nature of the electron systems in monolayer InN quantum wells embedded in GaN barriers. The electron density and mobility of the two-dimensional electron system (2DES) in these InN quantum wells are 5×1015 cm-2 and 420 cm2 /Vs, respectively. Moreover, the diagonal resistance of the 2DES shows virtually no temperature dependence in a wide temperature range, indicating the topological nature of the 2DES.
Two-dimensional electron gas in monolayer InN quantum wells
Pan, Wei; Dimakis, Emmanouil; Wang, George T.; Moustakas, Theodore D.; Tsui, Daniel C.
2014-11-24
We report in this letter experimental results that confirm the two-dimensional nature of the electron systems in monolayer InN quantum wells embedded in GaN barriers. The electron density and mobility of the two-dimensional electron system (2DES) in these InN quantum wells are 5×10^{15} cm^{-2} and 420 cm^{2 }/Vs, respectively. Moreover, the diagonal resistance of the 2DES shows virtually no temperature dependence in a wide temperature range, indicating the topological nature of the 2DES.
Practicing Identity: A Crafty Ideal?
NASA Astrophysics Data System (ADS)
Brysbaert, A.; Vetters, M.
This paper focuses on the materialization of technological practices as a form of identity expression. Contextual analyses of a Mycenaean workshop area in the Late Bronze Age citadel of Tiryns (Argolis, Greece) are presented to investigate the interaction of different artisans under changing socio-political and economic circumstances. The case study indicates that although certain technological practices are often linked to specific crafts, they do not necessarily imply the separation of job tasks related to the working of one specific material versus another. Shared technological practices and activities, therefore, may be a factor in shaping cohesive group identities of specialized artisans. Since tracing artisans' identities is easier said than done on the basis of excavated materials alone, we employ the concepts of multiple chaînes opératoires combined with cross-craft interactions as a methodology in order to retrieve distinctive sets of both social and technological practices from the archaeological remains. These methodological concepts are not restricted to a specific set of steps in the production cycle, but ideally encompass reconstructing contexts of extraction, manufacture, distribution and discard/reuse for a range of artefacts. Therefore, these concepts reveal both technological practices, and, by contextualising these technological practices in their spatial layout, equally focus on social contacts that would have taken place during any of these actions. Our detailed contextual study demonstrates that the material remains when analysed in their entirety are complementary to textual evidence. In this case study they even form a source of information on palatial spheres of life about which the fragmentary Linear B texts, so far, remain silent.
Suspended graphene films and their Casimir interaction with ideal conductor
I. V. Fialkovsky
2009-10-10
We adopt the Dirac model for graphene and calculate the Casimir interaction energy between a plane suspended graphene sample and a parallel plane ideal conductor. We employ both the Quantum Field Theory (QFT) approach, and the Lifshitz formula generalizations. The first approach turns out to be the leading order in the coupling constant of the second one. The Casimir interaction for this system appears to be rather weak but experimentally measurable. It exhibits a strong dependence on the mass of the quasi-particles in graphene.
Monitoring derivation of the quantum linear Boltzmann equation
Hornberger, Klaus; Vacchini, Bassano
2008-02-15
We show how the effective equation of motion for a distinguished quantum particle in an ideal gas environment can be obtained by means of the monitoring approach introduced by Hornberger [EPL 77, 50007 (2007)]. The resulting Lindblad master equation accounts for the quantum effects of the scattering dynamics in a nonperturbative fashion and it describes decoherence and dissipation in a unified framework. It incorporates various established equations as limiting cases and reduces to the classical linear Boltzmann equation once the state is diagonal in momentum.
Statistical mechanics based on fractional classical and quantum mechanics
Korichi, Z.; Meftah, M. T.
2014-03-15
The purpose of this work is to study some problems in statistical mechanics based on the fractional classical and quantum mechanics. At first stage we have presented the thermodynamical properties of the classical ideal gas and the system of N classical oscillators. In both cases, the Hamiltonian contains fractional exponents of the phase space (position and momentum). At the second stage, in the context of the fractional quantum mechanics, we have calculated the thermodynamical properties for the black body radiation, studied the Bose-Einstein statistics with the related problem of the condensation and the Fermi-Dirac statistics.
MULTIDIMENSIONAL RESIDUES AND IDEAL MEMBERSHIP Alessandro Perotti
Perotti, Alessandro
MULTIDIMENSIONAL RESIDUES AND IDEAL MEMBERSHIP Alessandro Perotti Abstract. Let I(f) be a zero-dimensional ideal in C[z1, . . . , zn] defined by a map- ping f. We compute the logarithmic residue of a polynomial case by means of a limiting process. We then consider the total sum of local residues of g w.r.t. f
Maintaining ideal body weight counseling sessions
Brammer, S.H.
1980-10-09
The purpose of this program is to provide employees with the motivation, knowledge and skills necessary to maintain ideal body weight throughout life. The target audience for this program, which is conducted in an industrial setting, is the employee 40 years of age or younger who is at or near his/her ideal body weight.
Closing the Idealization Gap with Theory Generation
Wing, Jeannette M.
Closing the Idealization Gap with Theory Generation (Extended Abstract) Darrell Kindred Jeannette M at a convenient level of abstraction; however, the gap between the "idealized" protocol 1 #12;theory generator process. We take a new approach, "theory generation," which allows highly automated reasoning
HOCHSCHILD COHOMOLOGY OF ALGEBRAS WITH HOMOLOGICAL IDEALS
Xi, Changchang
heredity ideal, then the long exact sequence provides information on H i (A), H i (B) and the extension, the quotient A # B := A/J is a homological epimorphism. Furthermore, if J is a heredity ideal of A, that is, J
Ideal and Nonideal Reasoning in Educational Theory
ERIC Educational Resources Information Center
Jaggar, Alison M.
2015-01-01
The terms "ideal theory" and "nonideal theory" are used in contemporary Anglophone political philosophy to identify alternative methodological approaches for justifying normative claims. Each term is used in multiple ways. In this article Alison M. Jaggar disentangles several versions of ideal and nonideal theory with a view to…
A New Criterion for the "Ideal" Child?
ERIC Educational Resources Information Center
Murphy, Douglas; And Others
1984-01-01
Teachers of gifted students and experts in creativity and gifted child education ranked personality characteristics of gifted students. Comparison with Torrance's Ideal Child Checklist (1963) revealed major shifts in the past 20 years in the image of the ideal child and in the extent of agreement between teachers and experts. (CL)
Computational chemistry, in conjunction with gas chromatography/mass spectrometry/Fourier transform infrared spectrometry (GC/MS/FT-IR), was used to tentatively identify seven tetrachlorobutadiene (TCBD) isomers detected in an environmental sample. Computation of the TCBD infrare...
A Quantum Chemistry Study of Natural Gas Hydrates Mert Atilhan,1
Pala, Nezih
, with shiftings rising from host-guest interactions, and useful patterns in the terahertz region rising from water and academia because of the massive amounts of gas in the form of hydrates in ocean bed and under permafrost
Quantum oscillations in a two-dimensional electron gas in black phosphorus thin films
NASA Astrophysics Data System (ADS)
Li, Likai; Ye, Guo Jun; Tran, Vy; Fei, Ruixiang; Chen, Guorui; Wang, Huichao; Wang, Jian; Watanabe, Kenji; Taniguchi, Takashi; Yang, Li; Chen, Xian Hui; Zhang, Yuanbo
2015-07-01
For decades, two-dimensional electron gases (2DEG) have allowed important experimental discoveries and conceptual developments in condensed-matter physics. When combined with the unique electronic properties of two-dimensional crystals, they allow rich physical phenomena to be probed at the quantum level. Here, we create a 2DEG in black phosphorus—a recently added member of the two-dimensional atomic crystal family—using a gate electric field. The black phosphorus film hosting the 2DEG is placed on a hexagonal boron nitride substrate. The resulting high carrier mobility in the 2DEG allows the observation of quantum oscillations. The temperature and magnetic field dependence of these oscillations yields crucial information about the system, such as cyclotron mass and lifetime of its charge carriers. Our results, coupled with the fact that black phosphorus possesses anisotropic energy bands with a tunable, direct bandgap, distinguish black phosphorus 2DEG as a system with unique electronic and optoelectronic properties.
Nonequilibrium statistical mechanics of classical nuclei interacting with the quantum electron gas
NASA Astrophysics Data System (ADS)
Wang, Yu; Kantorovich, Lev
2007-10-01
Kinetic equations governing time evolution of positions and momenta of atoms in extended systems are derived using quantum-classical ensembles within the nonequilibrium statistical operator method (NESOM). Ions are treated classically, while their electrons quantum mechanically; however, the statistical operator is not factorized in any way and no simplifying assumptions are made concerning the electronic subsystem. Using this method, we derive kinetic equations of motion for the classical degrees of freedom (atoms) which account fully for the interaction and energy exchange with the quantum variables (electrons). Our equations, alongside the usual “Newton-like” terms normally associated with the Ehrenfest dynamics, contain additional terms, proportional to the atoms velocities, which can be associated with the “electronic friction.” Although previously electronic friction was introduced into molecular dynamics equations of atoms only using model treatments, we show that this result is general and model independent and thus must be expected in treating any system as an additional force acting on slow degrees of freedom due to coupling with the fast ones. Possible ways of calculating the friction forces, which are shown to be given via complicated nonequilibrium correlation functions, are discussed. In particular, we demonstrate that the correlation functions are directly related to the thermodynamic Matsubara Green’s functions, and this relationship allows for the diagrammatic methods to be used in treating electron-electron interaction perturbatively when calculating the correlation functions.
On the Splitting of a Quantum Degenerate Gas of Identical Bosons
NASA Astrophysics Data System (ADS)
Faust, Douglas Karl
2011-12-01
The observation of Bose-Einstein condensation in dilute clouds of trapped atoms has stimulated a great deal of research in the last 15 years. Since the basic description of a single Bose-Einstein condensate (BEC) is that of a single macroscopic condensate wavefunction, or condensate order parameter, which displays all of the interference and non-local phenomena associated with the typical quantum mechanical wavefunction, yet describes up to millions of particles, these systems have the potential to bridge the quantum mechanical and visible classical worlds. Many basic scientific questions can be addressed by examining what happens when a single such system is split into multiple entities, independently manipulated and then recombined as has been done experimentally in the case of two potential welts [1] and many potential wells [2], [3]. This thesis shows that these experiments can operate in both a classical and quantum mechanical splitting regime and demarcates the boundary in between the two. By analyzing two specific BEC splitting experiments, it is shown that splitting experiments operating in the limit of a large number of particles per well can exhibit a phenomenon analogous to supercooling in classical phase transitions. In order to perform these simulations, a novel method, extending earlier theoretical work on the splitting problem is presented, computationally implemented, and supported by analytic calculations when possible.
Tan, Song; Liu, Wan-feng; Wang, Li-jun; Zhang, Jin-chuan; Li, Lu; Liu, Jun-qi; Liu, Feng-qi; Wang, Zhan-guo
2012-05-01
There have been considerable interests in methane detection based on infrared absorption spectroscopy for industrial and environment monitoring. The authors report on the realization of photoacoustic detection of methane (CH4) using mid-infrared distributed-feedback quantum cascade laser (DFB-QCL). The absorption line at 1316.83 cm(-1) was selected for CH4 detection, which can be reached by the self-manufactured DFB-QCL source operating in pulsed mode near 7.6 microm at room-temperature. The CH4 gas is filled to a Helmholtz resonant photoacoustic cell, which was equipped with a commercial electret microphone. The DFB-QCL was operated at 234 Hz with an 80 mW optical peak power. A detection limit of 189 parts per billion in volume was derived when the signal-to-noise ratio equaled 1. PMID:22827065
Quantum-tunneling dynamics of a spin-polarized Fermi gas in a double-well potential
Salasnich, L.; Mazzarella, G.; Toigo, F.; Salerno, M.
2010-02-15
We study the exact dynamics of a one-dimensional spin-polarized gas of fermions in a double-well potential at zero and finite temperature. Despite the system being made of noninteracting fermions, its dynamics can be quite complex, showing strongly aperiodic spatio-temporal patterns during the tunneling. The extension of these results to the case of mixtures of spin-polarized fermions interacting with self-trapped Bose-Einstein condensates (BECs) at zero temperature is considered as well. In this case we show that the fermionic dynamics remains qualitatively similar to that observed in the absence of BEC but with the Rabi frequencies of fermionic excited states explicitly depending on the number of bosons and on the boson-fermion interaction strength. From this, the possibility of controlling quantum fermionic dynamics by means of Feshbach resonances is suggested.
NASA Astrophysics Data System (ADS)
Chwiej, T.; Szafran, B.
2013-02-01
We present a systematic numerical simulation of the scanning gate microscopy experiment as performed on a quantum ring etched out of InGaAs/InAlAs heterostructure containing two-dimensional electron gas (2DEG). The present simulation accounts for 2DEG deformation under the presence of the tip, for modification of the electron charge trapped at the semiconductor/vacuum interface, for polarization effects at the interface, for the image charges related to the presence of the metal tip and for the three-dimensional character of the confinement. Once the potential is established by self-consistence of the Schrödinger-Poisson scheme, the linear conductance is evaluated by solution of the quantum scattering problem with several subbands at the Fermi level. We find that the conductance is a slowly varying function of the tip position in accordance with the experimental data. We study the high-pass-filtered conductance maps, which generally exhibit concentric patterns outside the ring area, and radial features inside the ring for negative charge at the tip. Influence of the surface charge and potential imperfections on conductance maps are also discussed.
Borisov, A. G.; Juaristi, J. I.
2006-01-15
Time-dependent density-functional theory is used to calculate quantum-size effects in the energy loss of antiprotons interacting with a confined two-dimensional electron gas. The antiprotons follow a trajectory normal to jellium circular clusters of variable size, crossing every cluster at its geometrical center. Analysis of the characteristic time scales that define the process is made. For high-enough velocities, the interaction time between the projectile and the target electrons is shorter than the time needed for the density excitation to travel along the cluster. The finite-size object then behaves as an infinite system, and no quantum-size effects appear in the energy loss. For small velocities, the discretization of levels in the cluster plays a role and the energy loss does depend on the system size. A comparison to results obtained using linear theory of screening is made, and the relative contributions of electron-hole pair and plasmon excitations to the total energy loss are analyzed. This comparison also allows us to show the importance of a nonlinear treatment of the screening in the interaction process.
Can non-ideal magnetohydrodynamics solve the magnetic braking catastrophe?
Wurster, James; Bate, Matthew R
2015-01-01
We investigate whether or not the low ionisation fractions in molecular cloud cores can solve the `magnetic braking catastrophe', where magnetic fields prevent the formation of circumstellar discs around young stars. We perform three-dimensional smoothed particle non-ideal magnetohydrodynamics (MHD) simulations of the gravitational collapse of one solar mass molecular cloud cores, incorporating the effects of ambipolar diffusion, Ohmic resistivity and the Hall effect alongside a self-consistent calculation of the ionisation chemistry assuming 0.1 micron grains. When including only ambipolar diffusion or Ohmic resistivity, discs do not form in the presence of strong magnetic fields, similar to the cases using ideal MHD. With the Hall effect included, disc formation depends on the direction of the magnetic field with respect to the rotation vector of the gas cloud. When the vectors are aligned, strong magnetic braking occurs and no disc is formed. When the vectors are anti-aligned, a disc with radius of 13AU ca...
Ideal regularization for learning kernels from labels.
Pan, Binbin; Lai, Jianhuang; Shen, Lixin
2014-08-01
In this paper, we propose a new form of regularization that is able to utilize the label information of a data set for learning kernels. The proposed regularization, referred to as ideal regularization, is a linear function of the kernel matrix to be learned. The ideal regularization allows us to develop efficient algorithms to exploit labels. Three applications of the ideal regularization are considered. Firstly, we use the ideal regularization to incorporate the labels into a standard kernel, making the resulting kernel more appropriate for learning tasks. Next, we employ the ideal regularization to learn a data-dependent kernel matrix from an initial kernel matrix (which contains prior similarity information, geometric structures, and labels of the data). Finally, we incorporate the ideal regularization to some state-of-the-art kernel learning problems. With this regularization, these learning problems can be formulated as simpler ones which permit more efficient solvers. Empirical results show that the ideal regularization exploits the labels effectively and efficiently. PMID:24824969
Perpetual motion of a mobile impurity in a one-dimensional quantum gas
NASA Astrophysics Data System (ADS)
Lychkovskiy, O.
2014-03-01
Consider an impurity particle injected in a degenerate one-dimensional gas of noninteracting fermions (or, equivalently, Tonks-Girardeau bosons) with some initial momentum p0. We examine the infinite-time value of the momentum of the impurity, p?, as a function of p0. A lower bound on |p?(p0)| is derived under fairly general conditions. The derivation, based on the existence of the lower edge of the spectrum of the host gas, does not resort to any approximations. The existence of such bound implies the perpetual motion of the impurity in a one-dimensional gas of noninteracting fermions or Tonks-Girardeau bosons at zero temperature. The bound admits an especially simple and useful form when the interaction between the impurity and host particles is everywhere repulsive.
Perpetual motion of a mobile impurity in a one-dimensional quantum gas
Oleg Lychkovskiy
2014-03-04
Consider an impurity particle injected in a degenerate one-dimensional gas of noninteracting fermions (or, equivalently, Tonks-Girardeau bosons) with some initial momentum $p_0$. We examine the infinite-time value of the momentum of the impurity, $p_\\infty$, as a function of $p_0$. A lower bound on $|p_\\infty(p_0)|$ is derived under fairly general conditions. The derivation, based on the existence of the lower edge of the spectrum of the host gas, does not resort to any approximations. The existence of such bound implies the perpetual motion of an impurity in a one-dimensional gas of noninteracting fermions or Tonks-Girardeau bosons at zero temperature. The bound has an especially simple and useful form when the interaction between the impurity and host particles is everywhere repulsive.
[The style of leadership idealized by nurses].
Higa, Elza de Fátima Ribeiro; Trevizan, Maria Auxiliadora
2005-01-01
This study focuses on nursing leadership on the basis of Grid theories. According to the authors, these theories are an alternative that allows for leadership development in nursing. The research aimed to identify and analyze the style of leadership idealized by nurses, according to their own view, and to compare the styles of leadership idealized by nurses between the two research institutions. Study subjects were 13 nurses. The results show that nurses at both institutions equally mention they idealize style 9.9, followed by 5.5 and 1.9, with a tendency to reject styles 9.1 and 1.1. PMID:15761581
Predicting film genres with implicit ideals.
Olney, Andrew McGregor
2012-01-01
We present a new approach to defining film genre based on implicit ideals. When viewers rate the likability of a film, they indirectly express their ideal of what a film should be. Across six studies we investigate the category structure that emerges from likability ratings and the category structure that emerges from the features of film. We further compare these data-driven category structures with human annotated film genres. We conclude that film genres are structured more around ideals than around features of film. This finding lends experimental support to the notion that film genres are set of shifting, fuzzy, and highly contextualized psychological categories. PMID:23423823
Predicting Film Genres with Implicit Ideals
Olney, Andrew McGregor
2013-01-01
We present a new approach to defining film genre based on implicit ideals. When viewers rate the likability of a film, they indirectly express their ideal of what a film should be. Across six studies we investigate the category structure that emerges from likability ratings and the category structure that emerges from the features of film. We further compare these data-driven category structures with human annotated film genres. We conclude that film genres are structured more around ideals than around features of film. This finding lends experimental support to the notion that film genres are set of shifting, fuzzy, and highly contextualized psychological categories. PMID:23423823
Finite-temperature quantum Monte Carlo study of the one-dimensional polarized Fermi gas
Wolak, M. J.; Rousseau, V. G.; Miniatura, C.; Gremaud, B.; Scalettar, R. T.; Batrouni, G. G.
2010-07-15
Quantum Monte Carlo (QMC) techniques are used to provide an approximation-free investigation of the phases of the one-dimensional attractive Hubbard Hamiltonian in the presence of population imbalance. The temperature at which the ''Fulde-Ferrell-Larkin-Ovchinnikov'' (FFLO) phase is destroyed by thermal fluctuations is determined as a function of the polarization. It is shown that the presence of a confining potential does not dramatically alter the FFLO regime and that recent experiments on trapped atomic gases likely lie just within the stable temperature range.
P-wave superfluid in a quasi-two-dimensional dipolar Bose-Fermi quantum gas mixture
NASA Astrophysics Data System (ADS)
Kain, Ben; Ling, Hong
2013-03-01
The p-wave (px + ipy) superfluid has attracted significant attention in recent years mainly because its vortex core supports a Majorana fermion which, due to its non-Abelian statistics, can be explored for implementing topological quantum computation (TQC). Mixing in bosons may lead to p-wave pairing in a Fermi gas. In a dipolar condensate, the dipole-dipole interaction represents a control knob inaccessible to nondipolar Bosons. Thus, mixing dipolar bosons with fermions opens up new possibilities. We consider a mixture of a spin-polarized Fermi gas and a dipolar Bose-Einstein condensate in a quasi-two-dimensional trap setting. We take the Hartree-Fock-Bogoliubov mean-field approach and develop a theory for studying the stability of the mixture and estimating the critical temperature of the p-wave superfluid. We use this theory to identify the experimentally accessible parameter space in which the mixture is stable against phase separation and the p-wave superfluid pairing can be resonantly enhanced. An enhanced p-wave superfluid order parameter can make the fault tolerant TQC less susceptible to thermal fluctuations. This work aims to stimulate experimental activity in creating dipolar Bose-Fermi mixtures. This work is supported by the US National Science Foundation and the US Army Research Office
Converging cylindrical shocks in ideal magnetohydrodynamics
Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.
2014-09-15
We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=?(?{sub 0}/p{sub 0}) I/(2 ?) where I is the current, ?{sub 0} is the permeability, and p{sub 0} is the pressure ahead of the shock. For shocks initiated at r ? R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then slows the shock Mach number growth producing a maximum followed by monotonic reduction towards magnetosonic conditions, even as the shock accelerates toward the axis. A parameter space of initial shock Mach number at a given radius is explored and the implications of the present results for inertial confinement fusion are discussed.
Converging cylindrical shocks in ideal magnetohydrodynamics
NASA Astrophysics Data System (ADS)
Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.
2014-09-01
We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=sqrt{? _0/p_0} I/(2 ? ) where I is the current, ?0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ? R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then slows the shock Mach number growth producing a maximum followed by monotonic reduction towards magnetosonic conditions, even as the shock accelerates toward the axis. A parameter space of initial shock Mach number at a given radius is explored and the implications of the present results for inertial confinement fusion are discussed.
Nearly ideal binary communication in squeezed channels Matteo G. A. Paris
Paris, Matteo G. A.
Nearly ideal binary communication in squeezed channels Matteo G. A. Paris Quantum Optics the channel in binary communication based on Gaussian states. We show that for coding on pure states, squeezing increases the detection probability at fixed size of the strategy, actually saturating the optimal
Quantum oscillations in a two-dimensional electron gas in black phosphorus thin films.
Li, Likai; Ye, Guo Jun; Tran, Vy; Fei, Ruixiang; Chen, Guorui; Wang, Huichao; Wang, Jian; Watanabe, Kenji; Taniguchi, Takashi; Yang, Li; Chen, Xian Hui; Zhang, Yuanbo
2015-07-01
For decades, two-dimensional electron gases (2DEG) have allowed important experimental discoveries and conceptual developments in condensed-matter physics. When combined with the unique electronic properties of two-dimensional crystals, they allow rich physical phenomena to be probed at the quantum level. Here, we create a 2DEG in black phosphorus--a recently added member of the two-dimensional atomic crystal family--using a gate electric field. The black phosphorus film hosting the 2DEG is placed on a hexagonal boron nitride substrate. The resulting high carrier mobility in the 2DEG allows the observation of quantum oscillations. The temperature and magnetic field dependence of these oscillations yields crucial information about the system, such as cyclotron mass and lifetime of its charge carriers. Our results, coupled with the fact that black phosphorus possesses anisotropic energy bands with a tunable, direct bandgap, distinguish black phosphorus 2DEG as a system with unique electronic and optoelectronic properties. PMID:25984835
Ideal magnetocaloric effect for active magnetic regenerators
NASA Astrophysics Data System (ADS)
Rowe, A. M.; Barclay, J. A.
2003-02-01
The active magnetic regenerator (AMR) uses a magnetic solid as a thermal storage medium and as a working material in a refrigeration cycle. Thermodynamically coupled to a heat transfer fluid, the regenerator produces a cooling effect and generates a temperature gradient across the AMR. The coupling between the heat transfer fluid and the magnetic refrigerant is a key aspect governing the operating characteristics of an AMR. To increase our understanding of AMR thermodynamics, we examine the entropy balance in an idealized active magnetic regenerator. A relation for the entropy generation in an AMR with varying fluid capacity ratios is derived. Subsequently, an expression describing the ideal magnetocaloric effect (MCE) as a function of temperature is developed for the case of zero entropy generation. Finally, the link between ideal MCE and refrigerant symmetry is discussed showing that an ideal reverse Brayton-type magnetic cycle cannot be achieved using materials undergoing a second-order magnetic phase transition.
Ideals and flexibility in close relationships
Campbell, Lorne John
1998-01-01
Two studies examined the roles that ideal standards aphics. for a romantic partner, and the flexibility of these standards, play in relationships. In the first study, 239 men and women involved in dating relationships were asked to rate themselves...
Ideal shrinking and expansion of discrete sequences
NASA Technical Reports Server (NTRS)
Watson, Andrew B.
1986-01-01
Ideal methods are described for shrinking or expanding a discrete sequence, image, or image sequence. The methods are ideal in the sense that they preserve the frequency spectrum of the input up to the Nyquist limit of the input or output, whichever is smaller. Fast implementations that make use of the discrete Fourier transform or the discrete Hartley transform are described. The techniques lead to a new multiresolution image pyramid.
The Americanization of catholic reproductive ideals.
Blake, J
1966-07-01
Abstract This paper considers the attitude of Roman Catholics in the United States of America towards family size and suggests that large family ideals are still being put forward by the Church in publications and periodicals. The second part of the paper considers the attitudes of American Roman Catholics towards family size and shows that though there are indications that Roman Catholics regard slightly larger families as ideal than do members of other religions, the difference is not now very great. PMID:22084869
Guiding Center Equations for Ideal Magnetohydrodynamic Modes
Roscoe B. White
2013-02-21
Guiding center simulations are routinely used for the discovery of mode-particle resonances in tokamaks, for both resistive and ideal instabilities and to find modifications of particle distributions caused by a given spectrum of modes, including large scale avalanches during events with a number of large amplitude modes. One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through ?~B = ? X (? X B) however perturbs the magnetic topology, introducing extraneous magnetic islands in the field. A proper treatment of an ideal perturbation involves a full Lagrangian displacement of the field due to the perturbation and conserves magnetic topology as it should. In order to examine the effect of ideal magnetohydrodynamic modes on particle trajectories the guiding center equations should include a correct Lagrangian treatment. Guiding center equations for an ideal displacement ? are derived which perserve the magnetic topology and are used to examine mode particle resonances in toroidal confinement devices. These simulations are compared to others which are identical in all respects except that they use the linear representation for the field. Unlike the case for the magnetic field, the use of the linear field perturbation in the guiding center equations does not result in extraneous mode particle resonances.
Guiding center equations for ideal magnetohydrodynamic modes
White, R. B.
2013-04-15
Guiding center simulations are routinely used for the discovery of mode-particle resonances in tokamaks, for both resistive and ideal instabilities and to find modifications of particle distributions caused by a given spectrum of modes, including large scale avalanches during events with a number of large amplitude modes. One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through {delta}B-vector={nabla} Multiplication-Sign ({xi}-vector Multiplication-Sign B-vector), however, perturbs the magnetic topology, introducing extraneous magnetic islands in the field. A proper treatment of an ideal perturbation involves a full Lagrangian displacement of the field due to the perturbation and conserves magnetic topology as it should. In order to examine the effect of ideal magnetohydrodynamic modes on particle trajectories, the guiding center equations should include a correct Lagrangian treatment. Guiding center equations for an ideal displacement {xi}-vector are derived which preserve the magnetic topology and are used to examine mode particle resonances in toroidal confinement devices. These simulations are compared to others which are identical in all respects except that they use the linear representation for the field. Unlike the case for the magnetic field, the use of the linear field perturbation in the guiding center equations does not result in extraneous mode particle resonances.
The Statistical Mechanics of Ideal MHD Turbulence
NASA Technical Reports Server (NTRS)
Shebalin, John V.
2003-01-01
Turbulence is a universal, nonlinear phenomenon found in all energetic fluid and plasma motion. In particular. understanding magneto hydrodynamic (MHD) turbulence and incorporating its effects in the computation and prediction of the flow of ionized gases in space, for example, are great challenges that must be met if such computations and predictions are to be meaningful. Although a general solution to the "problem of turbulence" does not exist in closed form, numerical integrations allow us to explore the phase space of solutions for both ideal and dissipative flows. For homogeneous, incompressible turbulence, Fourier methods are appropriate, and phase space is defined by the Fourier coefficients of the physical fields. In the case of ideal MHD flows, a fairly robust statistical mechanics has been developed, in which the symmetry and ergodic properties of phase space is understood. A discussion of these properties will illuminate our principal discovery: Coherent structure and randomness co-exist in ideal MHD turbulence. For dissipative flows, as opposed to ideal flows, progress beyond the dimensional analysis of Kolmogorov has been difficult. Here, some possible future directions that draw on the ideal results will also be discussed. Our conclusion will be that while ideal turbulence is now well understood, real turbulence still presents great challenges.
The quantum mechanics of ion-enhanced field emission and how it influences microscale gas breakdown
Li, Yingjie; Go, David B.
2014-09-14
The presence of a positive gas ion can enhance cold electron field emission by deforming the potential barrier and increasing the tunneling probability of electrons—a process known as ion-enhanced field emission. In microscale gas discharges, ion-enhanced field emission produces additional emission from the cathode and effectively reduces the voltage required to breakdown a gaseous medium at the microscale (<10 ?m). In this work, we enhance classic field emission theory by determining the impact of a gaseous ion on electron tunneling and compute the effect of ion-enhanced field emission on the breakdown voltage. We reveal that the current density for ion-enhanced field emission retains the same scaling as vacuum cold field emission and that this leads to deviations from traditional breakdown theory at microscale dimensions.
Relaxation explosion of a quantum degenerate exciton gas in Cu2O
NASA Astrophysics Data System (ADS)
Yoshioka, Kosuke; Kuwata-Gonokami, Makoto
2012-05-01
We present our recent experimental studies on anomalous luminescence and its connection to Bose-Einstein condensation (BEC) transition of dark excitons in a bulk semiconductor. Our sensitive and quantitative detection of this nonluminous quasi-particle using hydrogen-like internal transitions allows obtaining continuous spectra of dark excitons using a quantum cascade laser. According to quantitative measurements on the two-body inelastic collision cross section of excitons, the system needs to be cooled to sub-Kelvin temperatures. We discuss in detail our recent observation of an explosive phenomenon when the BEC criterion is satisfied (Yoshioka et al 2011 Nature Commun. 2 328) for trapped excitons using a helium-3 refrigerator, and outline a plausible scenario when the BEC transition occurs in an inelastic environment. We also discuss how to increase the condensate fraction in order to study the unique ground state of many-body electric excitations in solids.
Plasmon response of a quantum-confined electron gas probed by core-level photoemission
Ozer, Mustafa M; Moon, Eun Ju; Eguiluz, Adolfo G; Weitering, Harm H
2011-01-01
We demonstrate the existence of quantized 'bulk' plasmons in ultrathin magnesium films on Si(111) by analyzing plasmon-loss satellites in core-level photoemission spectra, recorded as a function of the film thickness d. Remarkably, the plasmon energy is shown to vary as 1/d{sup 2} all the way down to three atomic layers. The loss spectra are dominated by the n=1 and n=2 normal modes, consistent with the excitation of plasmons involving quantized electronic subbands. With decreasing film thickness, spectral weight is gradually transferred from the plasmon modes to the low-energy single-particle excitations. These results represent striking manifestations of the role of quantum confinement on plasmon resonances in precisely controlled nanostructures.
Plasmon Response of a Quantum-Confined Electron Gas Probed by Core-Level Photoemission
NASA Astrophysics Data System (ADS)
Özer, Mustafa M.; Moon, Eun Ju; Eguiluz, Adolfo G.; Weitering, Hanno H.
2011-05-01
We demonstrate the existence of quantized “bulk” plasmons in ultrathin magnesium films on Si(111) by analyzing plasmon-loss satellites in core-level photoemission spectra, recorded as a function of the film thickness d. Remarkably, the plasmon energy is shown to vary as 1/d2 all the way down to three atomic layers. The loss spectra are dominated by the n=1 and n=2 normal modes, consistent with the excitation of plasmons involving quantized electronic subbands. With decreasing film thickness, spectral weight is gradually transferred from the plasmon modes to the low-energy single-particle excitations. These results represent striking manifestations of the role of quantum confinement on plasmon resonances in precisely controlled nanostructures.
Visualizing edge states with an atomic Bose gas in the quantum Hall regime.
Stuhl, B K; Lu, H-I; Aycock, L M; Genkina, D; Spielman, I B
2015-09-25
Bringing ultracold atomic gases into the quantum Hall regime is challenging. We engineered an effective magnetic field in a two-dimensional lattice with an elongated-strip geometry, consisting of the sites of an optical lattice in the long direction and of three internal atomic spin states in the short direction. We imaged the localized states of atomic Bose-Einstein condensates in this strip; via excitation dynamics, we further observed both the skipping orbits of excited atoms traveling down the system's edges, analogous to edge magnetoplasmons in two-dimensional electron systems, and a dynamical Hall effect for bulk excitations. Our technique involves minimal heating, which will be important for spectroscopic measurements of the Hofstadter butterfly and realizations of Laughlin's charge pump. PMID:26404830
Visualizing edge states with an atomic Bose gas in the quantum Hall regime
NASA Astrophysics Data System (ADS)
Stuhl, B. K.; Lu, H.-I.; Aycock, L. M.; Genkina, D.; Spielman, I. B.
2015-09-01
Bringing ultracold atomic gases into the quantum Hall regime is challenging. We engineered an effective magnetic field in a two-dimensional lattice with an elongated-strip geometry, consisting of the sites of an optical lattice in the long direction and of three internal atomic spin states in the short direction. We imaged the localized states of atomic Bose-Einstein condensates in this strip; via excitation dynamics, we further observed both the skipping orbits of excited atoms traveling down the system’s edges, analogous to edge magnetoplasmons in two-dimensional electron systems, and a dynamical Hall effect for bulk excitations. Our technique involves minimal heating, which will be important for spectroscopic measurements of the Hofstadter butterfly and realizations of Laughlin’s charge pump.
Quantum oscillations of the two-dimensional hole gas at atomically flat diamond surfaces
NASA Astrophysics Data System (ADS)
Takahide, Yamaguchi; Okazaki, Hiroyuki; Deguchi, Keita; Uji, Shinya; Takeya, Hiroyuki; Takano, Yoshihiko; Tsuboi, Hidetoshi; Kawarada, Hiroshi
2014-06-01
Shubnikov-de Haas oscillations are observed in atomically flat hydrogen-terminated diamond surfaces with high-density hole carriers introduced by the electric field effect using an ionic liquid. The Shubnikov-de Haas oscillations depend only on the magnetic field component perpendicular to the diamond surface, thus providing evidence of two-dimensional Fermi surfaces. The effective masses estimated from the temperature dependence of the oscillations are close to the cyclotron effective masses of the valence band maxima in diamond. The estimated quantum scattering time is one order of magnitude longer than the transport scattering time and indicates that the carrier mobility is locally as high as several thousand cm2/V s at low temperature.
NASA Astrophysics Data System (ADS)
Cheng, Xiaolu; Cina, Jeffrey A.
2014-07-01
A variational mixed quantum-semiclassical theory for the internal nuclear dynamics of a small molecule and the induced small-amplitude coherent motion of a low-temperature host medium is developed, tested, and used to simulate the temporal evolution of nonstationary states of the internal molecular and surrounding medium degrees of freedom. In this theory, termed the Fixed Vibrational Basis/Gaussian Bath (FVB/GB) method, the system is treated fully quantum mechanically while Gaussian wave packets are used for the bath degrees of freedom. An approximate time-dependent wave function of the entire model is obtained instead of just a reduced system density matrix, so the theory enables the analysis of the entangled system and bath dynamics that ensues following initial displacement of the internal-molecular (system) coordinate from its equilibrium position. The norm- and energy-conserving properties of the propagation of our trial wave function are natural consequences of the Dirac-Frenkel-McLachlan variational principle. The variational approach also stabilizes the time evolution in comparison to the same ansatz propagated under a previously employed locally quadratic approximation to the bath potential and system-bath interaction terms in the bath-parameter equations of motion. Dynamics calculations are carried out for molecular iodine in a 2D krypton lattice that reveal both the time-course of vibrational decoherence and the details of host-atom motion accompanying energy dissipation and dephasing. This work sets the stage for the comprehensive simulation of ultrafast time-resolved optical experiments on small molecules in low-temperature solids.
Cheng, Xiaolu; Cina, Jeffrey A
2014-07-21
A variational mixed quantum-semiclassical theory for the internal nuclear dynamics of a small molecule and the induced small-amplitude coherent motion of a low-temperature host medium is developed, tested, and used to simulate the temporal evolution of nonstationary states of the internal molecular and surrounding medium degrees of freedom. In this theory, termed the Fixed Vibrational Basis/Gaussian Bath (FVB/GB) method, the system is treated fully quantum mechanically while Gaussian wave packets are used for the bath degrees of freedom. An approximate time-dependent wave function of the entire model is obtained instead of just a reduced system density matrix, so the theory enables the analysis of the entangled system and bath dynamics that ensues following initial displacement of the internal-molecular (system) coordinate from its equilibrium position. The norm- and energy-conserving properties of the propagation of our trial wave function are natural consequences of the Dirac-Frenkel-McLachlan variational principle. The variational approach also stabilizes the time evolution in comparison to the same ansatz propagated under a previously employed locally quadratic approximation to the bath potential and system-bath interaction terms in the bath-parameter equations of motion. Dynamics calculations are carried out for molecular iodine in a 2D krypton lattice that reveal both the time-course of vibrational decoherence and the details of host-atom motion accompanying energy dissipation and dephasing. This work sets the stage for the comprehensive simulation of ultrafast time-resolved optical experiments on small molecules in low-temperature solids. PMID:25053307
R. Tsekov
2015-06-06
The Brownian motion of a light quantum particle in a heavy classical gas is theoretically described and a new expression for the friction coefficient is obtained for arbitrary temperature. At zero temperature it equals to the de Broglie momentum of the mean free path divided by the mean free path. Alternatively, the corresponding mobility of the quantum particle in the classical gas is equal to the square of the mean free path divided by the Planck constant. The Brownian motion of a quantum particle in a quantum environment is also discussed.
NASA Astrophysics Data System (ADS)
Kovtun, Dmitry M.; Kochikov, Igor V.; Tarasov, Yury I.
2015-11-01
The equilibrium structure of the 2-chloro-3-nitrothiophene molecule and the internal rotation of the nitro group have been studied in gas phase using electron diffraction data and quantum chemical calculations in the framework of the large-amplitude motion model for internal rotation. Quantum chemical calculations at the MP2 and B3LYP levels of theory with various Pople and Dunning basis sets predict the planar minimum energy molecular conformation, with the internal rotation barrier height in the interval 1140-1560 cm-1. The experimental GED data are consistent with the dynamic model governed by the twofold cosine potential energy function with the barrier height in the range from 600 to 1400 cm-1. The main equilibrium structure parameters are as follows (values in parentheses correspond to 3 times standard deviations): re (Ndbnd O) = 1.225/1.227(3) Å, re(C - C)/re(C - N) = 1.362/1.376/1.403/1.438(3) Å, re(C - Cl)/re (C - S) = 1.700/1.712/1.715(2) Å, ?e C2SC5 = 92.2 (5)°, ?e C3C2S = 110.8 (6)°, ?e C4C5S = 111.3 (5)°, ?e C3C4C5 = 113.0 (7)°, ?e C2C3C4 = 112.7 (8)°, ?e C3NO11 = 116.9(6)°, ?eC3NO10 = 118.5 (6)°, ?e SCCl = 118.6 (5)°, ?e C4C3N = 121.8 (7)°, ?e ONO = 124.6(6)°, ?e C2C3N = 125.1 (6)°, ?e C3C2Cl = 130.7 (6)°. Thermally averaged parameters are provided for comparison with the results of traditional studies.
NASA Astrophysics Data System (ADS)
Devreese, Jeroen P. A.; Tempere, Jacques; Sá de Melo, Carlos A. R.
2015-10-01
We study the effect of spin-orbit coupling on both the zero-temperature and nonzero-temperature behavior of a two-dimensional Fermi gas. We include a generic combination of Rashba and Dresselhaus terms into the system Hamiltonian, which allows us to study both the experimentally relevant equal-Rashba-Dresselhaus (ERD) limit and the Rashba-only (RO) limit. At zero temperature, we derive the phase diagram as a function of the two-body binding energy and Zeeman field. In the ERD case, this phase diagram reveals several topologically distinct uniform superfluid phases, classified according to the nodal structure of the quasiparticle excitation energies. Furthermore, we use a momentum-dependent SU(2) rotation to transform the system into a generalized helicity basis, revealing that spin-orbit coupling induces a triplet pairing component of the order parameter. At nonzero temperature, we study the Berezinskii-Kosterlitz-Thouless (BKT) phase transition by including phase fluctuations of the order parameter up to second order. We show that the superfluid density becomes anisotropic due to the presence of spin-orbit coupling (except in the RO case). This leads both to elliptic vortices and antivortices, and to anisotropic sound velocities. The latter prove to be sensitive to quantum phase transitions between topologically distinct phases. We show further that at a fixed nonzero Zeeman field, the BKT critical temperature is increased by the presence of ERD spin-orbit coupling. Subsequently, we demonstrate that the Clogston limit becomes infinite: TBKT remains nonzero at all finite values of the Zeeman field. We conclude by extending the quantum phase transition lines to nonzero temperature, using the nodal structure of the quasiparticle spectrum, thus connecting the BKT critical temperature with the zero-temperature results.
Statistical properties of an ideal nonparabolic Fermi gas
NASA Astrophysics Data System (ADS)
Beresford, R.
1991-12-01
Formulas are derived for treating the carrier density and energy in isotropic nonparabolic bands using the framework of the Joyce-Dixon approximation [W. B. Joyce and R. W. Dixon, Appl. Phys. Lett. 31, 354 (1977)]. The approximations are worked out as a function of spatial dimension, including the quasi-one-dimensional case of a bulk semiconductor in a homogeneous magnetic field. Example calculations illustrate the utility of the methods for the narrow-gap III-V compounds, such as InAs and InSb, which are now being developed for device applications.
Ideal Gas: properties Collection of atoms/molecules that
Bertulani, Carlos A. - Department of Physics and Astronomy, Texas A&M University
.02 x 1023 particles Avogadro's number NA=6.02x1023 particles per mol It doesn't matter what kind The atoms/molecules R Potential Energy 0 Kinetic energy #12;3 Number of particles: mol 1 mol of particles: 6 of particles: 1 mol is always NA particles #12;4 What is the weight of 1 mol of atoms? X Z A Number of protons
Plasmon response of a quantum-confined electron gas probed by core-level photoemission
NASA Astrophysics Data System (ADS)
Ozer, Mustafa M.; Moon, Eun Ju; Eguiluz, Adolfo G.; Weitering, Hanno H.
2011-03-01
The emergence of the ``bulk'' plasmon in atomically-smooth ultrathin Mg(0001) films on Si(111) has been determined using x-ray photoelectron spectroscopy (XPS). Plasmons in this quasi two-dimensional (2D) regime turn out to be excited primarily via the sudden creation of the core hole, as the extrinsic loss channel (which is dominant in bulk XPS spectra) is suppressed by electron confinement. The collective plasmon response of the films is remarkably similar to that of a thin slice of bulk matter, subject to quantum-size boundary conditions, in spite of the fact that the one-electron degrees of freedom are quantized. The energy-loss spectra of the thinnest films are characterized by a gradual transfer of spectral-weight from the bulk-like collective modes to the low-energy one-electron excitations, and the plasmon ultimately collapses below six monolayers. Our results represent striking manifestations of the role of electronic confinement on plasmon resonances in precisely-controlled nanostructures. DOE Office of BES, Division of Materials Sciences and Engineering.
NASA Astrophysics Data System (ADS)
Le Gouët, Jean-Louis; Moiseev, Sergey
2012-06-01
Interaction of quantum radiation with multi-particle ensembles has sparked off intense research efforts during the past decade. Emblematic of this field is the quantum memory scheme, where a quantum state of light is mapped onto an ensemble of atoms and then recovered in its original shape. While opening new access to the basics of light-atom interaction, quantum memory also appears as a key element for information processing applications, such as linear optics quantum computation and long-distance quantum communication via quantum repeaters. Not surprisingly, it is far from trivial to practically recover a stored quantum state of light and, although impressive progress has already been accomplished, researchers are still struggling to reach this ambitious objective. This special issue provides an account of the state-of-the-art in a fast-moving research area that makes physicists, engineers and chemists work together at the forefront of their discipline, involving quantum fields and atoms in different media, magnetic resonance techniques and material science. Various strategies have been considered to store and retrieve quantum light. The explored designs belong to three main—while still overlapping—classes. In architectures derived from photon echo, information is mapped over the spectral components of inhomogeneously broadened absorption bands, such as those encountered in rare earth ion doped crystals and atomic gases in external gradient magnetic field. Protocols based on electromagnetic induced transparency also rely on resonant excitation and are ideally suited to the homogeneous absorption lines offered by laser cooled atomic clouds or ion Coulomb crystals. Finally off-resonance approaches are illustrated by Faraday and Raman processes. Coupling with an optical cavity may enhance the storage process, even for negligibly small atom number. Multiple scattering is also proposed as a way to enlarge the quantum interaction distance of light with matter. The quest for higher efficiency, better fidelity, broader bandwidth, multimode capacity and longer storage lifetime is pursued in all those approaches, as shown in this special issue. The improvement of quantum memory operation specifically requires in-depth study and control of numerous physical processes leading to atomic decoherence. The present issue reflects the development of rare earth ion doped matrices offering long lifetime superposition states, either as bulk crystals or as optical waveguides. The need for quantum sources and high efficiency detectors at the single photon level is also illustrated. Several papers address the networking of quantum memories either in long-haul cryptography or in the prospect of quantum processing. In this context, much attention has been paid recently to interfacing quantum light with superconducting qubits and with nitrogen-vacancy centers in diamond. Finally, the quantum interfacing of light with matter raises questions on entanglement. The last two papers are devoted to the generation of entanglement by dissipative processes. It is shown that long lifetime entanglement may be built in this way. We hope this special issue will help readers to become familiar with the exciting field of ensemble-based quantum memories and will stimulate them to bring deeper insights and new ideas to this area.
Quest for ideal weight: costs and consequences.
Lindeman, A K
1999-08-01
The quest to achieve the ideal weight comes with notable costs. Dieting carries the financial costs of professional consulting, low-calorie foods, books and materials, and diet programming. Club memberships, clothing, equipment, and time all contribute to the cost of exercise. Cosmetic surgery to achieve the desired physique carries a significant financial, and sometimes psychological, burden. Women often pursue thinner bodies despite already being at a healthy weight. This pursuit is motivated primarily to enhance appearance. The ideal body portrayed in the media has stabilized in thinness, but it is becoming increasingly tubular, i.e., taller with slimmer hips and thicker waist. This ideal is presented to adult and adolescent women in their popular magazines, and to little girls with their dolls. Exercise is promoted as an optimal means to achieve the ideal physique. Young American women tend to idealize an athletic body shape, especially with upper-body muscularity. This shape can be attained only through sustained exercise and upper-body strength training. High-level exercise may be a precursor to eating disorders. Women who exercise to excess, who are highly preoccupied with weight, and who are characterized by perfectionism and an obsessive compulsive personality are at risk for eating disorders. When body weight and shape are kept in perspective and realistic goals are set, the physical, psychological, and financial costs of achieving or maintaining a healthy weight may be minimized. PMID:10449015
Quantum gases. Critical dynamics of spontaneous symmetry breaking in a homogeneous Bose gas.
Navon, Nir; Gaunt, Alexander L; Smith, Robert P; Hadzibabic, Zoran
2015-01-01
Kibble-Zurek theory models the dynamics of spontaneous symmetry breaking, which plays an important role in a wide variety of physical contexts, ranging from cosmology to superconductors. We explored these dynamics in a homogeneous system by thermally quenching an atomic gas with short-range interactions through the Bose-Einstein phase transition. Using homodyne matter-wave interferometry to measure first-order correlation functions, we verified the central quantitative prediction of the Kibble-Zurek theory, namely the homogeneous-system power-law scaling of the coherence length with the quench rate. Moreover, we directly confirmed its underlying hypothesis, the freezing of the correlation length near the transition. Our measurements agree with a beyond-mean-field theory and support the expectation that the dynamical critical exponent for this universality class is z = 3/2. PMID:25574021
Reality television and the muscular male ideal.
Dallesasse, Starla L; Kluck, Annette S
2013-06-01
Although researchers have examined the negative effects of viewing reality television (RTV) on women's body image, this research has not been extended to men. Exploring the extent to which RTV depicts men who embody the muscular ideal may enhance our understanding of the potential influence of this media genre. We explored the extent to which RTV depicted men who embodied the muscular ideal using a quantitative content analysis. Based on binomial tests, the primary male cast members of programs airing on networks popular among young adult men during the Fall 2009 broadcast season were more muscular, with lower levels of body fat, than average U.S. men. The chest-to-waist and shoulder-to-waist ratios of these cast members did not differ as a function of program type (i.e., reality drama, endurance, and romance). Young men who view RTV programs included in the present study would be exposed to an unrepresentative muscular ideal. PMID:23523084
A trace methane gas sensor using mid-infrared quantum cascaded laser at 7.5 ?m
NASA Astrophysics Data System (ADS)
Chen, Chen; Newcomb, Robert W.; Wang, Yiding
2013-12-01
Presented is a compact instrument developed for in situ high-stable and sensitive continuous measurement of trace gases in air, with results shown for ambient methane (CH4) concentration. This instrument takes advantage of recent technology in thermoelectrically cooled pulsed Fabry-Perot (FP) quantum cascaded (QC) laser driving in a pulse mode operating at 7.5 ?m to monitor a well-isolated spectral line near the ?4 fundamental band of CH4. A high-quality liquid nitrogen cooled mercury cadmium telluride mid-infrared detector with time discriminating electronics is used along with a total reflection coated gold ellipsoid mirror offering 20 cm single pass optical absorption in an open-path cell to achieve stability of 5.2 × 10-3 under experimental condition of 200 ppm measured ambient CH4. The instrument operates continuously, and integrated software for laser control using direct absorption provides quantitative trace gas measurements without calibration. One may substitute a QC laser operating at a different wavelength to measure other gases. The instrument can be applied to field measurements of gases of environmental concern.
Wojcik, Michael D.; Phillips, Mark C.; Cannon, Bret D.; Taubman, Matthew S.
2006-10-01
We demonstrate the performance of a novel long-wave infrared photoacoustic laser absorbance spectrometer for gas-phase species using an amplitude modulated (AM) quantum cascade (QC) laser and a quartz tuning fork microphone. Photoacoustic signal was generated by focusing the output of a Fabry-Perot QC laser operating at 8.41 ?m between the legs of a quartz tuning fork which served as a transducer for the transient acoustic pressure wave. The QC laser was modulated at the resonant frequency of the tuning fork (32.8 kHz) and delivered a modest 5.3 mW at the tuning fork. This spectrometer was calibrated using the infrared absorber Freon-134a by performing a simultaneous absorption measurement using a 35 cm absorption cell. The NEAS of this instrument was determined to be 2 x 10{sup -8} W cm-1 Hz{sup -1/2}. A corresponding theoretical analysis of the instrument sensitivity is presented and is capable of quantitatively reproducing the experimental NEAS, indicating that the fundamental sensitivity of this technique is limited by the noise floor of the tuning fork itself.
Wojcik, Michael D.; Phillips, Mark C.; Cannon, Bret D.
2006-12-31
A paper to accompany a 20 minute talk about the progress of a DARPA funded project called LPAS. ABSTRACT: We demonstrate the performance of a novel long-wave infrared photoacoustic laser absorbance spectrometer for gas-phase species using an amplitude modulated (AM) quantum cascade (QC) laser and a quartz tuning fork microphone. Photoacoustic signal was generated by focusing the output of a Fabry-Perot QC laser operating at 8.41 micron between the legs of a quartz tuning fork which served as a transducer for the transient acoustic pressure wave. The QC laser was modulated at the resonant frequency of the tuning fork (32.8 kHz). This sensor was calibrated using the infrared absorber Freon-134a by performing a simultanious absorption measurement using a 35 cm absorption cell. The NEAS of this instrument was determined to be 2 x 10^-8 W cm^-1 /Hz^1/2 and the fundamental sensitivity of this technique is limited by the noise floor of the tuning fork itself.
Gil, Diego M; Tuttolomondo, María E; Blomeyer, Sebastian; Reuter, Christian G; Mitzel, Norbert W; Altabef, Aída Ben
2016-01-01
The molecular structure and conformational properties of 2,2,2-trichloroethyl chloroformate, ClC(O)OCH2CCl3 were determined experimentally using gas-phase electron diffraction (GED) and theoretically based on quantum-chemical calculations at the MP2 and DFT levels of theory. Further experimental measurements such as UV-visible, IR and Raman spectroscopy were complemented with the corresponding theoretical studies. All experimental results and calculations confirm the presence of two conformers namely anti-gauche (C1 symmetry) and anti-anti (Cs symmetry). The conformational preference was rationalised by NBO and AIM analyses. Molecular properties such as ionisation potential, electronegativity, chemical potential, chemical hardness and softness were deduced from HOMO-LUMO analyses. The TD-DFT approach was applied to assign the electronic transitions observed in the UV-visible spectrum. A detailed interpretation of the infrared and Raman spectra of the title compound are reported. Using calculated frequencies as a guide, IR and Raman spectra also provide evidence for the presence of both C1 and Cs conformers. PMID:26617390
NASA Astrophysics Data System (ADS)
Carelli, Fabio; Gianturco, Francesco Antonio; Franz, Jan; Satta, Mauro
2015-06-01
Electron and positron scattering processes in the gas-phase are analysed for uracil and pyrimidine molecules using a multichannel quantum approach at energies close to threshold. The special effects on the scattering dynamics induced by the large dipole moments in both molecules on the spatial features of the continuum leptonic wavefunctions are here linked to the possible bound states of the Rydberg-like molecular anions or `positroned' molecules which could be reached via further couplings with molecular internal degrees of freedom.
Primitive ideals of C q [ SL(3)
NASA Astrophysics Data System (ADS)
Hodges, Timothy J.; Levasseur, Thierry
1993-10-01
The primitive ideals of the Hopf algebra C q [ SL(3)] are classified. In particular it is shown that the orbits in Prim C q [ SL(3)] under the action of the representation group H ? C *× C * are parameterized naturally by W×W, where W is the associated Weyl group. It is shown that there is a natural one-to-one correspondence between primitive ideals of C q [ SL(3)] and symplectic leaves of the associated Poisson algebraic group SL(3, C).
Analysis of an idealized Stirling thermocompressor
Kornhauser, A.A.
1996-12-31
A thermocompressor uses thermal energy to increase the pressure of a fluid without the intermediate production of mechanical work. The thermocompressor described here is essentially a cold-connected Gamma Stirling engine with the power cylinder replaced by inlet and discharge check valves. It is analyzed based on assumptions similar to those made in the analysis of an ideal Stirling engine. The analysis gives closed form predictions for thermocompressor thermal efficiency, volumetric efficiency, and non-dimensional heat input as functions of pressure and temperature ratio. It is also used to compare thermocompressor performance to that of an ideal Otto engine-driven mechanical compressor.
Lecture by John F. Nash Jr. Ideal Money and Asymptotically Ideal Money
Babu, G. Jogesh
Lecture by John F. Nash Jr. Ideal Money and Asymptotically Ideal Money The special commodity or medium that we call money has a long and interesting history. And since we are so dependent on our use teaches, in effect, that "less is more" or that (in other words) "bad money is better than good money
Symmetries and currents of the ideal and unitary Fermi gases
Xavier Bekaert; Elisa Meunier; Sergej Moroz
2012-02-06
The maximal algebra of symmetries of the free single-particle Schroedinger equation is determined and its relevance for the holographic duality in non-relativistic Fermi systems is investigated. This algebra of symmetries is an infinite dimensional extension of the Schroedinger algebra, it is isomorphic to the Weyl algebra of quantum observables, and it may be interpreted as a non-relativistic higher-spin algebra. The associated infinite collection of Noether currents bilinear in the fermions are derived from their relativistic counterparts via a light-like dimensional reduction. The minimal coupling of these currents to background sources is rewritten in a compact way by making use of Weyl quantisation. Pushing forward the similarities with the holographic correspondence between the minimal higher-spin gravity and the critical O(N) model, a putative bulk dual of the unitary and the ideal Fermi gases is discussed.
Symmetries and currents of the ideal and unitary Fermi gases
Bekaert, Xavier; Moroz, Sergej
2011-01-01
The maximal algebra of symmetries of the free single-particle Schroedinger equation is determined and its relevance for the holographic duality in non-relativistic Fermi systems is investigated. This algebra of symmetries is an infinite dimensional extension of the Schroedinger algebra, it is isomorphic to the Weyl algebra of quantum observables, and it may be interpreted as a non-relativistic higher-spin algebra. The associated infinite collection of Noether currents bilinear in the fermions are derived from their relativistic counterparts via a light-like dimensional reduction. The minimal coupling of these currents to background sources is rewritten in a compact way by making use of Weyl quantisation. Pushing forward the similarities with the holographic correspondence between the minimal higher-spin gravity and the critical O(N) model, a putative bulk dual of the unitary and the ideal Fermi gases is discussed.
Gas-phase formation of the prebiotic molecule formamide: insights from new quantum computations
NASA Astrophysics Data System (ADS)
Barone, V.; Latouche, C.; Skouteris, D.; Vazart, F.; Balucani, N.; Ceccarelli, C.; Lefloch, B.
2015-10-01
New insights into the formation of interstellar formamide, a species of great relevance in prebiotic chemistry, are provided by electronic structure and kinetic calculations for the reaction NH2 + H2CO ? NH2CHO + H. Contrarily to what previously suggested, this reaction is essentially barrierless and can, therefore, occur under the low temperature conditions of intestellar objects thus providing a facile formation route of formamide. The rate coefficient parameters for the reaction channel leading to NH2CHO + H have been calculated to be A = 2.6 × 10-12 cm3 s-1, ? = -2.1 and ? = 26.9 K in the range of temperatures 10-300 K. Including these new kinetic data in a refined astrochemical model, we show that the proposed mechanism can well reproduce the abundances of formamide observed in two very different interstellar objects: the cold envelope of the Sun-like protostar IRAS16293-2422 and the molecular shock L1157-B2. Therefore, the major conclusion of this Letter is that there is no need to invoke grain-surface chemistry to explain the presence of formamide provided that its precursors, NH2 and H2CO, are available in the gas phase.
Nazir, Safdar; Behtash, Maziar; Yang, Kesong
2015-03-21
We explore the possibility of achieving highly confined two-dimensional electron gas (2DEG) within one single atomic layer through a comprehensive comparison study on three prototypical perovskite heterostructures, LaAlO{sub 3}/ATiO{sub 3} (A = Ca, Sr, and Ba), using first-principles electronic structure calculations. We predict that the heterostructure LaAlO{sub 3}/BaTiO{sub 3} has a highly confined 2DEG within a single atomic layer of the substrate BaTiO{sub 3}, and exhibits relatively higher interfacial charge carrier density and larger magnetic moments than the well-known LaAlO{sub 3}/SrTiO{sub 3} system. The long Ti-O bond length in the ab-plane of the LaAlO{sub 3}/BaTiO{sub 3} heterostructure is responsible for the superior charge confinement. We propose BaTiO{sub 3} as an exceptional substrate material for 2DEG systems with potentially superior properties.
Bristol, University of
Application of a Quantum Cascade Laser for Time-Resolved, in Situ Probing of CH4/H2 and C2H2/H2 Gas 10, 2006 First illustrations of the utility of pulsed quantum cascade lasers for in situ probing on such issues span optical emission spectroscopy, in situ mass spectrometry,4,5 and a number of laser
ERIC Educational Resources Information Center
Holko, David A.
1982-01-01
Presents a complete computer program demonstrating the relationship between volume/pressure for Boyle's Law, volume/temperature for Charles' Law, and volume/moles of gas for Avagadro's Law. The programing reinforces students' application of gas laws and equates a simulated moving piston to theoretical values derived using the ideal gas law.…
A jetlet hierarchy for ideal fluid dynamics
C. J. Cotter; D. D. Holm; H. O. Jacobs; D. M. Meier
2014-05-06
Truncated Taylor expansions of smooth flow maps are used in Hamilton's principle to derive a multiscale Lagrangian particle representation of ideal fluid dynamics. Numerical simulations for scattering of solutions at one level of truncation are found to produce solutions at higher levels. These scattering events to higher levels in the Taylor expansion are interpreted as modeling a cascade to smaller scales.
The World Grant Ideal and Engagement Scholarship
ERIC Educational Resources Information Center
Fitzgerald, Hiram E.; Simon, Lou Anna K.
2012-01-01
Michigan State University President Lou Anna Simon's concept of the world grant ideal is grounded in three core values: quality, inclusiveness, and connectivity. These core values fuel the 21st-century imperative to build sustainable global prosperity. They represent an affirmation of the Morrill Act of 1862 in the context of a global society and…
Embedding the Schwarzschild Ideal Fluid Metric
Earnest Harrison
2007-01-13
Certain semi-Riemannian metrics can be decomposed into a Riemannian part and an isochronal part. The properties of such metrics are particularly easy to visualize in a coordinate-free way, using isometric embedding. We present such an isochronal, isometric embedding of the well known Schwarzschild ideal fluid metric in an attempt to see what is happening when the pressure becomes singular.
Critical Reflection as a Rationalistic Ideal
ERIC Educational Resources Information Center
van Woerkom, Marianne
2010-01-01
There is a growing interest in the concept of critical reflection in the adult learning and management literature. In this article, the author examines four different intellectual traditions that inform the use of the term "critical reflection" on the different ideals they express and the different definitions of critical reflection they use. On…
Exact map through ideal bends (again?)
Michelotti, L.
1995-06-01
There are three logically independent facets to calculating the transfer map through a bend magnet: physics, geometry, and representation. We will derive the exact map for transit through ideal bends while separating these three, esp., isolating the geometry problem from the other two.
Ideal light concentrators with reflector gaps
Winston, Roland (Chicago, IL)
1980-01-01
A cylindrical or trough-like radiant energy concentration and collection device is provided. The device includes an energy absorber, a glazing enveloping the absorber and a reflective wall. The ideal contour of the reflective wall is determined with reference to a virtual absorber and not the actual absorber cross section.
Developing Ideal Student and Residency Programs.
ERIC Educational Resources Information Center
Selvin, Gerald J.
1993-01-01
The Veterans Administration (VA) is a primary educator of optometry students, with each college of optometry being affiliated with at least one VA hospital. Ideally, fourth-year optometry students rotate through a specific VA facility for about 12 weeks. Guidelines are designed to provide optimum care in a rich learning environment. (MSE)
Idealized Test Cases for Dynamical Core Experiments
Jablonowski, Christiane
Idealized Test Cases for Dynamical Core Experiments Christiane Jablonowski (University of Michigan-13/2006 #12;Motivation Â· Test cases for 3D dynamical cores on the sphere Â are hard to find in the literature groups Â lack standardized & easy-to-use analysis techniques Â· Idea: Establish a collection of test cases
Joint Custody: A Viable and Ideal Alternative
ERIC Educational Resources Information Center
Grote, Douglas F.; Weinstein, Jeffrey
1977-01-01
Defines and restructures custodial rights and remedies of parents involved in a divorce proceeding. Conveys an alternative to custodial awards as they exist today and points toward joint custody as an ideal solution and viable alternative that cries out for acceptance. (Author)
Axisymmetric ideal MHD stellar wind flow
NASA Technical Reports Server (NTRS)
Heinemann, M.; Olbert, S.
1978-01-01
The ideal MHD equations are reduced to a single equation under the assumption of axisymmetric flow. A variational principle from which the equation is derivable is given. The characteristics of the equation are briefly discussed. The equation is used to rederive the theorem of Gussenhoven and Carovillano.
Water: The Ideal Early Learning Environment
ERIC Educational Resources Information Center
Grosse, Susan J.
2008-01-01
Bathtubs and swimming pools provide the ideal learning environment for people with special needs. For young preschool children, the activities that take place through water can help them develop physical fitness, facilitate motor development, reinforce perceptual-motor ability, encourage social development, and enhance self-esteem and confidence.…
The Nautilus: An Ideal Elementary School.
ERIC Educational Resources Information Center
Webb, Gertrude M.
The author presents the design for an ideal elementary school that would create a climate in which children could be educated to their maximum potential. The design arises from a philosophical base that incorporates this century's research in child development and learning theory. Consideration is given to the needs of the individual at the…
The Ideal Man and Woman According to University Students
ERIC Educational Resources Information Center
Weinstein, Lawrence; Laverghetta, Antonio V.; Peterson, Scott A.
2009-01-01
The present study determined if the ideal man has changed over the years and who and what the ideal woman is. We asked students at Cameron University to rate the importance of character traits that define the ideal man and woman. Subjects also provided examples of famous people exemplifying the ideal, good, average, and inferior man and woman. We…
Int-Soft (Generalized) Bi-Ideals of Semigroups
Jun, Young Bae; Song, Seok-Zun
2015-01-01
The notions of int-soft semigroups and int-soft left (resp., right) ideals in semigroups are studied in the paper by Song et al. (2014). In this paper, further properties and characterizations of int-soft left (right) ideals are studied, and the notion of int-soft (generalized) bi-ideals is introduced. Relations between int-soft generalized bi-ideals and int-soft semigroups are discussed, and characterizations of (int-soft) generalized bi-ideals and int-soft bi-ideals are considered. Given a soft set (?;S) over U, int-soft (generalized) bi-ideals generated by (?;S) are established. PMID:25710051
Quantum simulation of energy transport with embedded Rydberg aggregates.
Schönleber, D W; Eisfeld, A; Genkin, M; Whitlock, S; Wüster, S
2015-03-27
We show that an array of ultracold Rydberg atoms embedded in a laser driven background gas can serve as an aggregate for simulating exciton dynamics and energy transport with a controlled environment. Energetic disorder and decoherence introduced by the interaction with the background gas atoms can be controlled by the laser parameters. This allows for an almost ideal realization of a Haken-Reineker-Strobl-type model for energy transport. The transport can be monitored using the same mechanism that provides control over the environment. The degree of decoherence is traced back to information gained on the excitation location through the monitoring, turning the setup into an experimentally accessible model system for studying the effects of quantum measurements on the dynamics of a many-body quantum system. PMID:25860741
M. Bahrami ENSC 461 (S 11) Jet Propulsion Cycle 1 Ideal JetPropulsion Cycle
Bahrami, Majid
is the aircraft velocity. The power developed from the thrust of the engine is called the propulsive power: k Cycle 4 Turbofan The most popular engine in aircrafts is the turbofan (or fanjet) where fan drivenM. Bahrami ENSC 461 (S 11) Jet Propulsion Cycle 1 Ideal JetPropulsion Cycle Gas-turbine engines
Ideal photon number amplifier and duplicator
NASA Technical Reports Server (NTRS)
Dariano, G. M.
1992-01-01
The photon number-amplification and number-duplication mechanism are analyzed in the ideal case. The search for unitary evolutions leads to consider also a number-deamplification mechanism, the symmetry between amplification and deamplification being broken by the integer-value nature of the number operator. Both transformations, amplification and duplication, need an auxiliary field which, in the case of amplification, turns out to be amplified in the inverse way. Input-output energy conservation is accounted for using a classical pump or through frequency-conversion of the fields. Ignoring one of the fields is equivalent to considering the amplifier as an open system involving entropy production. The Hamiltonians of the ideal devices are given and compared with those of realistic systems.
Defining the ideal femtosecond laser capsulotomy
Packer, Mark; Teuma, E Valas; Glasser, Adrian; Bott, Steven
2015-01-01
Purpose We define the ideal anterior capsulotomy through consideration of capsular histology and biomechanics. Desirable qualities include preventing posterior capsular opacification (PCO), maintaining effective lens position (ELP) and optimising capsular strength. Methods Laboratory study of capsular biomechanics and literature review of histology and published clinical results. Results Parameters of ideal capsulotomy construction include complete overlap of the intraocular lens to prevent PCO, centration on the clinical approximation of the optical axis of the lens to ensure concentricity with the capsule equator, and maximal capsular thickness at the capsulotomy edge to maintain integrity. Conclusions Constructing the capsulotomy centred on the clinical approximation of the optical axis of the lens with diameter 5.25?mm optimises prevention of PCO, consistency of ELP and capsular strength. PMID:25829488
Computational methods for ideal compressible flow
NASA Technical Reports Server (NTRS)
Vanleer, B.
1983-01-01
Conservative dissipative difference schemes for computing one dimensional flow are introduced, and the recognition and representation of flow discontinuities are discussed. Multidimensional methods are outlined. Second order finite volume schemes are introduced. Conversion of difference schemes for a single linear convection equation into schemes for the hyperbolic system of the nonlinear conservation laws of ideal compressible flow is explained. Approximate Riemann solvers are presented. Monotone initial value interpolation; and limiters, switches, and artificial dissipation are considered.
A non-ideal MHD Gadget: Simulating massive galaxy clusters
Bonafede, A; Stasyszyn, F; Murante, G; Borgani, S
2011-01-01
Magnetic fields in the intra-cluster medium of galaxy clusters have been studied in the past years through different methods. In the next years the up-coming generation of radio telescopes is going to provide new data that have the potential of setting constraints on the properties of magnetic fields in galaxy clusters. Here we present zoomed-in simulations for a set of massive galaxy clusters (M_v > 10^15 M_sun/h). This is an ideal sample to study the evolution of magnetic field during the process of structure formation in detail. Turbulent motions of the gas within the ICM will manifest themselves in a macroscopic magnetic resistivity eta_m, which has to be taken explicitly into account, especially at scales below the resolution limit. We have adapted the MHD GADGET code by Dolag & Stasyszyn (2009) to include the treatment of the magnetic resistivity and for the first time we have included non-ideal MHD equations to better follow the evolution of the magnetic field within galaxy clusters. We investigate...
Non-Ideal Behavior in Solvent Extraction
Peter Zalupski
2011-09-01
This report presents a summary of the work performed to meet FCR&D level 3 milestone M31SW050801, 'Complete the year-end report summarizing FY11 experimental and modeling activities.' This work was carried out under the auspices of the Non-Ideality in Solvent Extraction Systems FCR&D work package. The report summarizes our initial considerations of potential influences that non-ideal chemistry may impose on computational prediction of outcomes in solvent extraction systems. The report is packaged into three separate test cases where a robustness of the prediction by SXFIT program is under scrutiny. The computational exercises presented here emphasize the importance of accurate representation of both an aqueous and organic mixtures when modeling liquid-liquid distribution systems. Case No.1 demonstrates that non-ideal behavior of HDEHP in aliphatic diluents, such as n-dodecane, interferes with the computation. Cases No.2 and No.3 focus on the chemical complexity of aqueous electrolyte mixtures. Both exercises stress the need for an improved thermodynamic model of an aqueous environment present in the europium distribution experiments. Our efforts for year 2 of this project will focus on the improvements of aqueous and non-aqueous solution models using fundamental physical properties of mixtures acquired experimentally in our laboratories.
Dimensional Analysis Using Toric Ideals: Primitive Invariants
Atherton, Mark A.; Bates, Ronald A.; Wynn, Henry P.
2014-01-01
Classical dimensional analysis in its original form starts by expressing the units for derived quantities, such as force, in terms of power products of basic units etc. This suggests the use of toric ideal theory from algebraic geometry. Within this the Graver basis provides a unique primitive basis in a well-defined sense, which typically has more terms than the standard Buckingham approach. Some textbook examples are revisited and the full set of primitive invariants found. First, a worked example based on convection is introduced to recall the Buckingham method, but using computer algebra to obtain an integer matrix from the initial integer matrix holding the exponents for the derived quantities. The matrix defines the dimensionless variables. But, rather than this integer linear algebra approach it is shown how, by staying with the power product representation, the full set of invariants (dimensionless groups) is obtained directly from the toric ideal defined by . One candidate for the set of invariants is a simple basis of the toric ideal. This, although larger than the rank of , is typically not unique. However, the alternative Graver basis is unique and defines a maximal set of invariants, which are primitive in a simple sense. In addition to the running example four examples are taken from: a windmill, convection, electrodynamics and the hydrogen atom. The method reveals some named invariants. A selection of computer algebra packages is used to show the considerable ease with which both a simple basis and a Graver basis can be found. PMID:25436774
Word recognition using ideal word patterns
NASA Astrophysics Data System (ADS)
Zhao, Sheila X.; Srihari, Sargur N.
1994-03-01
The word shape analysis approach to text recognition is motivated by discoveries in psychological studies of the human reading process. It attempts to describe and compare the shape of the word as a whole object without trying to segment and recognize the individual characters, so it bypasses the errors committed in character segmentation and classification. However, the large number of classes and large variation and distortion expected in all patterns belonging to the same class make it difficult for conventional, accurate, pattern recognition approaches. A word shape analysis approach using ideal word patterns to overcome the difficulty and improve recognition performance is described in this paper. A special word pattern which characterizes a word class is extracted from different sample patterns of the word class and stored in memory. Recognition of a new word pattern is achieved by comparing it with the special pattern of each word class called ideal word pattern. The process of generating the ideal word pattern of each word class is proposed. The algorithm was tested on a set of machine printed gray scale word images which included a wide range of print types and qualities.
McCall, Benjamin J.
Cascade Lasers Prospectus for Preliminary Examination Department of Chemistry, School of Chemical Sciences University of Illinois Jacob T. Stewart 29 April 2011 B124 CLSL 11:00 AM #12;1 Introduction Quantum cascade spectrum by varying the underlying quantum well structure of the laser chip. The original lasers had
Oleg Kupervasser
2013-08-01
In the paper paradoxes underlying thermodynamics and a quantum mechanics are discussed. Their solution is given from the point of view of influence of the exterior observer (surrounding medium) destroying correlations of system, or boundedness of self-knowledge of system in a case when both the observer, and a surrounding medium are included in system. Concepts Real Dynamics, Ideal Dynamics and Unpredictable Dynamics are entered. Consideration an appearance of a life is given from the point of view of these three Dynamics.
NASA Astrophysics Data System (ADS)
Varfolomeev, Mikhail A.; Klimovitskii, Alexander E.; Abaidullina, Dilyara I.; Madzhidov, Timur I.; Solomonov, Boris N.
2012-06-01
Experimental study of hydrogen bond cooperativity in hetero-complexes in the gas phase was carried out by IR-spectroscopy method. Stretching vibration frequencies of Osbnd H groups in phenol and catechol molecules as well as of their complexes with nitriles and ethers were determined in the gas phase using a specially designed cell. Osbnd H groups experimental frequency shifts in the complexes of catechol induced by the formation of intermolecular hydrogen bonds are significantly higher than in the complexes of phenol due to the hydrogen bond cooperativity. It was shown that the cooperativity factors of hydrogen bonds in the complexes of catechol with nitriles and ethers in the gas phase are approximately the same. Quantum chemical calculations of the studied systems have been performed using density functional theory (DFT) methods. It was shown, that theoretically obtained cooperativity factors of hydrogen bonds in the complexes of catechol with proton acceptors are in good agreement with experimental values. Cooperative effects lead to a strengthening of intermolecular hydrogen bonds in the complexes of catechol on about 30%, despite the significant difference in the proton acceptor ability of the bases. The analysis within quantum theory of atoms in molecules was carried out for the explanation of this fact.
Mixed-state quantum transport in correlated spin networks
Ajoy, Ashok
Quantum spin networks can be used to transport information between separated registers in a quantum-information processor. To find a practical implementation, the strict requirements of ideal models for perfect state ...
S. Khlebnikov; I. Tkachev
1999-02-08
We consider phase separation in nonequilibrium Bose gas with an attractive interaction between the particles. Using numerical integrations on a lattice, we show that the system evolves into a state that contains drops of Bose-Einstein condensate suspended in uncondensed gas. When the initial gas is sufficiently rarefied, the rate of formation of this quantum dew scales with the initial density as expected for a process governed by two-particle collisions.
NASA Astrophysics Data System (ADS)
Kurakin, A. M.; Vitusevich, S. A.; Danylyuk, S. V.; Hardtdegen, H.; Klein, N.; Bougrioua, Z.; Naumov, A. V.; Belyaev, A. E.
2009-04-01
We report the results of direct measurements and a theoretical investigation of the in-plane effective mass in the two-dimensional electron gas of nominally undoped AlGaN/GaN heterostructures with a different degree of quantum confinement. It is shown that in most cases the conduction band nonparabolicity effect is overestimated and the electron wave-function penetration into the barrier layer should be taken into account. The contribution of the wave-function hybridization is determined to play the dominant role. The band edge effective mass value is deduced to be (0.2±0.01)m0.
Centeno, R.; Marchenko, D.; Mandon, J.; Cristescu, S. M.; Harren, F. J. M.; Wulterkens, G.
2014-12-29
We present a high power, widely tunable, continuous wave external cavity quantum cascade laser designed for infrared vibrational spectroscopy of molecules exhibiting broadband and single line absorption features. The laser source exhibits single mode operation with a tunability up to 303?cm{sup ?1} (?24% of the center wavelength) at 8??m, with a maximum optical output power of 200?mW. In combination with off-axis integrated output spectroscopy, trace-gas detection of broadband absorption gases such as acetone was performed and a noise equivalent absorption sensitivity of 3.7 × 10{sup ?8?}cm{sup ?1?}Hz{sup ?1/2} was obtained.
Statistical Theory of the Ideal MHD Geodynamo
NASA Technical Reports Server (NTRS)
Shebalin, J. V.
2012-01-01
A statistical theory of geodynamo action is developed, using a mathematical model of the geodynamo as a rotating outer core containing an ideal (i.e., no dissipation), incompressible, turbulent, convecting magnetofluid. On the concentric inner and outer spherical bounding surfaces the normal components of the velocity, magnetic field, vorticity and electric current are zero, as is the temperature fluctuation. This allows the use of a set of Galerkin expansion functions that are common to both velocity and magnetic field, as well as vorticity, current and the temperature fluctuation. The resulting dynamical system, based on the Boussinesq form of the magnetohydrodynamic (MHD) equations, represents MHD turbulence in a spherical domain. These basic equations (minus the temperature equation) and boundary conditions have been used previously in numerical simulations of forced, decaying MHD turbulence inside a sphere [1,2]. Here, the ideal case is studied through statistical analysis and leads to a prediction that an ideal coherent structure will be found in the form of a large-scale quasistationary magnetic field that results from broken ergodicity, an effect that has been previously studied both analytically and numerically for homogeneous MHD turbulence [3,4]. The axial dipole component becomes prominent when there is a relatively large magnetic helicity (proportional to the global correlation of magnetic vector potential and magnetic field) and a stationary, nonzero cross helicity (proportional to the global correlation of velocity and magnetic field). The expected angle of the dipole moment vector with respect to the rotation axis is found to decrease to a minimum as the average cross helicity increases for a fixed value of magnetic helicity and then to increase again when average cross helicity approaches its maximum possible value. Only a relatively small value of cross helicity is needed to produce a dipole moment vector that is aligned at approx.10deg with the rotation axis.
Frequency locking of single-mode 3.5-THz quantum cascade lasers using a gas cell
Ren, Y.
We report frequency locking of two 3.5-THz third-order distributed feedback (DFB)quantum cascade lasers(QCLs) by using methanol molecular absorption lines, a proportional-integral-derivative controller, and a NbN bolometer. ...
Broken symmetry in ideal magnetohydrodynamic turbulence
NASA Technical Reports Server (NTRS)
Shebalin, John V.
1993-01-01
A numerical study of the long-time evolution of a number of cases of inviscid, isotropic, incompressible, three-dimensional fluid, and magneto-fluid turbulence has been completed. The results confirm that ideal magnetohydrodynamic turbulence is non-ergodic if there is no external magnetic field present. This is due essentially to a canonical symmetry being broken in an arbitrary dynamical representation. The broken symmetry manifests itself as a coherent structure, i.e., a non-zero time-averaged part of the turbulent magnetic field. The coherent structure is observed, in one case, to contain about eighteen percent of the total energy.
Das ideale Quantenlabor: Bose-Einstein-Kondensation
NASA Astrophysics Data System (ADS)
Sengstock, Klaus; Bongs, Kai; Reichel, Jakob
2003-07-01
Bose-Einstein-Kondensate (BEC) sind extrem kalte Gase aus bosonischen Atomen, die sich alle im energetischen Grundzustand versammeln. Ein BEC ist ein perfektes Quantenlabor. Es bietet eine makroskopische Materiewelle aus vielen Tausend Teilchen an, die dem Experiment offen zugänglich ist. Das unterscheidet es von anderen makroskopischen Quantenzuständen wie der Suprafluidität oder der Supraleitung, denn diese verbergen sich in Flüssigkeiten oder Festkörpern. Das BEC ist also ein ideales Modellsystem, um diese und andere Phänomene der Quantenmechanik zu studieren. Neue Perspektiven eröffnet die schnelle Erzeugung und leichte Manipulation eines Kondensats auf einem Mikrochip. Dazu gehören auch vielfältige Anwendungen bis hin zum Quantencomputer.
The equations of the ideal latches
Serban E. Vlad
2008-04-05
The latches are simple circuits with feedback from the digital electrical engineering. We have included in our work the C element of Muller, the RS latch, the clocked RS latch, the D latch and also circuits containing two interconnected latches: the edge triggered RS flip-flop, the D flip-flop, the JK flip-flop, the T flip-flop. The purpose of this study is to model with equations the previous circuits, considered to be ideal, i.e. non-inertial. The technique of analysis is the pseudoboolean differential calculus.
Hamiltonian description of the ideal fluid
Morrison, P.J.
1994-01-01
Fluid mechanics is examined from a Hamiltonian perspective. The Hamiltonian point of view provides a unifying framework; by understanding the Hamiltonian perspective, one knows in advance (within bounds) what answers to expect and what kinds of procedures can be performed. The material is organized into five lectures, on the following topics: rudiments of few-degree-of-freedom Hamiltonian systems illustrated by passive advection in two-dimensional fluids; functional differentiation, two action principles of mechanics, and the action principle and canonical Hamiltonian description of the ideal fluid; noncanonical Hamiltonian dynamics with examples; tutorial on Lie groups and algebras, reduction-realization, and Clebsch variables; and stability and Hamiltonian systems.
McCollam, A. Guduru, V. K.; Zeitler, U.; Maan, J. C.; Wenderich, S.; Kruize, M. K.; Molegraaf, H. J. A.; Huijben, M.; Koster, G.; Blank, D. H. A.; Rijnders, G.; Brinkman, A.; Hilgenkamp, H.
2014-02-01
We have performed high field magnetotransport measurements to investigate the interface electron gas in a high mobility SrTiO{sub 3}/SrCuO{sub 2}/LaAlO{sub 3}/SrTiO{sub 3} heterostructure. Shubnikov-de Haas oscillations reveal several 2D conduction subbands with carrier effective masses of 0.9m{sub e} and 2m{sub e}, quantum mobilities of order 2000 cm{sup 2}/V s, and band edges only a few millielectronvolts below the Fermi energy. Measurements in tilted magnetic fields confirm the 2D character of the electron gas, and show evidence of inter-subband scattering.
ERIC Educational Resources Information Center
Tomba, J. Pablo
2015-01-01
The thermodynamic formalism of ideal solutions is developed in most of the textbooks postulating a form for the chemical potential of a generic component, which is adapted from the thermodynamics of ideal gas mixtures. From this basis, the rest of useful thermodynamic properties can be derived straightforwardly without further hypothesis. Although…
Global invariants in ideal magnetohydrodynamic turbulence
NASA Astrophysics Data System (ADS)
Shebalin, John V.
2013-10-01
Magnetohydrodynamic (MHD) turbulence is an important though incompletely understood factor affecting the dynamics of many astrophysical, geophysical, and technological plasmas. As an approximation, viscosity and resistivity may be ignored, and ideal MHD turbulence may be investigated by statistical methods. Incompressibility is also assumed and finite Fourier series are used to represent the turbulent velocity and magnetic field. The resulting model dynamical system consists of a set of independent Fourier coefficients that form a canonical ensemble described by a Gaussian probability density function (PDF). This PDF is similar in form to that of Boltzmann, except that its argument may contain not just the energy multiplied by an inverse temperature, but also two other invariant integrals, the cross helicity and magnetic helicity, each multiplied by its own inverse temperature. However, the cross and magnetic helicities, as usually defined, are not invariant in the presence of overall rotation or a mean magnetic field, respectively. Although the generalized form of the magnetic helicity is known, a generalized cross helicity may also be found, by adding terms that are linear in the mean magnetic field and angular rotation vectors, respectively. These general forms are invariant even in the presence of overall rotation and a mean magnetic field. We derive these general forms, explore their properties, examine how they extend the statistical theory of ideal MHD turbulence, and discuss how our results may be affected by dissipation and forcing.
Global invariants in ideal magnetohydrodynamic turbulence
Shebalin, John V.
2013-10-15
Magnetohydrodynamic (MHD) turbulence is an important though incompletely understood factor affecting the dynamics of many astrophysical, geophysical, and technological plasmas. As an approximation, viscosity and resistivity may be ignored, and ideal MHD turbulence may be investigated by statistical methods. Incompressibility is also assumed and finite Fourier series are used to represent the turbulent velocity and magnetic field. The resulting model dynamical system consists of a set of independent Fourier coefficients that form a canonical ensemble described by a Gaussian probability density function (PDF). This PDF is similar in form to that of Boltzmann, except that its argument may contain not just the energy multiplied by an inverse temperature, but also two other invariant integrals, the cross helicity and magnetic helicity, each multiplied by its own inverse temperature. However, the cross and magnetic helicities, as usually defined, are not invariant in the presence of overall rotation or a mean magnetic field, respectively. Although the generalized form of the magnetic helicity is known, a generalized cross helicity may also be found, by adding terms that are linear in the mean magnetic field and angular rotation vectors, respectively. These general forms are invariant even in the presence of overall rotation and a mean magnetic field. We derive these general forms, explore their properties, examine how they extend the statistical theory of ideal MHD turbulence, and discuss how our results may be affected by dissipation and forcing.
Thermodynamics of an idealized hydrologic cycle
NASA Astrophysics Data System (ADS)
Konings, Alexandra G.; Feng, Xue; Molini, Annalisa; Manzoni, Stefano; Vico, Giulia; Porporato, Amilcare
2012-05-01
The diurnal hydrologic cycle, a sequence of evapotranspiration, boundary layer growth, moist convection, and precipitation, is described in a thermodynamic framework, assuming an atmosphere composed solely of water. This idealized cycle is shown to be equivalent to an abbreviated version of the classical Rankine cycle where not all the water vapor is condensed. Energy and entropy fluxes of the processes involved in the cycle are quantified using the reversible approximation as a function of the quality of the liquid-vapor mixture (the ratio of the residual background vapor and the total mass of water) and the different temperatures at which evaporation and condensation take place. The proposed framework allows quantitative estimates of the net work (which is used by the cycle to drive the atmospheric circulation and dissipated by various frictional forces and nonidealities) as well as of the thermodynamic efficiency of the cycle. Possible extensions of the idealized framework relating to the role of dry air and the inclusion of various irreversible processes are also discussed.
Ideal fermion delocalization in Higgsless models
Chivukula, R. Sekhar; Simmons, Elizabeth H.; He, Hong-Jian; Kurachi, Masafumi; Tanabashi, Masaharu
2005-07-01
In this note we examine the properties of deconstructed Higgsless models for the case of a fermion whose SU(2) properties arise from delocalization over many sites of the deconstructed lattice. We derive expressions for the correlation functions and use these to establish a generalized consistency relation among correlation functions. We discuss the form of the W boson wavefunction and show that if the probability distribution of the delocalized fermions is appropriately related to the W wavefunction, then deviations in precision electroweak parameters are minimized. In particular, we show that this ''ideal fermion delocalization'' results in the vanishing of three of the four leading zero-momentum electroweak parameters defined by Barbieri et al. We then discuss ideal fermion delocalization in the context of two continuum Higgsless models, one in Anti-deSitter space and one in flat space. Our results may be applied to any Higgsless linear moose model with multiple SU(2) groups, including those with only a few extra vector bosons.
Ideal fermion delocalization in Higgsless models
NASA Astrophysics Data System (ADS)
Chivukula, R. Sekhar; Simmons, Elizabeth H.; He, Hong-Jian; Kurachi, Masafumi; Tanabashi, Masaharu
2005-07-01
In this note we examine the properties of deconstructed Higgsless models for the case of a fermion whose SU(2) properties arise from delocalization over many sites of the deconstructed lattice. We derive expressions for the correlation functions and use these to establish a generalized consistency relation among correlation functions. We discuss the form of the W boson wavefunction and show that if the probability distribution of the delocalized fermions is appropriately related to the W wavefunction, then deviations in precision electroweak parameters are minimized. In particular, we show that this “ideal fermion delocalization” results in the vanishing of three of the four leading zero-momentum electroweak parameters defined by Barbieri et al. We then discuss ideal fermion delocalization in the context of two continuum Higgsless models, one in Anti-deSitter space and one in flat space. Our results may be applied to any Higgsless linear moose model with multiple SU(2) groups, including those with only a few extra vector bosons.
Optimal forager against ideal free distributed prey.
Garay, József; Cressman, Ross; Xu, Fei; Varga, Zoltan; Cabello, Tomás
2015-07-01
The introduced dispersal-foraging game is a combination of prey habitat selection between two patch types and optimal-foraging approaches. Prey's patch preference and forager behavior determine the prey's survival rate. The forager's energy gain depends on local prey density in both types of exhaustible patches and on leaving time. We introduce two game-solution concepts. The static solution combines the ideal free distribution of the prey with optimal-foraging theory. The dynamical solution is given by a game dynamics describing the behavioral changes of prey and forager. We show (1) that each stable equilibrium dynamical solution is always a static solution, but not conversely; (2) that at an equilibrium dynamical solution, the forager can stabilize prey mixed patch use strategy in cases where ideal free distribution theory predicts that prey will use only one patch type; and (3) that when the equilibrium dynamical solution is unstable at fixed prey density, stable behavior cycles occur where neither forager nor prey keep a fixed behavior. PMID:26098343
Ideal teleradiology configuration from a physician's perspective
NASA Astrophysics Data System (ADS)
Leckie, Robert G.; de Treville, Robert E.; Lyche, David K.; Norton, Gary S.; Goeringer, Fred; Willis, Charles E.; Cawthon, Michael A.; Smith, Donald V.; Hansen, Mark
1993-09-01
Teleradiology systems are being developed and implemented around the world. The ultimate success of these systems depends on the acceptance by the end users -- the physicians. From a physician's perspective, several major areas need to be addressed in the ideal situation. The areas include (1) image quality and ease of manipulation of images on a workstation; (2) expert interpretation by a specialist or sub-specialist; (3) good communication between the radiologist, radiology technologist, primary care physician, and the patient; (4) accessibility to images; (5) system reliability; (6) costs and assistance in balancing workloads; and (7) education and research. The Medical Diagnostic Imaging Support (MDIS) System is a large tri-service project to install picture archive and communication systems (PACS) and teleradiology at military medical treatment facilities across the United States and abroad. The first sites primarily involved with teleradiology will be installed in the summer of 1993. Ways in which the MDIS teleradiology system address the physicians' ideal configuration as well as possible future improvements are discussed.
The Statistical Mechanics of Ideal Homogeneous Turbulence
NASA Technical Reports Server (NTRS)
Shebalin, John V.
2002-01-01
Plasmas, such as those found in the space environment or in plasma confinement devices, are often modeled as electrically conducting fluids. When fluids and plasmas are energetically stirred, regions of highly nonlinear, chaotic behavior known as turbulence arise. Understanding the fundamental nature of turbulence is a long-standing theoretical challenge. The present work describes a statistical theory concerning a certain class of nonlinear, finite dimensional, dynamical models of turbulence. These models arise when the partial differential equations describing incompressible, ideal (i.e., nondissipative) homogeneous fluid and magnetofluid (i.e., plasma) turbulence are Fourier transformed into a very large set of ordinary differential equations. These equations define a divergenceless flow in a high-dimensional phase space, which allows for the existence of a Liouville theorem, guaranteeing a distribution function based on constants of the motion (integral invariants). The novelty of these particular dynamical systems is that there are integral invariants other than the energy, and that some of these invariants behave like pseudoscalars under two of the discrete symmetry transformations of physics, parity, and charge conjugation. In this work the 'rugged invariants' of ideal homogeneous turbulence are shown to be the only significant scalar and pseudoscalar invariants. The discovery that pseudoscalar invariants cause symmetries of the original equations to be dynamically broken and induce a nonergodic structure on the associated phase space is the primary result presented here. Applicability of this result to dissipative turbulence is also discussed.
Operator Ideals in Lipschitz and Operator Spaces Categories
Chavez Dominguez, Javier
2012-10-19
nonlinear ideals of operators including the ideal of Lipschitz p-summing operators and the ideal of factorization through a subset of a Hilbert space. We prove metric characterizations of p-convex operators, and also of those with Rademacher type and cotype...
Moral Identity as Moral Ideal Self: Links to Adolescent Outcomes
ERIC Educational Resources Information Center
Hardy, Sam A.; Walker, Lawrence J.; Olsen, Joseph A.; Woodbury, Ryan D.; Hickman, Jacob R.
2014-01-01
The purposes of this study were to conceptualize moral identity as moral ideal self, to develop a measure of this construct, to test for age and gender differences, to examine links between moral ideal self and adolescent outcomes, and to assess purpose and social responsibility as mediators of the relations between moral ideal self and outcomes.…
Promoting Spiritual Ideals through Design Thinking in Public Schools
ERIC Educational Resources Information Center
Tan, Charlene; Wong, Yew-Leong
2012-01-01
Against a backdrop of the debates on religious education in public or state schools, we argue for the introduction of "spiritual ideals" into the public school curriculum. We distinguish our notion of spiritual ideals from "religious ideals" as conceptualised by De Ruyter and Merry. While we agree with De Ruyter and Merry that ideas drawn from…
Sex-Role Contradictions: Self-Perceptions and Ideal Perceptions.
ERIC Educational Resources Information Center
Scher, Dena
1984-01-01
Male and female college students described themselves and their ideal male and female with regard to sex-typed characteristics. Females described an androgynous model for themselves and their ideals. Males described an androgynous model for their self-portrayals but sex-typed portrayals for their ideals. (CMG)
The Transfer of Scientific Principles Using Concrete and Idealized
Goldstone, Robert
The Transfer of Scientific Principles Using Concrete and Idealized Simulations Robert L. Goldstone the first simulation was manipulated. The elements either remained concrete throughout the simulation, remained idealized, or switched midway into the simulation from concrete to idealized or vice versa
Taut ideal triangulations of 3manifolds Marc Lackenby
Lackenby, Marc
Taut ideal triangulations of 3Âmanifolds Marc Lackenby Mathematical Institute, Oxford University triangulation of a 3Âmanifold is a topological ideal triangulation with extra combinatorial structure: a choice is to demonstrate that taut ideal triangulations are very common, and that their behaviour is very similar
Taut ideal triangulations of 3-manifolds Marc Lackenby
Lackenby, Marc
Taut ideal triangulations of 3-manifolds Marc Lackenby Mathematical Institute, Oxford University triangulation of a 3-manifold is a topological ideal triangulation with extra combinatorial structure: a choice is to demonstrate that taut ideal triangulations are very common, and that their behaviour is very similar
Lecture 7: HC Cells and Primitive Ideals Department of Mathematics
Binegar, Birne
) Lecture 7: HC Cells and Primitive Ideals Nankai 2008 6 / 14 #12;Left Cells in W Definition LetLecture 7: HC Cells and Primitive Ideals B. Binegar Department of Mathematics Oklahoma State, 2008 B. Binegar (Oklahoma State University) Lecture 7: HC Cells and Primitive Ideals Nankai 2008 1 / 14
An ideal sealed source life-cycle
Tompkins, Joseph Andrew
2009-01-01
In the last 40 years, barriers to compliant and timely disposition of radioactive sealed sources have become apparent. The story starts with the explosive growth of nuclear gauging technologies in the 1960s. Dozens of companies in the US manufactured sources and many more created nuclear solutions to industrial gauging problems. Today they do not yet know how many Cat 1, 2, or 3 sources there are in the US. There are, at minimum, tens of thousands of sources, perhaps hundreds of thousands of sources. Affordable transportation solutions to consolidate all of these sources and disposition pathways for these sources do not exist. The root problem seems to be a lack of necessary regulatory framework that has allowed all of these problems to accumulate with no national plan for solving the problem. In the 1960s, Pu-238 displaced Pu-239 for most neutron and alpha source applications. In the 1970s, the availability of inexpensive Am-241 resulted in a proliferation of low energy gamma sources used in nuclear gauging, well logging, pacemakers, and X-ray fluorescence applications for example. In the 1980s, rapid expansion of worldwide petroleum exploration resulted in the expansion of Am-241 sources into international locations. Improvements of technology and regulation resulted in a change in isotopic distribution as Am-241 made Pu-239 and Pu-238 obsolete. Many early nuclear gauge technologies have been made obsolete as they were replaced by non-nuclear technoogies. With uncertainties in source end of life disposition and increased requirements for sealed source security, nuclear gauging technology is the last choice for modern process engineering gauging solutions. Over the same period, much was learned about licensing LLW disposition facilities as evident by the closure of early disposition facilities like Maxey Flats. The current difficulties in sealed source disposition start with adoption of the NLLW policy act of 1985, which created the state LLW compact system they we have today. This regulation created a new regulatory framework seen as promising at the time. However, now they recognize that, despite the good intentions, the NIJWP/85 has not solved any source disposition problems. The answer to these sealed source disposition problems is to adopt a philosophy to correct these regulatory issues, determine an interim solution, execute that solution until there is a minimal backlog of sources to deal with, and then let the mechanisms they have created solve this problem into the foreseeable future. The primary philosophical tenet of the ideal sealed source life cycle follows. You do not allow the creation (or importation) of any source whose use cannot be justified, which cannot be affordably shipped, or that does not have a well-delinated and affordable disposition pathway. The path forward dictates that we fix the problem by embracing the Ideal Source Life cycle. In figure 1, we can see some of the elements of the ideal source life cycle. The life cycle is broken down into four portions, manufacture, use, consolidation, and disposition. These four arbitrary elements allow them to focus on the ideal life cycle phases that every source should go through between manufacture and final disposition. As we examine the various phases of the sealed source life cycle, they pick specific examples and explore the adoption of the ideal life cycle model.
Concepts of Self, Ideal Self, and Ideal Woman Held by College Men and Women: A Comparison Study.
ERIC Educational Resources Information Center
Voss, Jacqueline
1980-01-01
Married and single male and female college students of 1966, 1973, and 1976 are compared in their perceptions of female sex role--self, ideal woman, and man's ideal woman. Differences between perceptions of the ideal woman espoused by males and females were the most significant findings. (Author)
On controlling nonlinear dissipation in high order filter methods for ideal and non-ideal MHD
NASA Technical Reports Server (NTRS)
Yee, H. C.; Sjogreen, B.
2004-01-01
The newly developed adaptive numerical dissipation control in spatially high order filter schemes for the compressible Euler and Navier-Stokes equations has been recently extended to the ideal and non-ideal magnetohydrodynamics (MHD) equations. These filter schemes are applicable to complex unsteady MHD high-speed shock/shear/turbulence problems. They also provide a natural and efficient way for the minimization of Div(B) numerical error. The adaptive numerical dissipation mechanism consists of automatic detection of different flow features as distinct sensors to signal the appropriate type and amount of numerical dissipation/filter where needed and leave the rest of the region free from numerical dissipation contamination. The numerical dissipation considered consists of high order linear dissipation for the suppression of high frequency oscillation and the nonlinear dissipative portion of high-resolution shock-capturing methods for discontinuity capturing. The applicable nonlinear dissipative portion of high-resolution shock-capturing methods is very general. The objective of this paper is to investigate the performance of three commonly used types of nonlinear numerical dissipation for both the ideal and non-ideal MHD.
Approximations of C*-algebras and the ideal property
NASA Astrophysics Data System (ADS)
Carrión, José R.; Pasnicu, Cornel
2008-02-01
We introduce several classes of C*-algebras (using for this local approximations by "nice" C*-algebras), that generalize the AH algebras, among others. We initiate their study, proving mainly results about the ideal property, but also about the ideals generated by their projections, the real rank zero, the weak projection property, minimal tensor products, extensions, quasidiagonal extensions, ideal structure, the largest ideal with the ideal property and short exact sequences. Some of the previous results of the second named author are generalized.
Broken Ergodicity in Ideal, Homogeneous, Incompressible Turbulence
NASA Technical Reports Server (NTRS)
Morin, Lee; Shebalin, John; Fu, Terry; Nguyen, Phu; Shum, Victor
2010-01-01
We discuss the statistical mechanics of numerical models of ideal homogeneous, incompressible turbulence and their relevance for dissipative fluids and magnetofluids. These numerical models are based on Fourier series and the relevant statistical theory predicts that Fourier coefficients of fluid velocity and magnetic fields (if present) are zero-mean random variables. However, numerical simulations clearly show that certain coefficients have a non-zero mean value that can be very large compared to the associated standard deviation. We explain this phenomena in terms of broken ergodicity', which is defined to occur when dynamical behavior does not match ensemble predictions on very long time-scales. We review the theoretical basis of broken ergodicity, apply it to 2-D and 3-D fluid and magnetohydrodynamic simulations of homogeneous turbulence, and show new results from simulations using GPU (graphical processing unit) computers.
Achieving ideal breast aesthetics with autologous reconstruction
2015-01-01
Achieving ideal breast aesthetic has become a top priority for women considering breast reconstruction following mastectomy. The use of autologous tissue is generally regarded as providing the most natural results because donor tissues quality and consistency is similar to that of the native breast. There are several donor sites that are particularly useful for autologous reconstruction that include the abdomen, gluteal region, posterior thorax, and the thigh. Traditional and microsurgical techniques can be used. Shaping is a critical component and involves a basic understanding of the footprint, conus, and skin envelope. This manuscript will review many aspects of breast shaping in-order to achieve aesthetically pleasing results in a predictable manner. PMID:26005645
Thermal stability of idealized folded carbyne loops
NASA Astrophysics Data System (ADS)
Cranford, Steven W.
2013-11-01
Self-unfolding items provide a practical convenience, wherein ring-like frames are contorted into a state of equilibrium and subsequently pop up' or deploy when perturbed from a folded structure. Can the same process be exploited at the molecular scale? At the limiting scale is a closed chain of single atoms, used here to investigate the limits of stability of such folded ring structures via full atomistic molecular dynamics. Carbyne is a one-dimensional carbon allotrope composed of sp-hybridized carbon atoms. Here, we explore the stability of idealized carbyne loops as a function of chain length, curvature, and temperature, and delineate an effective phase diagram between folded and unfolded states. We find that while overall curvature is reduced, in addition to torsional and self-adhesive energy barriers, a local increase in curvature results in the largest impedance to unfolding.
The Allee-type ideal free distribution.
K?ivan, Vlastimil
2014-12-01
The ideal free distribution (IFD) in a two-patch environment where individual fitness is positively density dependent at low population densities is studied. The IFD is defined as an evolutionarily stable strategy of the habitat selection game. It is shown that for low and high population densities only one IFD exists, but for intermediate population densities there are up to three IFDs. Population and distributional dynamics described by the replicator dynamics are studied. It is shown that distributional stability (i.e., IFD) does not imply local stability of a population equilibrium. Thus distributional stability is not sufficient for population stability. Results of this article demonstrate that the Allee effect can strongly influence not only population dynamics, but also population distribution in space. PMID:24306202
Review of Idealized Aircraft Wake Vortex Models
NASA Technical Reports Server (NTRS)
Ahmad, Nashat N.; Proctor, Fred H.; Duparcmeur, Fanny M. Limon; Jacob, Don
2014-01-01
Properties of three aircraft wake vortex models, Lamb-Oseen, Burnham-Hallock, and Proctor are reviewed. These idealized models are often used to initialize the aircraft wake vortex pair in large eddy simulations and in wake encounter hazard models, as well as to define matched filters for processing lidar observations of aircraft wake vortices. Basic parameters for each vortex model, such as peak tangential velocity and circulation strength as a function of vortex core radius size, are examined. The models are also compared using different vortex characterizations, such as the vorticity magnitude. Results of Euler and large eddy simulations are presented. The application of vortex models in the postprocessing of lidar observations is discussed.
Ideal magnetohydrodynamic interchanges in low density plasmas
Huang Yimin; Goel, Deepak; Hassam, A.B.
2005-03-01
The ideal magnetohydrodynamic equations are usually derived under the assumption V{sub A}<
Idealized simulations of sting jet cyclones
NASA Astrophysics Data System (ADS)
Baker, L. H.; Gray, S. L.; Clark, P. A.
2012-04-01
An idealized modeling study of sting-jet cyclones is presented. Sting jets are descending mesoscale jets that occur in some extratropical cyclones and produce localized regions of strong low-level winds in the frontal fracture region. Moist baroclinic lifecycle (LC1) simulations are performed with modifications to produce cyclones resembling observed sting-jet cyclones. Two jets exist in the control idealized cyclone that descend into the frontal fracture region and result in strong winds near to the top of the boundary layer; one of these satisfies the criteria for a sting jet, the other is associated with the warm front. Sensitivity experiments show that both these jets are robust features. The sting jet strength (measured by maximum low-level wind speed or descent rate) increases with the cyclone growth rate; growth rate increases with increasing basic-state zonal jet maximum or decreasing basic-state tropospheric static stability. The two cyclones with the weakest basic-state static stability have by far the strongest sting jets, with descent rates comparable to those observed. Evaporative cooling contributes up to 20% of the descent rate in these sting jets compared with up to 4% in the other sting jets. Conditional symmetric instability (CSI) release in the cloud head also contributes to the sting jet, although there is less extensive CSI than in observed cases. The robustness of the sting jets suggests that they could occur frequently in cyclones with frontal fracture; however, they are unlikely to be identified unless momentum transport through the boundary layer leads to strong surface wind gusts.
Buryak, Ilya; Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, 3 Pyzhevsky per., 119017 Moscow ; Frommhold, Lothar; Vigasin, Andrey A.
2014-04-21
We compare calculations of the translational collision-induced spectra and their integrated intensities of both He–Ar and Ne–Ar collisional complexes, using the quantum mechanical and a semiclassical formalism. Advanced potential energy and induced dipole functions are used for the calculations. The quantum method used is as described previously [L. Frommhold, Collision-induced Absorption in Gases (Cambridge University Press, 1993 and 2006)]. The semiclassical method is based on repeated classical atom-atom scattering calculations to simulate an ensemble average; subsequent Fourier transform then renders the binary absorption coefficient as a function of frequency. The problem of classical calculations is the violation of the principle of detailed balance, which may be introduced only artificially in classical calculations. Nevertheless, it is shown that the use of classical trajectories permits a fairly accurate reproduction of the experimental spectra, comparable to the quantum mechanical results at not too low temperatures and for collisional pairs of not too small reduced mass. Inexpensive classical calculations may thus be promising to compute spectra also of molecular pairs, or even of polyatomic collisional pairs with anisotropic intermolecular interactions, for which the quantum approach is still inefficient or impractical.
Family Life and Developmental Idealism in Yazd, Iran
Abbasi-Shavazi, Mohammad Jalal; Askari-Nodoushan, Abbas
2012-01-01
BACKGROUND This paper is motivated by the theory that developmental idealism has been disseminated globally and has become an international force for family and demographic change. Developmental idealism is a set of cultural beliefs and values about development and how development relates to family and demographic behavior. It holds that modern societies are causal forces producing modern families, that modern families help to produce modern societies, and that modern family change is to be expected. OBJECTIVE We examine the extent to which developmental idealism has been disseminated in Iran. We also investigate predictors of the dissemination of developmental idealism. METHODS We use survey data collected in 2007 from a sample of women in Yazd, a city in Iran. We examine the distribution of developmental idealism in the sample and the multivariate predictors of developmental idealism. RESULTS We find considerable support for the expectation that many elements of developmental idealism have been widely disseminated. Statistically significant majorities associate development with particular family attributes, believe that development causes change in families, believe that fertility reductions and age-at-marriage increases help foster development, and perceive family trends in Iran headed toward modernity. As predicted, parental education, respondent education, and income affect adherence to developmental idealism. CONCLUSIONS Developmental idealism has been widely disseminated in Yazd, Iran and is related to social and demographic factors in predicted ways. COMMENTS Although our data come from only one city, we expect that developmental idealism has been widely distributed in Iran, with important implications for family and demographic behavior. PMID:22942772
Engineering the Ideal Gigapixel Image Viewer
NASA Astrophysics Data System (ADS)
Perpeet, D. Wassenberg, J.
2011-09-01
Despite improvements in automatic processing, analysts are still faced with the task of evaluating gigapixel-scale mosaics or images acquired by telescopes such as Pan-STARRS. Displaying such images in ‘ideal’ form is a major challenge even today, and the amount of data will only increase as sensor resolutions improve. In our opinion, the ideal viewer has several key characteristics. Lossless display - down to individual pixels - ensures all information can be extracted from the image. Support for all relevant pixel formats (integer or floating point) allows displaying data from different sensors. Smooth zooming and panning in the high-resolution data enables rapid screening and navigation in the image. High responsiveness to input commands avoids frustrating delays. Instantaneous image enhancement, e.g. contrast adjustment and image channel selection, helps with analysis tasks. Modest system requirements allow viewing on regular workstation computers or even laptops. To the best of our knowledge, no such software product is currently available. Meeting these goals requires addressing certain realities of current computer architectures. GPU hardware accelerates rendering and allows smooth zooming without high CPU load. Programmable GPU shaders enable instant channel selection and contrast adjustment without any perceptible slowdown or changes to the input data. Relatively low disk transfer speeds suggest the use of compression to decrease the amount of data to transfer. Asynchronous I/O allows decompressing while waiting for previous I/O operations to complete. The slow seek times of magnetic disks motivate optimizing the order of the data on disk. Vectorization and parallelization allow significant increases in computational capacity. Limited memory requires streaming and caching of image regions. We develop a viewer that takes the above issues into account. Its awareness of the computer architecture enables previously unattainable features such as smooth zooming and image enhancement within high-resolution data. We describe our implementation, disclosing its novel file format and lossless image codec whose decompression is faster than copying the raw data in memory. Both provide crucial performance boosts compared to conventional approaches. Usability tests demonstrate the suitability of our viewer for rapid analysis of large SAR datasets, multispectral satellite imagery and mosaics.
Fedosov, Dmitry A; Gompper, Gerhard
2015-01-01
Janus colloids propelled by light, e.g., thermophoretic particles, offer promising prospects as artificial microswimmers. However, their swimming behavior and its dependence on fluid properties and fluid-colloid interactions remain poorly understood. Here, we investigate the behavior of a thermophoretic Janus colloid in its own temperature gradient using numerical simulations. The dissipative particle dynamics method with energy conservation is used to investigate the behavior in non-ideal and ideal-gas like fluids for different fluid-colloid interactions, boundary conditions, and temperature-controlling strategies. The fluid-colloid interactions appear to have a strong effect on the colloid behavior, since they directly affect heat exchange between the colloid surface and the fluid. The simulation results show that a reduction of the heat exchange at the fluid-colloid interface leads to an enhancement of colloid's thermophoretic mobility. The colloid behavior is found to be different in non-ideal and ideal f...
Einstein's idealism and a new kind of space research
NASA Astrophysics Data System (ADS)
Popov, M. A.
In 1935, Albert Einstein, Boris Podolsky and Nathan Rosen made an attempt to imagine quantum experimental nonsense or some impossible experiment (EPR-experiment) in order to justify their local realism in physics. However, in the mid-1960s, John Bell showed that it is possible to realize this kind of nonsense in laboratory. Today, when EPR-refutation of local realism is routine in modern experimental physics (Clauser and Freedman [1972]; Aspect, Dalibard and Roger [1982]; Zeilinger et al. [1998]), we must; nevertheless, remark that Albert Einstein was not always a realist. As is known, in his Special Relativitz A. Einstein introduced some pure idealistic principle which K. Godel developed in famous "Remark about the relationship between Relativity theorz and Idealistic Philosophy" (1949). Kurt Godel for the first time showed an existence of special-relativistic solipsism, assuming that objective simultaneity in experimental science "loses its objective meaning". Correspondingly, there is only subjective simultaneity, that is provable by calculations with the finite velocity of light and astronomical observations. In particular, this space solipsism means that when we observe the sun, we can see only what happend on Sun 8.33 minutes ago; in other words, we percieve only certain sensations or a certain collections of ideas of the past, but not the present. Similarly, when astronomers observe galaxies estimated to be two billion light years from the Earth, they see these galaxies as they were two billion light years ago not as they are Now. Thus, in accordance with this, we may await that in this context for some pairs of astronomical objects we cannot prove they exist NOW. Moreover, this new kind of space research could be connected with introduction of the Cognitive Dark Matter, or, what is associated with manifold of the large-scale events of the Universe as a whole which are realizing Now, beyond consciousness of the observers-humans. Because we cannot know present time in Cosmology, the Cognitive Dark Matter is Kant-like superphenomental, or transcendental "noumental process" (Noumena). To describe Transcendental Dark Matter by methods of experimental idealism is, probably, the most sursprising and profound task for new space discipline ("Space Idealism"). We may await also that some fundamental characteristics of physical Dark Matter, discovered by Ostiker, Steinhardt, Krauss and Turner (1955), can be explained by our hypothethis, because it is not impossible that the Dark Matter is a part of the Cognitive Dark Matter, contained an observer's impact, which cannot be neglected after Special Relativity.
PHYSICS 482, QUANTUM MECHANICS II Introductory Quantum Mechanics contd.
Akerib, Daniel S.
PHYSICS 482, QUANTUM MECHANICS II Introductory Quantum Mechanics contd. 1. Time dependent methods. Quantum Many-body physics: 1. Variational principle, simple applications. 2. Many body wave, ferromagnetism of the electron gas, Wigner crystals and quantum phase transitions. 4. Second quantization
Field topologies in ideal and near-ideal magnetohydrodynamics and vortex dynamics
NASA Astrophysics Data System (ADS)
Low, B. C.
2015-01-01
Magnetic field topology frozen in ideal magnetohydrodynamics (MHD) and its breakage in near-ideal MHD are reviewed in two parts, clarifying and expanding basic concepts. The first part gives a physically complete description of the frozen field topology derived from magnetic flux conservation as the fundamental property, treating four conceptually related topics: Eulerian and Lagrangian descriptions of three dimensional (3D) MHD, Chandrasekhar-Kendall and Euler-potential field representations, magnetic helicity, and inviscid vortex dynamics as a fluid system in physical contrast to ideal MHD. A corollary of these developments clarifies the challenge of achieving a high degree of the frozen-in condition in numerical MHD. The second part treats field-topology breakage centered around the Parker Magnetostatic Theorem on a general incompatibility of a continuous magnetic field with the dual demand of force-free equilibrium and an arbitrarily prescribed, 3D field topology. Preserving field topology as a global constraint readily results in formation of tangential magnetic discontinuities, or, equivalently, electric current-sheets of zero thickness. A similar incompatibility is present in the steady force-thermal balance of a heated radiating fluid subject to an anisotropic thermal flux conducted strictly along its frozen-in magnetic field in the low- ? limit. In a weakly resistive fluid the thinning of current sheets by these general incompatibilities inevitably results in sheet dissipation, resistive heating and topological changes in the field notwithstanding the small resistivity. Strong Faraday induction drives but also macroscopically limits this mode of energy dissipation, trapping or storing free energy in self-organized ideal-MHD structures. This property of MHD turbulence captured by the Taylor hypothesis is reviewed in relation to the Sun's corona, calling for a basic quantitative description of the breakdown of flux conservation in the low-resistivity limit. A cylindrical initial-boundary value problem provides specificity in the general MHD ideas presented.
Ideal bandpasses for type Ia supernova cosmology
Davis, Tamara M.; Schmidt, Brian P.; Kim, Alex G.
2005-10-24
To use type Ia supernovae as standard candles for cosmologywe need accurate broadband magnitudes. In practice the observed magnitudemay differ from the ideal magnitude-redshift relationship either throughintrinsic inhomogeneities in the type Ia supernova population or throughobservational error. Here we investigate how we can choose filterbandpasses to reduce the error caused by both these effects. We find thatbandpasses with large integral fluxes and sloping wings are best able tominimise several sources of observational error, and are also leastsensitive to intrinsic differences in type Ia supernovae. The mostimportant feature of a complete filter set for type Ia supernovacosmology is that each bandpass be a redshifted copy of the first. Wedesign practical sets of redshifted bandpasses that are matched totypical high resistivity CCD and HgCdTe infra-red detector sensitivities.These are designed to minimise systematic error in well observedsupernovae, final designs for specific missions should also considersignal-to-noise requirements and observing strategy. In addition wecalculate how accurately filters need to be calibrated in order toachieve the required photometric accuracy of future supernova cosmologyexperiments such as the SuperNova-Acceleration-Probe (SNAP), which is onepossible realisation of the Joint Dark-Energy mission (JDEM). We considerthe effect of possible periodic miscalibrations that may arise from theconstruction of an interference filter.
Flexibility mechanisms in ideal zeolite frameworks.
Treacy, M M J; Dawson, C J; Kapko, V; Rivin, I
2014-02-13
Zeolites are microporous crystalline aluminosilicate materials whose atomic structures can be usefully modelled in purely mechanical terms as stress-free periodic trusses constructed from rigid corner-connected SiO4 and AlO4 tetrahedra. When modelled this way, all of the known synthesized zeolite frameworks exhibit a range of densities, known as the flexibility window, over which they satisfy the framework mechanical constraints. Within the flexibility window internal stresses are accommodated by force-free coordinated rotations of the tetrahedra about their apices (oxygen atoms). We use rigidity theory to explore the folding mechanisms within the flexibility window, and derive an expression for the configurational entropic density throughout the flexibility window. By comparison with the structures of pure silica zeolite materials, we conclude that configurational entropy associated with the flexibility modes is not a dominant thermodynamic term in most bulk zeolite crystals. Nevertheless, the presence of a flexibility window in an idealized hypothetical tetrahedral framework may be thermodynamically important at the nucleation stage of zeolite formation, suggesting that flexibility is a strong indicator that the topology is realizable as a zeolite. Only a small fraction of the vast number of hypothetical zeolites that are known exhibit flexibility. The absence of a flexibility window may explain why so few hypothetical frameworks are realized in nature. PMID:24379426
[Tuberculosis and the modern ideal of living].
Medici, T C
2003-08-20
Sunlight and fresh air belong to the everyday life's myths. It has influenced our times and personal lives as much as industrialization. Today we are hardly aware of the multiple and omnipresent consequences of this myth. The modern movement with all its facets including modern architecture is barely conceivable without it. What is the link between this triad with all its effects and tuberculosis, the oldest and most important infectious disease which still claims more than 3 million deaths per year worldwide? Tuberculosis was treated by sunlight and fresh air at all times. This treatment was at its zenith during the second half of the 19th century after Hermann Brehmer had initiated this treatment within sanatoria in 1862. The sanatorium vogue lasted until the middle of the last century when streptomycin was isolated by Selman Waksman 1943. A new type of hospital was necessary for treating the patients with sunlight and fresh air: the sanatorium with its wide windows, sheltered open balconies, terraces and "Liegehallen". In return, this airy type of building was the forrunner of a new architectural style, called "Neues Bauen". The latter has profoundly influenced our modern ideal of living since Le Corbusiier built the Villa Savoye, one of the architectural highlights of the 20th century. PMID:14513485
Can curcumin provide an ideal contraceptive?
Naz, Rajesh K
2011-02-01
The population explosion, unintended pregnancies, sexually transmitted diseases, and cancer (cervical and breast) continue to cause major public health issues worldwide. Curcumin, diferuloyl methane, the yellow pigment component of the curry spice turmeric (Curcuma longa), has immense biological effects and has recently drawn considerable attention. Curcumin has antibacterial, antiviral, antiinflammatory, and anticancer properties. It has shown a lack of toxicity in animals and human clinical trials. Yet, its effect on reproduction has not been examined. The present study was conducted to examine if curcumin affects sperm function in vitro and fertility in vivo. Sperm (human and murine) were collected and incubated with curcumin to examine the effect on motility, capacitation/acrosome reaction, and in vitro fertilization. The effect on in vivo fertility using the mouse model was also examined. Incubation of sperm with curcumin caused a concentration-dependent decrease in sperm forward motility, capacitation/acrosome reaction, and murine fertilization in vitro. At higher concentrations, there was a complete block of sperm motility and function within 5-15 min. Administration of curcumin, especially intravaginally, caused a significant (P<0.001) reduction in fertility. The antifertility effect of curcumin was reversible. This is the first study to report the inhibitory effect of curcumin on sperm function, fertilization, and fertility. The findings suggest that curcumin may constitute a double-edged sword to block conception, infection, and cancer, thus providing an ideal contraceptive. PMID:21337449
Faked states attack and quantum cryptography protocols
Denny, Travis
2011-01-01
Leveraging quantum mechanics, cryptographers have devised provably secure key sharing protocols. Despite proving the security in theory, real-world application falls short of the ideal. Last year, cryptanalysts completed an experiment demonstrating a successful eavesdropping attack on commercial quantum key distribution (QKD) systems. This attack exploits a weakness in the typical real-world implementation of quantum cryptosystems. Cryptanalysts have successfully attacked several protocols. In this paper, we examine the Kak quantum cryptography protocol and how it may perform under such attacks.
Stier, A V; Ellis, C T; Kwon, J; Xing, H; Zhang, H; Eason, D; Strasser, G; Morimoto, T; Aoki, H; Zeng, H; McCombe, B D; Cerne, J
2015-12-11
We measure the Hall conductivity of a two-dimensional electron gas formed at a GaAs/AlGaAs heterojunction in the terahertz regime close to the cyclotron resonance frequency using highly sensitive Faraday rotation measurements. The sample is electrically gated, allowing the electron density to be changed continuously by more than a factor of 3. We observe clear plateaulike and steplike features in the Faraday rotation angle vs electron density and magnetic field (Landau-level filling factor) even at fields or frequencies very close to cyclotron resonance absorption. These features are the high frequency manifestation of quantum Hall plateaus-a signature of topologically protected edge states. We observe both odd and even filling factor plateaus and explore the temperature dependence of these plateaus. Although dynamical scaling theory begins to break down in the frequency region of our measurements, we find good agreement with theory. PMID:26705653
Quantum computation speedup limits from quantum metrological precision bounds
NASA Astrophysics Data System (ADS)
Demkowicz-Dobrza?ski, Rafa?; Markiewicz, Marcin
2015-06-01
We propose a scheme for translating metrological precision bounds into lower bounds on query complexity of quantum search algorithms. Within the scheme the link between quadratic performance enhancement in idealized quantum metrological and quantum computing schemes becomes clear. More importantly, we utilize results from the field of quantum metrology on a generic loss of quadratic quantum precision enhancement in the presence of decoherence to infer an analogous generic loss of quadratic speedup in oracle based quantum computing. While most of our reasoning is rigorous, at one of the final steps, we need to make use of an unproven technical conjecture. We hope that we will be able to amend this deficiency in the near future, but we are convinced that even without the conjecture proven our results provide a deep insight into the relationship between quantum algorithms and quantum metrology protocols.
Quantum computation speedup limits from quantum metrological precision bounds
Rafal Demkowicz-Dobrzanski; Marcin Markiewicz
2015-06-17
We propose a scheme for translating metrological precision bounds into lower bounds on query complexity of quantum search algorithms. Within the scheme the link between quadratic performance enhancement in idealized quantum metrological and quantum computing schemes becomes clear. More importantly, we utilize results from the field of quantum metrology on a generic loss of quadratic quantum precision enhancement in presence of decoherence to infer an analogous generic loss of quadratic speed-up in oracle based quantum computing. While most of our reasoning is rigorous, at one of the final steps, we need to make use of an unproven technical conjecture. We hope that we will be able to amend this deficiency in the near future, but we are convinced that even without the conjecture proven our results provide a novel and deep insight into relationship between quantum algorithms and quantum metrology protocols.
NASA Astrophysics Data System (ADS)
Motyka, M.; Ryczko, K.; S?k, G.; Janiak, F.; Misiewicz, J.; Bauer, A.; Höfling, S.; Forchel, A.
2012-05-01
Optical properties of InAs/GaInSb/InAs type II quantum wells grown on GaSb substrate have been studied by Fourier transformed photoreflectance and photoluminescence supported by electronic structure calculations. Such a broken gap material system is utilized for the active region of interband cascade lasers and further for laser-based gas sensors operating at room temperature. Based on the measured absorption-like and emission-like spectra in the range from about 2 to above 5 ?m, we indicate the potential of such type II structures for detecting such environmentally relevant gasses as HCl, CO2, N2O, and NH3 which have their absorption lines at wavelengths longer than about 3.5 ?m, i.e. beyond the already explored range characteristic for hydrocarbons. We investigate the issue of the type II transition oscillator strength versus the InAs well width and temperature for two different quantum well layer structures. Significant enhancement of the type II transition intensities could be predicted for W-like design of the well and increasing with temperature, as a consequence of various thermal energy gap coefficients of the involved materials and weakening of the confinement for electrons. The concept of compensating the electric field effect in the real operational device, affecting the transition probability, by intentionally introducing an asymmetry of the double quantum well structure has been shown to be functional for various emission wavelengths. Reasonable values of the transition oscillator strengths could still be demonstrated at about 5 ?m.
Idealized Computational Models for Auditory Receptive Fields
Lindeberg, Tony; Friberg, Anders
2015-01-01
We present a theory by which idealized models of auditory receptive fields can be derived in a principled axiomatic manner, from a set of structural properties to (i) enable invariance of receptive field responses under natural sound transformations and (ii) ensure internal consistency between spectro-temporal receptive fields at different temporal and spectral scales. For defining a time-frequency transformation of a purely temporal sound signal, it is shown that the framework allows for a new way of deriving the Gabor and Gammatone filters as well as a novel family of generalized Gammatone filters, with additional degrees of freedom to obtain different trade-offs between the spectral selectivity and the temporal delay of time-causal temporal window functions. When applied to the definition of a second-layer of receptive fields from a spectrogram, it is shown that the framework leads to two canonical families of spectro-temporal receptive fields, in terms of spectro-temporal derivatives of either spectro-temporal Gaussian kernels for non-causal time or a cascade of time-causal first-order integrators over the temporal domain and a Gaussian filter over the logspectral domain. For each filter family, the spectro-temporal receptive fields can be either separable over the time-frequency domain or be adapted to local glissando transformations that represent variations in logarithmic frequencies over time. Within each domain of either non-causal or time-causal time, these receptive field families are derived by uniqueness from the assumptions. It is demonstrated how the presented framework allows for computation of basic auditory features for audio processing and that it leads to predictions about auditory receptive fields with good qualitative similarity to biological receptive fields measured in the inferior colliculus (ICC) and primary auditory cortex (A1) of mammals. PMID:25822973
Large ion Coulomb crystals: A near-ideal medium for coupling optical cavity modes to matter
Dantan, A.; Albert, M.; Marler, J. P.; Herskind, P. F.; Drewsen, M.
2009-10-15
We present an investigation of the coherent coupling of various transverse field modes of an optical cavity to ion Coulomb crystals. The obtained experimental results, which include the demonstration of identical collective coupling rates for different transverse modes of a cavity field to ions in the same large Coulomb crystal, are in excellent agreement with theoretical predictions. The results furthermore suggest that Coulomb crystals in the future may serve as near-ideal media for high-fidelity multimode quantum information processing and communication purposes, including the generation and storage of single-photon qubits encoded in different transverse modes.
Kupervasser Oleg
2013-08-01
The paper discusses the basic paradoxes of thermodynamics and quantum mechanics. The approaches to solution of these paradoxes are suggested. The first one relies on the influence of the external observer (environment), which disrupts the correlations in the system. The second one is based on the limits of self-knowledge of the system in case of both the external observer and the environment is included in the considered system. The concepts of Real Dynamics, Ideal Dynamics, and Unpredictable dynamics are introduced. The phenomenon of Life is contemplated from the point of view of these Dynamics.
Ramsey interferometry with a two-level generalized Tonks-Girardeau gas
Mousavi, S. V.; Campo, A. del; Lizuain, I.; Muga, J. G.
2007-09-15
We propose a solvable generalization of the Tonks-Girardeau model that describes a coherent one-dimensional (1D) gas of cold two-level bosons which interact with two external fields in a Ramsey interferometer. They also interact among themselves by idealized, infinitely strong contact potentials, with interchange of momentum and internal state. We study the corresponding Ramsey fringes and the quantum projection noise which, essentially unaffected by the interactions, remains that for ideal bosons. The dual system of this gas, an ideal gas of two-level fermions coupled by the interaction with the separated fields, produces the same fringes and noise fluctuations. The cases of time-separated and spatially separated fields are studied. For spatially separated fields the fringes may be broadened slightly by increasing the number of particles, but only for large particle numbers far from present experiments with Tonks-Girardeau gases. The uncertainty in the determination of the atomic transition frequency diminishes, essentially with the inverse root of the particle number. The difficulties to implement the model experimentally and possible shortcomings of strongly interacting 1D gases for frequency standards and atomic clocks are discussed.
Phillips, Mark C.; Taubman, Matthew S.; Bernacki, Bruce E.; Cannon, Bret D.; Stahl, Robert D.; Schiffern, John T.; Myers, Tanya L.
2014-05-04
We present results demonstrating real-time sensing of four different fluorocarbons at low-ppb concentrations using an external cavity quantum cascade laser (ECQCL) operating in a swept-wavelength configuration. The ECQCL was repeatedly swept over its full tuning range at a 20 Hz rate with a scan rate of 3535 cm-1/s, and a detailed characterization of the ECQCL scan stability and repeatability is presented. The sensor was deployed on a mobile automotive platform to provide spatially resolved detection of fluorocarbons in outdoor experiments. Noise-equivalent detection limits of 800-1000 parts-per-trillion (ppt) are demonstrated for 1 s integration times.
Quantum Shock Waves and Domain Walls in the Real-Time Dynamics of a Superfluid Unitary Fermi Gas
Bulgac, Aurel; Luo, Yuan-Lung; Roche, Kenneth J.
2012-04-10
We show that in the collision of two superfluid fermionic atomic clouds one observes the formation of quantum shock waves as discontinuities in the number density and collective flow velocity. Domain walls, which are topological excitations of the superfluid order parameter, are also generated and exhibit abrupt phase changes by $\\pi$ and slower motion than the shock waves. The domain walls are distinct from the gray soliton train or number density ripples formed in the wake of the shock waves and observed in the collisions of superfluid bosonic atomic clouds. Domain walls with opposite phase jumps collide elastically.
Molecular Dynamics Simulations of an Idealized Shock Tube: N2 in Ar Bath Driven by He
NASA Astrophysics Data System (ADS)
Piskulich, Ezekiel Ashe; Sewell, Thomas D.; Thompson, Donald L.
2015-06-01
The dynamics of 10% N2 in Ar initially at 298 K in an idealized shock tube driven by He was studied using molecular dynamics. The simulations were performed using the Large-Scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. Nitrogen was modeled as a Morse oscillator and non-covalent interactions were approximated by the Buckingham exponential-6 pair potential. The initial pressures in the He driver gas and the driven N2/Ar gas were 1000 atm and 20 atm, respectively. Microcanonical trajectories were followed for 2 ns following release of the driver gas. Results for excitation and subsequent relaxation of the N2, as well as properties of the gas during the simulations, will be reported.
Quantum Computation Quantum Information
Lomonaco Jr., Samuel J.
Quantum Computation and Quantum Information Samuel J. Lomonaco, Jr. and Howard E. Brandt editors pages Havel, Timothy F., and Chris J. L. Doran Quantum Computing and the Jones Polynomial. Hadi Madjid Quantum Computation by Geometrical Means .................................... 6 pages
Comparison of Hugoniots calculated for aluminum in the framework of three quantum-statistical models
NASA Astrophysics Data System (ADS)
Kadatskiy, M. A.; Khishchenko, K. V.
2015-11-01
The results of calculations of thermodynamic properties of aluminum under shock compression in the framework of the Thomas-Fermi model, the Thomas-Fermi model with quantum and exchange corrections and the Hartree-Fock-Slater model are presented. The influences of the thermal motion and the interaction of ions are taken into account in the framework of three models: the ideal gas, the one-component plasma and the charged hard spheres. Calculations are performed in the pressure range from 1 to 107 GPa. Calculated Hugoniots are compared with available experimental data.
Comparison of Hugoniots calculated for aluminum in the framework of three quantum-statistical models
Kadatskiy, Maxim A
2015-01-01
The results of calculations of thermodynamic properties of aluminum under shock compression in the framework of the Thomas--Fermi model, the Thomas--Fermi model with quantum and exchange corrections and the Hartree--Fock--Slater model are presented. The influences of the thermal motion and the interaction of ions are taken into account in the framework of three models: the ideal gas, the one-component plasma and the charged hard spheres. Calculations are performed in the pressure range from 1 to $10^7$ GPa. Calculated Hugoniots are compared with available experimental data.
Quantum computation: algorithms and implementation in quantum dot devices
NASA Astrophysics Data System (ADS)
Gamble, John King
In this thesis, we explore several aspects of both the software and hardware of quantum computation. First, we examine the computational power of multi-particle quantum random walks in terms of distinguishing mathematical graphs. We study both interacting and non-interacting multi-particle walks on strongly regular graphs, proving some limitations on distinguishing powers and presenting extensive numerical evidence indicative of interactions providing more distinguishing power. We then study the recently proposed adiabatic quantum algorithm for Google PageRank, and show that it exhibits power-law scaling for realistic WWW-like graphs. Turning to hardware, we next analyze the thermal physics of two nearby 2D electron gas (2DEG), and show that an analogue of the Coulomb drag effect exists for heat transfer. In some distance and temperature, this heat transfer is more significant than phonon dissipation channels. After that, we study the dephasing of two-electron states in a single silicon quantum dot. Specifically, we consider dephasing due to the electron-phonon coupling and charge noise, separately treating orbital and valley excitations. In an ideal system, dephasing due to charge noise is strongly suppressed due to a vanishing dipole moment. However, introduction of disorder or anharmonicity leads to large effective dipole moments, and hence possibly strong dephasing. Building on this work, we next consider more realistic systems, including structural disorder systems. We present experiment and theory, which demonstrate energy levels that vary with quantum dot translation, implying a structurally disordered system. Finally, we turn to the issues of valley mixing and valley-orbit hybridization, which occurs due to atomic-scale disorder at quantum well interfaces. We develop a new theoretical approach to study these effects, which we name the disorder-expansion technique. We demonstrate that this method successfully reproduces atomistic tight-binding techniques, while using a fraction of the computational resources and providing considerably more physical insight. Using this technique, we demonstrate that large dipole moments can exist between valley states in disordered systems, and calculate corrections to intervalley tunnel rates..
Games and the Impossibility of Realizable Ideal Functionality
International Association for Cryptologic Research (IACR)
Games and the Impossibility of Realizable Ideal Functionality Anupam Datta1 , Ante Derek1 , John C or a security mechanism can be specified in a variety of ways, such as a condition involving a game against of attack. While game conditions are widely used, an ideal functionality is appealing because a mechanism
Gr\\"obner bases of ideals cogenerated by Pfaffians
De Negri, Emanuela
2010-01-01
We characterise the class of one-cogenerated Pfaffian ideals whose natural generators form a Gr\\"obner basis with respect to any anti-diagonal term-order. We describe their initial ideals as well as the associated simplicial complexes, which turn out to be shellable and thus Cohen-Macaulay. We also provide a formula for computing their multiplicity.
Degrees of Generators of Ideals Defining Subschemes of Projective Space
Degrees of Generators of Ideals Defining Subschemes of Projective Space Heath M. Martin Florida an upper bound for the degrees of the generators for an ideal defining a curve in projective space for degrees of generators. In contrast to the minimal degree of a generator, in most cases, the maximal degree
CENTRAL IDEALS AND CARTAN INVARIANTS OF SYMMETRIC ALGEBRAS
algebras to symmetric algebras, and we obtain some new results as well. In case p = 2, these ideals detect. Furthermore, HA denotes the Higman ideal of A, defined as the image of the trace map # : A -# A, x #-# n # i=1 conjugacy class of 2defect zero if and only if the Cartan matrix of G in characteristic 2 contains an odd
CENTRAL IDEALS AND CARTAN INVARIANTS OF SYMMETRIC ALGEBRAS
algebras to symmetric algebras, and we obtain some new results as well. In case p = 2, these ideals detect the Higman ideal of A, defined as the image of the trace map : A - A, x - n i=1 bixai; here a1 groups. We will see that a finite group G contains a real conjugacy class of 2-defect zero if and only
The Ideal Train Timetabling Problem Tomas Robenek a,1
Bierlaire, Michel
is presented. Given the recent changes in legislature allowing competitors to enter the railway industry occupation, ticket sales, etc.) in order to construct the ideal timetables. For the first time in this field, we tackle the problem of ideal timetables in railway industry from passenger behavior point of view
CLONES FROM IDEALS MATHIAS BEIGLBOCK, MARTIN GOLDSTERN, LUTZ HEINDORF,
BeiglbÃ¶ck, Mathias
CLONES FROM IDEALS MATHIAS BEIGLBÂ¨OCK, MARTIN GOLDSTERN, LUTZ HEINDORF, AND MICHAEL PINSKER Abstract. On an infinite base set X, every ideal of subsets of X can be associated with the clone of those of such clones in the clone lattice. 0. Introduction 0.1. Clones. Let X be an infinite set and denote the set
COMPUTATION OF MINIMAL GENERATORS OF IDEALS OF FAT POINTS
Orecchia, Ferruccio
COMPUTATION OF MINIMAL GENERATORS OF IDEALS OF FAT POINTS FRANCESCA CIOFFI AND FERRUCCIO ORECCHIA generators of ideals of fat points. First we construct a set of generators by an interpolating method which p i , for every i = 1; : : : ; n. The points p 1 ; : : : ; pn are called fat points
Idealization in Chemistry: Pure Substance and Laboratory Product
NASA Astrophysics Data System (ADS)
Fernández-González, Manuel
2013-07-01
This article analyzes the concept of idealization in chemistry and the role played by pure substance and laboratory product. This topic has evident repercussions in the educational contexts that are applied to the science classroom, which are highlighted throughout the text. A common structure for knowledge construction is proposed for both physics and chemistry with particular emphasis on the relations between two of the levels: the ideal level and the quasi-ideal level. The ideal level is crucial for operations related to theoretical constructions and explanations, whereas the quasi-ideal level is of special importance in the verification of propositions. In chemistry, the ideal level and the quasi-ideal level include the entities, pure substance and laboratory product, respectively. This article provides an in-depth discussion of the concept of pure substance, an idealized entity whose empirical correlate is laboratory product. The study of the link between the two is a very significant part of the problem of the relations between theory and reality in chemistry. These entities are used to analyze and interpret different situations and contexts in research as well as teaching. The article concludes by using classroom examples to illustrate the didactic implications of the issues addressed.
Constructive Notions of Maximality for Ideals Douglas S. Bridges
Constructive Notions of Maximality for Ideals Douglas S. Bridges (Department of Mathematics the constructive study of rings and ideals begun in [Bridges 2001], by examining two constructively distinct and Statistics, University of Canterbury, Christchurch, New Zealand d.bridges@math.canterbury.ac.nz) Robin S
UNIFORM APPROXIMATION OF ABHYANKAR VALUATION IDEALS IN SMOOTH FUNCTION FIELDS
UNIFORM APPROXIMATION OF ABHYANKAR VALUATION IDEALS IN SMOOTH FUNCTION FIELDS LAWRENCE EIN, ROBERT that the valuation ideals of a rank one Abhyankar valuation centered at a smooth point of a complex algebraic variety be a rank one valuation centered on R. Recall that this is equivalent to asking that Å¡ be an R
What Do Doctoral Students Value in Their Ideal Mentor?
ERIC Educational Resources Information Center
Bell-Ellison, Bethany A.; Dedrick, Robert F.
2008-01-01
The purpose of this study was to contribute to the construct validity of the scores from Rose's (2003) 34-item "Ideal Mentor Scale" (IMS) and to examine whether male and female doctoral students value different attributes in their ideal mentor. Two hundred and twenty-four doctoral students from colleges (Education, Public Health, Nursing, Arts and…
Allylic alcohols: ideal radical allylating agents?
Debien, Laurent; Quiclet-Sire, Béatrice; Zard, Samir Z
2015-05-19
Radical allylations represent effective routes to various alkenes, but to date they have relied chiefly on organostannane derivatives and still suffer from significant limitations with respect to the substitution pattern of the starting allylating agent. Indeed, while substituents at the ?-position relative to the radical leaving group are well-tolerated, introduction of ?-substituents induces a major complication due to the rapid and usually irreversible isomerization of the starting allylating agents. Although a number of research groups have made substantial efforts to develop heavy-metal-free radical allylations, methods compatible with ?-substitution of the allylating agent are still scarce. Furthermore, quite a few systems are limited by the relative inaccessibility of the substrates. This Account summarizes our sustained efforts regarding the development of allylic alcohols into "ideal" radical allylating agents and presents published as well as some unpublished results. The systems we have developed combine the use of readily available xanthates and allylic alcohol derivatives under metal-free conditions to furnish not only alkenes but also aldehydes and saturated and unsaturated ketones through the virtually unprecedented homolytic cleavage of the normally strong C-O or C-C bond. The former route hinges on first converting the allylic alcohol into a 2-fluoro-6-pyridoxy derivative by reacting the corresponding alcoholate with 2,6-difluoropyridine, while the latter relies on attaching a cumyl group to the carbon bearing the free allylic alcohol. Either substrate is then exposed to the action of a suitable xanthate in the presence of a stoichiometric amount of a peroxide, usually lauroyl peroxide (DLP) in refluxing ethyl acetate or di-tert-butyl peroxide (TBHP) in refluxing chlorobenzene for the more difficult cases. Even though C-O or C-C bond homolysis leads to a stabilized 2-fluoro-6-pyridinyloxyl radical or a cumyl radical, respectively, the ?-scission in both cases is relatively slow and at the lower limit of useful elementary radical steps. The kinetic barrier of the fragmentation can nevertheless be overcome because of the long relative lifetime of radicals generated by the degenerate transfer of the xanthate group, and this is a key element for success. This novel technology offers numerous advantages. The starting activated allylic alcohol derivatives are readily accessible in two steps from aldehydes or ketones. They can also be obtained by base-induced opening of epoxides. Numerous functional groups are tolerated under the mild reaction conditions for the radical addition-elimination, as nicely illustrated by over 150 examples of radical allylations, not all of which can be included in the present Account. In addition, substitution at both the ?- and ?-positions of the allylating agent is possible, a rare feature in this area. PMID:25905563
NASA Astrophysics Data System (ADS)
Goldenstein, Christopher S.; Miller, Victor A.; Hanson, Ronald K.
2015-08-01
The design and demonstration of a new infrared laser-induced fluorescence (IR-LIF) technique that enables spatially resolved measurements of CO2, temperature, and pressure, with potential for velocity, are presented. A continuous-wave, wavelength-tunable, quantum-cascade laser (QCL) near with up to 120 mW was used to directly excite the asymmetric-stretch fundamental-vibration band of CO2 for approximately 200 to times more absorbance compared with previous IR-LIF techniques. This enabled LIF detection limits (signal-to-noise ratio of 1) of 20 and 70 ppm of CO2 in Ar and , respectively, at 1 bar and 296 K in static-cell experiments. Simplified and detailed kinetic models for simulating the LIF signal as a function of gas properties are presented and enable quantitative, calibration-free, IR-LIF measurements of CO2 mole fraction within 1-8 % of known values at 0.5-1 bar. By scanning the laser across two absorption transitions and performing a multi-line Voigt fit to the LIF signal, measurements of temperature, pressure, and within 2 % of known values were obtained. LIF measurements of gas pressure at a repetition rate up to 200 Hz (in argon) are also presented. Planar-LIF (PLIF) was used to image steady and unsteady CO2-Ar jets at 330 frames per second with a spatial signal-to-noise ratio (SNR) up to 25, corresponding to a detection limit (SNR = 1) of 200 ppm with a projected pixel size of . The gas pressure was measured within % of the known value (1 bar) at 5 Hz by scanning the QCL across the P(42) absorption transition and least-squares fitting a Voigt profile to the PLIF signal. Spatially resolved measurements of absolute CO2 mole fraction in a laminar jet are also presented.
Ideal ages for family formation among immigrants in Europe.
Holland, Jennifer A; de Valk, Helga A G
2013-12-01
This paper investigates ideal ages for marriage and parenthood among immigrants from over 160 countries origins living in 25 European countries. Ideals regarding the timing of family formation are indicative of how individuals perceive the family life course and provide insight into family-life aspirations and the meaning attached to these transitions. Using data from the European Social Survey (Round 3, 2006; N=6330) and a cross-classified multilevel modeling approach, we investigate associations between the influences of the dominant family formation timing patterns in countries of origin and settlement, individual-level characteristics, and ideal ages. We make innovative use of a standard demographic measure, the singulate mean age of marriage, to measure family formation patterns. Results suggest that residential context influences are associated with the timing ideals of all migrants, but origin influences seem to be associated with the ideals of only the most recent migrants. PMID:24796710
Moral identity as moral ideal self: links to adolescent outcomes.
Hardy, Sam A; Walker, Lawrence J; Olsen, Joseph A; Woodbury, Ryan D; Hickman, Jacob R
2014-01-01
The purposes of this study were to conceptualize moral identity as moral ideal self, to develop a measure of this construct, to test for age and gender differences, to examine links between moral ideal self and adolescent outcomes, and to assess purpose and social responsibility as mediators of the relations between moral ideal self and outcomes. Data came from a local school sample (Data Set 1: N = 510 adolescents; 10-18 years of age) and a national online sample (Data Set 2: N = 383 adolescents; 15-18 years of age) of adolescents and their parents. All outcome measures were parent-report (Data Set 1: altruism, moral personality, aggression, and cheating; Data Set 2: environmentalism, school engagement, internalizing, and externalizing), whereas other variables were adolescent-report. The 20-item Moral Ideal Self Scale showed good reliability, factor structure, and validity. Structural equation models demonstrated that, even after accounting for moral identity internalization, in Data Set 1 moral ideal self positively predicted altruism and moral personality and negatively predicted aggression, whereas in Data Set 2 moral ideal self positively predicted environmentalism and negatively predicted internalizing and externalizing symptoms. Further, purpose and social responsibility mediated most relations between moral ideal self and the outcomes in Data Set 2. Moral ideal self was unrelated to age but differentially predicted some outcomes across age. Girls had higher levels of moral ideal self than boys, although moral identity did not differentially predict outcomes between genders. Thus, moral ideal self is a salient element of moral identity and may play a role in morally relevant adolescent outcomes. PMID:23895167
Purification of noisy quantum measurements
Dall'Arno, Michele; D'Ariano, Giacomo Mauro; Sacchi, Massimiliano F.
2010-10-15
We consider the problem of improving noisy quantum measurements by suitable preprocessing strategies making many noisy detectors equivalent to a single ideal detector. For observables pertaining to finite-dimensional systems (e.g., qubits or spins) we consider preprocessing strategies that are reminiscent of quantum error correction procedures and allow one to perfectly measure an observable on a single quantum system for increasing number of inefficient detectors. For measurements of observables with an unbounded spectrum (e.g., photon number and homodyne and heterodyne detection), the purification of noisy quantum measurements can be achieved by preamplification as suggested by Yuen [Opt. Lett. 12, 789 (1987)].
Optimal minimum-cost quantum measurements for imperfect detection
Erika Andersson
2012-01-01
Knowledge of optimal quantum measurements is important for a wide range of situations, including quantum communication and quantum metrology. Quantum measurements are usually optimised with an ideal experimental realisation in mind. Real devices and detectors are, however, imperfect. This has to be taken into account when optimising quantum measurements. In this paper, we derive the optimal minimum-cost and minimum-error measurements for a general model of imperfect detection.
Statistical Thermodynamics of Polymer Quantum Systems
Guillermo Chacón-Acosta; Elisa Manrique; Leonardo Dagdug; Hugo A. Morales-Técotl
2011-12-02
Polymer quantum systems are mechanical models quantized similarly as loop quantum gravity. It is actually in quantizing gravity that the polymer term holds proper as the quantum geometry excitations yield a reminiscent of a polymer material. In such an approach both non-singular cosmological models and a microscopic basis for the entropy of some black holes have arisen. Also important physical questions for these systems involve thermodynamics. With this motivation, in this work, we study the statistical thermodynamics of two one dimensional {\\em polymer} quantum systems: an ensemble of oscillators that describe a solid and a bunch of non-interacting particles in a box, which thus form an ideal gas. We first study the spectra of these polymer systems. It turns out useful for the analysis to consider the length scale required by the quantization and which we shall refer to as polymer length. The dynamics of the polymer oscillator can be given the form of that for the standard quantum pendulum. Depending on the dominance of the polymer length we can distinguish two regimes: vibrational and rotational. The first occur for small polymer length and here the standard oscillator in Schr\\"odinger quantization is recovered at leading order. The second one, for large polymer length, features dominant polymer effects. In the case of the polymer particles in the box, a bounded and oscillating spectrum that presents a band structure and a Brillouin zone is found. The thermodynamical quantities calculated with these spectra have corrections with respect to standard ones and they depend on the polymer length. For generic polymer length, thermodynamics of both systems present an anomalous peak in their heat capacity $C_V$.
Non-ideal Effects in Streaming Bi-Dust Acoustic Instability
Puerta, J.; Castro, E.; Martin, P.; Arias, H.
2006-12-04
Streaming dust acoustic instabilities in the presence of a dust beam in a weakly non-ideal dusty plasma have been studied considering a new form for the state equation with two kind of grains. Fluctuating charging effects are not considered in this work. Homogeneous dust-acoustic waves (DAWS) are studied for a perturbed plasma in a very low frequency regime, where dusty plasmas support new kind of waves and instabilities due to the dust collective dynamics. In this analysis a fluid model is used and electrons and ions are determined by their Boltzmann factors in order to find an adequate dispersion relation, which has several parameters depending of the state equation constants. In this paper we use the state equation structured by Ree and Hoover using Pade approximant for a hard-sphere gas in the form P = nT 1 + nb{sub 0} (1 + a{sub 1}b{sub 0}n + a{sub 2}b{sub 0}{sup 2}n{sup 2}/1 - b{sub 1}b{sub 0}n + b{sub 2}b{sub 0}{sup 2}n{sup 2}) is applied, where b0 is calculated by the second virial term for the hard-core model. This type of equation is more accurate than other expressions and easier to manipulate. Comparisons between the ideal and non ideal cases is performed. Constants a1, a2, b1, b2, are calculated with the Pade method. The onset of the instability and also the growth rates are studied in function of relevant parameters of the system as the radius of the grains and their densities. In our analysis the instability region for non ideal plasma is compared with that of the ideal ones.
Unconditional Room Temperature Quantum Memory
M. Hosseini; G. Campbell; B. M. Sparkes; P. K. Lam; B. C. Buchler
2015-02-10
Just as classical information systems require buffers and memory, the same is true for quantum information systems. The potential that optical quantum information processing holds for revolutionising computation and communication is therefore driving significant research into developing optical quantum memory. A practical optical quantum memory must be able to store and recall quantum states on demand with high efficiency and low noise. Ideally, the platform for the memory would also be simple and inexpensive. Here, we present a complete tomographic reconstruction of quantum states that have been stored in the ground states of rubidium in a vapour cell operating at around 80$^o$C. Without conditional measurements, we show recall fidelity up to 98% for coherent pulses containing around one photon. In order to unambiguously verify that our memory beats the quantum no-cloning limit we employ state independent verification using conditional variance and signal transfer coefficients.
The Quantum World of Ultra-Cold Atoms and Light - Book 1: Foundations of Quantum Optics
NASA Astrophysics Data System (ADS)
Gardiner, Crispin; Zoller, Peter
2014-03-01
Abstract The Table of Contents is as follows: * I - THE PHYSICAL BACKGROUND * 1. Controlling the Quantum World * 1.1 Quantum Optics * 1.2 Quantum Information * 2. Describing the Quantum World * 2.1 Classical Stochastic Processes * 2.2. Theoretical Quantum Optics * 2.3. Quantum Stochastic Methods * 2.4. Ultra-Cold Atoms * II - CLASSICAL STOCHASTIC METHODS * 3. Physics in a Noisy World * 3.1. Brownian Motion and the Thermal Origin of Noise * 3.2. Brownian Motion, Friction, Noise and Temperature * 3.3. Measurement in a Fluctuating System * 4. Stochastic Differential Equations * 4.1. Ito Stochastic Differential Equation * 4.2. The Fokker-Planck Equation * 4.3. The Stratonovich Stochastic Differential Equation * 4.4. Systems with Many Variables * 4.5. Numerical Simulation of Stochastic Differential Equations * 5. The Fokker-Planck Equation * 5.1. Fokker-Planck Equation in One Dimension * 5.2. Eigenfunctions of the Fokker-Planck Equation * 5.3. Many-Variable Fokker-Planck Equations * 6. Master Equations and Jump Processes * 6.1. The Master Equation * 7. Applications of Random Processes * 7.1. The Ornstein-Uhlenbeck Process * 7.2. Johnson Noise * 7.3. Complex Variable Oscillator Processes * 8. The Markov Limit * 8.1. The White Noise Limit * 8.2. Interpretation and Generalizations of the White Noise Limit * 8.3. Linear Non-Markovian Stochastic Differential Equations * 9. Adiabatic Elimination of Fast Variables * 9.1 Slow and Fast Variables * 9.2. Other Applications of the Adiabatic Elimination Method * III - FIELDS, QUANTA AND ATOMS * 10. Ideal Bose and Fermi Systems * 10.1. The Quantum Gas * 10.2. Thermal States * 10.3. Fluctuations in the Ideal Bose Gas * 10.4. Bosonic Quantum Gaussian Systems * 10.5. Coherent States * 10.6. Fluctuations in Systems of Fermions * 10.7. Two-Level Systems and Pauli Matrices * 11. Quantum Fields * 11.1 Kinds of Quantum Field * 11.2 Coherence and Correlation Functions * 12. Atoms, Light and their Interaction * 12.1. Interaction with the Quantized Radiation Field * 12.2. Decay of an Excited Atom * 12.3. The Two-Level Atom in a Strong Classical Driving Field * 12.4. Interaction of a Two-Level Atom with a Single Mode * IV - QUANTUM STOCHASTIC PROCESSES * 13. Quantum Markov Processes * 13.1. Two-Level Atom in a Finite-Temperature Electromagnetic Field * 13.2. Derivation of theMaster Equation * 13.3. More General Heat Baths * 13.4. Quantum Correlation Functions and Spectra * 14. Applications of the Master Equation * 14.1. A Two-Level Atom Interacting with a Thermal Heat Bath * 14.2. The Two-Level Atom Driven by a Coherent Light Field * 14.3. Master Equations for Harmonic Oscillator Systems * 14.4. A Simple Model of Laser Cooling * V - PHASE SPACE METHODS * 15. Phase Space Representations for Bosons * 15.1. The Quantum Characteristic Function * 15.2. Phase Space Representations of the Density Operator * 16. Wigner Function Methods * 16.1. Operator Correspondences and Equations of Motion * 16.2. Damped and Driven Systems * 16.3. The Wigner Distribution Function f (x, p) * 16.4. Quantum Fluctuations in Equations of Motion * 17. P-Function Methods * 17.1. Introduction * 17.2. Artificial Neural Networks * 17.3. Clinical Example * VI - QUANTUM MEASUREMENT THEORY * 18. Foundations and Formalism of Quantum Measurement * 18.1. Formulations of Quantum Mechanics * 18.2. Modelling a Measurement-Tracks in a Cloud Chamber * 18.3. Formal Quantum Measurement Theory * 18.4. Multitime Measurements * 19. Continuous Measurements * 19.1. Photon Counting * 19.2. Wavefunction Interpretation of Continuous Measurement * 19.3. Application to Matter Wave Interference * 19.4. Damping of Quantum Coherence * 19.5. The Emergence of the oscopic World * 20. The Quantum Zeno Effect * 20.1. Theoretical Basis for the Quantum Zeno Effect * 20.2. A Quantum Model of Trapped Atoms * 20.3. Quantum Zeno Effect for a Bose-Einstein Condensate * References * Author Index * Subject Index
NASA Astrophysics Data System (ADS)
Holmes, R.; Wang, B.; Aljama, H.; Rupp, E.; Wilcox, J.
2014-12-01
One method for mitigating the impacts of anthropogenic CO2-related climate change is the sequestration of CO2 in depleted gas and oil reservoirs, including shale. The accurate characterization of the heterogeneous material properties of shale, including pore volume, surface area, pore size distributions (PSDs) and composition is needed to understand the interaction of CO2 with shale. Idealized powdered shale sorption isotherms were created by varying incremental amounts of four essential components by weight. The first two components, organic carbon and clay, have been shown to be the most important components for CO2 uptake in shales. Organic carbon was represented by kerogen isolated from a Silurian shale, and clay groups were represented by illite from the Green River shale formation. The rest of the idealized shale was composed of equal parts by weight of SiO2 to represent quartz and CaCO3 to represent carbonate components. Baltic, Eagle Ford, and Barnett shale sorption measurements were used to validate the idealized samples. The idealized and validation shale sorption isotherms were measured volumetrically using low pressure N2 (77K) and CO2 (273K) adsorbates on a Quantachrome Autosorb IQ2. Gravimetric isotherms were also produced for a subset of these samples using CO2 and CH4adsorbates under subsurface temperature and pressure conditions using a Rubotherm magnetic suspension balance. Preliminary analyses were inconclusive in validating the idealized samples. This could be a result of conflicting reports of total organic carbon (TOC) content in each sample, a problem stemming from the heterogeneity of the samples and different techniques used for measuring TOC content. The TOC content of the validation samples (Eagle Ford and Barnett) was measured by Rock-Eval pyrolysis at Weatherford Laboratories, while the TOC content in the Baltic validation samples was determined by LECO TOC. Development of a uniform process for measuring TOC in the validation samples is underway. The validity of the idealized samples can be reevaluated upon obtaining reliable and consistent TOC measurements. Validated idealized sample data will lend itself toward the development of predictive models weighted and scaled by the percentages of these essential components in the shales' corresponding compositional breakdown.
NASA Astrophysics Data System (ADS)
Elia, A.; Spagnolo, V.; Di Franco, C.; Lugarà, P. M.; Scamarcio, G.
2010-03-01
We will report here on the design and realization of an optoacoustic sensor for the detection of formaldehyde. The sensor consists of a commercial QCL and a resonant PA cell. Two different cell configurations have been investigated: a "standard" H cell and an innovative T-cell with an optical fiber directly inserted into. Two different type of sound detector have been employed: electret microphones and optical MEMS-based microphone. As possible applications, we will describe the results obtained in the detection of formaldehyde (CH2O), a gas of great interest for industrial processes and environmental monitoring.
Interacting ions in biophysics: real is not ideal.
Eisenberg, Bob
2013-05-01
Ions in water are important throughout biology, from molecules to organs. Classically, ions in water were treated as ideal noninteracting particles in a perfect gas. Excess free energy of each ion was zero. Mathematics was not available to deal consistently with flows, or interactions with other ions or boundaries. Nonclassical approaches are needed because ions in biological conditions flow and interact. The concentration gradient of one ion can drive the flow of another, even in a bulk solution. A variational multiscale approach is needed to deal with interactions and flow. The recently developed energetic variational approach to dissipative systems allows mathematically consistent treatment of the bio-ions Na(+), K(+), Ca(2+), and Cl(-) as they interact and flow. Interactions produce large excess free energy that dominate the properties of the high concentration of ions in and near protein active sites, ion channels, and nucleic acids: the number density of ions is often >10 M. Ions in such crowded quarters interact strongly with each other as well as with the surrounding protein. Nonideal behavior found in many experiments has classically been ascribed to allosteric interactions mediated by the protein and its conformation changes. The ion-ion interactions present in crowded solutions-independent of conformation changes of the protein-are likely to change the interpretation of many allosteric phenomena. Computation of all atoms is a popular alternative to the multiscale approach. Such computations involve formidable challenges. Biological systems exist on very different scales from atomic motion. Biological systems exist in ionic mixtures (like extracellular and intracellular solutions), and usually involve flow and trace concentrations of messenger ions (e.g., 10(-7) M Ca(2+)). Energetic variational methods can deal with these characteristic properties of biological systems as we await the maturation and calibration of all-atom simulations of ionic mixtures and divalents. PMID:23663828
Annular self-similar solutions in ideal magnetogasdynamics
NASA Astrophysics Data System (ADS)
Lock, R. M.; Mestel, A. J.
2008-08-01
We consider the possibility of self-similar solutions describing the implosion of hollow cylindrical annuli driven by an azimuthal magnetic field, in essence a self-similar imploding liner z-pinch. We construct such solutions for gasdynamics, for ideal ‘?=0’ plasma and for ideal magnetogasdynamics (MGD). In the latter two cases some quantities are singular at the annular boundaries. Numerical solutions of the full ideal MGD initial value problem indicate that the self-similar solutions are not attractive for arbitrary initial conditions, possibly as a result of flux-freezing.
Chemistry 223: Some Properties of Ideal and Non-Ideal Materials David Ronis
Ronis, David M.
Constant 8.314442 J/(K mol) NA Avogadro's Number 6. 0225 × 1023 molecules/mol Note that 1 standard (Pascale) Pa kg/(m sec2 ) V Volume m3 N Number of moles. mol moles T Absolute Temperature K Kelvin R Gas number of moles in the gas, i.e., N Ntotal i Ni, i.e., P = RT V i Ni = i Pi, (2) where Pi Ni RT
NASA Astrophysics Data System (ADS)
Diehl, S.; Baranov, M.; Daley, A. J.; Zoller, P.
2010-08-01
We analyze the ground-state phase diagram of attractive lattice bosons, which are stabilized by a three-body onsite hardcore constraint. A salient feature of this model is an Ising-type transition from a conventional atomic superfluid to a dimer superfluid with vanishing atomic condensate. The study builds on an exact mapping of the constrained model to a theory of coupled bosons with polynomial interactions, proposed in a related paper [S. Diehl, M. Baranov, A. Daley, and P. Zoller, Phys. Rev. B 82, 064509 (2010).10.1103/PhysRevB.82.064509]. In this framework, we focus by analytical means on aspects of the phase diagram which are intimately connected to interactions, and are thus not accessible in a mean-field plus spin-wave approach. First, we determine shifts in the mean-field phase border, which are most pronounced in the low-density regime. Second, the investigation of the strong coupling limit reveals the existence of a “continuous supersolid,” which emerges as a consequence of enhanced symmetries in this regime. We discuss its experimental signatures. Third, we show that the Ising-type phase transition, driven first order via the competition of long-wavelength modes at generic fillings, terminates into a true Ising quantum critical point in the vicinity of half filling.
Oscillations and evolution of a hot and dense gas of flavor neutrinos: a quantum field theory study
D. Boyanovsky; C. M. Ho
2004-04-09
We study the time evolution of the distribution functions for hot and or degenerate gases of two flavors of Dirac neutrinos as a result of flavor mixing and dephasing. This is achieved by obtaining the time evolution of the flavor density matrix directly from quantum field theory at finite temperature and density. The time evolution features a rich hierarchy of scales which are widely separated in the nearly degenerate or relativistic cases and originate in interference phenomena between particle and antiparticle states. In the degenerate case the flavor asymmetry $\\Delta N(t)$ relaxes to the asymptotic limit $\\Delta N(\\infty)=\\Delta N(0)\\cos^2(2\\theta)$ via dephasing resulting from the oscillations between flavor modes that are not Pauli blocked, with a power law $1/t$ for $t>t_s \\approx 2 k_F/\\Delta M^2$. $k_F$ is the largest of the Fermi momenta. The distribution function for flavor neutrinos and antineutrinos as well as off-diagonal densities are obtained. Flavor particle-antiparticle pairs are produced by mixing and oscillations with typical momentum $k\\sim \\bar{M}$ the average mass of the neutrinos. An effective field theory description emerges on long time scales in which the Heisenberg operators obey a Bloch-type equation of motion valid in the relativistic and nearly degenerate cases. We find the non-equilibrium propagators and correlation functions in this effective theory and discuss its regime of validity as well as the potential corrections.
Ideal Based Cyber Security Technical Metrics for Control Systems
W. F. Boyer; M. A. McQueen
2007-10-01
Much of the world's critical infrastructure is at risk from attack through electronic networks connected to control systems. Security metrics are important because they provide the basis for management decisions that affect the protection of the infrastructure. A cyber security technical metric is the security relevant output from an explicit mathematical model that makes use of objective measurements of a technical object. A specific set of technical security metrics are proposed for use by the operators of control systems. Our proposed metrics are based on seven security ideals associated with seven corresponding abstract dimensions of security. We have defined at least one metric for each of the seven ideals. Each metric is a measure of how nearly the associated ideal has been achieved. These seven ideals provide a useful structure for further metrics development. A case study shows how the proposed metrics can be applied to an operational control system.
Contributions of ideal observer theory to vision research.
Geisler, Wilson S
2011-04-13
An ideal observer is a hypothetical device that performs optimally in a perceptual task given the available information. The theory of ideal observers has proven to be a powerful and useful tool in vision research, which has been applied to a wide range of problems. Here I first summarize the basic concepts and logic of ideal observer analysis and then briefly describe applications in a number of different areas, including pattern detection, discrimination and estimation, perceptual grouping, shape, depth and motion perception and visual attention, with an emphasis on recent applications. Given recent advances in mathematical statistics, in computational power, and in techniques for measuring behavioral performance, neural activity and natural scene statistics, it seems certain that ideal observer theory will play an ever increasing role in basic and applied areas of vision science. PMID:20920517
Some remarks on non-commutative principal ideal rings
Sylvain Carpentier; Alberto De Sole; Victor G. Kac
2013-05-02
We prove some algebraic results on the ring of matrix differential operators over a differential field in the generality of non-commutative principal ideal rings. These results are used in the theory of non-local Poisson structures.
Evaluation of compression members with non-ideal end conditions
Marek, David Leslie
1993-01-01
This thesis presents the results of research in which a formulation was developed for the effective length factor for compression members with non-ideal end conditions. This research stems from previous research conducted by Kohutek, Nunn...
Contributions of Ideal Observer Theory to Vision Research
Geisler, Wilson S.
2010-01-01
An ideal observer is a hypothetical device that performs optimally in a perceptual task given the available information. The theory of ideal observers has proven to be a powerful and useful tool in vision research, which has been applied to a wide range of problems. Here I first summarize the basic concepts and logic of ideal observer analysis and then briefly describe applications in a number of different areas, including pattern detection, discrimination and estimation, perceptual grouping, shape, depth and motion perception and visual attention, with an emphasis on recent applications. Given recent advances in mathematical statistics, in computational power, and in techniques for measuring behavioral performance, neural activity and natural scene statistics, it seems certain that ideal observer theory will play an ever increasing role in basic and applied areas of vision science. PMID:20920517
Arctic Ocean circulation in an idealized numerical model
Sugimura, Peter Joseph
2008-01-01
The mid-to-deep Arctic Ocean is generally characterized by a cyclonic circulation, contained along shelves and ridges. Here we analyze the general Arctic circulation using an idealized numerical model consisting of a ...
Measurable Control System Security through Ideal Driven Technical Metrics
Miles McQueen; Wayne Boyer; Sean McBride; Marie Farrar; Zachary Tudor
2008-01-01
The Department of Homeland Security National Cyber Security Division supported development of a small set of security ideals as a framework to establish measurable control systems security. Based on these ideals, a draft set of proposed technical metrics was developed to allow control systems owner-operators to track improvements or degradations in their individual control systems security posture. The technical metrics development effort included review and evaluation of over thirty metrics-related documents. On the bases of complexity, ambiguity, or misleading and distorting effects the metrics identified during the reviews were determined to be weaker than necessary to aid defense against the myriad threats posed by cyber-terrorism to human safety, as well as to economic prosperity. Using the results of our metrics review and the set of security ideals as a starting point for metrics development, we identified thirteen potential technical metrics - with at least one metric supporting each ideal. Two case study applications of the ideals and thirteen metrics to control systems were then performed to establish potential difficulties in applying both the ideals and the metrics. The case studies resulted in no changes to the ideals, and only a few deletions and refinements to the thirteen potential metrics. This led to a final proposed set of ten core technical metrics. To further validate the security ideals, the modifications made to the original thirteen potential metrics, and the final proposed set of ten core metrics, seven separate control systems security assessments performed over the past three years were reviewed for findings and recommended mitigations. These findings and mitigations were then mapped to the security ideals and metrics to assess gaps in their coverage. The mappings indicated that there are no gaps in the security ideals and that the ten core technical metrics provide significant coverage of standard security issues with 87% coverage. Based on the two case studies and evaluation of the seven assessments, the security ideals demonstrated their value in guiding security thinking. Further, the final set of core technical metrics has been demonstrated to be both usable in the control system environment and provide significant coverage of standard security issues.
Geller, Michael R.
2015-01-01
, Augusta, Georgia 30912, USA (Received 18 October 2012; published 8 June 2015) Current quantum computing an alternative method for general-purpose quantum computation that is ideally suited for such "prethreshold.25.Cp I. INTRODUCTION AND MOTIVATION A. The promise of quantum computation A universal quantum computer
Ideal spiral bevel gears: A new approach to surface geometry
NASA Technical Reports Server (NTRS)
Huston, R. L.; Coy, J. J.
1980-01-01
The fundamental geometrical characteristics of spiral bevel gear tooth surfaces are discussed. The parametric representation of an ideal spiral bevel tooth is developed based on the elements of involute geometry, differential geometry, and fundamental gearing kinematics. A foundation is provided for the study of nonideal gears and the effects of deviations from ideal geometry on the contact stresses, lubrication, wear, fatigue life, and gearing kinematics.
The ideal-column concept: applying exergy to distillation
Kaiser, V.
1985-08-19
An ideal model is described to determine minimum energy requirements and perhaps other system parameters. The concept of exergy analysis is used here to formulate an ideal model for distillation, one that will be applicable to real systems, since exergy provides a comparable base for all energy forms. The analysis is used not only for ranking various setups according to overall results, but to provide comparisons for each section of the system. The paper examines binary mixtures, and characterizes distillation.
Epifanovsky, Evgeny; Polyakov, Igor; Grigorenko, Bella; Nemukhin, Alexander; Krylov, Anna I
2009-07-14
We present the results of quantum chemical calculations of the electronic properties of the anionic form of the green fluorescent protein chromophore in the gas phase. The vertical detachment energy of the chromophore is found to be 2.4-2.5 eV, which is below the strongly absorbing ??* state at 2.6 eV. The vertical excitation of the lowest triplet state is around 1.9 eV, which is below the photodetachment continuum. Thus, the lowest bright singlet state is a resonance state embedded in the photodetachment continuum, whereas the lowest triplet state is a regular bound state. Based on our estimation of the vertical detachment energy, we attribute a minor feature in the action spectrum as due to the photodetachment transition. The benchmark results for the bright ??* state demonstrated that the scaled opposite-spin method yields vertical excitation within 0.1 eV (20 nm) from the experimental maximum at 2.59 eV (479 nm). We also report estimations of the vertical excitation energy obtained with the equation-of-motion coupled cluster with the singles and doubles method, a multireference perturbation theory corrected approach MRMP2 as well as the time-dependent density functional theory with range-separated functionals. Expanding the basis set with diffuse functions lowers the ??* vertical excitation energy by 0.1 eV at the same time revealing a continuum of "ionized" states, which embeds the bright ??* transition. PMID:26610014
Detonation Failure Characterization of Non-Ideal Explosives
NASA Astrophysics Data System (ADS)
Janesheski, Robert; Son, Steven; Groven, Lori
2011-06-01
Non-ideal explosives are currently poorly characterized, which limits the modeling of them. Current characterization requires large-scale testing to obtain detonation wave characterization for analysis due to the relatively thick reaction zones. Use of a microwave interferometer applied to small-scale confined experiments is being implemented to allow for time resolved characterization of a failing detonation. The microwave interferometer measures the failing detonation wave in a tube, and this experiment only requires small amounts of non-ideal explosives. A non-ideal explosive is initiated with a booster charge and a measurement of the failure distance and a continuous position-time trace of the detonation front location can be obtained. Initial tests have been performed that show this method is feasible using an ammonium perchlorate (AP) composite propellant as a model non-ideal explosive. Future work will apply this approach to non-ideal explosives. Successful results of this method would allow for the calibration of detonation models for many different non-ideal explosives. This project was funded by the Department of Homeland Security through the Center of Excellence for Explosive Detection, Mitigation, and Response under award number 080409/0002251.
Quantum Kinematics of Bosonic Vortex Loops
Goldin, G.A.; Owczarek, R.; Sharp, D.H.
1999-05-06
Poisson structure for vortex filaments (loops and arcs) in 2D ideal incompressible fluid is analyzed in detail. Canonical coordinates and momenta on coadjoint orbits of the area-preserving diffeomorphism group, associated with such vortices, are found. The quantum space of states in the simplest case of ''bosonic'' vortex loops is built within a geometric quantization approach to the description of a quantum fluid. Fock-like structure and non-local creation and annihilation operators of quantum vortex filaments are introduced.
Quantum light in coupled interferometers for quantum gravity tests.
Ruo Berchera, I; Degiovanni, I P; Olivares, S; Genovese, M
2013-05-24
In recent years quantum correlations have received a lot of attention as a key ingredient in advanced quantum metrology protocols. In this Letter we show that they provide even larger advantages when considering multiple-interferometer setups. In particular, we demonstrate that the use of quantum correlated light beams in coupled interferometers leads to substantial advantages with respect to classical light, up to a noise-free scenario for the ideal lossless case. On the one hand, our results prompt the possibility of testing quantum gravity in experimental configurations affordable in current quantum optics laboratories and strongly improve the precision in "larger size experiments" such as the Fermilab holometer; on the other hand, they pave the way for future applications to high precision measurements and quantum metrology. PMID:23745871
The Brian\\c{c}on-Skoda Theorem and Coefficient Ideals for Non m-Primary Ideals
Aberbach, Ian M
2010-01-01
We generalize a Brian\\c{c}on-Skoda type theorem first studied by Aberbach and Huneke. With some conditions on a regular local ring $(R,\\m)$ containing a field, and an ideal $I$ of $R$ with analytic spread $\\ell$ and a minimal reduction $J$, we prove that for all $w \\geq -1$, $ \\bar{I^{\\ell+w}} \\subseteq J^{w+1} \\mathfrak{a} (I,J),$ where $\\mathfrak{a}(I,J)$ is the coefficient ideal of $I$ relative to $J$, i.e. the largest ideal $\\mathfrak{b}$ such that $I\\mathfrak{b}=J\\mathfrak{b}$. Previously, this result was known only for $\\m$-primary ideals.
Idealized Closed Form Performance Modeling of a Closed Cycle Joule-Thomson Cryocooler
NASA Astrophysics Data System (ADS)
Maytal, B.-Z.
2004-06-01
The characteristic parameters of a closed cycle Joule-Thomson cryocooler would be: the charging pressure, discharge and suction volumes of the loop, volumetric displacement of the compressor and the extent of throttling restriction. A series of idealizing assumption are applied. The volumetric behavior of the coolant is assumed to obey the ideal gas equation. The recuperator and compressor's volumetric delivery are completely efficient. There are no pressure losses along the circulating path. On this basis is developed a closed form model of the system, interrelating the relevant parameters. Performance at steady state is expressed in terms of the circulating flow rate, discharge and suction pressures and cooling power. The model predicts the optimal size of equivalent orifice and the maximized cooling power. Also derived is the hydrodynamic time constant of building up the discharge pressure. This analysis is relevant for mixed coolants as well as for pure coolants closed cycles. The former typically employ lower pressure and therefore the idealized assumptions are even more applicable.
Monsoons and Their Response to Climate Change in Idealized GCM Experiments
NASA Astrophysics Data System (ADS)
Laraia, A.; Bordoni, S.
2014-12-01
Monsoons are prominent features of the tropical and subtropical atmospheric circulation, affecting 60% of the world's population (Wang 2006) and sustaining rapidly growing economies. Understanding how monsoons will change with changing climate is of pressing societal importance, and yet remains a challenge: Numerous studies have explored the impact of global warming on monsoons, but many questions remain unanswered. In this study, we perform experiments with an idealized General Circulation Model (GCM) to investigate the response of an idealized monsoon to climate change. We focus on two idealized continental geometries, an Africa-like continent stretching from pole to pole with a fixed longitudinal width, and an Asia-like continent that spans all longitudes north of 10°N. The climate is varied by perturbing the atmospheric longwave absorber, in analogy to changes in greenhouse gas concentrations. We use the moist static energy, moisture and zonal momentum budgets (e.g., Chou et al. 2001, Bordoni and Schneider 2008) to interpret the simulated changes in monsoon onset, circulation strength and precipitation. Each budget is decomposed into mean, stationary and transient eddy fluxes, to explore the relative role of these circulations in the maintenance of the monsoonal precipitation. We specifically focus on how the distribution, both spatially and temporally, of precipitation changes as the climate is varied in the two different continental configurations.
Entanglement purification and quantum error correction
W. Dür; H. J. Briegel
2007-08-07
We give a review on entanglement purification for bipartite and multipartite quantum states, with the main focus on theoretical work carried out by our group in the last couple of years. We discuss entanglement purification in the context of quantum communication, where we emphasize its close relation to quantum error correction. Various bipartite and multipartite entanglement purification protocols are discussed, and their performance under idealized and realistic conditions is studied. Several applications of entanglement purification in quantum communication and computation are presented, which highlights the fact that entanglement purification is a fundamental tool in quantum information processing.
Numerical computation for teaching quantum statistics
NASA Astrophysics Data System (ADS)
Price, Tyson; Swendsen, Robert H.
2013-11-01
The study of ideal quantum gases reveals surprising quantum effects that can be observed in macroscopic systems. The properties of bosons are particularly unusual because a macroscopic number of particles can occupy a single quantum state. We describe a computational approach that supplements the usual analytic derivations applicable in the thermodynamic limit. The approach involves directly summing over the quantum states for finite systems and avoids the need for doing difficult integrals. The results display the unusual behavior of quantum gases even for relatively small systems.
Kostanyan, Artak E
2015-12-01
The ideal (the column outlet is directly connected to the column inlet) and non-ideal (includes the effects of extra-column dispersion) recycling equilibrium-cell models are used to simulate closed-loop recycling counter-current chromatography (CLR CCC). Simple chromatogram equations for the individual cycles and equations describing the transport and broadening of single peaks and complex chromatograms inside the recycling closed-loop column for ideal and non-ideal recycling models are presented. The extra-column dispersion is included in the theoretical analysis, by replacing the recycling system (connecting lines, pump and valving) by a cascade of Nec perfectly mixed cells. To evaluate extra-column contribution to band broadening, two limiting regimes of recycling are analyzed: plug-flow, Nec??, and maximum extra-column dispersion, Nec=1. Comparative analysis of ideal and non-ideal models has shown that when the volume of the recycling system is less than one percent of the column volume, the influence of the extra-column processes on the CLR CCC separation may be neglected. PMID:26518496
Quantum rotor in nanostructured superconductors
Lin, Shi-Hsin; Miloševi?, M. V.; Covaci, L.; Jankó, B.; Peeters, F. M.
2014-01-01
Despite its apparent simplicity, the idealized model of a particle constrained to move on a circle has intriguing dynamic properties and immediate experimental relevance. While a rotor is rather easy to set up classically, the quantum regime is harder to realize and investigate. Here we demonstrate that the quantum dynamics of quasiparticles in certain classes of nanostructured superconductors can be mapped onto a quantum rotor. Furthermore, we provide a straightforward experimental procedure to convert this nanoscale superconducting rotor into a regular or inverted quantum pendulum with tunable gravitational field, inertia, and drive. We detail how these novel states can be detected via scanning tunneling spectroscopy. The proposed experiments will provide insights into quantum dynamics and quantum chaos. PMID:24686241
Quantum rotor in nanostructured superconductors
NASA Astrophysics Data System (ADS)
Lin, Shi-Hsin; Miloševi?, M. V.; Covaci, L.; Jankó, B.; Peeters, F. M.
2014-04-01
Despite its apparent simplicity, the idealized model of a particle constrained to move on a circle has intriguing dynamic properties and immediate experimental relevance. While a rotor is rather easy to set up classically, the quantum regime is harder to realize and investigate. Here we demonstrate that the quantum dynamics of quasiparticles in certain classes of nanostructured superconductors can be mapped onto a quantum rotor. Furthermore, we provide a straightforward experimental procedure to convert this nanoscale superconducting rotor into a regular or inverted quantum pendulum with tunable gravitational field, inertia, and drive. We detail how these novel states can be detected via scanning tunneling spectroscopy. The proposed experiments will provide insights into quantum dynamics and quantum chaos.
Quantum rotor in nanostructured superconductors.
Lin, Shi-Hsin; Miloševi?, M V; Covaci, L; Jankó, B; Peeters, F M
2014-01-01
Despite its apparent simplicity, the idealized model of a particle constrained to move on a circle has intriguing dynamic properties and immediate experimental relevance. While a rotor is rather easy to set up classically, the quantum regime is harder to realize and investigate. Here we demonstrate that the quantum dynamics of quasiparticles in certain classes of nanostructured superconductors can be mapped onto a quantum rotor. Furthermore, we provide a straightforward experimental procedure to convert this nanoscale superconducting rotor into a regular or inverted quantum pendulum with tunable gravitational field, inertia, and drive. We detail how these novel states can be detected via scanning tunneling spectroscopy. The proposed experiments will provide insights into quantum dynamics and quantum chaos. PMID:24686241
NASA Astrophysics Data System (ADS)
Vogt, Natalja; Abaev, Maxim A.; Karasev, Nikolai M.
2011-02-01
The molecular structure of fumaric acid was reinvestigated by the gas phase electron diffraction (GED) method because it was determined several years ago assuming the existence of one conformer only. According to MP2/cc-pVTZ predictions, the molecule has six stable conformations, and three of them, sp,sp,sp,sp (I), ap,sp,sp,sp (II) and ap,ap,sp,sp (III), with relative energies within ca. 3 kJ mol -1 should be present in detectable amounts at the experimental temperature of ca. 480 K. The best fit to the GED intensities was achieved at the approximately equal amounts of the conformers I-III. To take into account vibrational effects, the corrections to the experimental r a bond lengths ( r e - r a) were calculated using quadratic and cubic force constants from high-level ab initio calculations (MP2/cc-pVTZ). The deduced equilibrium bond lengths of the conformer II with the estimated total errors (in Å) are the following: r e(C dbnd C) = 1.331(3), r e(C sbnd C) s-trans = 1.473(3), r e(C sbnd C) s-cis = 1.479(3), r e(C sbnd O) s-trans = 1.345(3), r e(C sbnd O) s-cis = 1.344(3), r e(C dbnd O) s-trans = 1.205(3), r e(C dbnd O) s-cis = 1.204(3). The structural effects arising due to presence of the C dbnd C double bond were analysed. In comparison to the experiment, the MP2/cc-pVQZ approximation overestimates some bond lengths in fumaric acid and similar molecules by up to 0.005 Å. The rotational constants of the conformers I-III were derived from the GED equilibrium geometries.
Childhood Lifestyle and Clinical Determinants of Adult Ideal
Laitinen, Tomi T.; Pahkala, Katja; Venn, Alison; Woo, Jessica G; Oikonen, Mervi; Dwyer, Terence; Mikkilä, Vera; Hutri-Kähönen, Nina; Smith, Kylie J.; Gall, Seana L.; Morrison, John A.; Viikari, Jorma S.A.; Raitakari, Olli T.; Magnussen, Costan G.; Juonala, Markus
2013-01-01
Background The American Heart Association recently defined ideal cardiovascular health by simultaneous presence of seven health behaviors and factors. The concept is associated with cardiovascular disease incidence, and cardiovascular disease and all-cause mortality. To effectively promote ideal cardiovascular health already early in life, childhood factors predicting future ideal cardiovascular health should be investigated. Our aim was thus to comprehensively explore childhood determinants of adult ideal cardiovascular health in population based cohorts from three continents. Methods The sample comprised a total of 4409 participants aged 3–19 years at baseline from the Cardiovascular Risk in Young Finns Study (YFS; N=1883) from Finland, Childhood Determinants of Adult Health Study (CDAH; N=1803) from Australia and Princeton Follow-up Study (PFS; N=723) from the United States. Participants were re-examined 19–31 years later when aged 30–48 years. Results In multivariable analyses, independent childhood predictors of adult ideal cardiovascular health were family socioeconomic status (P<0.01; direct association) and BMI (P<0.001; inverse association) in all cohorts. In addition, blood pressure (P=0.007), LDL-cholesterol (P<0.001) and parental smoking (P=0.006) in the YFS, and own smoking (P=0.001) in CDAH were inversely associated with future ideal cardiovascular health. Conclusions Among several lifestyle and clinical indicators studied, higher family socioeconomic status and non-smoking (parental/own) in childhood independently predict ideal cardiovascular health in adulthood. As atherosclerotic cardiovascular diseases are rooted in childhood, our findings suggest that special attention could be paid to children who are from low socioeconomic status families, and who smoke or whose parents smoke, to prevent cardiovascular disease morbidity and mortality. PMID:24075574
Developmental Idealism and Cultural Models of the Family in Malawi
Pierotti, Rachael S.; Young-DeMarco, Linda; Watkins, Susan
2014-01-01
This paper examines the extent to which developmental idealism has been disseminated in Malawi. Developmental idealism is a set of beliefs and values about development and the relationships between development and family structures and behavior. Developmental idealism states that attributes of societies and families defined as modern are better than attributes defined as traditional, that modern societies help produce modern families, that modern families facilitate the achievement of modern societies, and that the future will bring family change in the direction of modernity. Previous research has demonstrated that knowledge of developmental idealism is widespread in many places around the world, but provides little systematic data about it in sub-Saharan Africa or how knowledge of it is associated with certain demographic characteristics in that region. In this paper, we address this issue by examining whether ordinary people in two settings in Malawi, a sub-Saharan African country, have received and understood messages that are intended to associate development with certain types of family forms and family behaviors. We then examine associations between demographic characteristics and developmental idealism to investigate possible mechanisms linking global discourse about development to the grassroots. We analyze data collected in face-to-face surveys from two samples of Malawian men in 2009 and 2010, one rural, the other in a low-to-medium income neighborhood of a city. Our analysis of these survey data shows considerable evidence that many developmental idealism beliefs have been spread in that country and that education has positive effects on beliefs in the association between development and family attributes. We also find higher levels of developmental idealism awareness in the urban sample than we do in the rural sample, but once dissimilarities in education and wealth between the two samples are controlled, awareness levels no longer differed between urban and rural respondents. We explore how these beliefs intersect with longstanding local values and beliefs in Malawi. PMID:25197155
Superradiant Quantum Heat Engine
NASA Astrophysics Data System (ADS)
Hardal, Ali Ü. C.; Müstecapl?o?lu, Özgür E.
2015-08-01
Quantum physics revolutionized classical disciplines of mechanics, statistical physics, and electrodynamics. One branch of scientific knowledge however seems untouched: thermodynamics. Major motivation behind thermodynamics is to develop efficient heat engines. Technology has a trend to miniaturize engines, reaching to quantum regimes. Development of quantum heat engines (QHEs) requires emerging field of quantum thermodynamics. Studies of QHEs debate whether quantum coherence can be used as a resource. We explore an alternative where it can function as an effective catalyst. We propose a QHE which consists of a photon gas inside an optical cavity as the working fluid and quantum coherent atomic clusters as the fuel. Utilizing the superradiance, where a cluster can radiate quadratically faster than a single atom, we show that the work output becomes proportional to the square of the number of the atoms. In addition to practical value of cranking up QHE, our result is a fundamental difference of a quantum fuel from its classical counterpart.
Superradiant Quantum Heat Engine
Hardal, Ali Ü. C.; Müstecapl?o?lu, Özgür E.
2015-01-01
Quantum physics revolutionized classical disciplines of mechanics, statistical physics, and electrodynamics. One branch of scientific knowledge however seems untouched: thermodynamics. Major motivation behind thermodynamics is to develop efficient heat engines. Technology has a trend to miniaturize engines, reaching to quantum regimes. Development of quantum heat engines (QHEs) requires emerging field of quantum thermodynamics. Studies of QHEs debate whether quantum coherence can be used as a resource. We explore an alternative where it can function as an effective catalyst. We propose a QHE which consists of a photon gas inside an optical cavity as the working fluid and quantum coherent atomic clusters as the fuel. Utilizing the superradiance, where a cluster can radiate quadratically faster than a single atom, we show that the work output becomes proportional to the square of the number of the atoms. In addition to practical value of cranking up QHE, our result is a fundamental difference of a quantum fuel from its classical counterpart. PMID:26260797
Superradiant Quantum Heat Engine
Ali Ü. C. Hardal; Özgür E. Müstecapl?oglu
2015-07-16
Quantum physics revolutionized classical disciplines of mechanics, statistical physics, and electrodynamics. One branch of scientific knowledge however seems untouched: thermodynamics. Major motivation behind thermodynamics is to develop efficient heat engines. Technology has a trend to miniaturize engines, reaching to quantum regimes. Development of quantum heat engines (QHEs) requires emerging field of quantum thermodynamics. Studies of QHEs debate whether quantum coherence can be used as a resource. We explore an alternative where it can function as an effective catalyst. We propose a QHE which consists of a photon gas inside an optical cavity as the working fluid and quantum coherent atomic clusters as the fuel. Utilizing the superradiance, where a cluster can radiate quadratically faster than a single atom, we show that the work output becomes proportional to the square of the number of the atoms. In addition to practical value of cranking up QHE, our result is a fundamental difference of a quantum fuel from its classical counterpart.
Ultra LI-ideals in lattice implication algebras and MTL-algebras
Xiaohong Zhang; Keyun Qin; Wieslaw A. Dudek
2007-10-20
A mistake concerning the ultra \\textit{LI}-ideal of a lattice implication algebra is pointed out, and some new sufficient and necessary conditions for an \\textit{LI}-ideal to be an ultra \\textit{LI}-ideal are given. Moreover, the notion of an \\textit{LI}-ideal is extended to MTL-algebras, the notions of a (prime, ultra, obstinate, Boolean) \\textit{LI}-ideal and an \\textit{ILI}-ideal of an MTL-algebra are introduced, some important examples are given, and the following notions are proved to be equivalent in MTL-algebra: (1) prime proper \\textit{LI}-ideal and Boolean \\textit{LI}-ideal, (2) prime proper \\textit{LI}-ideal and \\textit{ILI}-ideal, (3) proper obstinate \\textit{LI}-ideal, (4) ultra \\textit{LI}-ideal.
Perceived current and ideal body size in female undergraduates.
MacNeill, Lillian P; Best, Lisa A
2015-08-01
Body image dissatisfaction and disordered eating attitudes and behaviors are pervasive problems in Western society, particularly for females. The female "thin-ideal" is a potent contributor to the growing discontent with the female body and research has shown that even females who are normal or underweight, perceive themselves as overweight. The goal of the current study was to examine correlates of body image satisfaction and the perception of the female body. One hundred and sixty six female undergraduates (Mean Age=21.40 years) completed self-report measures pertaining to disordered eating (EAT-26) and body dissatisfaction (BIQ and ABS). Body image perception and satisfaction were measured using ratings of female bodies on a weight perception scale (PFRS). Overall, disordered eating was related to a lower ideal body size and greater body dissatisfaction. In support of previous research, the most common ideal female body had a BMI categorized as underweight. Although females in the current sample reported an ideal that was smaller than their current size, participants underestimated their current body size, which, given the amount of dieting and weight pressure in present Western society, seems counterintuitive. It is possible that thin ideal portrayed in the media is increasingly different from and at odds with the average female body. PMID:25955887
Care Ideals in the Netherlands: Shifts between 2002 and 2011.
van den Broek, Thijs; Dykstra, Pearl A; van der Veen, Romke J
2015-09-01
Our study's premise was that normative care beliefs can inform the current care policy debate. We conducted latent class regression analyses on two waves of Netherlands Kinship Panel Study data (n = 4,163) to distinguish care ideals that captured multiple dimensions of normative care beliefs simultaneously. We also assessed how these care ideals have shifted in the early twenty-first century. We distinguished four care ideals: warm-modern (family and state jointly responsible for caring, egalitarian gender roles), cold-modern (large state responsibility, restricted family responsibility, egalitarian gender roles), traditional (restricted state responsibility, large family responsibility, moderately traditional gender roles), and cold-traditional (large state responsibility, restricted family responsibility, traditional gender roles). Between 2002 and 2011, there has been a shift away from warm-modern care ideals and towards cold-modern care ideals. This is remarkable, because Dutch policy makers have increasingly encouraged family members to take on an active role in caring for dependent relatives. PMID:26300187
Informational derivation of Quantum Theory
G. Chiribella; G. M. D'Ariano; P. Perinotti
2011-07-15
Quantum theory can be derived from purely informational principles. Five elementary axioms-causality, perfect distinguishability, ideal compression, local distinguishability, and pure conditioning-define a broad class of theories of information-processing that can be regarded as a standard. One postulate-purification-singles out quantum theory within this class. The main structures of quantum theory, such as the representation of mixed states as convex combinations of perfectly distinguishable pure states, are derived directly from the principles without using the Hilbert space framework.
Relativistic quantum private database queries
NASA Astrophysics Data System (ADS)
Sun, Si-Jia; Yang, Yu-Guang; Zhang, Ming-Ou
2015-04-01
Recently, Jakobi et al. (Phys Rev A 83, 022301, 2011) suggested the first practical private database query protocol (J-protocol) based on the Scarani et al. (Phys Rev Lett 92, 057901, 2004) quantum key distribution protocol. Unfortunately, the J-protocol is just a cheat-sensitive private database query protocol. In this paper, we present an idealized relativistic quantum private database query protocol based on Minkowski causality and the properties of quantum information. Also, we prove that the protocol is secure in terms of the user security and the database security.
Quantum information processing and relativistic quantum fields
NASA Astrophysics Data System (ADS)
Benincasa, Dionigi M. T.; Borsten, Leron; Buck, Michel; Dowker, Fay
2014-04-01
It is shown that an ideal measurement of a one-particle wave packet state of a relativistic quantum field in Minkowski spacetime enables superluminal signalling. The result holds for a measurement that takes place over an intervention region in spacetime whose extent in time in some frame is longer than the light-crossing time of the packet in that frame. Moreover, these results are shown to apply not only to ideal measurements but also to unitary transformations that rotate two orthogonal one-particle states into each other. In light of these observations, possible restrictions on the allowed types of intervention are considered. A more physical approach to such questions is to construct explicit models of the interventions as interactions between the field and other quantum systems such as detectors. The prototypical Unruh-DeWitt detector couples to the field operator itself and so most likely respects relativistic causality. On the other hand, detector models which couple to a finite set of frequencies of field modes are shown to lead to superluminal signalling. Such detectors do, however, provide successful phenomenological models of atom-qubits interacting with quantum fields in a cavity but are valid only on time scales many orders of magnitude larger than the light-crossing time of the cavity.
Becerra, Rosa; Cannady, J Pat; Pfrang, Christian; Walsh, Robin
2015-11-19
Time-resolved kinetics studies of silylene, SiH2, generated by laser flash photolysis of phenylsilane, were performed to obtain rate coefficients for its bimolecular reaction with 2,5-dihydrofuran (2,5-DHF). The reaction was studied in the gas phase over the pressure range of 1-100 Torr in SF6 bath gas, at five temperatures in the range of 296-598 K. The reaction showed pressure dependences characteristic of a third body assisted association. The second-order rate coefficients obtained by Rice-Ramsperger-Kassel-Marcus (RRKM)-assisted extrapolation to the high-pressure limit at each temperature fitted the following Arrhenius equation where the error limits are single standard deviations: log(k/cm(3) molecule(-1) s(-1)) = (-9.96 ± 0.08) + (3.38 ± 0.62 kJ mol(-1))/RT ln 10. End-product analysis revealed no GC-identifiable product. Quantum chemical (ab initio) calculations indicate that reaction of SiH2 with 2,5-DHF can occur at both the double bond (to form a silirane) and the O atom (to form a donor-acceptor, zwitterionic complex) via barrierless processes. Further possible reaction steps were explored, of which the only viable one appears to be decomposition of the O-complex to give 1,3-butadiene + silanone, although isomerization of the silirane cannot be completely ruled out. The potential energy surface for SiH2 + 2,5-DHF is consistent with that of SiH2 with Me2O, and with that of SiH2 with cis-but-2-ene, the simplest reference reactions. RRKM calculations incorporating reaction at both ?- and O atom sites, can be made to fit the experimental rate coefficient pressure dependence curves at 296-476 K, giving values for k(?)(?) and k(?)(O) that indicate the latter is larger in magnitude at all temperatures, in contrast to values from individual model reactions. This unexpected result suggests that, in 2,5-DHF with its two different reaction sites, the O atom exerts the more pronounced electrophilic attraction on the approaching silylene. Arrhenius parameters for the individual pathways were obtained. The lack of a fit at 598 K is consistent with decomposition of the O-complex to give 1,3-butadiene + silanone. PMID:26487151
Rebollo-Neira, Laura
, Natural Gas History, Natural Gas Origin and Composition, Gas Sources, Gas Laws, Temperature measurement and Physical Properties, Gas Specific Gravity, Ideal and Real Gas Laws, Gas Formation Volume Factor, GasApproved Module Information for ME1F20, 2014/5 Module Title/Name: Gas Engineering Principles Module
Cartan ideal, prolongation, and Baecklund transformations for Einstein's equations
Bilge, A.H.; Guerses, M.
1986-07-01
Einstein's equations in the Newman--Penrose formalism for vacuum, vacuum with cosmological constant, and electrovacuum fields are expressed as Cartan ideals. Two different prolongations of these ideals are obtained. These two types of prolonged ideals generalize previous prolongations for vacuum fields to vacuum with cosmological constant and electrovacuum fields. Some Baecklund transformations are obtained for vacuum, vacuum with cosmological constant, and electrovacuum fields. These Baecklund transformations include the generalized Kerr--Schild (GKS) transformation, and a two-parameter generalization of the GKS transformation. GKS transformations are studied in detail. Expressions for the transformation of Newman--Penrose quantities are given and algebraic properties are discussed. It is shown that the GKS transformation cannot give algebraically general and asymptotically flat vacuum and electrovacuum space-time metrics.