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1

Quantum degeneracy effect on performance of irreversible Otto cycle with ideal Bose gas  

Microsoft Academic Search

An Otto cycle working with an ideal Bose gas is called a Bose Otto cycle. The internal irreversibility of the cycle is included in the factors of internal irreversibility degree. The quantum degeneracy effect on the performance of the cycle is investigated based on quantum statistical mechanics and thermodynamics. Variations of the maximum work output ratio RW and the efficiency

Feng Wu; Lingen Chen; Fengrui Sun; Chih Wu; Fangzhong Guo; Qing Li

2006-01-01

2

High-order kinetic flux vector splitting schemes in general coordinates for ideal quantum gas dynamics  

NASA Astrophysics Data System (ADS)

A class of high-order kinetic flux vector splitting schemes are presented for solving ideal quantum gas dynamics based on quantum statistical mechanics. The collisionless quantum Boltzmann equation approach is adopted and both Bose Einstein and Fermi Dirac gases are considered. The formulas for the split flux vectors are derived based on the general three-dimensional distribution function in velocity space and formulas for lower dimensions can be directly deduced. General curvilinear coordinates are introduced to treat practical problems with general geometry. High-order accurate schemes using weighted essentially non-oscillatory methods are implemented. The resulting high resolution kinetic flux splitting schemes are tested for 1D shock tube flows and shock wave diffraction by a 2D wedge and by a circular cylinder in ideal quantum gases. Excellent results have been obtained for all examples computed.

Yang, Jaw-Yen; Hsieh, Tse-Yang; Shi, Yu-Hsin; Xu, Kun

2007-12-01

3

High-order kinetic flux vector splitting schemes in general coordinates for ideal quantum gas dynamics  

SciTech Connect

A class of high-order kinetic flux vector splitting schemes are presented for solving ideal quantum gas dynamics based on quantum statistical mechanics. The collisionless quantum Boltzmann equation approach is adopted and both Bose-Einstein and Fermi-Dirac gases are considered. The formulas for the split flux vectors are derived based on the general three-dimensional distribution function in velocity space and formulas for lower dimensions can be directly deduced. General curvilinear coordinates are introduced to treat practical problems with general geometry. High-order accurate schemes using weighted essentially non-oscillatory methods are implemented. The resulting high resolution kinetic flux splitting schemes are tested for 1D shock tube flows and shock wave diffraction by a 2D wedge and by a circular cylinder in ideal quantum gases. Excellent results have been obtained for all examples computed.

Yang, J.-Y. [Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan (China)], E-mail: yangjy@iam.ntu.edu.tw; Hsieh, T.-Y.; Shi, Y.-H. [Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan (China); Xu Kun [Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

2007-12-10

4

?-DIMENSIONAL Ideal Quantum q-GAS:. Bose-Einstein Condensation and ?-POINT Transition  

NASA Astrophysics Data System (ADS)

We consider an ideal quantum q-gas in ? spatial dimensions and energy spectrum ?i? p? Departing from the Hamiltonian H=?[N], we study the effect of the deformation on thermodynamic functions and equation of state of that system. The virial expansion is obtained for the high temperature (or low density) regime. The critical temperature is higher than in non-deformed ideal gases. We show that Bose-Einstein condensation always exists (unless when ?/?=1) for finite q but not for q=?. Employing numerical calculations and selecting for v/? the values 3/2, 2 and 3, we show the critical temperature as a function of q, the specific heat CV and the chemical potential µ as functions of {T {T {Tcq }}} ; } {Tcq }} for q=1.05 and q=4.5. CV exhibits a ?-point discontinuity in all cases, instead of the cusp singularity found in the usual ideal gas. Our results indicate that physical systems which have quantum symmetries can exhibit Bose-Einstein condensation phenomenon, the critical temperature being favored by the deformation parameter.

R-Monteiro, M.; Roditi, Itzhak; Rodrigues, Ligia M. C. S.

5

Influence of quantum degeneracy on the performance of a Stirling refrigerator working with an ideal Fermi gas  

Microsoft Academic Search

The influence of quantum degeneracy on the performance of a Stirling refrigeration cycle is investigated, based on the equation of state of an ideal Fermi gas. The inherent regenerative losses and the coefficient of performance (COP) of the cycle are calculated. It is found that, under the condition of strong gas degeneracy, the COP of the cycle in the first

Jizhou He; Jincan Chen; Ben Hua

2002-01-01

6

Ecological Optimization Performance of An Irreversible Quantum Otto Cycle Working with an Ideal Fermi Gas  

Microsoft Academic Search

The model of an irreversible Otto cycle using an ideal Fermi gas as the working fluid, which is called as the irreversible\\u000a Fermi Otto cycle, is established in this paper. Based on the equation of state of an ideal Fermi gas, the ecological optimization\\u000a performance of an irreversible Fermi Otto cycle is examined by taking an ecological optimization criterion as

Feng Wu; Lingen Chen; Fengrui Sun; Chih Wu; Fangzhong Guo; Qing Li

2006-01-01

7

Ideal Gas of Tachyons.  

National Technical Information Service (NTIS)

The properties of the ideal gas of classical (nonquantum) faster than light particles-tachyons have been considered. The basic notions of thermodynamics of tachyons have been introduced. We have found the partition function and other thermodynamical quant...

S. Mrowczynski

1983-01-01

8

Chemical potential for the interacting classical gas and the ideal quantum gas obeying a generalized exclusion principle  

NASA Astrophysics Data System (ADS)

In this work, we address the concept of the chemical potential ? in classical and quantum gases towards the calculation of the equation of state ? = ?(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 presented with detailed calculations. The first one refers to the explicit calculation of ? for the interacting classical gas exemplified by van der Waals gas. For this purpose, we used the method described by van Kampen (1961 Physica 27 783). The second one refers to the calculation of ? for ideal quantum gases that obey a generalized Pauli's exclusion principle that leads to statistics that go beyond the Bose-Einstein and Fermi-Dirac cases. The audience targeted in this work corresponds mainly to advanced undergraduates and graduate students in the physical-chemical sciences but it is not restricted to them. In regard of this, we have put a special emphasis on showing some additional details of calculations that usually do not appear explicitly in textbooks.

Sevilla, F. J.; Olivares-Quiroz, L.

2012-05-01

9

Ideal Gas Expansion  

NSDL National Science Digital Library

The EJS Ideal Gas Expansion model simulates a two-dimensional ideal gas in a square box. This simulation can be used as part of the activity described in "The Statistical Interpretation of Entropy: An Activity" by Todd Timberlake, to be published in The Physics Teacher. In the model, the particles are initially all on the left (red) side of the box with otherwise random positions and random velocities (distributed according to a Maxwell distribution). Separate windows show the motion of the gas particles, a plot of the number of particles on each side versus time, and a histogram of the number of occurrences of a given number of particles on the left. The user can modify this simulation if EJS is installed locally by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. EJS Ideal Gas Expansion model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_entropy_IdealGasExpansion.jar file will run the program if Java is installed. EJS is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional EJS models re available. They can be found by searching ComPADRE for Open Source Physics, OSP, or EJS.

Timberlake, Todd

2010-06-18

10

Thermodynamics of ideal quantum gas with fractional statistics in D dimensions.  

PubMed

We present exact and explicit results for the thermodynamic properties (isochores, isotherms, isobars, response functions, velocity of sound) of a quantum gas in dimensions D > or = 1 and with fractional exclusion statistics 0 < or = g < or =1 connecting bosons (g=0) and fermions (g=1) . In D=1 the results are equivalent to those of the Calogero-Sutherland model. Emphasis is given to the crossover between bosonlike and fermionlike features, caused by aspects of the statistical interaction that mimic long-range attraction and short-range repulsion. A phase transition along the isobar occurs at a nonzero temperature in all dimensions. The T dependence of the velocity of sound is in simple relation to isochores and isobars. The effects of soft container walls are accounted for rigorously for the case of a pure power-law potential. PMID:17677233

Potter, Geoffrey G; Müller, Gerhard; Karbach, Michael

2007-06-21

11

Re-Optimisation of Otto Power Cycles Working with Ideal Quantum Gases  

Microsoft Academic Search

To analyse the effect of quantum degeneracy of a working gas on the work optimisation of an ideal gas cycle, Otto power cycles working with ideal Bose and Fermi type quantum gases are considered. They are called Bose and Fermi Otto cycles respectively. Expressions for their net work outputs per cycle are derived by using the corrected ideal gas equation

Altu Altu; Hasan Saygin

2001-01-01

12

Chemical Potential for the Interacting Classical Gas and the Ideal Quantum Gas Obeying a Generalized Exclusion Principle  

ERIC Educational Resources Information Center

|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…

Sevilla, F. J.; Olivares-Quiroz, L.

2012-01-01

13

Ideal Gas Law and the Gas Constant  

NSDL National Science Digital Library

This site offers an interactive tutorial in which students test the validity of the ideal gas law by measuring the pressure of a gas at various molar concentrations. The value of the gas constant is determined graphically. This tutorial is coupled to others to further guide the student to a better understanding of the principles which govern the behavior of gases.

Blauch, David N.

14

Ideal Gas with Maxwell's Demon  

NSDL National Science Digital Library

The EJS Ideal Gas with Maxwell's Demon model simulates a two-dimensional ideal gas in a square box, monitored by Maxwell's Demon (which allows only faster than average particles to move from the right side to the left side, while allowing only slower than average particles to move the other way). This simulation can be used as part of the activity described in "The Statistical Interpretation of Entropy: An Activity" by Todd Timberlake, to be published in The Physics Teacher. In the model, the particles are initially spread throughout the box with random positions and random velocities (with a Maxwell distribution of speeds). One window shows an animation of the motion of the particles in the box, while another window plots the temperature of the gas on each side of the box as a function of time. The user can turn the Demon on/off, or reverse the velocities of all particles. You can modify this simulation if you have EJS installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. EJS Ideal Gas with Maxwell's Demon model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_entropy_IdealGasMaxwellsDemon.jar file will run the program if Java is installed. EJS is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional EJS models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or EJS.

Timberlake, Todd

2010-07-01

15

ChemTeacher: Ideal Gas Law  

NSDL National Science Digital Library

ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Ideal Gas Law page includes resources for teaching students about the definition and applications of the Ideal Gas Law.

2011-01-01

16

Ideal Gas Laws: Experiments for General Chemistry  

ERIC Educational Resources Information Center

Describes a series of experiments designed to verify the various relationships implicit in the ideal gas equation and shows that the success of the Graham's law effusion experiments can be explained by elementary hydrodynamics. (GS)

Deal, Walter J.

1975-01-01

17

Derivation of the Ideal Gas Law  

ERIC Educational Resources Information Center

|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…

Laugier, Alexander; Garai, Jozsef

2007-01-01

18

Ideal gas matching for thermal Galilean holography  

SciTech Connect

We exhibit a nonrelativistic ideal gas with a Kaluza-Klein tower of species, featuring a singular behavior of thermodynamic functions at zero chemical potential. In this way, we provide a qualitative match to the thermodynamics of recently found black holes in backgrounds with asymptotic nonrelativistic conformal symmetry.

Barbon, Jose L. F.; Fuertes, Carlos A. [Instituto de Fisica Teorica IFT UAM/CSIC, Facultad de Ciencias C-XVI, C.U. Cantoblanco, E-28049 Madrid (Spain)

2009-07-15

19

Riemann scalar curvature of ideal quantum gases obeying Gentile's statistics  

Microsoft Academic Search

The scalar curvature (R) of ideal quantum gases obeying Gentile's statistics is investigated by the method of information geometrical theory. The R value is specified by the fugacity icons\\/Journals\\/Common\\/eta\\

Hiroshi Oshima; Tsunehiro Obata; Hiroaki Hara

1999-01-01

20

Exact State and Fugacity Equations for the Ideal Quantum Gases  

Microsoft Academic Search

The fully relativistic expressions for the density, pressure, and energy density of the ideal quantum gases are solved exactly for the fugacity. This allows the exact, fully relativistic equations of state to be obtained for the ideal Fermi and Bose gases. All these expressions are studied in detail, including a discussion of physical implications and various limiting cases.

Michael Martin Nieto

1970-01-01

21

Re-Optimisation of Otto Power Cycles Working with Ideal Quantum Gases  

NASA Astrophysics Data System (ADS)

To analyse the effect of quantum degeneracy of a working gas on the work optimisation of an ideal gas cycle, Otto power cycles working with ideal Bose and Fermi type quantum gases are considered. They are called Bose and Fermi Otto cycles respectively. Expressions for their net work outputs per cycle are derived by using the corrected ideal gas equation of state, which considers the quantum degeneracy of the working gas. For Bose and Fermi Otto cycles, the maximum net work output condition (MWOC) is re-derived. It is seen that this condition is different from that of the classical Otto cycle, which works with classical ideal gases. Therefore, expressions for maximum work output and efficiency at MWOC become different from their classical expressions. These new expressions are more general expressions which are valid under both classical and quantum ideal gas conditions. It is shown that maximum work output and efficiency at MWOC of a Bose Otto cycle can be higher than that of a classical Otto cycle. On the other hand, both quantities of the Fermi Otto cycle are always lower than their classical values.

Altu, Altu; Sayg?n, Hasan

22

Ideal-gas thermodynamic properties for natural-gas applications  

Microsoft Academic Search

Calculating caloric properties from a thermal equation of state requires information such as isobaric heat capacities in the ideal-gas state as a function of temperature. In this work, values for the parameters of thecp0 correlation proposed by Aly and Lee were newly determined for 21 pure gases which are compounds of natural gas mixtures. The values of the parameters were

M. Jaeschke; P. Schley

1995-01-01

23

Large deviations for ideal quantum systems  

Microsoft Academic Search

We consider a general d-dimensional quantum system of non-interacting particles in a very large (formally infinite) container. We prove that, in equilibrium, the fluctuations in the density of particles in a subdomain Lambda of the container are described by a large deviation function related to the pressure of the system. That is, untypical densities occur with a probability exponentially small

Joel L. Lebowitz; Marco Lenci; Herbert Spohn

2000-01-01

24

Quantum Afterburner: Improving the Efficiency of an Ideal Heat Engine  

NASA Astrophysics Data System (ADS)

By using a laser and maser in tandem, it is possible to obtain laser action in the hot exhaust gases of a heat engine. Such a ``quantum afterburner'' involves the internal quantum states of the working molecules as well as the techniques of cavity quantum electrodynamics and is therefore in the domain of quantum thermodynamics. It is shown that Otto cycle engine performance can be improved beyond that of the ``ideal'' Otto heat engine. Furthermore, the present work demonstrates a new kind of lasing without initial inversion.

Scully, Marlan O.

2002-02-01

25

Exact equation of state for ideal relativistic quantum gases  

Microsoft Academic Search

The use of analytical methods yields the fugacity of the ideal relativistic quantum gases in terms of the particle densities, pressures, and energy densities, which we compute numerically. The exact equation of state in the thermodynamic limit arising from these solutions may be computed and compared with their respective series expansions.

Frithjof Karsch; David E. Miller

1980-01-01

26

Quantum state of an ideal propagating laser field.  

PubMed

We give a quantum information-theoretic description of an ideal propagating cw laser field and reinterpret typical quantum-optical experiments in light of this. In particular, we show that, contrary to recent claims [T. Rudolph and B. C. Sanders, Phys. Rev. Lett. 87, 077903 (2001)], a conventional laser can be used for quantum teleportation with continuous variables and for generating continuous-variable entanglement. Optical coherence is not required, but phase coherence is. We also show that coherent states play a privileged role in the description of laser light. PMID:11801038

van Enk, S J; Fuchs, Christopher A

2001-12-26

27

Ideal gas behavior of a strongly coupled complex (dusty) plasma.  

PubMed

In a laboratory, a two-dimensional complex (dusty) plasma consists of a low-density ionized gas containing a confined suspension of Yukawa-coupled plastic microspheres. For an initial crystal-like form, we report ideal gas behavior in this strongly coupled system during shock-wave experiments. This evidence supports the use of the ideal gas law as the equation of state for soft crystals such as those formed by dusty plasmas. PMID:23863006

Oxtoby, Neil P; Griffith, Elias J; Durniak, Céline; Ralph, Jason F; Samsonov, Dmitry

2013-07-01

28

The Multidimensional Gibbs Distribution and AN Ideal Gas of Non-Relativistic Particles  

NASA Astrophysics Data System (ADS)

We generalized the standard methods of quantum statistical physics and thermodynamics to the multidimensional case and applied them in order to derive different thermodynamic quantities, characterizing an ideal gas of non-relativistic particles. In particular, we obtained the formula for the pressure in the internal space.

Kusevich, A. E.; Eingorn, M. V.; Zhuk, A. I.

29

Why quantum bit commitment and ideal quantum coin tossing are impossible  

NASA Astrophysics Data System (ADS)

There had been well-known claims of unconditionally secure quantum protocols for bit commitment. However, we, and independently Mayers, showed that all proposed quantum bit commitment schemes are, in principle, insecure because the sender, Alice, can almost always cheat successfully by using an Einstein-Podolsky-Rosen (EPR) type of attack and delaying her measurements. One might wonder if secure quantum bit commitment protocols exist at all. We answer this question by showing that the same type of attack by Alice will, in principle, break any bit commitment scheme. The cheating strategy generally requires a quantum computer. We emphasize the generality of this ``no-go theorem'': Unconditionally secure bit commitment schemes based on quantum mechanics-fully quantum, classical or quantum but with measurements-are all ruled out by this result. Since bit commitment is a useful primitive for building up more sophisticated protocols such as zero-knowledge proofs, our results cast very serious doubt on the security of quantum cryptography in the so-called ``post-cold-war'' applications. We also show that ideal quantum coin tossing is impossible because of the EPR attack. This no-go theorem for ideal quantum coin tossing may help to shed some lights on the possibility of non-ideal protocols.

Lo, Hoi-Kwong; Chau, H. F.

1998-09-01

30

Riemann scalar curvature of ideal quantum gases obeying Gentile's statistics  

NASA Astrophysics Data System (ADS)

The scalar curvature (R) of ideal quantum gases obeying Gentile's statistics is investigated by the method of information geometrical theory. The R value is specified by the fugacity icons/Journals/Common/eta" ALT="eta" ALIGN="TOP"/> and the maximum number, p, of particles in a state. The lowest case p = 1, corresponds to Fermi-Dirac statistics and the unbounded case, picons/Journals/Common/to" ALT="to" ALIGN="TOP"/>icons/Journals/Common/infty" ALT="infty" ALIGN="TOP"/>, to Bose-Einstein statistics. In contrast to R = 0 for ideal classical gases obeying Boltzmann statistics, we find R = (2)1/2/32 for picons/Journals/Common/ge" ALT="ge" ALIGN="TOP"/>2 and R = -(2)1/2/32 for p = 1, in icons/Journals/Common/eta" ALT="eta" ALIGN="TOP"/>icons/Journals/Common/to" ALT="to" ALIGN="TOP"/>0 which is the classical limit. This means that a quantum statistical character is left in R, in the classical limit. Also, a correlation between the sign of R and a quantum mechanical exchange effect is recognized for icons/Journals/Common/eta" ALT="eta" ALIGN="TOP"/>icons/Journals/Common/to" ALT="to" ALIGN="TOP"/>0 and icons/Journals/Common/eta" ALT="eta" ALIGN="TOP"/>>>1. Furthermore, we obtain results that support the instability interpretation of R proposed by Janyszek and Mrugala.

Oshima, Hiroshi; Obata, Tsunehiro; Hara, Hiroaki

1999-09-01

31

Gas lift systems make ideal offshore workers  

SciTech Connect

With a low initial installation cost and small footprint, gas lift systems are well suited for offshore installations where compressed gas is usually already available. These systems are used on multiple and slimhole completions and handle sandy conditions well. They are also used to kick off wells that will flow naturally once the heavier completion fluids leave the production string. Gas lift itself is a mature workaday technology. Measurement and control of gas flow is an area of intense development in gas lift technology. One new control method involves production of multiple completions through a single wellbore. Typically, gas lift valves are opened and closed through tubing pressure. But downhole measurement technology does not yet yield information good enough for stable gas lift control of multiple completions. Gas lift is proving to be a useful AL technique in conjunction with electric submersible pumps (ESP). Located above the ESP pump, the gas lift can reduce the head and allow greater flow. This is helpful when small casing restricts the size of the downhole ESP pump. Wells can usually be produced by the gas lift alone in case of ESP failure, or by replacing the ESP where schedules, high repair costs or low prices rule out repair.

NONE

1999-05-01

32

Isobaric Heat Capacity of an Ideal Bose Gas  

Microsoft Academic Search

It is demonstrated that the heat capacity of an ideal Bose gas at constant pressure increases infinitely when its temperature approaches the Bose condensation temperature from above and is infinite for the phase with a Bose condensate.

Yu. M. Poluektov

2001-01-01

33

Ideal-gas and saturation properties of methanol  

SciTech Connect

Properties of the ideal gas have been considered in detail and new equations for the ideal-gas heat capacity enthalpy, and entropy are given which are valid from 100 to 1000 K. Saturation-curve data have been reviewed and an equation for the vapor pressure is given which covers the whole range from the triple point to the critical point. A tentative equation for the saturated liquid density is also given. The necessity for new experimental measurements is discussed.

Craven, R.J.B.; de Reuck, K.M.; Hauley, H.J.M; Cezairliyan, A.

1986-05-01

34

Anomaly/transport in an Ideal Weyl gas  

NASA Astrophysics Data System (ADS)

We study some of the transport processes which are specific to an ideal gas of relativistic Weyl fermions and relate the corresponding transport coefficients to various anomaly coefficients of the system. We propose that these transport processes can be thought of as arising from the continuous injection of chiral states and their subsequent adiabatic flow driven by vorticity. This in turn leads to an elegant expression relating the anomaly induced transport coefficients to the anomaly polynomial of the Ideal Weyl gas.

Loganayagam, R.; Surówka, Piotr

2012-04-01

35

The performance evaluation of a micro/nano-scaled cooler working with an ideal Bose gas  

NASA Astrophysics Data System (ADS)

Based on the size effect of a confined ideal Bose gas, the design concept of a quantum cooler is originally put forward. The cooler consists of two long tubes with the same length but different sizes of cross section, which are filled up with the ideal Bose gas, and is operated between two heat reservoirs. Expressions for the refrigeration rate and coefficient of performance (COP) of the cooler are derived. The effects of the size effect on the refrigeration rate and COP are discussed. The general performance characteristics of the cooler are revealed.

Guo, Juncheng; Su, Guozhen; Chen, Jincan

2012-01-01

36

Quantum chaos in gas.  

PubMed

A new approach to the description of gas kinetics is proposed. The approach is based on a fundamental presumption which states that binary collisions of gas atoms, moving in a chaotic way, can serve as "interior measurements." These "measurements" result in collapses of atomic wave functions. The ensuing decoherence is capable of transforming the wave function of gas atoms into a set of small-size wave packets. Their kinetics is considered in detail. Quantum effects linear in the Planck constant are taken into account. (c) 1996 American Institute of Physics. PMID:12780269

Kadomtsev, B. B.; Kadomtsev, M. B.

1996-09-01

37

Quantum-statistics-induced flow patterns in driven ideal Fermi gases  

NASA Astrophysics Data System (ADS)

While classical or quantum interacting liquids become turbulent under sufficiently strong driving, it is not obvious what flow pattern an ideal quantum gas develops under similar conditions. Unlike classical noninteracting particles which exhibit rather trivial flow, ideal fermions have to satisfy the exclusion principle, which acts as a form of collective repulsion. We thus study the flow of an ideal Fermi gas as it is driven out of a narrow orifice of width comparable to the Fermi wavelength, employing both a microcanonical approach to transport, and solving a Lindblad equation for Markovian driving leads. Both methods are in good agreement and predict an outflowing current density with a complex microscopic pattern of vorticity in the steady state. Applying a bias of the order of the chemical potential results in a short-range correlated antiferromagnetic vorticity pattern, corresponding to local moments of the order of a tenth of a magneton, e?/2m, if the fermions are charged. The latter may be detectable by magnetosensitive spectroscopy in strongly driven cold gases (atoms) or clean electronic nanostructures (electrons).

Beria, Marco; Iqbal, Yasir; Di Ventra, Massimiliano; Müller, Markus

2013-10-01

38

Dislocations as ideal metallic quantum wires in topological insulators  

NASA Astrophysics Data System (ADS)

Topological insulators are novel states of matter that have been realized in the recently discovered systems such as Bi0.9Sb0.1. What happens if a topological defect is present in such a material? In this talk I will show that strikingly, dislocation lines in a topological insulator can be metallic - i.e. associated with one dimensional fermionic excitations. The condition for the appearance of these modes is derived, and only found to depend on the ``weak'' topological indices. In contrast to electrons in a regular quantum wire, these modes are topologically protected, and not scattered by disorder. Our results provide a novel route to creating a potentially ideal quantum wire in a bulk solid. Since dislocations are ubiquitous in real materials, they could dominate spin and charge transport in topological insulators. Experimental signatures of such dislocation hosted 1D metals are discussed. The existence of these metallic modes has important consequences for the classification of topological band structures in the presence of lattice order. We also report new results for lattice topological superconductors in three dimensions, where both the two and one dimensional indices appear. (Ref: Ying Ran, Yi Zhang and Ashvin Vishwanath, Nature Physics 5, 298, 2009)

Ran, Ying

2010-03-01

39

Hierarchy of free heat convection models for an ideal gas  

NASA Astrophysics Data System (ADS)

Derivations of different asymptotic models of the free heat convection of an ideal gas are presented. By comparing solutions to the convection problem for a closed rectangular region, obtained on the basis of the full system of Navier-Stokes equations for a compressible gas, with those based on the models proposed here, the applicability limits of the models are analyzed with respect to the hydrostatic compressibility parameter and flow nonisothermality.

Nekhamkina, O. A.; Nikulin, D. A.; Strelets, M. Kh.

1989-12-01

40

From Free Expansion to Abrupt Compression of an Ideal Gas  

ERIC Educational Resources Information Center

|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.…

Anacleto, Joaquim; Pereira, Mario G.

2009-01-01

41

Experimental Verification of Boyle's Law and the Ideal Gas Law  

ERIC Educational Resources Information Center

|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…

Ivanov, Dragia Trifonov

2007-01-01

42

Analytical and Experimental Studies With Idealized Gas Turbine Combustors1  

Microsoft Academic Search

Problems of flow, heat release, and mixing in gas turbine combustion chambers are dis- cussed and analyzed. The analysis is based on an idealized or equivalent chamber in which the end result is the same as in the conventional chamber, but in which the functions are separate and distinct. A large primary zone is advantageous, but the combustion process still

Fillmer W. Ruegg; Howard J. Klug

43

A Demonstration of Ideal Gas Principles Using a Football  

Microsoft Academic Search

A class demonstration and cooperative learning activity in which the ideal gas law is applied to determine the volume of a football is described. The mass of an air-filled football is recorded at two or more pressures, and students are asked to use these data to solve problems involving the volume, pressure, and mass of the football and the molecular

William D. Bare; Lester Andrews; Timothy L. Pickering

1999-01-01

44

Condensation of an ideal gas obeying non-Abelian statistics  

NASA Astrophysics Data System (ADS)

We consider the thermodynamic geometry of an ideal non-Abelian gas. We show that, for a certain value of the fractional parameter and at the relevant maximum value of fugacity, the thermodynamic curvature has a singular point. This indicates a condensation such as Bose-Einstein condensation for non-Abelian statistics and we work out the phase transition temperature in various dimensions.

Mirza, Behrouz; Mohammadzadeh, Hosein

2011-09-01

45

Experimental verification of Boyle's law and the ideal gas law  

NASA Astrophysics Data System (ADS)

We offer two new experiments concerning the experimental verification of Boyle's law and the ideal gas law. To carry out the experiments we use glass tubes, water, a syringe and a metal manometer. The pressure of the saturated water vapour is taken into consideration. For educational purposes, the experiments are characterized by their accessibility and the considerable precision of results.

Trifonov Ivanov, Dragia

2007-03-01

46

Quantum arrival and dwell times via idealized clocks  

SciTech Connect

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.

Yearsley, J. M.; Downs, D. A.; Halliwell, J. J.; Hashagen, A. K. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)

2011-08-15

47

Representation of the ideal-gas thermodynamic properties of water  

Microsoft Academic Search

An equation, in the form of a summation of simple harmonic oscillator functions, for dimensionless isobaric heat capacity (specific isobaric heat-capacity divided by the specific ideal-gas constant, c P\\/R) for water at zero pressure has been fitted to the values published by Woolley. The equation has a very good agreement with the values to which it has been fitted. Comparisons

J. R. Cooper

1982-01-01

48

Representation of the ideal-gas thermodynamic properties of water  

Microsoft Academic Search

An equation, in the form of a summation of simple harmonic oscillator functions, for dimensionless isobaric heat capacity (specific isobaric heat-capacity divided by the specific ideal-gas constant, cP\\/R) for water at zero pressure has been fitted to the values published by Woolley. The equation has a very good agreement with the values to which it has been fitted. Comparisons are

J. R. Cooper

1982-01-01

49

Correlation of the ideal gas properties of five aromatic hydrocarbons  

Microsoft Academic Search

The ideal gas thermodynamic properties of isobaric heat capacity, entropy, and enthalpy have been correlated for benzene, toluene, o-xylene, m-xylene, and p-xylene by a uniform, semiempirical function of temperature. The correlation is based on literature values calculated from statistical mechanics for temperature up to 1,500K for benzene and up to 3,000K for the other molecules. The temperature function chosen is

Arno Laesecke

1993-01-01

50

Condensation of an ideal gas obeying non-Abelian statistics.  

PubMed

We consider the thermodynamic geometry of an ideal non-Abelian gas. We show that, for a certain value of the fractional parameter and at the relevant maximum value of fugacity, the thermodynamic curvature has a singular point. This indicates a condensation such as Bose-Einstein condensation for non-Abelian statistics and we work out the phase transition temperature in various dimensions. PMID:22060335

Mirza, Behrouz; Mohammadzadeh, Hosein

2011-09-13

51

The critical properties of the magnetised ideal Bose gas  

Microsoft Academic Search

The critical behaviour of a d-dimensional ideal gas of uncharged bosons with spin S in an uniform magnetic field is examined. The critical exponents associated with the spontaneous magnetisation, the zero-field magnetic susceptibility, the equation of state, and the density-density correlation function are calculated as well as their relationship to the critical exponents obtained by Gunton and Buckingham (1968) for

H. O. da Frota; M. S. Silva; S. G. Rosa Jr.

1984-01-01

52

Suppression of Density Fluctuations in a Quantum Degenerate Fermi Gas  

NASA Astrophysics Data System (ADS)

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.

Sanner, Christian; Su, Edward J.; Keshet, Aviv; Gommers, Ralf; Shin, Yong-Il; Huang, Wujie; Ketterle, Wolfgang

2010-07-01

53

Correlation of the ideal gas properties of five aromatic hydrocarbons  

SciTech Connect

The ideal gas thermodynamic properties of isobaric heat capacity, entropy, and enthalpy have been correlated for benzene, toluene, o-xylene, m-xylene, and p-xylene by a uniform, semiempirical function of temperature. The correlation is based on literature values calculated from statistical mechanics for temperature up to 1,500K for benzene and up to 3,000K for the other molecules. The temperature function chosen is more accurate than that used for previous correlations, and can be used in a wider temperature range.

Laesecke, A. (National Inst. of Standards and Technology, Boulder, CO (United States))

1993-04-01

54

What Is Entropy? Advanced Undergraduate Performance Comparing Ideal Gas Processes  

NSDL National Science Digital Library

We report data on upper-level student understanding of entropy and the Second Law of Thermodynamics when comparing the isothermal and free expansions of an ideal gas. Data from pre- and post-instruction written questions are presented, and several noteworthy features of student performance are identified and discussed. These features include ways students think about these topics prior to instruction as well as specific difficulties and other interesting aspects of student thought that persist after instruction. Implications for future research are also addressed.

Bucy, Brandon; Thompson, John R.; Mountcastle, Donald B.

2009-07-13

55

Microeconomics of the ideal gas like market models  

NASA Astrophysics Data System (ADS)

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.

Chakrabarti, Anindya S.; Chakrabarti, Bikas K.

2009-10-01

56

Statistical mechanics of an ideal gas of non-Abelian anyons  

NASA Astrophysics Data System (ADS)

We study the thermodynamical properties of an ideal gas of non-Abelian Chern-Simons particles and we compute the second virial coefficient, considering the effect of general soft-core boundary conditions for the two-body wavefunction at zero distance. The behaviour of the second virial coefficient is studied as a function of the Chern-Simons coupling, the isospin quantum number and the hard-core parameters. Expressions for the main thermodynamical quantities at the lower order of the virial expansion are also obtained: we find that at this order the relation between the internal energy and the pressure is the same found (exactly) for 2D Bose and Fermi ideal gases. A discussion of the comparison of obtained findings with available results in literature for systems of hard-core non-Abelian Chern-Simons particles is also supplied.

Mancarella, Francesco; Trombettoni, Andrea; Mussardo, Giuseppe

2013-02-01

57

Ideal quantum gases in D-dimensional space and power-law potentials  

Microsoft Academic Search

We investigate ideal quantum gases in D-dimensional space and confined in a generic external potential by using the semiclassical approximation. In particular, we derive density of states, density profiles and critical temperatures for Fermions and Bosons trapped in isotropic power-law potentials. From such results, one can easily obtain those of quantum gases in a rigid box and in a harmonic

Luca Salasnich

2000-01-01

58

Quantum degenerate dipolar Fermi gas.  

PubMed

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

Lu, Mingwu; Burdick, Nathaniel Q; Lev, Benjamin L

2012-05-21

59

Quantum Degenerate Dipolar Fermi Gas  

NASA Astrophysics Data System (ADS)

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 Dy161 is produced by laser cooling to 10?K before sympathetically cooling with ultracold, bosonic Dy162. The temperature of the spin-polarized Dy161 is a factor T/TF=0.2 below the Fermi temperature TF=300nK. The cotrapped Dy162 concomitantly cools to approximately Tc 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 Dy161 without Dy162 to T/TF=0.7. That such a low temperature ratio is achieved may be a first signature of universal dipolar scattering.

Lu, Mingwu; Burdick, Nathaniel Q.; Lev, Benjamin L.

2012-05-01

60

Performance of a multilevel quantum heat engine of an ideal N-particle Fermi system  

NASA Astrophysics Data System (ADS)

We generalize the quantum heat engine (QHE) model which was first proposed by Bender [J. Phys. A10.1088/0305-4470/33/24/302 33, 4427 (2000)] to the case in which an ideal Fermi gas with an arbitrary number N of particles in a box trap is used as the working substance. Besides two quantum adiabatic processes, the engine model contains two isoenergetic processes, during which the particles are coupled to energy baths at a high constant energy Eh and a low constant energy Ec, respectively. Directly employing the finite-time thermodynamics, we find that the power output is enhanced by increasing particle number N (or decreasing minimum trap size LA) for given LA (or N), without reduction in the efficiency. By use of global optimization, the efficiency at possible maximum power output (EPMP) is found to be universal and independent of any parameter contained in the engine model. For an engine model with any particle-number N, the efficiency at maximum power output (EMP) can be determined under the condition that it should be closest to the EPMP. Moreover, we extend the heat engine to a more general multilevel engine model with an arbitrary 1D power-law potential. Comparison between our engine model and the Carnot cycle shows that, under the same conditions, the efficiency ?=1-(Ec)/(Eh) of the engine cycle is bounded from above the Carnot value ?c=1-(Tc)/(Th).

Wang, Rui; Wang, Jianhui; He, Jizhou; Ma, Yongli

2012-08-01

61

Application of quantum cascade lasers to trace gas analysis  

Microsoft Academic Search

Quantum cascade (QC) lasers are virtually ideal mid-infrared sources for trace gas monitoring. They can be fabricated to operate\\u000a at any of a very wide range of wavelengths from ??3 ?m to ??24 ?m. Seizing the opportunity presented by mid-infrared QC lasers,\\u000a several groups world-wide are actively applying them to trace gas sensing. Real world applications include environmental monitoring,\\u000a industrial process control

A. Kosterev; G. Wysocki; Y. Bakhirkin; S. So; R. Lewicki; M. Fraser; F. Tittel; R. F. Curl

2008-01-01

62

Influence of quantum degeneracy on the performance of a gas Stirling engine cycle  

NASA Astrophysics Data System (ADS)

Based on the state equation of an ideal quantum gas, the regenerative loss of a Stirling engine cycle working with an ideal quantum gas is calculated. Thermal efficiency of the cycle is derived. Furthermore, under the condition of quantum degeneracy, several special thermal efficiencies are discussed. Ratios of thermal efficiencies versus the temperature ratio and volume ratio of the cycle are made. It is found that the thermal efficiency of the cycle not only depends on high and low temperatures but also on maximum and minimum volumes. In a classical gas state the thermal efficiency of the cycle is equal to that of the Carnot cycle. In an ideal quantum gas state the thermal efficiency of the cycle is smaller than that of the Carnot cycle. This will be significant for deeper understanding of the gas Stirling engine cycle.

He, Ji-Zhou; Mao, Zhi-Yuan; Wang, Jian-Hui

2006-09-01

63

Ideal gas relations for the description of the real gas isentropic changes  

Microsoft Academic Search

Using the best available relations describing the thermal and caloric behaviour of the media H2O, air, NH3 and of the refrigerants R12 and R22, numerous isentropic expansions starting at different initial points, have been computed.\\u000a The results obtained were approximated by explicit relations having mathematical forms similar to those of the ideal gas but\\u000a with different constants and exponents. The

Dimitrios A. Kouremenos; Xenofon K. Kakatsios

1985-01-01

64

Quasi-similar solution of the strong shock wave problem in non-ideal gas dynamics  

NASA Astrophysics Data System (ADS)

The quasisimilar theory is used to investigate the solution of the blast wave problem with generalized geometries in a non-ideal gas satisfying the equation of state of the Van der Waals type. Here it is assumed that the distribution of normalized velocity, pressure and density are nearly similar in the narrow range of the shock strength. A comparison between approximate analytical solution and numerical solution of the problem is presented for the cylindrical geometry. The numerical solutions are presented for the generalized geometry in a non-ideal gas. It is also assessed as to how the non-idealness of the gas affects the behavior of the flow parameters.

Singh, L. P.; Ram, S. D.; Singh, D. B.

2012-02-01

65

Ideal gas thermodynamic properties of methanoic and ethanoic acids  

Microsoft Academic Search

The thermodynamic properties (H0?H00, (G0?H00)\\/T, (H0?H00)\\/T, S0, Cp0, ?Hf0, ?Gf0, and log Kf] for methanoic (formic) and ethanoic (acetic) acid monomers and dimers in the ideal gaseous state over the temperature range from 0 to 1500 K and 1 atm have been calculated by the statistical thermodynamic method using the most recent and reliable molecular and spectroscopic constants. The internal

Jing Chao; Bruno J. Zwolinski

1978-01-01

66

Why quantum bit commitment and ideal quantum coin tossing are impossible  

Microsoft Academic Search

There had been well known claims of ``provably unbreakable'' quantum protocols for bit commitment and coin tossing. However, we, and independently Mayers, showed that all proposed quantum bit commitment (and therefore coin tossing) schemes are, in principle, insecure because the sender, Alice, can always cheat successfully by using an EPR-type of attack and delaying her measurements. One might wonder if

Hoi-Kwong Lo; H. F. Chau

1996-01-01

67

Relativistic d-dimensional ideal Bose gas with pair creation  

Microsoft Academic Search

The thermodynamic properties of a d-dimensional relativistic Bose gas mixture of particles and antiparticles are studied. The anomaly in the specific heat of the relativistic gas is removed by the pair-creation mechanism. The crossover from the nonrelativistic limit to the ultrarelativistic limit is also analyzed.

H. O. Frota; Melquisedech S. Silva; S. Goulart Rosa Jr.

1989-01-01

68

Jump relations across a shock in non-ideal gas flow  

NASA Astrophysics Data System (ADS)

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.

Anand, R. K.

2012-12-01

69

The Ideal Gas and Real Gas Heat Capacity of Sodium Atoms  

NASA Astrophysics Data System (ADS)

The ideal gas heat capacity of sodium atoms in the vapor phase is calculated to high temperatures using statistical mechanics. Since there are, in principle, an infinite number of atomic energy levels, the partition function and the heat capacity will grow very large unless the summation over energy levels is constrained as temperature increases. At higher temperatures, the increasing size of the atoms, which is a consequence of the increased population of highly excited energy levels, is used as a mechanism for limiting the summation over energy levels. The " {IP-kT}" and "Bethe" procedures for cutting off the summation over energy levels will be discussed, and the results obtained using the two methods will be compared. In addition, although experimental information is available about lower atomic energy levels and some theoretical calculations are available for excited energy levels, information is lacking for most individual atomic states associated with highly excited energy levels. A "fill" procedure for approximating the energy of the unknown states will be discussed. Sodium vapor will also be considered to be a real gas that obeys the virial equation of state. The first non-ideal term in the power series expansion of the heat capacity in terms of virial coefficients involves the second virial coefficient, B(T). This depends on the interaction potential energy between two sodium atoms, i.e., the potential energy curves for the sodium dimer. Accurate interaction potential energies can be obtained from either experimental or theoretical information for the lowest ten electronic states of the sodium dimer. These are used to calculate B(T) for each state, and the averaged value of B(T) for all ten states is used to calculate the non-ideal contribution to the heat capacity of sodium atoms as a function of temperature.

Biolsi, Louis

2013-03-01

70

Ultracold strongly coupled gas: A near-ideal liquid  

SciTech Connect

Feshbach resonances of trapped ultracold alkali-metal atoms allow to vary the atomic scattering length a. At very large values of a the system enters an universal strongly coupled regime in which its properties--the ground-state energy, pressure, etc.--become independent of a. We discuss the transport properties of such systems. In particular, the universality arguments imply that the shear viscosity of ultracold Fermi atoms at the Feschbach resonance is proportional to the particle number density n and the Plank constant ({Dirac_h}/2{pi}): {eta}=({Dirac_h}/2{pi})n{alpha}{sub {eta}}, where {alpha}{sub {eta}} is a universal constant. Using Heisenberg uncertainty principle and Einstein's relation between diffusion and viscosity we argue that the viscosity has the lower bound given by {alpha}{sub {eta}}{<=}(6{pi}){sup -1}. We relate the damping of low-frequency density oscillations of ultracold optically trapped {sup 6}Li atoms to viscosity and find that the value of the coefficient {alpha}{sub {eta}} is about 0.3. We also show that such a small viscosity cannot be explained by kinetic theory based on binary scattering. We conclude that the system of ultracold atoms near the Feshbach resonance is a near-ideal liquid.

Gelman, Boris A.; Shuryak, Edward V.; Zahed, Ismail [Department of Physics and Astronomy, State University of New York, Stony Brook, New York 11794-3800 (United States)

2005-10-15

71

Distribution of Zeros and the Equation of State. IV Ideal Bose-Einstein Gas  

Microsoft Academic Search

The ideal Bose-Einstein gas is investigated on the basis of the fundamental concept of the distribution of zeros of the grand partition function on the complex z(= activity) plane. For this gas there are no zeros; but poles play essentially the same role as zeros from an analytical point of view, and are distributed on the part of the positive

Kazuyosi Ikeda

1982-01-01

72

A Systematic Experimental Test of the Ideal Gas Equation for the General Chemistry Laboratory  

NASA Astrophysics Data System (ADS)

A set of experiments that examines each one of the terms of the ideal gas equation is described. Boyle's Law, Charles-Gay Lussac's Law, Amonton's Law, the number of moles or Molecular Weight, and the Gas Constant are studied. The experiments use very simple, easy to obtain equipment and common gases, mainly air. The results gathered by General Chemistry College students are satisfactory.

Blanco, Luis H.; Romero, Carmen M.

1995-10-01

73

The relativistic transformation law for the ideal-gas scale of temperature  

NASA Astrophysics Data System (ADS)

The physical meaning of the concept of temperature is discussed with regard to the situation in which two inertial frames are in a state of uniform relative motion. Using the 'asynchronous' formulation of Cavalleri and Salgarelli (1969), a simple experiment is described, using a constant-volume gas thermometer at rest with a body to show that the ideal-gas scale is Lorentz invariant. The statement that thermodynamic temperature is Lorentz invariant is then equivalent to the requirement that the thermodynamic temperature scale and the ideal-gas scale should be identical in all frames of reference.

Goodinson, P. A.; Luffman, B. L.

1980-11-01

74

Interferometric measurement of local spin fluctuations in a quantum gas  

NASA Astrophysics Data System (ADS)

Ultracold gases provide a controlled environment that is ideal for studying many intriguing phenomena associated with quantum correlated systems. Current efforts are directed towards the identification of magnetic properties, as well as the creation and detection of exotic quantum phases. In this context, a mapping of the spin polarization of the atoms to the state of a single-mode light beam has been proposed. Here we introduce a quantum-limited interferometer that realizes such an atom-light interface with high spatial resolution. We measure the probability distribution of the local spin polarization in a trapped Fermi gas, showing a reduction of spin fluctuations by up to 4.6(3) dB below shot noise in weakly interacting Fermi gases, and by 9.4(8) dB for strong interactions. We deduce the magnetic susceptibility as a function of temperature and discuss our measurements in terms of an entanglement witness.

Meineke, Jakob; Brantut, Jean-Philippe; Stadler, David; Müller, Torben; Moritz, Henning; Esslinger, Tilman

2012-06-01

75

Redundant imprinting of information in non-ideal environments: Quantum Darwinism via a noisy channel  

NASA Astrophysics Data System (ADS)

Quantum Darwinism provides an information-theoretic framework for the emergence of the classical world from the quantum substrate. It recognizes that we - the observers - acquire our information about the "systems of interest" indirectly from their imprints on the environment. Objectivity, a key property of the classical world, arises via the proliferation of redundant information into the environment where many observers can then intercept it and independently determine the state of the system. While causing a system to decohere, environments that remain nearly invariant under the Hamiltonian dynamics, such as very mixed states, have a diminished ability to transmit information about the system, yet can still acquire redundant information about the system [1,2]. Our results show that Quantum Darwinism is robust with respect to non-ideal initial states of the environment.[4pt] [1] M. Z., H. T. Q., W. H. Z., Phys. Rev. Lett. 103, 110402 (2009)[0pt] [2] M. Z., H. T. Q., W. H. Z., Phys. Rev. A 81, 062110 (2010)

Zwolak, Michael; Quan, Haitao; Zurek, Wojciech

2011-03-01

76

Heat capacity of an ideal free-electron gas: A rigorous derivation  

NSDL National Science Digital Library

It is shown that the usual derivation of the heat capacity of an ideal free-electron gas is made invalid by the use of a divergent series. A plausible argument is offered to indicate that these series are asymptotic expansions which provide good approximations through their first few terms. The usual procedure is modified by the replacement of an infinite series by its first two terms plus a remainder whose bounds are estimated as being negligible to the accuracy required; a rigorous derivation of the well-known temperature dependence of the electronic heat capacity of an ideal Fermi gas results.

Weinstock, Robert

2011-08-30

77

Student understanding of the ideal gas law, Part I: A macroscopic perspective  

NSDL National Science Digital Library

Our findings from a long-term investigation indicate that many students cannot properly interpret or apply the ideal gas law after instruction in introductory physics and chemistry as well as more advanced courses. The emphasis in this paper is on the concepts of pressure, volume, and temperature at the macroscopic level. We describe some serious conceptual and reasoning difficulties that we have identified. Results from our research were applied in the design of a curriculum that has helped improve student understanding of the ideal gas law.

Kautz, Christian H.; Heron, Paula R.; Loverude, Michael E.; Mcdermott, Lillian C.

2012-07-12

78

Quantized Vortices in the Ideal Bose Gas: A Physical Realization of Random Polynomials  

SciTech Connect

We propose a physical system allowing one to experimentally observe the distribution of the complex zeros of a random polynomial. We consider a degenerate, rotating, quasi-ideal atomic Bose gas prepared in the lowest Landau level. Thermal fluctuations provide the randomness of the bosonic field and of the locations of the vortex cores. These vortices can be mapped to zeros of random polynomials, and observed in the density profile of the gas.

Castin, Yvan; Hadzibabic, Zoran; Stock, Sabine; Dalibard, Jean [Laboratoire Kastler Brossel, Ecole normale superieure, 24 rue Lhomond, 75005 Paris (France); Stringari, Sandro [Laboratoire Kastler Brossel, Ecole normale superieure, 24 rue Lhomond, 75005 Paris (France); College de France, 11 place Marcelin Berthelot, 75005 Paris (France); Dipartimento di Fisica, Universita di Trento and CNR-INFM BEC Center, I-38050 Povo, Trento (Italy)

2006-02-03

79

Cooking under Pressure: Applying the Ideal Gas Law in the Kitchen  

ERIC Educational Resources Information Center

|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…

Chen, Ling; Anderson, Jennifer Y.; Wang, Diane R.

2010-01-01

80

Ideal-Gas Heat Capacities and Virial Coefficients of HFC Refrigerants  

Microsoft Academic Search

Thermodynamic properties of HFC (hydrofluorocarbon) compounds have been extensively studied with worldwide interest as alternative refrigerants. Both quality and quantity in the experimental data far exceed those for the CFC and HCFC refrigerants. These data now provide a great opportunity to examine the validity of theoretical models, and vice versa. Among them, the ideal-gas heat capacity Cp0 and virial coefficients

A. Yokozeki; H. Sato; K. Watanabe

1998-01-01

81

Case Study: Cooking Under Pressure--Applying the Ideal Gas Law in the Kitchen  

NSDL National Science Digital Library

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 ra

Wang, Diane R.; Anderson, Jennifer Y.; Chen, Ling

2010-11-01

82

Unitary quantum lattice gas representation of 2D quantum turbulence  

Microsoft Academic Search

Quantum vortex structures and energy cascades are examined for two dimensional quantum turbulence (2D QT) using a special unitary evolution algorithm. The qubit lattice gas (QLG) algorithm, is employed to simulate the weakly-coupled Bose-Einstein condensate (BEC) governed by the Gross-Pitaevskii (GP) equation. A parameter regime is uncovered in which, as in 3D QT, there is a very short Poincare recurrence

Bo Zhang; George Vahala; Linda Vahala; Min Soe

2011-01-01

83

A Quantum Lattice-Gas Model for Computational Fluid Dynamics  

Microsoft Academic Search

Quantum-computing ideas are applied to the practical and ubiquitous problem of fluid dynamics simulation. Hence, this paper addresses two separate areas of physics: quantum mechanics and fluid dynamics (or specially, the computational simulation of fluid dynamics). The quantum algorithm is called a quantum lattice gas. An analytical treatment of the microscopic quantum lattice-gas system is carried out to predict its

Jerey Yepez

1999-01-01

84

Using Rubber-Elastic Material-Ideal Gas Analogies To Teach Introductory Thermodynamics. Part I: Equations of State.  

ERIC Educational Resources Information Center

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.)…

Smith, Brent

2002-01-01

85

Critical behavior of the ideal-gas Bose-Einstein condensation in the Apollonian network  

NASA Astrophysics Data System (ADS)

We show that the ideal Boson gas displays a finite-temperature Bose-Einstein condensation transition in the complex Apollonian network exhibiting scale-free, small-world, and hierarchical properties. The single-particle tight-binding Hamiltonian with properly rescaled hopping amplitudes has a fractal-like energy spectrum. The energy spectrum is analytically demonstrated to be generated by a nonlinear mapping transformation. A finite-size scaling analysis over several orders of magnitudes of network sizes is shown to provide precise estimates for the exponents characterizing the condensed fraction, correlation size, and specific heat. The critical exponents, as well as the power-law behavior of the density of states at the bottom of the band, are similar to those of the ideal Boson gas in lattices with spectral dimension ds=2ln(3)/ln(9/5)?3.74.

de Oliveira, I. N.; dos Santos, T. B.; de Moura, F. A. B. F.; Lyra, M. L.; Serva, M.

2013-08-01

86

Critical behavior of the ideal-gas Bose-Einstein condensation in the Apollonian network.  

PubMed

We show that the ideal Boson gas displays a finite-temperature Bose-Einstein condensation transition in the complex Apollonian network exhibiting scale-free, small-world, and hierarchical properties. The single-particle tight-binding Hamiltonian with properly rescaled hopping amplitudes has a fractal-like energy spectrum. The energy spectrum is analytically demonstrated to be generated by a nonlinear mapping transformation. A finite-size scaling analysis over several orders of magnitudes of network sizes is shown to provide precise estimates for the exponents characterizing the condensed fraction, correlation size, and specific heat. The critical exponents, as well as the power-law behavior of the density of states at the bottom of the band, are similar to those of the ideal Boson gas in lattices with spectral dimension d_{s}=2ln(3)/ln(9/5)?3.74. PMID:24032807

de Oliveira, I N; Dos Santos, T B; de Moura, F A B F; Lyra, M L; Serva, M

2013-08-26

87

Low-temperature behaviour of an ideal Bose gas and some forbidden thermodynamic cycles  

NASA Astrophysics Data System (ADS)

Based on the equation of state of an ideal Bose gas, the heat capacities at constant volume and constant pressure of the Bose system are derived and used to analyse the low-temperature behaviour of the Bose system. It is expounded that some important thermodynamic processes such as a constant pressure and an adiabatic process cannot be carried out from the region of T > Tc to that of T < Tc, where Tc is the critical temperature of Bose-Einstein condensation of the Bose system. Consequently, some typical thermodynamic cycles such as the Carnot cycle, Brayton cycle, Otto cycle, Ericsson cycle, Diesel cycle and Atkinson cycle cannot be operated across the critical temperature Tc of Bose-Einstein condensation of an ideal Bose gas.

Chen, Jincan; Lin, Bihong

2003-11-01

88

Quantum gas-liquid condensation in an attractive Bose gas  

SciTech Connect

Gas-liquid condensation (GLC) in an attractive Bose gas is studied on the basis of statistical mechanics. Using some results in combinatorial mathematics, the following are derived. (1) With decreasing temperature, the Bose-statistical coherence grows in the many-body wave function, which gives rise to the divergence of the grand partition function prior to Bose-Einstein condensation. It is a quantum-mechanical analogue to the GLC in a classical gas (quantum GLC). (2) This GLC is triggered by the bosons with zero momentum. Compared with the classical GLC, an incomparably weaker attractive force creates it. For the system showing the quantum GLC, we discuss a cold helium 4 gas at sufficiently low pressure.

Koh, Shun-ichiro [Physics Division, Faculty of Education, Kochi University, Akebono-cho, 2-5-1, Kochi 780 (Japan)

2005-07-01

89

David Maloney's Physics Examples: Thermo Example 4-Work Done by Ideal Gas  

NSDL National Science Digital Library

This item is an annotated homework problem for introductory physics students relating to the amount of work done by, or on, an ideal gas. The author provides explicit explanations of the steps required to solve for net work during four stages involving isobaric and non-isobaric processes. This resource is intended to supplement classroom instruction and traditional text materials. It is part of a larger collection of similar introductory physics homework problems.

Maloney, David

2008-10-03

90

Gaussian fluctuations in an ideal bose-gas - a simple model  

NASA Astrophysics Data System (ADS)

Based on the canonical ensemble, we suggested the simple scheme for taking into account Gaussian fluctuations in a finite system of ideal boson gas. Within framework of scheme we investigated the influence of fluctuations on the particle distribution in Bose -gas for two cases - with taking into account the number of particles in the ground state and without this assumption. The temperature and fluctuation parameter dependences of the modified Bose-Einstein distribution have been determined. Also the dependence of the condensation temperature on the fluctuation distribution parameter has been obtained.

Petrova, A.; Nedopekin, O.; Tayurskii, D.; Wang, Q. A.

2011-10-01

91

On the power cycles working with ideal quantum gases: I. The Ericsson cycle  

NASA Astrophysics Data System (ADS)

The Ericsson power cycles working with ideal Bose and Fermi monoatomic gases are examined. They are conveniently called the Bose and Fermi cycles. Efficiencies of Bose and Fermi cycles are derived (0022-3727/32/6/011/img1 and 0022-3727/32/6/011/img2 respectively). Variations of them with the temperature ratio 0022-3727/32/6/011/img3 and pressure ratio of the cycle are examined. A comparison of the efficiencies with each other and that of the classical Ericsson cycle 0022-3727/32/6/011/img4 is made. In the degenerate gas state it is seen that 0022-3727/32/6/011/img5, although 0022-3727/32/6/011/img6 in the classical gas state. In a Bose cycle, it is shown that there is an optimum value for the lowest temperature 0022-3727/32/6/011/img7 at which the efficiency reaches its maximum value for a given pressure ratio. Furthermore, Bose-Einstein condensation restricts the value of 0022-3727/32/6/011/img8 of a Bose cycle for a given value of 0022-3727/32/6/011/img9. In a Fermi cycle, there is no an optimum value for 0022-3727/32/6/011/img8. However, 0022-3727/32/6/011/img2 goes to a finite value of less than unity when 0022-3727/32/6/011/img12 goes to zero.

Sisman, Altug; Saygin, Hasan

1999-03-01

92

Aspects of planar, oblique and interacting shock waves in an ideal dissociating gas  

NASA Astrophysics Data System (ADS)

We develop a compact dimensionless framework for the analysis of canonical thermo-chemical nonequilibrium flow fields involving normal, oblique and interacting shock waves. Discontinuous solutions of the conservation equations are coupled with thermodynamic and kinetic models for an ideal dissociating gas. Convenient forms are provided for the variation of the relevant dimensionless parameters across shock waves in dissociating gases. The treatment is carried through in a consistent manner for the pressure-flow deflection angle plane representation of shock wave interaction problems. The contribution of the current paper is a careful nondimensionalization of the problem that yields a tractable formulation and allows results with considerable generality to be obtained.

Sanderson, S. R.; Hornung, H. G.; Sturtevant, B.

2003-06-01

93

Probability theory for 3-layer remote sensing in ideal gas law environment.  

PubMed

We extend the probability model for 3-layer radiative transfer [Opt. Express 20, 10004 (2012)] to ideal gas conditions where a correlation exists between transmission and temperature of each of the 3 layers. The effect on the probability density function for the at-sensor radiances is surprisingly small, and thus the added complexity of addressing the correlation can be avoided. The small overall effect is due to (a) small perturbations by the correlation on variance population parameters and (b) cancelation of perturbation terms that appear with opposite signs in the model moment expressions. PMID:24105525

Ben-David, Avishai; Davidson, Charles E

2013-08-26

94

Speed of sound and ideal-gas heat capacity of freon R-236ea  

NASA Astrophysics Data System (ADS)

Speed of sound in the gaseous freon R-236ea with the purity of 99.68 mol. % has been measured by the method of ultrasonic interferometer in the range from 263 to 423 K and at pressures from 17 kPA to 4.2 MPa. Errors of temperature, pressure, and speed of sound measurement were estimated to be within +/- 20 mK, ± 1.5 kPa, and ±(0.1+0.2) % respectively. Temperature dependence of ideal-gas heat capacity of R-236ea has been calculated on the basis of the obtained data.

Komarov, S. G.; Gruzdev, V. A.; Stankus, S. V.

2008-09-01

95

Supersonic beams at high particle densities: model description beyond the ideal gas approximation.  

PubMed

Supersonic molecular beams constitute a very powerful technique in modern chemical physics. They offer several unique features such as a directed, collision-free flow of particles, very high luminosity, and an unsurpassed strong adiabatic cooling during the jet expansion. While it is generally recognized that their maximum flow velocity depends on the molecular weight and the temperature of the working fluid in the stagnation reservoir, not a lot is known on the effects of elevated particle densities. Frequently, the characteristics of supersonic beams are treated in diverse approximations of an ideal gas expansion. In these simplified model descriptions, the real gas character of fluid systems is ignored, although particle associations are responsible for fundamental processes such as the formation of clusters, both in the reservoir at increased densities and during the jet expansion. In this contribution, the various assumptions of ideal gas treatments of supersonic beams and their shortcomings are reviewed. It is shown in detail that a straightforward thermodynamic approach considering the initial and final enthalpy is capable of characterizing the terminal mean beam velocity, even at the liquid-vapor phase boundary and the critical point. Fluid properties are obtained using the most accurate equations of state available at present. This procedure provides the opportunity to naturally include the dramatic effects of nonideal gas behavior for a large variety of fluid systems. Besides the prediction of the terminal flow velocity, thermodynamic models of isentropic jet expansions permit an estimate of the upper limit of the beam temperature and the amount of condensation in the beam. These descriptions can even be extended to include spinodal decomposition processes, thus providing a generally applicable tool for investigating the two-phase region of high supersaturations not easily accessible otherwise. PMID:20961156

Christen, Wolfgang; Rademann, Klaus; Even, Uzi

2010-10-28

96

Determination of quantum instrument parameters for a Stern-Gerlach non-ideal device  

Microsoft Academic Search

The paper identifies and determines some parameters with experimental relevance, which could describe the influence of the non-ideality for the measurement of the intrinsic spin of an atom, using a real Stern-Gerlach device.

Ioan Sturzu

2002-01-01

97

Teleportation of a general two-mode coherent-state superposition via attenuated quantum channels with ideal and/or threshold detectors  

NASA Astrophysics Data System (ADS)

Three novel probabilistic yet conclusive schemes are proposed to teleport a general two-mode coherent-state superposition via attenuated quantum channels with ideal and/or threshold detectors. The calculated total success probability is highest (lowest) when only ideal (threshold) detectors are used.

An, Nguyen Ba

2009-04-01

98

Introducing the Reduced Monte Carlo Scheme (RMCS): Application to ideal quantum gases and classical hard sphere systems  

NASA Astrophysics Data System (ADS)

The development of a new Monte Carlo scheme is provided -- the Reduced Monte Carlo Scheme (RMCS). The term ``reduced'' is used because only a small number of particles (n) is needed in the simulation for accurate calculation of material properties. Ie., n >˜ 10. The fundamental ensemble used as basis for the scheme is the canonical ensemble. The power and efficiency of RMCS is demonstrated by reproducing well known results for the statistical thermodynamic properties of ideal quantum systems (Fermi and Bose cases) and the classical hard sphere system at all densities.

Edgal, Uduzei

2010-03-01

99

Isobars of an ideal Bose gas within the grand canonical ensemble  

SciTech Connect

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.

Jeon, Imtak; Park, Jeong-Hyuck [Department of Physics, Sogang University, Seoul 121-742 (Korea, Republic of); Kim, Sang-Woo [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

2011-08-15

100

Exact Inversion of the Fugacity-Density Relation for Ideal Quantum Gases  

Microsoft Academic Search

The fugacities of ideal Fermi and Bose gases are calculated explicity as a function of density and temperature, using the analytic properties of the integral appearing in the fugacity-density equation. The Hilbert problem of the theory of analytic functions is encountered.

A. Leonard

1968-01-01

101

Quantum degenerate Fermi gas entanglement in optomechanics  

NASA Astrophysics Data System (ADS)

We explain the steady-state entanglement of a quantum degenerate Fermi gas with a light field inside a Fabry-Perot cavity. The logarithmic negativity, from the covariance matrix formalism in a unified framework, shows that the bi-stability parameter and the effective detuning depend explicitly on the behavior of the entanglement. Numerical experiments reveal the sensitivity of the entanglement to experimentally controlled parameters such as, the mass of the atoms, the pump rate of the cavity, the effective detuning, and the bi-stability parameters.

Asjad, Muhammad; Adnan Shahzad, Muhammad; Saif, Farhan

2013-09-01

102

Analytical theory of mesoscopic Bose-Einstein condensation in an ideal gas  

SciTech Connect

We find the universal structure and scaling of the Bose-Einstein condensation (BEC) statistics and thermodynamics (Gibbs free energy, average energy, heat capacity) for a mesoscopic canonical-ensemble ideal gas in a trap with an arbitrary number of atoms, any volume, and any temperature, including the whole critical region. We identify a universal constraint-cutoff mechanism that makes BEC fluctuations strongly non-Gaussian and is responsible for all unusual critical phenomena of the BEC phase transition in the ideal gas. The main result is an analytical solution to the problem of critical phenomena. It is derived by, first, calculating analytically the universal probability distribution of the noncondensate occupation, or a Landau function, and then using it for the analytical calculation of the universal functions for the particular physical quantities via the exact formulas which express the constraint-cutoff mechanism. We find asymptotics of that analytical solution as well as its simple analytical approximations which describe the universal structure of the critical region in terms of the parabolic cylinder or confluent hypergeometric functions. The obtained results for the order parameter, all higher-order moments of BEC fluctuations, and thermodynamic quantities perfectly match the known asymptotics outside the critical region for both low and high temperature limits. We suggest two- and three-level trap models of BEC and find their exact solutions in terms of the cutoff negative binomial distribution (which tends to the cutoff gamma distribution in the continuous limit) and the confluent hypergeometric distribution, respectively. Also, we present an exactly solvable cutoff Gaussian model of BEC in a degenerate interacting gas. All these exact solutions confirm the universality and constraint-cutoff origin of the strongly non-Gaussian BEC statistics. We introduce a regular refinement scheme for the condensate statistics approximations on the basis of the infrared universality of higher-order cumulants and the method of superposition and show how to model BEC statistics in the actual traps. In particular, we find that the three-level trap model with matching the first four or five cumulants is enough to yield remarkably accurate results for all interesting quantities in the whole critical region. We derive an exact multinomial expansion for the noncondensate occupation probability distribution and find its high-temperature asymptotics (Poisson distribution) and corrections to it. Finally, we demonstrate that the critical exponents and a few known terms of the Taylor expansion of the universal functions, which were calculated previously from fitting the finite-size simulations within the phenomenological renormalization-group theory, can be easily obtained from the presented full analytical solutions for the mesoscopic BEC as certain approximations in the close vicinity of the critical point.

Kocharovsky, Vitaly V. [Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States); Institute of Applied Physics, Russian Academy of Science, RU-603950 Nizhny Novgorod (Russian Federation); Kocharovsky, Vladimir V. [Institute of Applied Physics, Russian Academy of Science, RU-603950 Nizhny Novgorod (Russian Federation)

2010-03-15

103

Analytical theory of mesoscopic Bose-Einstein condensation in an ideal gas  

NASA Astrophysics Data System (ADS)

We find the universal structure and scaling of the Bose-Einstein condensation (BEC) statistics and thermodynamics (Gibbs free energy, average energy, heat capacity) for a mesoscopic canonical-ensemble ideal gas in a trap with an arbitrary number of atoms, any volume, and any temperature, including the whole critical region. We identify a universal constraint-cutoff mechanism that makes BEC fluctuations strongly non-Gaussian and is responsible for all unusual critical phenomena of the BEC phase transition in the ideal gas. The main result is an analytical solution to the problem of critical phenomena. It is derived by, first, calculating analytically the universal probability distribution of the noncondensate occupation, or a Landau function, and then using it for the analytical calculation of the universal functions for the particular physical quantities via the exact formulas which express the constraint-cutoff mechanism. We find asymptotics of that analytical solution as well as its simple analytical approximations which describe the universal structure of the critical region in terms of the parabolic cylinder or confluent hypergeometric functions. The obtained results for the order parameter, all higher-order moments of BEC fluctuations, and thermodynamic quantities perfectly match the known asymptotics outside the critical region for both low and high temperature limits. We suggest two- and three-level trap models of BEC and find their exact solutions in terms of the cutoff negative binomial distribution (which tends to the cutoff gamma distribution in the continuous limit) and the confluent hypergeometric distribution, respectively. Also, we present an exactly solvable cutoff Gaussian model of BEC in a degenerate interacting gas. All these exact solutions confirm the universality and constraint-cutoff origin of the strongly non-Gaussian BEC statistics. We introduce a regular refinement scheme for the condensate statistics approximations on the basis of the infrared universality of higher-order cumulants and the method of superposition and show how to model BEC statistics in the actual traps. In particular, we find that the three-level trap model with matching the first four or five cumulants is enough to yield remarkably accurate results for all interesting quantities in the whole critical region. We derive an exact multinomial expansion for the noncondensate occupation probability distribution and find its high-temperature asymptotics (Poisson distribution) and corrections to it. Finally, we demonstrate that the critical exponents and a few known terms of the Taylor expansion of the universal functions, which were calculated previously from fitting the finite-size simulations within the phenomenological renormalization-group theory, can be easily obtained from the presented full analytical solutions for the mesoscopic BEC as certain approximations in the close vicinity of the critical point.

Kocharovsky, Vitaly V.; Kocharovsky, Vladimir V.

2010-03-01

104

Physical model for the generation of ideal resources in multipartite quantum networking  

SciTech Connect

We propose a physical model for generating multipartite entangled states of spin-s particles that have important applications in distributed quantum information processing. Our protocol is based on a process where mobile spins induce the interaction among remote scattering centers. As such, a major advantage lies in the management of stationary and well-separated spins. Among the generable states, there is a class of N-qubit singlets allowing for optimal quantum telecloning in a scalable and controllable way. We also show how to prepare Aharonov, W, and Greenberger-Horne-Zeilinger states.

Ciccarello, F.; Zarcone, M. [CNISM and Dipartimento di Fisica e Tecnologie Relative, Universita degli Studi di Palermo, Viale delle Scienze, Edificio 18, I-90128 Palermo (Italy); Paternostro, M. [School of Mathematics and Physics, Queen's University, Belfast BT7 1NN (United Kingdom); Bose, S.; Browne, D. E. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Palma, G. M. [NANO-Istituto Nanoscienze-CNR and Dipartimento di Scienze Fisiche ed Astronomiche, Universita degli Studi di Palermo, Via Archirafi 36, I-90123 Palermo (Italy)

2010-09-15

105

Stability of solutions of hydrodynamic equations describing the scaling limit of a massive piston in an ideal gas  

Microsoft Academic Search

We analyse the stability of stationary solutions of a singular Vlasov type hydrodynamic equation (HE). This equation was derived (under suitable assumptions) as the hydrodynamical scaling limit of the Hamiltonian evolution of a system consisting of a massive piston immersed in an ideal gas of point particles in a box. We find explicit criteria for global stability as well as

E. Caglioti; N. Chernov; J. L. Lebowitz

2004-01-01

106

On ideals and idealization.  

PubMed

This chapter repositions ideals away from their role as defensive structures restraining aggressive and lustful drives (as traditionally viewed) toward their place in shaping creativity and love. We select and mold our particular ideals in providing meaning and in this manner help to create those selfobjects needed to resolve or soothe our needs. This creative process may include "reshaping" of the available object to represent the "idealized other." From this perspective, Kohut's view of idealization and the idealized parental imago will be considered, including my own notion of a one-and-a-half person psychology. Our ideals inevitably conflict and clash, leading to internal self-conflicts that generate what I call the dialectic of narcissism. Narcissism is here considered broadly, reflecting all attributes of self-experience. Shame plays an important role in this dialectic, relating to failure with regard to ideals and to falling short of cherished goals. Ultimately, it is the shaping of, and approximation to, flexible and meaningful ideals that comprise that lofty, ineffable, human ideal--wisdom. Clinical vignettes will be offered to illustrate these themes. PMID:19379233

Morrison, Andrew P

2009-04-01

107

The Heat Capacity of Ideal Gases  

ERIC Educational Resources Information Center

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…

Scott, Robert L.

2006-01-01

108

Ideal-viscoplastic extrusion model with application to deforming pistons in light-gas guns  

Microsoft Academic Search

An approximate, one-dimensional, ideal viscoplastic model of the axisymmetric extrusion process through rigid circular-cross section channels is presented. The ideal viscoplastic model incorporates the fundamental effects associated with the physical phenomenon of inertia, plastic deformation, strain-rate behavior, and surface friction. By using the Bingham body constitutive relations, employing quasi-steady kinematically-admissible approximations to actual flow fields, and making various relevant simple

C. P. T. Groth; J. J. Gottlieb; C. Bourget

1987-01-01

109

Analytical Solution of the Blast Wave Problem in a Non-Ideal Gas  

NASA Astrophysics Data System (ADS)

An analytical approach is used to construct the exact solution of the blast wave problem with generalized geometries in a non-ideal medium. It is assumed that the density ahead of the shock front varies according to a power of distance from the source of the blast wave. Also, an analytical expression for the total energy in a non-ideal medium is derived.

P. Singh, L.; D. Ram, S.; B. Singh, D.

2011-11-01

110

Ionization equilibrium and partition functions of high-temperature weakly non-ideal Flibe gas  

Microsoft Academic Search

A model for the ionization equilibrium of weakly non-ideal Flibe plasma is presented in terms of a set of coupled non-linear Saha equations supplemented by electro-neutrality and conservation of nuclei. Non-ideality effects have been taken into account in terms of lowering of the ionization potentials and truncated partition functions. A simple formulation and solution strategy of the Saha equations for

Mofreh R. Zaghloul; Mofreh R

2003-01-01

111

Validation of the Jarzynski relation for a system with strong thermal coupling: An isothermal ideal gas model  

NASA Astrophysics Data System (ADS)

We revisit the paradigm of an ideal gas under isothermal conditions. A moving piston performs work on an ideal gas in a container that is strongly coupled to a heat reservoir. The thermal coupling is modeled by stochastic scattering at the boundaries. In contrast to recent studies of an adiabatic ideal gas with a piston [R.C. Lua and A.Y. Grosberg, J. Phys. Chem. B 109, 6805 (2005); I. Bena , Europhys. Lett. 71, 879 (2005)], the container and piston stay in contact with the heat bath during the work process. Under this condition the heat reservoir as well as the system depend on the work parameter ? and microscopic reversibility is broken for a moving piston. Our model is thus not included in the class of systems for which the nonequilibrium work theorem has been derived rigorously either by Hamiltonian [C. Jarzynski, J. Stat. Mech. (2004) P09005] or stochastic methods [G.E. Crooks, J. Stat. Phys. 90, 1481 (1998)]. Nevertheless the validity of the nonequilibrium work theorem is confirmed both numerically for a wide range of parameter values and analytically in the limit of a very fast moving piston, i.e., in the far nonequilibrium regime.

Baule, A.; Evans, R. M. L.; Olmsted, P. D.

2006-12-01

112

On the Equipartition of Kinetic Energy in an Ideal Gas Mixture  

ERIC Educational Resources Information Center

|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.)|

Peliti, L.

2007-01-01

113

Off-diagonal long-range order, cycle probabilities, and condensate fraction in the ideal Bose gas.  

PubMed

We discuss the relationship between the cycle probabilities in the path-integral representation of the ideal Bose gas, off-diagonal long-range order, and Bose-Einstein condensation. Starting from the Landsberg recursion relation for the canonic partition function, we use elementary considerations to show that in a box of size L3 the sum of the cycle probabilities of length k>L2 equals the off-diagonal long-range order parameter in the thermodynamic limit. For arbitrary systems of ideal bosons, the integer derivative of the cycle probabilities is related to the probability of condensing k bosons. We use this relation to derive the precise form of the pik in the thermodynamic limit. We also determine the function pik for arbitrary systems. Furthermore, we use the cycle probabilities to compute the probability distribution of the maximum-length cycles both at T=0, where the ideal Bose gas reduces to the study of random permutations, and at finite temperature. We close with comments on the cycle probabilities in interacting Bose gases. PMID:18233625

Chevallier, Maguelonne; Krauth, Werner

2007-11-09

114

Quantum memory in warm Rb vapor with buffer gas  

NASA Astrophysics Data System (ADS)

Quantum memory is considered to be one of the key elements in the fields of quantum computing and quantum communication. Warm atomic vapor cells for quantum memory in DLCZ (for Duan, Lukin, Cirac, and Zoller) protocol are appealing due to the perceived reduction in experimental complexity and commercial availability. However, reported results on quantum memory using warm vapor cells were done under widely different experimental conditions and produced ambiguous results. In order for the memory to exhibit non-classical behavior, to a high degree of certainty, the cross-correlation value between the Stokes and anti-Stokes photons needs to be greater than two. In this work we demonstrate quantum memory with cross-correlation value between the Stokes and anti-Stokes photons greater than two lasting for 4 ?s using warm Rb vapor with buffer gas for nearly co-propagating write and read beams.

Bashkansky, Mark; Fatemi, Fredrik K.; Vurgaftman, Igor

2012-02-01

115

Hydraulic Jet Flow of an Ideal Liquid and Gas-Liquid Mixtures.  

National Technical Information Service (NTIS)

The report contains articles on the performance of a reaction engine with an ejector shroud, the numerical solution to the problem of cooling a hot gas bubble in liquid, and the theory of gas-hydraulic propulsion engines.

G. V. Logvinovich V. M. Ivchenko I. M. Chernyi

1972-01-01

116

Test of dilute gas approximation in quantum mechanical model  

Microsoft Academic Search

The validity of dilute gas approximation is explored by making use of the large-sized instanton in quantum mechanical model. It is shown that the Euclidean probability amplitude derived through a dilute gas approximation not only cannot explain the result of the linear combination of atomic orbitals approximation, but also does not exhibit a proper limiting case when the size of

D. K. Park; Soo-Young Lee; Jae-Rok Kahng; Sahng-Kyoon Yoo; C. H. Lee; Chang Soo Park; Eui-Soon Yim

1996-01-01

117

Ionization equilibrium and partition functions of high-temperature weakly non-ideal Flibe gas  

NASA Astrophysics Data System (ADS)

A model for the ionization equilibrium of weakly non-ideal Flibe plasma is presented in terms of a set of coupled non-linear Saha equations supplemented by electro-neutrality and conservation of nuclei. Non-ideality effects have been taken into account in terms of lowering of the ionization potentials and truncated partition functions. A simple formulation and solution strategy of the Saha equations for the single element case has been extended for application to the case of plasma mixtures and has been used to calculate the composition of partially ionized Flibe plasma over a wide range of temperatures and densities. A criterion for the validity of the assumption of local thermodynamic equilibrium is presented and applied to the result. Effects of non-ideality corrections and approximating the partition function to the statistical weight of the ground state have been quantified and presented. Much of this work has been presented at the 15th ANS Topical Meeting on the Technology of Fusion Energy (TOFE) (Washington, DC, November 2002).

Zaghloul, Mofreh R.

2003-09-01

118

Quantum lattice gas algorithm for quantum turbulence and vortex reconnection in the Gross-Pitaevskii equation  

NASA Astrophysics Data System (ADS)

The ground state wave function for a Bose Einstein condensate is well described by the Gross-Pitaevskii equation. A Type-II quantum algorithm is devised that is ideally parallelized even on a classical computer. Only 2 qubits are required per spatial node. With unitary local collisions, streaming of entangled states and a spatially inhomogeneous unitary gauge rotation one recovers the Gross-Pitaevskii equation. Quantum vortex reconnection is simulated - even without any viscosity or resistivity (which are needed in classical vortex reconnection).

Vahala, George; Yepez, Jeffrey; Vahala, Linda

2008-05-01

119

Ideal-Gas Heat Capacity Values and Equations for Hydrofluorocarbon (HFC) Refrigerants Based on Speed-of-Sound Measurements  

Microsoft Academic Search

Final values of ideal-gas heat capacity c0p derived from speed-of-sound measurements using an acoustic spherical resonator and equations of c0p as a simple function of temperature are provided from an overall assessment of speed-of-sound measurements for five hydrofluorocarbon (HFC) refrigerants, difluoromethane (R32), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 1,1,1-trifluoroethane (R143a), and 1,1-difluoroethane (R152a). Some of the experimental results had systematic errors in

H. Sato; T. Kojima; K. Ogawa

2002-01-01

120

Quantum lattice gas algorithm for quantum turbulence and vortex reconnection in the Gross-Pitaevskii equation  

Microsoft Academic Search

The ground state wave function for a Bose Einstein condensate is well described by the Gross-Pitaevskii equation. A Type-II quantum algorithm is devised that is ideally parallelized even on a classical computer. Only 2 qubits are required per spatial node. With unitary local collisions, streaming of entangled states and a spatially inhomogeneous unitary gauge rotation one recovers the Gross-Pitaevskii equation.

George Vahala; Jeffrey Yepez; Linda Vahala

2008-01-01

121

Emissivity and radiative cooling of weakly non-ideal high-temperature Flibe gas  

Microsoft Academic Search

A theoretical model is developed to predict “rough estimates” of the isochors of the radiative cooling time of the high-temperature partially ionized Flibe gas at conditions relevant to the inertial fusion energy (IFE) chamber conditions. The model embodies the calculation of the occupational densities of all plasma species, calculation of the gas specific heat at constant volume, cv along with

Mofreh R. Zaghloul

2008-01-01

122

Expansion of a Quantum Gas Released from an Optical Lattice  

SciTech Connect

We analyze the interference pattern produced by ultracold atoms released from an optical lattice, commonly interpreted as the momentum distributions of the trapped quantum gas. We show that for finite times of flight the resulting density distribution can, however, be significantly altered, similar to a near-field diffraction regime in optics. We illustrate our findings with a simple model and realistic quantum Monte Carlo simulations for bosonic atoms and compare the latter to experiments.

Gerbier, F. [Laboratoire Kastler Brossel, ENS, UPMC, CNRS, 24 rue Lhomond, 75005 Paris (France); Trotzky, S.; Schnorrberger, U.; Thompson, J. D.; Bloch, I. [Institut fuer Physik, Johannes Gutenberg-Universitaet, 55099 Mainz (Germany); Foelling, S. [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Widera, A. [Institut fuer Angewandte Physik, 53115 Bonn (Germany); Pollet, L.; Troyer, M. [Theoretische Physik, ETH Zurich, 8093 Zurich (Switzerland); Capogrosso-Sansone, B. [Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003 (United States); Prokof'ev, N. V. [Theoretische Physik, ETH Zurich, 8093 Zurich (Switzerland) and Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003 (United States); Russian Research Center 'Kurchatov Institute', 123182 Moscow (Russian Federation); Svistunov, B. V. [Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003 (United States); Russian Research Center 'Kurchatov Institute', 123182 Moscow (Russian Federation)

2008-10-10

123

Bose-Einstein condensation of photons in an ideal atomic gas  

NASA Astrophysics Data System (ADS)

We study peculiarities of Bose-Einstein condensation of photons that are in thermodynamic equilibrium with atoms of noninteracting gases. General equations of the thermodynamic equilibrium of the system under study are obtained. We examine solutions of these equations in the case of high temperatures, when the atomic components of the system can be considered as nondegenerated ideal gases of atoms, and the photonic component can form a state with the Bose condensate. Transcendental equation for transition temperature and expression for the density of condensed photons in the considered system are derived. We also obtain analytical solutions of the equation for the critical temperature in a number of particular cases. The existence of two regimes of Bose condensation of photons, which differ significantly in nature of transition temperature dependence on the total density of photons pumped into the system, is revealed. In one case, this dependence is a traditional fractional-power law, and in another one it is the logarithmic law. Applying numerical methods, we determine boundaries of existence and implementation conditions for different regimes of condensation depending on the physical parameters of the system under study. We also show that for a large range of physical systems that are in equilibrium with photons (from ultracold gases of alkali metals to certain types of ideal plasma), the condensation of photons should occur according to the logarithmic regime.

Kruchkov, Alex; Slyusarenko, Yurii

2013-07-01

124

Student understanding of the first law of thermodynamics: Relating work to the adiabatic compression of an ideal gas  

NSDL National Science Digital Library

We report on an investigation of student understanding of the first law of thermodynamics. The students involved were drawn from first-year university physics courses and a second-year thermal physics course. The emphasis was on the ability of the students to relate the first law to the adiabatic compression of an ideal gas. Although they had studied the first law, few students recognized its relevance. Fewer still were able to apply the concept of work to account for a change in temperature in an adiabatic process. Instead most of the students based their predictions and explanations on a misinterpretation of the ideal gas law. Even when ideas of energy and work were suggested, many students were unable to give a correct analysis. They frequently failed to differentiate the concepts of heat, temperature, work, and internal energy. Some of the difficulties that students had in applying the concept of work in a thermal process seemed to be related to difficulties with mechanics. Our findings also suggest that a misinterpretation of simple microscopic models may interfere with student ability to understand macroscopic phenomena. Implications for instruction in thermal physics and in mechanics are discussed.

Loverude, Michael E.; Kautz, Christian H.; Heron, Paula R.

2005-10-27

125

Quantum hydrodynamics and expansion of a strongly interacting Fermi gas  

NASA Astrophysics Data System (ADS)

We generalize the quantum hydrodynamical equations and study the dynamics of a strongly interacting Fermi gas trapped in an anisotropic harmonic trap. By using this simple theory to simulate the expansion of the Fermi gas observed experimentally by O'Hara et al., Science, 298 (2002) 2179, we find that the density profiles of the system are well described by the Fetter-like form in the dynamical process in all spatial directions. We also discuss the anisotropic dependence on the expansion.

Zhang, W. Y.; Zhou, L.; Ma, Y. L.

2009-11-01

126

Ideal-Modified Bosonic Gas Trapped in AN Arbitrary Three-Dimensional Power-Law Potential  

NASA Astrophysics Data System (ADS)

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 three-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. In addition, 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.

Castellanos, E.; Lämmerzahl, C.

2012-10-01

127

Choking of ideal-gas flow in convergent nozzles and integral nozzle characteristics  

SciTech Connect

The results of a numerical and theoretical investigation of the local and integral characteristics of convergent nozzles are presented. It is shown that self-similar (choked) nozzle flow, when the gas flow rate does not depend on the external pressure, may occur at subcritical values of the pressure ratio {pi}{sub c} this nozzle will have a higher thrust coefficient than the initial conical nozzle.

Yagudin, S.V.

1995-05-01

128

Ideal-Gas Heat Capacity for 2,3,3,3-Tetrafluoropropene (HFO-1234yf) Determined from Speed-of-Sound Measurements  

NASA Astrophysics Data System (ADS)

The isobaric ideal-gas heat capacity for HFO-1234yf, which is expected to be one of the best alternative refrigerants for HFC-134a, was determined on the basis of speed-of-sound measurements in the gaseous phase. The speed of sound was measured by means of the acoustic resonance method using a spherical cavity. The resonance frequency in the spherical cavity containing the sample gas was measured to determine the speed of sound. After correcting for some effects such as the thermal boundary layer and deformation of the cavity on the resonance frequency, the speed of sound was obtained with a relative uncertainty of 0.01 %. Using the measured speed-of-sound data, the acoustic-virial equation was formulated and the isobaric ideal-gas heat capacity was determined with a relative uncertainty of 0.1 %. A temperature correlation function of the isobaric ideal-gas heat capacity for HFO-1234yf was also developed.

Kano, Yuya; Kayukawa, Yohei; Fujii, Kenichi; Sato, Haruki

2010-12-01

129

Ideal gas in a strong gravitational field: Area dependence of entropy  

SciTech Connect

We study the thermodynamic parameters like entropy, energy etc. of a box of gas made up of indistinguishable particles when the box is kept in various static background spacetimes having a horizon. We compute the thermodynamic variables using both statistical mechanics as well as by solving the hydrodynamical equations for the system. When the box is far away from the horizon, the entropy of the gas depends on the volume of the box except for small corrections due to background geometry. As the box is moved closer to the horizon with one (leading) edge of the box at about Planck length (L{sub p}) away from the horizon, the entropy shows an area dependence rather than a volume dependence. More precisely, it depends on a small volume A{sub perpendicular}L{sub p}/2 of the box, up to an order O(L{sub p}/K){sup 2} where A{sub perpendicular} is the transverse area of the box and K is the (proper) longitudinal size of the box related to the distance between leading and trailing edge in the vertical direction (i.e. in the direction of the gravitational field). Thus the contribution to the entropy comes from only a fraction O(L{sub p}/K) of the matter degrees of freedom and the rest are suppressed when the box approaches the horizon. Near the horizon all the thermodynamical quantities behave as though the box of gas has a volume A{sub perpendicular}L{sub p}/2 and is kept in a Minkowski spacetime. These effects are: (i) purely kinematic in their origin and are independent of the spacetime curvature (in the sense that the Rindler approximation of the metric near the horizon can reproduce the results) and (ii) observer dependent. When the equilibrium temperature of the gas is taken to be equal to the horizon temperature, we get the familiar A{sub perpendicular}/L{sub p}{sup 2} dependence in the expression for entropy. All these results hold in a D+1 dimensional spherically symmetric spacetime. The analysis based on methods of statistical mechanics and the one based on thermodynamics applied to the gas treated as a fluid in static geometry, lead to the same results showing the consistency. The implications are discussed.

Kolekar, Sanved; Padmanabhan, T. [IUCAA, Pune University Campus, Ganeshkhind, Pune 411007 (India)

2011-03-15

130

Ideal gas solubilities and solubility selectivities in a binary mixture of room-temperature ionic liquids.  

PubMed

This study focuses on the solubility behaviors of CO2, CH4, and N2 gases in binary mixtures of imidazolium-based room-temperature ionic liquids (RTILs) using 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][Tf2N]) and 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2mim][BF4]) at 40 degrees C and low pressures (approximately 1 atm). The mixtures tested were 0, 25, 50, 75, 90, 95, and 100 mol % [C2mim][BF4] in [C2mim][Tf2N]. Results show that regular solution theory (RST) can be used to describe the gas solubility and selectivity behaviors in RTIL mixtures using an average mixture solubility parameter or an average measured mixture molar volume. Interestingly, the solubility selectivity, defined as the ratio of gas mole fractions in the RTIL mixture, of CO2 with N2 or CH4 in pure [C2mim][BF4] can be enhanced by adding 5 mol % [C2mim][Tf2N]. PMID:18247501

Finotello, Alexia; Bara, Jason E; Narayan, Suguna; Camper, Dean; Noble, Richard D

2008-02-02

131

FRW quantum cosmology with a generalized Chaplygin gas  

SciTech Connect

Cosmologies with a Chaplygin gas have recently been explored with the objective of explaining the transition from a dust dominated epoch towards an accelerating expansion stage. In this context, we consider the hypothesis that this transition involves a quantum mechanical process. Our analysis is entirely analytical, with the objective of finding explicit mathematical expressions for the different quantum mechanical states and their cosmological implications. We employ a Friedmann-Robertson-Walker (FRW) minisuperspace model, characterized by two Lorentzian sectors, separated by a classically forbidden region. This is the configuration associated with the evolution of a generalized Chaplygin gas in a FRW universe. The Hartle-Hawking and Vilenkin wave functions are then computed, together with the transition amplitudes towards the accelerating epoch. Furthermore, for specific initial conditions we found that the generalized Chaplygin gas parameters become related through an expression involving an integer n. We also introduce a phenomenological association between some brane-world scenarios and a FRW minisuperspace cosmology with a generalized Chaplygin gas. The aim is to promote a discussion and subsequent research on the quantum creation of brane cosmologies from such a perspective. Additional results in this paper suggest that the brane tension would become related with the generalized Chaplygin gas parameters through another expression involving an integer.

Bouhmadi-Lopez, Mariam; Moniz, Paulo Vargas [Institute of Cosmology and Gravitation, University of Portsmouth, Mercantile House, Hampshire Terrace, Portsmouth PO1 2EG (United Kingdom); Astronomy Unit, School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom)

2005-03-15

132

Quantum hydrodynamics in dilute-gas Bose-Einstein condensates  

NASA Astrophysics Data System (ADS)

The peculiar dynamics of superfluids are a fascinating research topic. Since the first generation of a dilute gas Bose-Einstein condensate (BEC) in 1995, quantum degenerate atomic gases have taken the investigation of quantum hydrodynamics to a new level. The atomic physics toolbox has grown tremendously and now provides unique and powerful ways to explore nonlinear quantum systems. As an example, pioneering results have recently revealed that the counterflow between two superfluids can be used as a well controlled tool to access the rich dynamics of vector systems. New structures, such as beating dark-dark solitons which only exist in multicomponent systems and have never been observed before, can now be realized in the lab for the first time. Furthermore, the field of nonlinear quantum hydrodynamics is entering new regimes by exploiting Raman dressing as a tool to directly modify the dispersion relation. This leads to the generation of spin-orbit coupled BECs, artificial gauge fields, etc. that are currently receiving tremendous interest due to their parallels to complex condensed-matter systems. Studies of quantum hydrodynamics help to develop a profound understanding of nonlinear quantum dynamics, which is not only of fundamental interest but also of eminent importance for future technological applications, e.g. in telecommunication applications using optical solitons in fibers. This talk will showcase some ``classic'' hallmark results and highlight recent advances from the forefront of the field.

Engels, Peter

2012-10-01

133

The spin Hall effect in a quantum gas.  

PubMed

Electronic properties such as current flow are generally independent of the electron's spin angular momentum, an internal degree of freedom possessed by quantum particles. The spin Hall effect, first proposed 40 years ago, is an unusual class of phenomena in which flowing particles experience orthogonally directed, spin-dependent forces--analogous to the conventional Lorentz force that gives the Hall effect, but opposite in sign for two spin states. Spin Hall effects have been observed for electrons flowing in spin-orbit-coupled materials such as GaAs and InGaAs (refs 2, 3) and for laser light traversing dielectric junctions. Here we observe the spin Hall effect in a quantum-degenerate Bose gas, and use the resulting spin-dependent Lorentz forces to realize a cold-atom spin transistor. By engineering a spatially inhomogeneous spin-orbit coupling field for our quantum gas, we explicitly introduce and measure the requisite spin-dependent Lorentz forces, finding them to be in excellent agreement with our calculations. This 'atomtronic' transistor behaves as a type of velocity-insensitive adiabatic spin selector, with potential application in devices such as magnetic or inertial sensors. In addition, such techniques for creating and measuring the spin Hall effect are clear prerequisites for engineering topological insulators and detecting their associated quantized spin Hall effects in quantum gases. As implemented, our system realizes a laser-actuated analogue to the archetypal semiconductor spintronic device, the Datta-Das spin transistor. PMID:23739329

Beeler, M C; Williams, R A; Jiménez-García, K; LeBlanc, L J; Perry, A R; Spielman, I B

2013-06-05

134

When is a quantum cellular automaton (QCA) a quantum lattice gas automaton (QLGA)?  

NASA Astrophysics Data System (ADS)

Quantum cellular automata (QCA) are models of quantum computation of particular interest from the point of view of quantum simulation. Quantum lattice gas automata (QLGA - equivalently partitioned quantum cellular automata) represent an interesting subclass of QCA. QLGA have been more deeply analyzed than QCA, whereas general QCA are likely to capture a wider range of quantum behavior. Discriminating between QLGA and QCA is therefore an important question. In spite of much prior work, classifying which QCA are QLGA has remained an open problem. In the present paper we establish necessary and sufficient conditions for unbounded, finite QCA (finitely many active cells in a quiescent background) to be QLGA. We define a local condition that classifies those QCA that are QLGA, and we show that there are QCA that are not QLGA. We use a number of tools from functional analysis of separable Hilbert spaces and representation theory of associative algebras that enable us to treat QCA on finite but unbounded configurations in full detail.

Shakeel, Asif; Love, Peter J.

2013-09-01

135

Ideal-Gas Heat Capacity for 2,3,3,3-Tetrafluoropropene (HFO1234yf) Determined from Speed-of-Sound Measurements  

Microsoft Academic Search

The isobaric ideal-gas heat capacity for HFO-1234yf, which is expected to be one of the best alternative refrigerants for\\u000a HFC-134a, was determined on the basis of speed-of-sound measurements in the gaseous phase. The speed of sound was measured\\u000a by means of the acoustic resonance method using a spherical cavity. The resonance frequency in the spherical cavity containing\\u000a the sample gas

Yuya Kano; Yohei Kayukawa; Kenichi Fujii; Haruki Sato

2010-01-01

136

Exploring the Ideal Gas Law through a Quantitative Gasometric Analysis of Nitrogen Produced by the Reaction of Sodium Nitrite with Sulfamic Acid  

ERIC Educational Resources Information Center

|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…

Yu, Anne

2010-01-01

137

DIPPER project 871 determination of ideal-gas enthalpies of formation for key compounds, The 1991 project results  

SciTech Connect

Results of a study aimed at improving group-contribution methodology for estimating thermodynamic properties of organic 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 condensed phase, vapor-pressure measurements, and differential scanning calorimetric (d.s.c.) heat-capacity measurements. Ideal-gas enthalpies of formation of cyclohexene, phthalan (2,5-dihydrobenzo-3,4-furan), isoxazole, n-octylamine, di-n-octylamine, tri-n-octylamine, phenyl isocyanate, and 1,4,5,6-tetrahydropyrimidine are reported. Two-phase (liquid + vapor) heat capacities were determined for phthalan, isoxazole, the three octylamines, and phenyl isocyanate. Liquid-phase densities along the saturation line were measured for phthalan and isoxazole at 298 to 425 K. The critical temperature and critical density of n-octylamine were determined from d.s.c. results and critical pressure derived from the fitting procedures. Fitting procedures were used to derive critical temperatures, pressures, and densities for cyclohexene (pressure and density only), phthalan, isoxazole, di-n-octylamine, and phenyl isocyanate. Group-additivity parameters or ring-correction terms are derived.

Steele, W.V.; Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Tasker, I.R.

1993-09-01

138

A quantum gas of ground state molecules in an optical lattice  

NASA Astrophysics Data System (ADS)

Ultracold samples of molecules are ideally suited for fundamental studies in physics and chemistry. For many of the proposed experiments full molecular state control and high phase space densities are needed. We create a dense quantum gas of ground state Cs2 molecules trapped at the wells of a 3D optical lattice, i.e. a molecular Mott-insulator-like state with ground state molecules with vibrational quantum number v = 0. We first efficiently produce weakly bound molecules with v 155 on a Feshbach resonance out of an atomic Mott-insulator state that is obtained from a Bose-Einstein condensate (BEC) of Cs atoms. These molecules are then (coherently) transferred to the ground state by two sequential two-photon STIRAP processes via the intermediate vibrational level v 73 ^1. The molecule production efficiency and the single-step STIRAP transfer efficiency reach 50% and 80%, respectively. We discuss the stability of the system and our progress towards the creation of a BEC of ground state molecules, which is expected to form when the molecular Mott-like state is ``melted'' upon lowering the lattice depth and releasing the molecules from the wells into a large volume trap. ^1J. G. Danzl, E. Haller, M. Gustavsson, M. Mark, R. Hart, N. Bouloufa, O. Dulieu, H. Ritsch, H.-C. Nägerl, Science 321, 1062 (2008).

Danzl, Johann; Mark, Manfred; Haller, Elmar; Gustavsson, Mattias; Hart, Russell; Nägerl, Hanns-Christoph

2009-05-01

139

Quintessence and (anti-)Chaplygin gas in loop quantum cosmology  

SciTech Connect

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.

Lamon, Raphael; Woehr, Andreas J. [Institut fuer Theoretische Physik, Universitaet Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany)

2010-01-15

140

External cavity tunable quantum cascade lasers and their applications to trace gas monitoring.  

PubMed

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

Rao, Gottipaty N; Karpf, Andreas

2011-02-01

141

Spherical shock wave generated by a moving piston in mixture of a non-ideal gas and small solid particles under a gravitational field  

NASA Astrophysics Data System (ADS)

Self-similar solutions are obtained for one-dimensional isothermal and adiabatic unsteady flows behind a strong spherical shock wave propagating in a dusty gas. The shock is assumed to be driven out by a moving piston and the dusty gas to be a mixture of a non-ideal (or perfect) gas and small solid particles, in which solid particles are continuously distributed. It is assumed that the equilibrium flow-conditions are maintained and variable energy input is continuously supplied by the piston. The medium is under the influence of the gravitational field due to a heavy nucleus at the origin (Roche model). The effects of an increase in the mass concentration of solid particles, the ratio of the density of the solid particles to the initial density of the gas, the gravitational parameter and the parameter of non-idealness of the gas in the mixture, are investigated. It is shown that due to presence of gravitational field the compressibility of the medium at any point in the flow-field behind the shock decreases and all other flow-variables and the shock strength increase. A comparison has also been made between the isothermal and adiabatic flows. It is investigated that the singularity in the density and compressibility distributions near the piston in the case of adiabatic flow are removed when the flow is isothermal.

Vishwakarma, J. P.; Nath, G.

2012-06-01

142

Self-similar flow behind a spherical shock wave a non-ideal dusty gas under a gravitational field: isothermal flow  

NASA Astrophysics Data System (ADS)

Similarity solutions are obtained for one-dimensional unsteady isothermal flow of a dusty gas behind a spherical shock wave with time dependent energy input. The dusty gas is assumed to be a mixture of a non-ideal (or perfect) gas and small solid particles, in which solid particles are continuously distributed. It is assumed that the equilibrium flow-conditions are maintained and the viscous stress and heat conduction of the mixture are negligible. The medium is under the influence of the gravitational field due to a heavy nucleus at the origin (Roche model). The total energy of the flow-field behind the shock is increasing. The effects of an increase in the mass concentration of solid particles, the ratio of the density of the solid particles to the initial density of the gas, the gravitational parameter (or shock Mach number) and the parameter of non-idealness of the gas in the mixture, are investigated. It is shown that due to presence of gravitational field the compressibility of the medium at any point in the flow-field behind the shock decreases and all other flow-variables and the shock strength increase. A comparison has also been made between the medium with or without gravitational field.

Nath, Gorakh

2012-07-01

143

Self-similar flow behind a spherical shock wave in a non-ideal dusty gas under a gravitational field: Isothermal flow  

NASA Astrophysics Data System (ADS)

Similarity solutions are obtained for one-dimensional unsteady isothermal flow of a dusty gas behind a spherical shock wave with time dependent energy input. The dusty gas is assumed to be a mixture of non-ideal (or perfect) gas and small solid particles, in which solid particles are continuously distributed. It is assumed that the equilibrium flow-conditions are maintained, and the viscous stress and heat conduction of the mixture are negligible. The medium is taken to be under the influence of the gravitational field due to a heavy nucleus at the origin (Roche model). The total energy of the flow-field behind the shock is increasing. The effects of an increase in the mass concentration of solid particles, the ratio of the density of the solid particles to the initial density of the gas, the gravitational parameter (or shock Mach number), and the parameter of non-idealness of the gas in the mixture, are investigated. It is shown that due to presence of gravitational field the isothermal compressibility of the medium and the flow-variables increases and the shock strength decreases. A comparison has also been made between the medium with and without gravitational field. The shock waves in dusty medium can be important for description of star formation, shocks in supernova explosions, etc.

Nath, G.

2013-10-01

144

Suppression of the quantum-mechanical collapse by repulsive interactions in a quantum gas  

NASA Astrophysics Data System (ADS)

The quantum-mechanical collapse (alias fall onto the center of particles attracted by potential -r-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 Schrödinger equation. The addition of the harmonic trap gives rise to a tristability, in the case when the Schrödinger 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-2. The 2D vortical modes avoid the phase singularity at the pivot (r=0) by having the amplitude diverging at r?0 instead of the usual situation with the amplitude of the vortical mode vanishing at r?0 (the norm of the mode converges despite of the singularity of the amplitude at r?0). In the presence of the harmonic trap, the 2D quintic model with a weakly repulsive central potential r-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.

Sakaguchi, Hidetsugu; Malomed, Boris A.

2011-01-01

145

Suppression of the quantum-mechanical collapse by repulsive interactions in a quantum gas  

SciTech Connect

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.

Sakaguchi, Hidetsugu [Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Malomed, Boris A. [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)

2011-01-15

146

Quantum-electrodynamical parametric instability in the incoherent photon gas.  

PubMed

We present a theory for the quantum-electrodynamical (QED) parametric scattering instability of an intense photon pulse in an incoherent radiation background. The pump electromagnetic (EM) wave can decay into a scattered daughter EM wave and an acousticlike wave due to the QED vacuum polarization nonlinearity. By a linear instability analysis we obtain a nonlinear dispersion relation for the growth rate of the scattering instability. The nonlinear QED scattering instability can give rise to the exchange of orbital angular momentum between intense Laguerre-Gaussian mode photon pulses and the two daughter waves, which may be a useful method to detect the highly energetic photon gases existing in the vicinity of rotating dense bodies in the Universe, such as pulsars and magnetars. The observation of the scattered waves may reveal information about the twisted acoustic waves in the incoherent photon gas. PMID:23496629

Wang, Yunliang; Shukla, P K; Eliasson, B

2013-02-25

147

Quantum-electrodynamical parametric instability in the incoherent photon gas  

NASA Astrophysics Data System (ADS)

We present a theory for the quantum-electrodynamical (QED) parametric scattering instability of an intense photon pulse in an incoherent radiation background. The pump electromagnetic (EM) wave can decay into a scattered daughter EM wave and an acousticlike wave due to the QED vacuum polarization nonlinearity. By a linear instability analysis we obtain a nonlinear dispersion relation for the growth rate of the scattering instability. The nonlinear QED scattering instability can give rise to the exchange of orbital angular momentum between intense Laguerre-Gaussian mode photon pulses and the two daughter waves, which may be a useful method to detect the highly energetic photon gases existing in the vicinity of rotating dense bodies in the Universe, such as pulsars and magnetars. The observation of the scattered waves may reveal information about the twisted acoustic waves in the incoherent photon gas.

Wang, Yunliang; Shukla, P. K.; Eliasson, B.

2013-02-01

148

Quantum Lattice-Gas Model for the Burgers Equation  

Microsoft Academic Search

A quantum algorithm is presented for modeling the time evolution of a continuous field governed by the nonlinear Burgers equation in one spatial dimension. It is a microscopic-scale algorithm for a type-II quantum computer, a large lattice of small quantum computers interconnected in nearest neighbor fashion by classical communication channels. A formula for quantum state preparation is presented. The unitary

Jeffrey Yepez

2002-01-01

149

Sex education and ideals  

Microsoft Academic Search

This article argues that sex education should include sexual ideals. Sexual ideals are divided into sexual ideals in the strict sense and sexual ideals in the broad sense. It is argued that ideals that refer to the context that is deemed to be most ideal for the gratification of sexual ideals in the strict sense are rightfully called sexual ideals.

Doret J. de Ruyter; Ben Spiecker

2008-01-01

150

Finite-difference solution for laminar or turbulent boundary layer flow over axisymmetric bodies with ideal gas, CF4, or equilibrium air chemistry  

NASA Astrophysics Data System (ADS)

A computer code was developed that uses an implicit finite-difference technique to solve nonsimilar, axisymmetric boundary layer equations for both laminar and turbulent flow. The code can treat ideal gases, air in chemical equilibrium, and carbon tetrafluoride (CF4), which is a useful gas for hypersonic blunt-body simulations. This is the only known boundary layer code that can treat CF4. Comparisons with experimental data have demonstrated that accurate solutions are obtained. The method should prove useful as an analysis tool for comparing calculations with wind tunnel experiments and for making calculations about flight vehicles where equilibrium air chemistry assumptions are valid.

Hamilton, H. Harris, II; Millman, Daniel R.; Greendyke, Robert B.

1992-12-01

151

Thermodynamics of an Ideal Bose Gas with a Finite Number of Particles Confined in a Three-Dimensional Quartic Trap  

NASA Astrophysics Data System (ADS)

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.

Wang, Jianhui; Zhuang, Bo; He, Jizhou

2013-01-01

152

Recent advances of trace gas sensors based on diode and quantum cascade lasers  

Microsoft Academic Search

Diode and quantum cascade lasers can be used for trace gas detection in ambient air based on absorption and photoacoustic spectroscopy. Advances in spectroscopic detection techniques have resulted in minimum detectable absorbances of 10-5 in several applications.

Frank K. Tittel; Anatoliy A. Kosterev; Yury A. Bakhirkin; Gerard Wysocki; Chad B. Roller; Stephen So; Damien Weidmann; Markus Horstjann; Robert F. Curl

2004-01-01

153

Physical and mathematical modeling of pyrometallurgical channel reactors with bottom gas injection: Residence time distribution analysis and ideal- reactor- network model  

NASA Astrophysics Data System (ADS)

An ideal-reactor-network model has been developed to describe the fluid flow and mixing observed in pyrometallurgical channel reactors with countercurrent liquid flow and high-strength bottom gas injection. Experiments were performed in a cold model under various operating conditions to determine the effects of liquid density, viscosity, flow rate, gas injection rates, injector diameter, and injector spacing on the residence time distribution (RTD) behavior of the channel reactor. The ideal-reactor-network model was used to represent the experimentally observed RTD behavior in both heavy- and light-liquid phases in the channel reactor. The model requires one parameter for each liquid, and all other model parameters are determined on the basis of this parameter. Correlations were developed for the parameters using dimensionless variables. There is excellent agreement between model predictions and experimental measurements for a wide range of experimental conditions. Scale-up calculations and RTD predictions have been made for a QSL leadmaking reactor as well as for proposed channel reactors for coppermaking and steelmaking.

Iyer, Kumar M.; Sohn, H. Y.

1994-04-01

154

Sex Education and Ideals  

ERIC Educational Resources Information Center

This article argues that sex education should include sexual ideals. Sexual ideals are divided into sexual ideals in the strict sense and sexual ideals in the broad sense. It is argued that ideals that refer to the context that is deemed to be most ideal for the gratification of sexual ideals in the strict sense are rightfully called sexual…

de Ruyter, Doret J.; Spiecker, Ben

2008-01-01

155

Quantum drag forces on a sphere moving through a rarefied gas.  

PubMed

As an application of quantum fluid mechanics, we consider the drag force exerted on a sphere by an ultradilute gas. Quantum mechanical diffraction scattering theory enters in that regime wherein the mean free path of a molecule in the gas is large compared with the sphere radius. The drag force is computed in a model specified by the "sticking fraction" of events in which a gaseous molecule is adsorbed by the spherical surface. Classical inelastic scattering theory is shown to be inadequate for physically reasonable sticking fraction values. The quantum mechanical scattering drag force is exhibited theoretically and compared with experimental data. PMID:16089521

Drosdoff, D; Widom, A; Srivastava, Y

2005-05-27

156

Master Equation for a Quantum Particle in a Gas  

SciTech Connect

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.

Hornberger, Klaus [Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universitaet Muenchen, Theresienstrasse 37, 80333 Munich (Germany)

2006-08-11

157

Quantum-cascade laser photoacoustic detection of methane emitted from natural gas powered engines  

NASA Astrophysics Data System (ADS)

In this work we present a laser photoacoustic arrangement for the detection of the important greenhouse gas methane. A quantum-cascade laser and a differential photoacoustic cell were employed. A detection limit of 45 ppbv in nitrogen was achieved as well as a great selectivity. The same methodology was also tested in the detection of methane issued from natural gas powered vehicles (VNG) in Brazil, which demonstrates the excellent potential of this arrangement for greenhouse gas detection emitted from real sources.

Rocha, M. V.; Sthel, M. S.; Silva, M. G.; Paiva, L. B.; Pinheiro, F. W.; Miklòs, A.; Vargas, H.

2012-03-01

158

Modeling Quantum Spin Dynamics in an Ultracold Gas  

NASA Astrophysics Data System (ADS)

A recent experiment in our lab focuses on investigating spin dynamics in the quantum regime, where mean field approaches fail. Previous theoretical models for the quantum dynamical evolution of a spin-1 Bose-Einstein condensate do not include the effects of atomic loss that is unavoidable in experiment. Here, we present results of different loss models including a fully quantum calculation of this complicated many body system using a Monte-Carlo approach. We compare the results of these methods to recent experimental measurements and obtain good agreement.

Land, B. J.; Hamley, C. D.; Gerving, C. S.; Hoang, T. M.; Anquez, M. L. B.; Chapman, M. S.

2012-06-01

159

A novel method to prepare carbon-coated quantum dots by an advanced gas evaporation method  

Microsoft Academic Search

Metallic quantum dots coated by amorphous carbon were produced by simultaneous evaporation of carbon and metal in Ar gas at 13 kPa. Carbon-coated Ag, Fe and Au dots with a size of 2–20 nm can be easily obtained. In the present experimental system, C60 crystals were also observed. The quantum dots included in C60 crystals have been indicated. The growth

Chihiro Kaito; Takemasa Sakamoto; Daisuke Ban; Takashi Izuta; Yasushi Kitano; Yoshio Saito

1996-01-01

160

Van der Waals and ideal gas models for compressibility by means of pressure in pneumatic pipes from 1 to 100 Lpm.  

PubMed

The general aim is to develop a Venturi flow sensor for the inspiration line to be used in mechanical ventilation. This work is an advance for the development and construction of this sensor and to explain some of its characteristics in mechanical ventilation. The Mach number in this sensor grows with the pipe diameter, but it is less than 0.3 to diameters higher than 3mm, and according to the traditional bibliography it can be used as incompressible fluid for the design. For this reason the simulations were done between 2:1 and 6:1 to simulation pressures from 15 to 16.5 Psi (mechanical ventilation range). The results of these simulations are: it needs to consider the gas compressibility levels for Mach numbers smaller than 0.3 because the error of flow measure can be between 5 and 15% for the pattern of ideal gas and enter 7.5 to 20% for the Van Der Waals model above the incompressibility pattern, and these results were used for the construction of the small reduction the Venturi's pipe from 3 to 78 Lpm, taken from absolute pressure to complete the norm ISO9360. PMID:17272118

Mugruza Vassallo, Carlos

2004-01-01

161

Carbon Quantum Dot-Functionalized Aerogels for NO2 Gas Sensing.  

PubMed

Silica aerogels functionalized with strongly fluorescent carbon quantum dots were first prepared and used for simple, sensitive, and selective sensing of NO2 gas. In the presence of ethanol, homemade silica aerogels with a large specific surface area of 801.17 m(2)/g were functionalized with branched polyethylenimine-capped quantum dots (BPEI-CQDs) with fluorescence quantum yield higher than 40%. The prepared porous CQD-aerogel hybrid material could maintain its excellent fluorescence (FL) activity in its solid state. The FL of CQD-aerogel hybrid material could be selectively and sensitively quenched by NO2 gas, suggesting a promising application of the new FL-functionalized aerogels in gas sensing. PMID:23905622

Wang, Ruixue; Li, Geli; Dong, Yongqiang; Chi, Yuwu; Chen, Guonan

2013-08-14

162

TRANSITIVE PROPERTIES OF IDEALS  

Microsoft Academic Search

In this paper we present a wide range of results connected with transitive properties of ideals. In particular, we present relations between standard and transitive coecients of ideals and compute transitive cardinal coecients of ideals on generalized Cantor spaces.

JAN KRASZEWSKI

163

Creating a quantum degenerate gas of stable molecules via weak photoassociation  

SciTech Connect

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.

Mackie, Matt; Phou, Pierre [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States)

2010-07-15

164

Nonlinear constitutive equations derived for fluids obeying an ideal gas, a Tait-Kirkwood or a B/A type equation of state  

NASA Astrophysics Data System (ADS)

A generalized theoretical framework for acoustic, electromagnetic and elastodynamic waves would give fruitful insights into equivalent phenomena in these physical domains and would form a basis to draw up general analytical or numerical solution methods. In this contribution we adopt the structure of Maxwell's equations for electromagnetic fields, encompassing the formulation of two first-order field equations and two first-order constitutive equations, and we apply it to the area of nonlinear acoustics. We derive the constitutive equations of a fluid directly from its thermodynamic equation of state (EOS). In the constitutive equations, the nonlinear medium behaviour of the fluid is described by a pressure-dependent density and compressibility. The resulting equations are general, making them valid for phenomena occuring in applications with finite amplitude waves of any magnitude, like waveform distortion or radiation pressure. This paper concerns with obtaining constitutive equations for fluids obeying an ideal gas law, a Tait-Kirkwood EOS or a 2-term Taylor approximation of the EOS employing the B/A nonlinearity parameter. The latter EOS is used in many of the classical model equations of nonlinear acoustics. We show that all three types result in simple expressions for the density and compressibility.

Huijssen, Jacob; Verweij, Martin D.

2006-05-01

165

The Quantum Mechanics of Chemical Kinetics of Homogeneous Gas Phase Reactions I. General Considerations  

Microsoft Academic Search

From the zeroth order Born-Oppenheimer approximation to the wave functions of a molecular system and the first order time-dependent perturbation theory of quantum mechanics it has been possible to deduce: (1) the adiabatic hypothesis; (2) the dependence of the rate of homogeneous gas phase chemical reactions upon the composition of reaction mixtures; (3) the condition for zero net rate of

Sidney Golden

1949-01-01

166

Quantum criticality of a one-dimensional attractive Fermi gas  

SciTech Connect

We obtain an analytical equation of state for one-dimensional strongly attractive Fermi gases for all parameter regimes in current experiments. From the equation of state, we derive universal scaling functions that control whole thermodynamical properties in quantum critical regimes and illustrate the physical origin of quantum criticality. It turns out that the critical properties of the system are described by those of free fermions and those of mixtures of fermions with masses m and 2m. We also show how these critical properties of bulk systems can be revealed from the density profile of trapped Fermi gases at finite temperatures and can be used to determine the T=0 phase boundaries without any arbitrariness.

Guan Xiwen; Ho, Tin-Lun [Department of Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States)

2011-08-15

167

Impurity transport through a strongly interacting bosonic quantum gas  

SciTech Connect

Using near-exact numerical simulations, we study the propagation of an impurity through a one-dimensional Bose lattice gas for varying bosonic interaction strengths and filling factors at zero temperature. The impurity is coupled to the Bose gas and confined to a separate tilted lattice. The precise nature of the transport of the impurity is specific to the excitation spectrum of the Bose gas, which allows one to measure properties of the Bose gas nondestructively, in principle, by observing the impurity; here we focus on the spatial and momentum distributions of the impurity as well as its reduced density matrix. For instance, we show it is possible to determine whether the Bose gas is commensurately filled as well as the bandwidth and gap in its excitation spectrum. Moreover, we show that the impurity acts as a witness to the crossover of its environment from the weakly to the strongly interacting regime, i.e., from a superfluid to a Mott insulator or Tonks-Girardeau lattice gas, and the effects on the impurity in both of these strongly interacting regimes are clearly distinguishable. Finally, we find that the spatial coherence of the impurity is related to its propagation through the Bose gas.

Johnson, T. H. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Clark, S. R. [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore); Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Keble College, University of Oxford, Parks Road, Oxford OX1 3PG (United Kingdom); Bruderer, M. [Fachbereich Physik, Universitaet Konstanz, D-78457 Konstanz (Germany); Jaksch, D. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore); Keble College, University of Oxford, Parks Road, Oxford OX1 3PG (United Kingdom)

2011-08-15

168

Coherent electron focusing with quantum point contacts in a two-dimensional electron gas  

NASA Astrophysics Data System (ADS)

Transverse electron focusing in a two-dimensional electron gas is investigated experimentally and theoretically for the first time. A split Schottky gate on top of a GaAs-AlxGa1-xAs heterostructure defines two point contacts of variable width, which are used as injector and collector of ballistic electrons. As evidenced by their quantized conductance, these are quantum point contacts with a width comparable to the Fermi wavelength. At low magnetic fields, skipping orbits at the electron-gas boundary are directly observed, thereby establishing that boundary scattering is highly specular. Large additional oscillatory structure in the focusing spectra is observed at low temperatures and for small point-contact size. This new phenomenon is interpreted in terms of interference of coherently excited magnetic edge states in a two-dimensional electron gas. A theory for this effect is given, and the relation with nonlocal resistance measurements in quantum ballistic transport is discussed. It is pointed out, and experimentally demonstrated, that four-terminal transport measurements in the electron-focusing geometry constitute a determination of either a generalized longitudinal resistance or a Hall resistance. At high magnetic fields the electron-focusing peaks are suppressed, and a transition is observed to the quantum Hall regime. The anomalous quantum Hall effect in this geometry is discussed in light of a four-terminal resistance formula.

van Houten, H.; Beenakker, C. W. J.; Williamson, J. G.; Broekaart, M. E. I.; van Loosdrecht, P. H. M.; van Wees, B. J.; Mooij, J. E.; Foxon, C. T.; Harris, J. J.

1989-04-01

169

Spontaneous Pattern Formation in an Antiferromagnetic Quantum Gas  

SciTech Connect

In this Letter we report on the spontaneous formation of surprisingly regular periodic magnetic patterns in an antiferromagnetic Bose-Einstein condensate (BEC). The structures evolve within a quasi-one-dimensional BEC of {sup 87}Rb atoms on length scales of a millimeter with typical periodicities of 20...30 {mu}m, given by the spin healing length. We observe two sets of characteristic patterns which can be controlled by an external magnetic field. We identify these patterns as linearly unstable modes within a mean-field approach and calculate their mode structure as well as time and energy scales, which we find to be in good agreement with observations. These investigations open new prospects for controlled studies of symmetry breaking and complex quantum magnetism in bulk BEC.

Kronjaeger, Jochen; Bongs, Kai [MUARC, School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Institut fuer Laser-Physik, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Becker, Christoph; Soltan-Panahi, Parvis; Sengstock, Klaus [Institut fuer Laser-Physik, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

2010-08-27

170

Quantum phase transitions in a polarized gas of dipolar molecules forming flexible chain  

NASA Astrophysics Data System (ADS)

We numerically demonstrate the formation of quantum flexible chains in a gas of polar molecules confined into a stack of N 1d or 2d optical lattice layers, and with dipole moment aligned perpendicularly to the layers. Molecules interact via dipole-dipole interaction. Ab initio simulations of a single chain pinned at one end reveal quantum roughening transition. Multi-chain ensemble is studied in the J-current model approximation and chain superfluidity (CSF) is found. Increasing density of the chains leads to quantum phase transition from CSF to N-layered molecular superfluid (N-SF). We discuss the nature of this transition and its dependence on density, and the conditions for experimental realization and detection of the chain soup.

Capogrosso-Sansone, Barbara; Kuklov, Anatoly

2011-03-01

171

Vlasov hydrodynamics of a quantum mechanical model  

Microsoft Academic Search

We derive the Vlasov hydrodynamics from the microscopic equations of a quantum mechanical model, which simulates that of an assembly of gravitating particles. In addition we show that the local microscopic dynamics of the model corresponds, on a suitable time-scale, to that of an ideal Fermi gas.

Heide Narnhofer; Geoffrey L. Sewell

1981-01-01

172

Temperature Dependence of Electron Tunneling between Two Dimensional Electron Gas and Si Quantum Dots  

NASA Astrophysics Data System (ADS)

Quantum mechanical electron tunneling has potential applications in both science and technology, such as flash memories in modern LSI technologies and electron transport chains in biosystems. Although it is known that one-dimensional quantum electron tunneling lacks temperature dependence, the behavior of electron tunneling between different dimensional systems is still an open question. Here, we investigated the electron tunneling between a two-dimensional electron gas (2DEG) and zero-dimensional Si quantum dots and discovered an unexpected temperature dependence: At high temperature, the gate voltage necessary for electron injection from 2DEG to Si quantum dots becomes markedly small. This unusual tunneling behavior was phenomenologically explained by considering the geometrical matching of wave functions between different dimensional systems. We assumed that electron tunneling would occur within a finite experimental measurement time. Then, the observed electron tunneling is explained only by the contributions of wave packets below the quantum dot with a finite lifetime rather than the ordinary thermal excited states of 2DEG.

Sakurai, Yoko; Iwata, Jun-ichi; Muraguchi, Masakazu; Shigeta, Yasuteru; Takada, Yukihiro; Nomura, Shintaro; Endoh, Tetsuo; Saito, Shin-ichi; Shiraishi, Kenji; Ikeda, Mitsuhisa; Makihara, Katsunori; Miyazaki, Seiichi

2010-01-01

173

Single-site resolved studies of a bilayer quantum degenerate gas  

NASA Astrophysics Data System (ADS)

Ultracold atoms in optical lattices are a versatile platform for quantum many-body simulation with the promise of insights into quantum magnetism, superconductivity, and superfluidity. In recent years, quantum gas microscopes with single-site resolution have opened the door to local observation and manipulation of strongly correlated two-dimensional quantum gases. Here we present techniques for extending study to two tunnel-coupled planes. Using an axial superlattice we prepare a bilayer system, with full control of the inter-plane tunnel coupling and detuning. We observe coherent inter-plane population transfer with single-site resolution in both planes. A collisional energy blockade in the bilayer system allows us to go beyond parity imaging and unambiguously identify site occupations from zero to three atoms. We have obtained site-resolved images of the ``wedding-cake'' Mott insulator structure and antiferromagnetic ordering in a quantum Ising model. Further applications include spin-dependent readout and in situ phase imaging.

Ma, Ruichao; Preiss, Philipp; Tai, Ming; Bakr, Waseem; Simon, Jonathan; Greiner, Markus

2012-06-01

174

Pulsed Quantum-Cascade Laser-Based Sensor for Trace-Gas Detection of Carbonyl Sulfide  

Microsoft Academic Search

Simultaneous exhaled carbonyl sulfide (OCS) and carbon dioxide concentration measurements in human breath are demonstrated with a compact pulsed quantum-cascade laser-based gas sensor. We achieved a noise-equivalent sensitivity (1sigma) of 1.2 parts per billion by measuring a well-isolated OCS P(11) absorption line in the nu3 band at 2057.6 cm^-1 using an astigmatic Herriott cell of 36-m optical path length and

Gerard Wysocki; Matt McCurdy; Stephen So; Damien Weidmann; Chad Roller; Robert F. Curl; Frank K. Tittel

2004-01-01

175

Asymmetric double two-dimensional electron gas structures for electrical quantum metrology  

Microsoft Academic Search

We study growth and low temperature magnetotransport of Ga(Al)As based asymmetric double two-dimensional electron gas (2DEG) structures consisting of a quantum well stacked on top of a heterojunction. These structures allow for matching the electron densities in the two parallel 2DEGs by variation of a single growth parameter without the appearance of any parasitic transport channel. At filling factor 2,

K. Pierz; G. Hein; E. Pesel; B. Schumacher; H. W. Schumacher; U. Siegner

2008-01-01

176

Synthesis and gas sensing properties of ZnO quantum dots  

Microsoft Academic Search

ZnO nanocrystals (2.5–4.5nm) were prepared by a wet chemical method based on alkaline-activated hydrolysis and condensation of zinc acetate solutions. Dropcasting of the nanocrystals onto alumina substrates allowed the fabrication of gas sensing devices, that were tested towards NO2, acetone and methanol and showed promising results. At low working temperature, the ZnO quantum dots based sensors are selective to nitrogen

A. Forleo; L. Francioso; S. Capone; P. Siciliano; P. Lommens; Z. Hens

2010-01-01

177

Probing the Quantum State of a 1D Bose Gas Using Off-Resonant Light Scattering  

SciTech Connect

We present a theoretical treatment of coherent light scattering from an interacting 1D Bose gas at finite temperatures. We show how this can provide a nondestructive measurement of the atomic system states. The equilibrium states are determined by the temperature and interaction strength, and are characterized by the spatial density-density correlation function. We show how this correlation function is encoded in the angular distribution of the fluctuations of the scattered light intensity, thus providing a sensitive, quantitative probe of the density-density correlation function and therefore the quantum state of the gas.

Sykes, A. G. [Jack Dodd Centre for Quantum Technology, Department of Physics, University of Otago, PO Box 56, Dunedin (New Zealand); Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Ballagh, R. J. [Jack Dodd Centre for Quantum Technology, Department of Physics, University of Otago, PO Box 56, Dunedin (New Zealand)

2011-12-30

178

Trace-gas sensing using the compliance voltage of an external cavity quantum cascade laser  

NASA Astrophysics Data System (ADS)

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 acetone 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.

Phillips, Mark C.; Taubman, Matthew S.

2013-05-01

179

Carbon Dioxide Gas Sensing Application of GRAPHENE/Y2O3 Quantum Dots Composite  

NASA Astrophysics Data System (ADS)

Graphene/Y2O3 quantum dots (QDs) composite was investigated towards the carbon dioxide (CO2) gas at room temperature. Graphene synthesized by electrochemical exfoliation of graphite. The composite prepared by mixing 20-wt% graphene into the 1 g Y2O3 in organic medium (acetone). The chemiresistor of composite prepared by screen-printing on glass substrate. The optimum value of sensing response (1.08) was showed by 20-wt% graphene/Y2O3 QDs composite. The excellent stability with optimum sensing response evidenced for the composite. The gas sensing mechanism discussed on the basis of electron transfer reaction.

Nemade, K. R.; Waghuley, S. A.

180

Improvement on multiparameter equations of state for dimethylsiloxanes by adopting more accurate ideal-gas isobaric heat capacities: Supplementary to P. Colonna, N.R. Nannan, A. Guardone, E.W. Lemmon, Fluid Phase Equilib. 244, 193 (2006)  

Microsoft Academic Search

A recent paper by the authors reports ideal-gas isobaric heat capacities (CP0) for several siloxanes. These values were determined using ad hoc speed-of-sound measurements and ab initio calculations. Thermodynamic models for some siloxanes documented in an earlier work by the same authors adopted less accurate estimations for CP0(T). This note reports coefficients for the substance-specific Aly–Lee correlations for CP0(T) which

N. R. Nannan; P. Colonna

2009-01-01

181

Quantum control of gas-phase and liquid-phase femtochemistry.  

PubMed

Active control of chemical reactions on a microscopic (molecular) level, that is, the selective breaking or making of chemical bonds, is an old dream. However, conventional control agents used in chemical synthesis are macroscopic variables such as temperature, pressure or concentration, which gives no direct access to the quantum-mechanical reaction pathway. In quantum control, by contrast, molecular dynamics are guided with specifically designed light fields. Thus it is possible to efficiently and selectively reach user-defined reaction channels. In the last years, experimental techniques were developed by which many breakthroughs in this field were achieved. Femtosecond laser pulses are manipulated in so-called pulse shapers to generate electric field profiles which are specifically adapted to a given quantum system and control objective. The search for optimal fields is guided by an automated learning loop, which employs direct feedback from experimental output. Thereby quantum control over gas-phase as well as liquid-phase femtochemical processes has become possible. In this review, we first discuss the theoretical and experimental background for many of the recent experiments treated in the literature. Examples from our own research are then used to illustrate several fundamental and practical aspects in gas-phase as well as liquid-phase quantum control. Some additional technological applications and developments are also described, such as the automated optimization of the output from commercial femtosecond laser systems, or the control over the polarization state of light on an ultrashort timescale. The increasing number of successful implementations of adaptive learning techniques points at the great versatility of computer-guided optimization methods. The general approach to active control of light-matter interaction has also applications in many other areas of modern physics and related disciplines. PMID:12785256

Brixner, Tobias; Gerber, Gustav

2003-04-14

182

Suppression of quantum collapse in an anisotropic gas of dipolar bosons  

SciTech Connect

In recent work [Sakaguchi and Malomed, Phys. Rev. A 83, 013607 (2011)], a solution to the problem of the quantum collapse (fall onto the center) in the three-dimensional space with the attractive potential -(U{sub 0}/2)r{sup -2} was proposed, based on the replacement of the linear Schroedinger equation by the Gross-Pitaevskii (GP) equation with the repulsive cubic term. The model applies to a quantum gas of molecules carrying permanent electric dipole moments, with the attraction center representing a fixed electric charge. It was demonstrated that the repulsive nonlinearity suppresses the quantum collapse and creates the corresponding spherically symmetric ground state (GS), which was missing in the case of the linear Schroedinger equation. Here, we aim to extend the analysis to the cylindrical geometry and to eigenstates carrying angular momentum. The cylindrical anisotropy is imposed by a uniform dc field, which fixes the orientation of the dipole moments, thus altering the potential of the attraction to the center. First, we analyze the modification of the condition for the onset of the quantum collapse in the framework of the linear Schroedinger equation with the cylindrically symmetric potential for the states with azimuthal quantum numbers m=0 (the GS) and m=1, 2. The corresponding critical values of the strength of the attractive potential (U{sub 0}){sub cr}(m) are found. Next, a numerical solution of the nonlinear GP equation is developed, which demonstrates the replacement of the quantum collapse by the originally missing eigenstates with m=0,1,2. Their dynamical stability is verified by means of numerical simulations of the perturbed evolution. For m=0, the Thomas-Fermi approximation is presented too, in an analytical form. Crucially important for the solution is the proper choice of the boundary conditions at r{yields}0.

Sakaguchi, Hidetsugu [Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Malomed, Boris A. [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv IL-69978 (Israel); ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, ES-08860 Castelldefels (Barcelona) (Spain)

2011-09-15

183

Time dependent quantum mechanical theory of gas--surface energy transfer  

SciTech Connect

A fully quantum mechanical theory for phonon inelastic gas--surface scattering is presented. Both surface and bulk phonons are coupled to the molecule via perturbation theory. The reduced density matrix of the molecule is written in terms of three wave-function-like objects, which obey Schrodinger-like equations of motion. These highly coupled equations of motion are evolved simultaneously in time, using standard techniques. The method can be applied to any of several recent quantum and semiclassical time dependent scattering theories, and allows one to compute the thermally averaged properties of the system at all times. The total computational effort is only about three times that of the zero temperature calculation. Results are presented for the inelastic scattering of He and Ne beams from Cu(111), Cu(100), and Ni(111).

Jackson, B.

1988-01-15

184

Quantum fluctuations of the vortex-lattice state in an ultrafast rotating Bose gas  

NASA Astrophysics Data System (ADS)

Quantum fluctuations in an ultrafast rotating Bose gas at zero temperature are investigated. We calculate the condensate density perturbatively to show that no condensate is present in the thermodynamic limit. The excitation from Gaussian fluctuations around the mean-field solution causes infrared divergences in loop diagrams, nevertheless, in calculating the atom number density, the correlation functions and the free energy, we find that the sum of the divergences in the same loop order vanishes and we obtain finite physical quantities. The long-range correlation is explored and the algebraic decay exponent for the single-particle correlation function is obtained. The atom number density distribution is obtained at the one-loop level, which illustrates the quantum fluctuation effects to melt the mean-field vortex lattice. By the nonperturbative Gaussian variational method, we locate the spinodal point of the vortex-lattice state.

Li, Qiong; Feng, Bo; Li, Dingping

2011-04-01

185

Ideals and Category Typicality  

ERIC Educational Resources Information Center

|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…

Kim, ShinWoo; Murphy, Gregory L.

2011-01-01

186

Tunnel-field-effect-transistor based gas-sensor: Introducing gas detection with a quantum-mechanical transducer  

NASA Astrophysics Data System (ADS)

A gas-sensor based on tunnel-field-effect-transistor (TFET) is proposed that leverages the unique current injection mechanism in the form of quantum-mechanical band-to-band tunneling to achieve substantially improved performance compared to conventional metal-oxide-semiconductor field-effect-transistors (MOSFETs) for detection of gas species under ambient conditions. While nonlocal phonon-assisted tunneling model is used for detailed device simulations, in order to provide better physical insights, analytical formula for sensitivity is derived for both metal as well as organic conducting polymer based sensing elements. Analytical derivations are also presented for capturing the effects of temperature on sensor performance. Combining the developed analytical and numerical models, intricate properties of the sensor such as gate bias dependence of sensitivity, relationship between the required work-function modulation and subthreshold swing, counter-intuitive increase in threshold voltage for MOSFETs and reduction in tunneling probability for TFETs with temperature are explained. It is shown that TFET gas-sensors can not only lead to more than 10 000× increase in sensitivity but also provide design flexibility and immunity against screening of work-function modulation through non-specific gases as well as ensure stable operation under temperature variations.

Sarkar, Deblina; Gossner, Harald; Hansch, Walter; Banerjee, Kaustav

2013-01-01

187

Chemical dynamics in the gas phase : quantum mechanics of chemical reactions.  

SciTech Connect

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.

Gray, S. K.

1999-07-02

188

Exciton gas compression and metallic condensation in a single semiconductor quantum wire.  

PubMed

We study the metal-insulator transition in individual self-assembled quantum wires and report optical evidence of metallic liquid condensation at low temperatures. First, we observe that the temperature and power dependence of the single nanowire photoluminescence follow the evolution expected for an electron-hole liquid in one dimension. Second, we find novel spectral features that suggest that in this situation the expanding liquid condensate compresses the exciton gas in real space. Finally, we estimate the critical density and critical temperature of the phase transition diagram at n{c} approximately 1 x 10;{5} cm;{-1} and T{c} approximately 35 K, respectively. PMID:18764504

Alén, B; Fuster, D; Muñoz-Matutano, G; Martínez-Pastor, J; González, Y; Canet-Ferrer, J; González, L

2008-08-08

189

Quantum and Thermal Effects of Dark Solitons in a One-Dimensional Bose Gas  

SciTech Connect

We numerically study the imprinting and dynamics of dark solitons in a bosonic atomic gas in a tightly confined one-dimensional harmonic trap both with and without an optical lattice. Quantum and thermal fluctuations are synthesized within the truncated Wigner approximation in the quasicondensate description. We track the soliton coordinates and calculate position and velocity uncertainties. We find that the phase fluctuations lower the classically predicted soliton speed and seed instabilities. Individual runs show interactions of solitons with sound waves, splitting, and disappearing solitons.

Martin, A. D.; Ruostekoski, J. [School of Mathematics, University of Southampton, Southampton SO17 1BJ (United Kingdom)

2010-05-14

190

Hot and Cold Ideal Gases  

NSDL National Science Digital Library

The EJS Hot and Cold Ideal Gases model simulates the mixing of hot and cold two-dimensional ideal gases in a square box. This simulation can be used as part of the activity described in "The Statistical Interpretation of Entropy: An Activity" by Todd Timberlake, to be published in The Physics Teacher. In the model, one gas is initially confined to the left side of the box while the other gas is confined to the right side. An animation window shows the motion of the particles in the box, while an optional graph window plots the temperature of each side of the box, which is determined by measuring the average KE of the particles on each side. The initial number of particles and temperature on each side of the square can be changed and a button allows the user to reverse the particle velocities at any time. The user can modify this simulation if EJS is installed locally by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. EJS Hot and Cold Ideal Gases model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_entropy_HotAndColdIdealGases.jar file will run the program if Java is installed. EJS is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional EJS models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or EJS.

Timberlake, Todd

2010-07-01

191

Anisotropic scattering of elongated GaSb\\/GaAs quantum dots embedded near two-dimensional electron gas  

Microsoft Academic Search

Elongated GaSb\\/GaAs quantum dots (QDs) with a lateral aspect ratio of 2~3 is synthesized by the molecular beam epitaxy (MBE) with carefully controlling the Sb4 beam flux and As4 background pressure. These self-assembled quantum dots having geometrical anisotropy are embedded in the vicinity of the two-dimensional electron gas (2DEG). Anisotropic hall mobilities of the 2DEG under the helium temperature transport

Guodong Li; Chao Jiang; Hiroyuki Sakaki

2010-01-01

192

Ideal female brow aesthetics.  

PubMed

The concept of the ideal female eyebrow has changed over time. Modern studies examining youthful brow aesthetics are reviewed. An analysis of ideal female brow characteristics as depicted in the Western print media between 1945 and 2011 was performed. This analysis provided objective evidence that the ideal youthful brow peak has migrated laterally over time to lie at the lateral canthus. There has been a nonstatistically significant trend toward lower and flatter brows. These findings are discussed in relation to current concepts of female brow aging, with repercussions regarding endoscopic brow lift and aesthetic forehead surgery. PMID:23186765

Griffin, Garrett R; Kim, Jennifer C

2012-09-08

193

Itinerant Ferromagnetism of a Repulsive Atomic Fermi Gas: A Quantum Monte Carlo Study  

SciTech Connect

We investigate the phase diagram of a two-component repulsive Fermi gas at T=0 by means of quantum Monte Carlo simulations. Both purely repulsive and resonant attractive model potentials are considered in order to analyze the limits of the universal regime where the details of interatomic forces can be neglected. The equation of state of both balanced and unbalanced systems is calculated as a function of the interaction strength and the critical density for the onset of ferromagnetism is determined. The energy of the strongly polarized gas is calculated and parametrized in terms of the physical properties of repulsive polarons, which are relevant for the stability of the fully ferromagnetic state. Finally, we analyze the phase diagram in the interaction-polarization plane under the assumption that only phases with homogeneous magnetization can be produced.

Pilati, S.; Troyer, M. [Theoretische Physik, ETH Zurich, CH-8093 Zurich (Switzerland); Bertaina, G.; Giorgini, S. [Dipartimento di Fisica, Universita di Trento and INO-CNR BEC Center , I-38050 Povo, Trento (Italy)

2010-07-16

194

Eulerian and Newtonian dynamics of quantum particles  

NASA Astrophysics Data System (ADS)

We derive the classical equations of hydrodynamics (the Euler and continuity equations), from which the Schrödinger equation follows as a limit case. It is shown that the statistical ensemble corresponding to a quantum system and described by the Schrödinger equation can be considered an inviscid gas that obeys the ideal gas law with a quickly oscillating sign-alternating temperature. This statistical ensemble performs the complex movements consisting of smooth average movement and fast oscillations. It is shown that the average movements of the statistical ensemble are described by the Schrödinger equation. A model of quantum motion within the limits of classical mechanics that corresponds to the hydrodynamic system considered is suggested.

Rashkovskiy, S. A.

2013-06-01

195

Interacting Generalized Cosmic Chaplygin Gas in Loop Quantum Cosmology: A Singularity Free Universe  

NASA Astrophysics Data System (ADS)

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.

Chowdhury, Ratul; Rudra, Prabir

2013-02-01

196

Collective motions of a quantum gas confined in a harmonic trap  

NASA Astrophysics Data System (ADS)

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 ?c is invariant under a squeeze-type unitary transformation, which gives collective radial breathing motion of frequency 2?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?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.

Song, Dae-Yup

2005-08-01

197

Quantum Control of Femtochemistry in the Gas Phase, Liquid Phase and on Surfaces  

NASA Astrophysics Data System (ADS)

By using coherent control techniques we control the behavior of quantum systems on their natural fs-time scale by applying ultrashort coherent light fields in the wavelength range from the IR to the UV. These laser pulses can be variably shaped in space and time using a laser pulse shaper consisting of a liquid-crystal display [1]. Laser-optimized femtochemistry in the gas phase and liquid phase is one field in which this new technique is successfully employed. Automated optimization of branching ratios and total product yields of gas phase photodissociation reactions as well as chemically selective molecular excitation in the liquid phase is performed [2][3]. Structural changes of a molecule in the liquid phase have been controlled by laser-optimized photoisomerization of a cyanine dye molecule [4] and of retinal in bacteriorhodopsin [5]. So far, optimal control techniques have been restricted to gas phase and condensed phase optimization experiments. Recently we have demonstrated femtosecond laser-assisted catalytic reactions on a Pd(100) single crystal surface. By applying a closed-loop optimal control scheme, we manipulate these reactions and selectively optimize the ratio of different bond-forming reaction channels, in contrast to previous quantum control experiments aiming at bond-cleavage. The results represent a first step towards selective photocatalysis of molecules. [1] T. Baumert et al, Appl. Phys. B 65, 779 (1997) [2] A. Assion et al, Science 282, 919(1998); T. Brixner et al, J. Mod. Opt. 50, 539 (2003) [3] T. Brixner et al, Nature, Vol. 414, 57 (2001) and J. Chem. Phys. 118, 3692 (2003) [4] G. Krampert et al, Phys. Rev. Lett. 94, 068305 (2005) [5] G. Vogt et al, Chem. Phys. Lett. 433, 211 (2006) P. Nuernberger et al, Phys. Chem. Chem. Phys. 9, 2470 (2007)

Gerber, Gustav

2008-03-01

198

Assembling gas-phase reaction mechanisms for high temperature inorganic systems based on quantum chemistry calculations and reaction rate theories  

Microsoft Academic Search

Detailed chemical kinetic modeling based on computational quantum chemistry has been quite successful in making quantitative predictions about some systems, particularly the combustion of small hydrocarbons and certain areas of atmospheric chemistry. The gas phase chemistry of many processes in high-temperature inorganic systems, from materials synthesis to propulsion to waste incineration, could in principle be modeled with equal or greater

Mark T. Swihart

2005-01-01

199

Dual quantum cascade laser trace gas instrument with astigmatic Herriott cell at high pass number.  

PubMed

We have developed and demonstrated a high-sensitivity trace gas instrument employing two mid-infrared quantum cascade lasers and an astigmatic Herriott sample cell with up to a 240?m path length. Several aspects of astigmatic Herriott cell optics have been addressed to enable operation at a high pass number (up to 554), including aberrations and pattern selection to minimize interference fringes. The new instrument design, based on the 200?m cell, can measure various atmospheric trace gases, depending on the installed lasers, with multiple trace gases measured simultaneously. Demonstrated concentration noise levels (1?s average) are 40?parts per trillion [(ppt) 10(-12)] for formaldehyde, 10?ppt for carbonyl sulfide, 110?ppt for hydrogen peroxide (H2O2), and 180?ppt for nitrous acid (HONO). High-precision measurements of nitrous oxide and methane have been recorded at the same time as high-sensitivity measurements of HONO and H2O2. PMID:21283223

McManus, J Barry; Zahniser, Mark S; Nelson, David D

2011-02-01

200

First-principles method for impurities in quantum fluids: Positron in an electron gas  

NASA Astrophysics Data System (ADS)

We propose a first-principles methodology for calculating the behavior of isolated impurities immersed in quantum fluids. To obtain an accurate description of correlation effects between the impurity and the host, we work in the frame of reference in which the impurity is stationary, building on the work of C. H. Leung, M. J. Stott, and C. O. Almbladh [Phys. Lett. 57A, 26 (1976)]10.1016/0375-9601(76)90441-2. We apply our methodology to the case of a positron immersed in an electron gas. Our positron relaxation energies and annihilation rates are similar to those from the best existing many-body calculations. Our annihilating-pair momentum densities are significantly different from previous data and include a “tail” after the Fermi edge.

Drummond, N. D.; López Ríos, P.; Pickard, C. J.; Needs, R. J.

2010-07-01

201

Quantum nematic as ground state of a two-dimensional electron gas in a magnetic field  

NASA Astrophysics Data System (ADS)

We study the ground state of a nematic phase of the two-dimensional electron gas at filling fraction ?=1/2 using a variational wave function having Jastrow pair correlations of the form ?iquantum nematic is energetically favorable relative to the stripe ordered Wigner crystal phase.

Doan, Quoc M.; Manousakis, Efstratios

2007-05-01

202

Quaternions and ideal flows  

NASA Astrophysics Data System (ADS)

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.

Eshraghi, H.; Gibbon, J. D.

2008-08-01

203

Probing Three-Body Correlations in a Quantum Gas Using the Measurement of the Third Moment of Density Fluctuations  

SciTech Connect

We perform measurements of the third moment of atom number fluctuations in small slices of a very elongated weakly interacting degenerate Bose gas. We find a positive skewness of the atom number distribution in the ideal gas regime and a reduced skewness compatible with zero in the quasicondensate regime. For our parameters, the third moment is a thermodynamic quantity whose measurement constitutes a sensitive test of the equation of state, and our results are in agreement with a modified Yang-Yang thermodynamic prediction. Moreover, we show that the measured skewness reveals the presence of true three-body correlations in the system.

Armijo, J.; Jacqmin, T.; Bouchoule, I. [Laboratoire Charles Fabry, UMR 8501 du CNRS, Institut d'Optique, 91 127 Palaiseau Cedex (France); Kheruntsyan, K. V. [ARC Centre of Excellence for Quantum-Atom Optics, School of Mathematics and Physics, University of Queensland, Brisbane, Queensland 4072 (Australia)

2010-12-03

204

Probing three-body correlations in a quantum gas using the measurement of the third moment of density fluctuations.  

PubMed

We perform measurements of the third moment of atom number fluctuations in small slices of a very elongated weakly interacting degenerate Bose gas. We find a positive skewness of the atom number distribution in the ideal gas regime and a reduced skewness compatible with zero in the quasicondensate regime. For our parameters, the third moment is a thermodynamic quantity whose measurement constitutes a sensitive test of the equation of state, and our results are in agreement with a modified Yang-Yang thermodynamic prediction. Moreover, we show that the measured skewness reveals the presence of true three-body correlations in the system. PMID:21231431

Armijo, J; Jacqmin, T; Kheruntsyan, K V; Bouchoule, I

2010-11-30

205

Conductance quantization of an ideal Sharvin contact  

SciTech Connect

Thorough calculations of the conductance of an idealized quantum point contact are presented. The point contact is modelled as a configuration in which two conductive half-spaces are separated by a non-conductive planar screen with a circular window of a given radius a. The screen is considered as opaque for the electrons with the exception of the window. From the viewpoint of the electrical conduction, the half-spaces are interpreted as leads which are perfectly coalesced with one another across the window. We assume that the leads are reservoirs of a strongly degenerate gas of electrons. If the leads are made from an n-type degenerate semiconductor, the Fermi wavelength {lambda}{sub F} = 2{pi}/k{sub F} = 2{pi}/(3{pi}{sup 2}n){sup 1/3} may be tens of nanometers. The theory of the conductance {gamma}{sub S} of such a point contact is reconsidered. Within the framework of the approximation that we use assuming that T = 0, we show that the dependence of {gamma}{sub S} on the variable k{sub F}a manifests curved steps terminated by singular spikes. Owing to stochastic influences, the spikes should be seen as maxima in measured spectra. We predict that these maxima should demarcate the edges of the steps in the {gamma}{sub S} vs. k{sub F}a plot. This prediction is in agreement with the STM observations reported recently by Nagaoka et al. [K. Nagaoka, S. Yaginuma, T. Nagao, T. Nakayama, Phys. Rev. B. 74 (2006) 033310].

Bezak, Viktor [Department of Experimental Physics, Comenius University, 84248 Bratislava (Slovakia)], E-mail: bezak@fmph.uniba.sk

2007-11-15

206

Singlet oxygen in microporous silica xerogel: quantum yield and oxidation at the gas-solid interface.  

PubMed

The quantum yields of singlet oxygen ((1)O(2)) production (Phi(Delta)) and (1)O(2) lifetimes (tau(Delta)) at the gas-solid interface in silica gel material are determined. Different photosensitizers (PS) are encapsulated in parallelepipedic xerogel monoliths (PS-SG). PS were chosen according to their known photooxidation properties: 9,10-dicyanoanthracene (DCA), 9,10-anthraquinone (ANT), and a benzophenone derivative, 4-benzoyl benzoic acid (4BB). These experiments are mainly based on time-resolved (1)O(2) phosphorescence detection, and the obtained Phi(Delta) and tau(Delta) values are compared with those of a reference sensitizer for (1)O(2) production, 1H-phenalen-1-one (PN), included in the same xerogel. The trend between their ability to oxidize organic pollutants in the gas phase and their efficiency for (1)O(2) production is investigated through photooxidation experiments of a test pollutant dimethylsulfide (DMS). The Phi(Delta) value is high for DCA-SG relative to the PN reference, whereas it is slightly lower for 4BB-SG and for ANT-SG. Phi(Delta) is related to the production of sulfoxide and sulfone as the main oxidation products for DMS photosensitized oxidation. Additional mechanisms, leading to C--S bond cleaveage, appear to mainly occur for the less efficient singlet oxygen sensitizers 4BB-SG and ANT-SG. PMID:17948322

Cantau, Christophe; Pigot, Thierry; Manoj, Narayanapillai; Oliveros, Esther; Lacombe, Sylvie

2007-11-12

207

Quantum state-resolved gas/surface reaction dynamics probed by reflection absorption infrared spectroscopy  

NASA Astrophysics Data System (ADS)

We report the design and characterization of a new molecular-beam/surface-science apparatus for quantum state-resolved studies of gas/surface reaction dynamics combining optical state-specific reactant preparation in a molecular beam by rapid adiabatic passage with detection of surface-bound reaction products by reflection absorption infrared spectroscopy (RAIRS). RAIRS is a non-invasive infrared spectroscopic detection technique that enables online monitoring of the buildup of reaction products on the target surface during reactant deposition by a molecular beam. The product uptake rate obtained by calibrated RAIRS detection yields the coverage dependent state-resolved reaction probability S(?). Furthermore, the infrared absorption spectra of the adsorbed products obtained by the RAIRS technique provide structural information, which help to identify nascent reaction products, investigate reaction pathways, and determine branching ratios for different pathways of a chemisorption reaction. Measurements of the dissociative chemisorption of methane on Pt(111) with this new apparatus are presented to illustrate the utility of RAIRS detection for highly detailed studies of chemical reactions at the gas/surface interface.

Chen, Li; Ueta, Hirokazu; Bisson, Régis; Beck, Rainer D.

2013-05-01

208

Quantum state-resolved gas/surface reaction dynamics probed by reflection absorption infrared spectroscopy.  

PubMed

We report the design and characterization of a new molecular-beam/surface-science apparatus for quantum state-resolved studies of gas/surface reaction dynamics combining optical state-specific reactant preparation in a molecular beam by rapid adiabatic passage with detection of surface-bound reaction products by reflection absorption infrared spectroscopy (RAIRS). RAIRS is a non-invasive infrared spectroscopic detection technique that enables online monitoring of the buildup of reaction products on the target surface during reactant deposition by a molecular beam. The product uptake rate obtained by calibrated RAIRS detection yields the coverage dependent state-resolved reaction probability S(?). Furthermore, the infrared absorption spectra of the adsorbed products obtained by the RAIRS technique provide structural information, which help to identify nascent reaction products, investigate reaction pathways, and determine branching ratios for different pathways of a chemisorption reaction. Measurements of the dissociative chemisorption of methane on Pt(111) with this new apparatus are presented to illustrate the utility of RAIRS detection for highly detailed studies of chemical reactions at the gas/surface interface. PMID:23742561

Chen, Li; Ueta, Hirokazu; Bisson, Régis; Beck, Rainer D

2013-05-01

209

Three-Level Maser Action in Gas I. Theory of Multiple Quantum Transition and Doppler Effect in Three-Level Gas Maser  

Microsoft Academic Search

The multiple quantum process in the off-resonant condition of the three-level gas maser is discussed. The intensity of the emission produced by this process is calculated by a perturbation theory and also by a more general treatment which is the application of Javan's theory to the off-resonant case. Some graphical representations of the signal line under off-resonant pumping are given

Tatsuo Yajima

1961-01-01

210

Short range scattering mechanism of type-II GaSb\\/GaAs quantum dots on the transport properties of two-dimensional electron gas  

Microsoft Academic Search

We have studied the scattering process of AlGaAs\\/GaAs two-dimensional electron gas with the nearby embedded GaSb\\/GaAs type-II quantum dots (QDs) at low temperature. Quantum Hall effect and Shubnikov-de Haas oscillation were performed to measure the electron density n2D, the transport lifetime taut, and the quantum lifetime tauq under various biased gate voltage. By comparing measured results of QDs sample with

Guodong Li; Hong Yin; Qinsheng Zhu; Hiroyuki Sakaki; Chao Jiang

2010-01-01

211

Molecular simulation of hydrogen adsorption in single-walled carbon nanotubes and idealized carbon slit pores  

NASA Astrophysics Data System (ADS)

The adsorption of hydrogen gas into single-walled carbon nanotubes (SWNTs) and idealized carbon slit pores is studied by computer simulation. Hydrogen-hydrogen interactions are modeled with the Silvera-Goldman potential. The Crowell-Brown potential is used to model the hydrogen-carbon interactions. Calculations include adsorption inside the tubes, in the interstitial regions of tube arrays, and on the outside surface of isolated tubes. Quantum effects are included through implementation of the path integral formalism. Comparison with classical simulations gives an indication of the importance of quantum effects for hydrogen adsorption. Quantum effects are important even at 298 K for adsorption in tube interstices. We compare our simulations with experimental data for SWNTs, graphitic nanofibers, and activated carbon. Adsorption isotherms from simulations are in reasonable agreement with experimental data for activated carbon, but do not confirm the large uptake reported for SWNTs and nanofibers. Although the adsorption potential for hydrogen in SWNTs is enhanced relative to slit pores of the same size, our calculations show that the storage capacity of an array of tubes is less than that for idealized slit pore geometries, except at very low pressures. Ambient temperature isotherms indicate that an array of nanotubes is not a suitable sorbent material for achieving DOE targets for vehicular hydrogen storage.

Wang, Qinyu; Johnson, J. Karl

1999-01-01

212

Ideal polyethylene nanocrystals.  

PubMed

The water-soluble catalyst precursor [[(2,4,6-(3,5-(CF3)2C6H3)3-C6H2)-N?C(H)-(3-(9-anthryl)-2-O-C6H3)-?(2)-N,O]Ni(CH3)(TPPTS)] (TPPTS = tri(sodiumphenylsulfonate)phosphine) polymerizes ethylene to aqueous dispersions of highly ordered nanoscale crystals (crystallinity ?(DSC) ? 90%) of strictly linear polyethylene (<0.7 methyl-branches/1000 carbon atoms, Mn = 4.2 × 10(5) g mol(-1)). SAXS in combination with cryo-TEM confirms this unusually high degree of order (?(SAXS) = 82%) and shows the nanoparticles to possess a very thin amorphous layer on the crystalline lamella, just sufficient to accommodate a loop, but likely no entanglements. This ideal chain-folded structure is corroborated by annealing studies on the aqueous-dispersed nanoparticles, which show that the chain can move through the crystal as evidenced by lamella thickening without disturbing the crystalline order as concluded from an unaltered low thickness of the amorphous layers. These ideal chain-folded polyethylene nanocrystals arise from the crystallization in the confined environment of a nanoparticle and a deposition of the growing polymer chain on the crystal growth front as the chain is formed by the catalyst. PMID:23855756

Osichow, Anna; Rabe, Christian; Vogtt, Karsten; Narayanan, Theyencheri; Harnau, Ludger; Drechsler, Markus; Ballauff, Matthias; Mecking, Stefan

2013-07-26

213

Unified theory of ideals  

NASA Astrophysics Data System (ADS)

Unified field theories try to merge the internal symmetries of the standard model into a single group. Here we lay out something different. We give evidence that a theory may be ultraunified; that is, beyond aiming to unify the internal symmetries into a single group, those groups may be unified together with the quarks and leptons that they act on. Furthermore, the (3+1) Lorentz transformations may likewise be unified with the scalars, spinors, four-vectors, and field strength tensors that they act on. These simplifications occur because the representations can be found in the form of an algebra acting on itself. The approach described in this paper is meant to tie everything into the Dixon algebra: R?C?H?O, the tensor product of the division algebras, whose connection to the standard model was earlier advocated for in Dixon [Division Algebras: Octonions, Quaternions, Complex Numbers and the Algebraic Design of Physics (Kluwer Academic Publishers, Dordrecht, 1994).]. Here we propose a principle of ideals, which states that particle sectors of the standard model are given by generalized ideals of the algebra. As we show, this method very quickly uncovers all of the Lorentz representations of the standard model and one full generation of quarks and leptons.

Furey, Cohl

2012-07-01

214

Molecular structure of tris(cyclopropylsilyl)amine as determined by gas electron diffraction and quantum-chemical calculations  

Microsoft Academic Search

The molecular structure and conformation of tris(cyclopropylsilyl)amine (TCPSA) has been studied by means of gas-phase electron diffraction at 338K and quantum-chemical calculations. A total of 12 relatively stable conformations of TCPSA molecule were considered. According to the experimental results and the DFT calculations the most stable conformer corresponds to a configuration (according to the Prelog–Klyne notation) of the type (?ac)(?ac)(+ac)-(?ac)(?ac)(+ac),

Yuri V. Vishnevskiy; Maxim A. Abaev; Arkadii A. Ivanov; Lev V. Vilkov; Marwan Dakkouri

2008-01-01

215

The structure and conformations of piracetam (2-oxo-1-pyrrolidineacetamide): Gas-phase electron diffraction and quantum chemical calculations  

Microsoft Academic Search

The geometric structure of piracetam was studied by quantum chemical calculations (DFT and ab initio), gas electron diffraction (GED), and FTIR spectroscopy. Two stable mirror symmetric isomers of piracetam were found. The conformation of pyrrolidine ring is an envelope in which the C4 atom deviates from the ring plane, the angle between the planes (C3C4C5) and (C2C3C5) is 154.1°. The

Denis N. Ksenafontov; Natalia F. Moiseeva; Lyudmila V. Khristenko; Nikolai M. Karasev; Igor F. Shishkov; Lev V. Vilkov

2010-01-01

216

All-Optical Production of a Lithium Quantum Gas Using Narrow-Line Laser Cooling  

NASA Astrophysics Data System (ADS)

We have used the narrow 2S1/2->3P3/2 transition in the ultraviolet (UV) to laser cool and magneto-optically trap (MOT) ^6Li atoms.ootnotetextP. M. Duarte et al., Phys. Rev. A 84, 061406 (2011). Laser cooling of lithium is usually performed on the 2S1/2->3P3/2 (D2) transition, and temperatures of ˜300 ?K are typically achieved. The linewidth of the UV transition is seven times narrower than the D2 line, resulting in lower laser cooling temperatures. We demonstrate that a MOT operating on the UV transition reaches temperatures as low as 59 ?K. Furthermore, we find that the light shift of the UV transition in an optical dipole trap at 1070 nm is small and blue-shiftedootnotetextM. Safronova, Personal Communication., facilitating efficient loading from the UV MOT. After loading from the UV MOT, 6 x10^6 atoms with peak density n0=2.7x10^13 ,-3 remain at T=60,K, which corresponds to T/TF 2.7. Evaporative cooling of a two spin-state mixture of ^6Li in the optical trap produces a quantum degenerate Fermi gas with 3 x10^6 atoms in only 5 s.

Yang, Tsung-Lin; Duarte, Pedro M.; Hart, Russell A.; Hulet, Randall G.

2012-06-01

217

All-optical production of a lithium quantum gas using narrow-line laser cooling  

NASA Astrophysics Data System (ADS)

We have used the narrow 2S1/2?3P3/2 transition in the ultraviolet (uv) to laser cool and magneto-optically trap (MOT) 6Li atoms. Laser cooling of lithium is usually performed on the 2S1/2?2P3/2 (D2) transition, and temperatures of ˜300 ?K are typically achieved. The linewidth of the uv transition is seven times narrower than the D2 line, resulting in lower laser cooling temperatures. We demonstrate that a MOT operating on the uv transition reaches temperatures as low as 59 ?K. Furthermore, we find that the light shift of the uv transition in an optical dipole trap at 1070 nm is small and blueshifted, facilitating efficient loading from the uv MOT. Evaporative cooling of a two spin-state mixture of 6Li in the optical trap produces a quantum degenerate Fermi gas with 3×106 atoms in a total cycle time of only 11 s.

Duarte, P. M.; Hart, R. A.; Hitchcock, J. M.; Corcovilos, T. A.; Yang, T.-L.; Reed, A.; Hulet, R. G.

2011-12-01

218

Enhancing Otto-Mobile Efficiency via Addition of a Quantum Carnot Cycle  

NASA Astrophysics Data System (ADS)

It was shown recently that one can improve the efficiency of the Otto cycle by taking advantage of the internal degrees of freedom of an ideal gas [M. O. Scully, “The Quantum Afterburner”, Phys. Rev. Lett., to be published]. Here we discuss the limiting improvement of the efficiency by considering reversible cycles with both internal and external degrees of freedom.

Opatrný, Tomáš; Scully, Marlan O.

2003-09-01

219

Gröbner Bases and Determinantal Ideals  

Microsoft Academic Search

\\u000a We give an introduction to the theory of determinantal ideals and rings, their Grobner bases, initial ideals and algebras,\\u000a respectively. The approach is based on the straightening law and the Knuth-Robinson-Schensted correspondence. The article\\u000a contains a section treating the basic results about the passage to initial ideals and algebras.

Winfried Bruns; ALDO CONCA

2003-01-01

220

Photoelectron spectroscopy of CdSe nanocrystals in the gas phase: a direct measure of the evanescent electron wave function of quantum dots.  

PubMed

We present the first photoelectron spectroscopy measurements of quantum dots (semiconductor nanocrystals) in the gas phase. By coupling a nanoparticle aerosol source to a femtosecond velocity map imaging photoelectron spectrometer, we apply robust gas-phase photoelectron spectroscopy techniques to colloidal quantum dots, which typically must be studied in a liquid solvent or while bound to a surface. Working with a flowing aerosol of quantum dots offers the additional advantages of providing fresh nanoparticles for each laser shot and removing perturbations from bonding with a surface or interactions with the solvent. In this work, we perform a two-photon photoionization experiment to show that the photoelectron yield per exciton depends on the physical size of the quantum dot, increasing for smaller dots. Next, using effective mass modeling we show that the extent to which the electron wave function of the exciton extends from the quantum dot, the so-called "evanescent electron wavefunction", increases as the size of the quantum dot decreases. We show that the photoelectron yield is dominated by the evanescent electron density due to quantum confinement effects, the difference in the density of states inside and outside of the quantum dots, and the angle-dependent transmission probability of electrons through the surface of the quantum dot. Therefore, the photoelectron yield directly reflects the fraction of evanescent electron wave function that extends outside of the quantum dot. This work shows that gas-phase photoelectron spectroscopy is a robust and general probe of the electronic structure of quantum dots, enabling the first direct measurements of the evanescent exciton wave function. PMID:23688290

Xiong, Wei; Hickstein, Daniel D; Schnitzenbaumer, Kyle J; Ellis, Jennifer L; Palm, Brett B; Keister, K Ellen; Ding, Chengyuan; Miaja-Avila, Luis; Dukovic, Gordana; Jimenez, Jose L; Murnane, Margaret M; Kapteyn, Henry C

2013-05-22

221

The ideal physician entrepreneur.  

PubMed

How does the sometimes elusive and high-stakes world of venture capital really work? How can physician executives with innovative ideas or new technologies approach venture capitalists to help them raise capital to form a start-up company? These important questions are explored in this new column on the physician as entrepreneur. The ideal physician executive is described as: (1) an expert in an area that Wall Street perceives as hot; (2) a public speaker who can enthusiastically communicate scientific and business plans to a variety of audiences; (3) a team leader who is willing to share equity in the company with other employees; (4) a recruiter and a motivator; (5) an implementer who can achieve milestones quickly that allow the company to go public as soon as possible; and (6) a realist who does not resent the terms of the typical deal. The lucrative world of the venture capitalists is foreign territory for physician executives and requires a great idea, charisma, risk-taking, connections, patience, and perseverance to navigate it successfully. PMID:11187408

Bottles, K

222

Electrostatic modulation of periodic potentials in a two-dimensional electron gas: from antidot lattice to quantum dot lattice  

NASA Astrophysics Data System (ADS)

We use a dual gated device structure to introduce a gate-tunable periodic potential in a GaAs/AlGaAs two dimensional electron gas (2DEG). Using a suitable choice of gate voltages we can controllably alter the potential landscape in the 2DEG, thereby inducing either a periodic array of antidots or quantum dots. Antidots are artificial scattering centers, and therefore allow for a study of electron dynamics. On the other hand, a quantum dot lattice provides the opportunity to study correlated electron physics. We use a variety of electrical measurements such as magneto-resistance, thermo-voltage and current-voltage characteristics to probe these two contrasting regimes.

Goswami, Srijit; Aamir, Mohammad Ali; Shamim, Saquib; Siegert, Christoph; Pepper, Michael; Farrer, Ian; Ritchie, David; Ghosh, Arindam

2012-02-01

223

Space Sciences and Idealism  

NASA Astrophysics Data System (ADS)

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.

Popov, M.

224

Ideals of generalized matrix rings  

SciTech Connect

Let R and S be rings, and {sub R}M{sub S} and {sub S}N{sub R} bimodules. In the paper, in terms of isomorphisms of lattices, relationships between the lattices of one-sided and two-sided ideals of the generalized matrix ring and the corresponding lattices of ideals of the rings R and S are described. Necessary and sufficient conditions for a pair of ideals I, J of rings R and S, respectively, to be the main diagonal of some ideal of the ring K are also obtained. Bibliography: 8 titles.

Budanov, Aleksandr V [Tomsk State University, Tomsk (Russian Federation)

2011-01-31

225

Energy partitioning in polyatomic chemical reactions: Quantum state resolved studies of highly exothermic atom abstraction reactions from molecules in the gas phase and at the gas-liquid interface  

Microsoft Academic Search

This thesis recounts a series of experiments that interrogate the dynamics of elementary chemical reactions using quantum state resolved measurements of gas-phase products. The gas-phase reactions F + HCl --> HF + Cl and F + H2O --> HF + OH are studied using crossed supersonic jets under single collision conditions. Infrared (IR) laser absorption probes HF product with near

Alexander M. Zolot

2009-01-01

226

Tunable Interactions in Quantum Degenerate Lithium  

NASA Astrophysics Data System (ADS)

Quantum degenerate gases provide an ideal environment for studying fundamental physics. In these systems, a Feshbach resonance can be utilized to tune the interactions between certain colliding pairs of atoms, yielding control over both the magnitude and sign of the interactions. This has opened the doorway to a new area in which the underlying physics of non-linear optical phenomena and many solid-state effects can be explored in the ideal environment of a quantum degenerate gas. We will first discuss the experimental realization of a quantum degenerate Bose-Fermi mixture via sympathetic cooling [truscott01]. By confining this quantum degenerate gas in an all optical potential, the atom-atom interactions of the bosons can be manipulated to produce bright matter-wave solitons [strecker02] which are individual Bose-Einstein condensates (BEC) that we have observed to propagate for over 3 seconds without dispersion. Further, a highly interacting Fermi gas can be produced near a Feshbach resonance, and through manipulation of the external magnetic field, long lived ultra-cold bosonic molecules can be formed from the Fermi gas [strecker03]. The unexpected long lifetime of these vibrationally excited (v' = 38) molecules enables them to be evaporatively cooled to a molecular BEC. We use a pure molecular condensate as a probe of the BEC/BCS crossover region within the broad Feshbach resonance. Using an interrogation laser tuned to a bound-bound molecular resonance, the deeply bound molecular component of the gas is measured as a function of magnetic field, probing the fundamental many-body physics of a strongly interacting Fermi gas. [truscott01] A. G. Truscott, K. E. Strecker, W. I. McAlexander, G. B. Patridge, and R. G. Hulet, Science 291, 2570 (2001). [strecker02] K. E. Strecker, G. B. Partridge, A. G. Truscott, and R.G Hulet, Nature 417, 150 (2002). [strecker03] K. E. Strecker, G. B. Partridge and R. G. Hulet, Phys Rev. Lett. 91, 080406 (2003).

Strecker, Kevin

2005-05-01

227

Quantum memory Quantum memory  

NASA Astrophysics Data System (ADS)

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.

Le Gouët, Jean-Louis; Moiseev, Sergey

2012-06-01

228

The influence of molecular complexity on expanding flows of ideal and dense gases  

Microsoft Academic Search

This paper presents an investigation about the effect of the complexity of a fluid molecule on the fluid dynamic quantities sound speed, velocity, and Mach number in isentropic expansions. Ideal-gas and dense-gas expansions are analyzed, using the polytropic ideal gas and Van der Waals thermodynamic models to compute the properties of the fluid. In these equations, the number of active

J. Harinck; A. Guardone; P. Colonna

2009-01-01

229

Coherent quantum transport in two-dimensional electron gas/superconductor double junctions with Rashba spin-orbit coupling  

NASA Astrophysics Data System (ADS)

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.

Bai, C.; Yang, Y.-L.; Zhang, X.-D.

2008-09-01

230

Direct observation of quantum phonon fluctuations in a one-dimensional Bose gas.  

PubMed

We report the first direct observation of collective quantum fluctuations in a continuous field. Shot-to-shot atom number fluctuations in small subvolumes of a weakly interacting, ultracold atomic 1D cloud are studied using in situ absorption imaging and statistical analysis of the density profiles. In the cloud centers, well in the quantum quasicondensate regime, the ratio of chemical potential to thermal energy is ?/k(B)T?4, and, owing to high resolution, up to 20% of the microscopically observed fluctuations are quantum phonons. Within a nonlocal analysis at variable observation length, we observe a clear deviation from a classical field prediction, which reveals the emergence of dominant quantum fluctuations at short length scales, as the thermodynamic limit breaks down. PMID:23003615

Armijo, Julien

2012-06-01

231

Femtosecond pump-probe spectroscopy of I2 in a dense rare gas environment: a mixed quantum/classical study of vibrational decoherence.  

PubMed

The process of decoherence of vibrational states of I2 in a dense helium environment is studied theoretically using the mixed quantum/classical method based on the Bohmian formulation of quantum mechanics [E. Gindensperger, C. Meier, and J. A. Beswick, J. Chem. Phys. 113, 9369 (2000)]. Specifically, the revival of vibrational wave packets is a quantum phenomena which depends sensitively on the coherence between the vibrational states excited by an ultrafast laser pulse. Its detection by a pump-probe setup as a function of rare gas pressure forms a very accurate way of detecting vibrational dephasing. Vibrational revivals of I2 in high pressure rare gas environments have been observed experimentally, and the very good agreement with the simulated spectra confirms that the method can accurately describe decoherence processes of quantum systems in interaction with an environment. PMID:15332885

Meier, C; Beswick, J A

2004-09-01

232

Quantum partition functions from classical distributions: Application to rare-gas clusters  

NASA Astrophysics Data System (ADS)

We investigate the thermodynamic behavior of quantum many-body systems using several methods based on classical calculations. These approaches are compared for the melting of Lennard-Jones (LJ) clusters, where path-integral Monte Carlo (PIMC) results are also available. First, we examine two quasiclassical approaches where the classical potential is replaced by effective potentials accounting for quantum corrections of low order in ?. Of the Wigner-Kirkwood and Feynman-Hibbs effective potentials, only the latter is found to be in quantitative agreement with quantum simulations. However, both potentials fail to describe even qualitatively the low-temperature regime, where quantum effects are strong. Our second approach is based on the harmonic superposition approximation, but with explicit quantum oscillators. In its basic form, this approach is in good qualitative agreement with PIMC results, and becomes more accurate at low temperatures. By including anharmonic corrections in the form of temperature-dependent frequency shifts, the agreement between the quantum superposition and the PIMC results becomes quantitative for the caloric curve of neon clusters. The superposition method is then applied to larger clusters to study the influence of quantum delocalization on the melting and premelting of LJ19, LJ31, LJ38, and LJ55. The quantum character strongly affects the thermodynamics via changes in the ground state structure due to increasing zero-point energies. Finally, we focus on the lowest temperature range, and we estimate the Debye temperatures of argon clusters and their size variation. A strong sensitivity to the cluster structure is found, especially when many surface atoms reorganize as in the anti-Mackay/Mackay transition. In the large size regime, the Debye temperature smoothly rises to its bulk limit, but still depends slightly on the growth sequence considered.

Calvo, F.; Doye, J. P. K.; Wales, D. J.

2001-05-01

233

The Boltzmann Equation for a One-Dimensional Quantum Lorentz Gas  

Microsoft Academic Search

:  We study the macroscopic behavior of a quantum particle under the action of randomly distributed scatterers on the real line.\\u000a Each scatterer generates a ?-potential. We prove that, in the low density limit, the Wigner function of the system converges\\u000a to a probability distribution satisfying a classical linear Boltzmann equation, with a scattering cross section computed according\\u000a to the Quantum

R. Esposito; M. Pulvirenti; A. Teta

1999-01-01

234

The Confucian ideal of harmony  

Microsoft Academic Search

He ? (harmony, harmonization) is probably the most cherished ideal in Chinese culture. Unfortunately, given its significance, it is arguably also the most understudied. It is therefore high time for some serious study of this ideal. This essay focuses on the Confucian tradition. It first explores the meaning of the Confucian notion of he; then it provides a philosophical analysis

Chenyang Li

2006-01-01

235

Selecting the ideal landfill site  

Microsoft Academic Search

The number of active landfills has decreased by nearly 3000 since 1984 as sites have run out of space and cannot be upgraded to meet tough new environmental requirements. How is the ideal landfill site defined This paper discusses the numerous considerations which would categorize an ideal landfill site. These include deep soils with low hydraulic conductivity; abundant workable soils

1989-01-01

236

Re-entrant behavior of the ?=4\\/3 fractional quantum Hall effect in a front-and-back-gated 2D hole gas  

Microsoft Academic Search

The fractional quantum Hall (FQH) effect of a two-dimensional hole gas has been studied in a modulation-doped quantum well (QW) with front and back gates. We found that the ?=4\\/3 state shows intriguing re-entrant behavior; as the hole density was varied with the front gate, the ?=4\\/3 state was observed to weaken in two regions of magnetic field. Temperature-dependent measurements

K. Muraki; Y. Hirayama

1998-01-01

237

Sub-Poissonian fluctuations in a 1D Bose gas: from the quantum quasicondensate to the strongly interacting regime.  

PubMed

We report on local, in situ measurements of atom number fluctuations in slices of a one-dimensional Bose gas on an atom chip setup. By using current modulation techniques to prevent cloud fragmentation, we are able to probe the crossover from weak to strong interactions. For weak interactions, fluctuations go continuously from super- to sub-Poissonian as the density is increased, which is a signature of the transition between the subregimes where the two-body correlation function is dominated, respectively, by thermal and quantum contributions. At stronger interactions, the super-Poissonian region disappears, and the fluctuations go directly from Poissonian to sub-Poissonian, as expected for a "fermionized" gas. PMID:21770488

Jacqmin, Thibaut; Armijo, Julien; Berrada, Tarik; Kheruntsyan, Karen V; Bouchoule, Isabelle

2011-06-10

238

Sub-Poissonian Fluctuations in a 1D Bose Gas: From the Quantum Quasicondensate to the Strongly Interacting Regime  

SciTech Connect

We report on local, in situ measurements of atom number fluctuations in slices of a one-dimensional Bose gas on an atom chip setup. By using current modulation techniques to prevent cloud fragmentation, we are able to probe the crossover from weak to strong interactions. For weak interactions, fluctuations go continuously from super- to sub-Poissonian as the density is increased, which is a signature of the transition between the subregimes where the two-body correlation function is dominated, respectively, by thermal and quantum contributions. At stronger interactions, the super-Poissonian region disappears, and the fluctuations go directly from Poissonian to sub-Poissonian, as expected for a ''fermionized'' gas.

Jacqmin, Thibaut; Armijo, Julien; Bouchoule, Isabelle [Laboratoire Charles Fabry, Institut d'Optique, UMR8501 du CNRS, 91127 Palaiseau Cedex (France); Berrada, Tarik [Laboratoire Charles Fabry, Institut d'Optique, UMR8501 du CNRS, 91127 Palaiseau Cedex (France); Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, 1020 Vienna (Austria); Kheruntsyan, Karen V. [School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072 (Australia)

2011-06-10

239

Density Fluctuations in Uniform Quantum Gases  

SciTech Connect

Analytical expressions are given for the static structure factor S(k) and the pair correlation function g(r) for uniform ideal Bose-Einstein and Fermi-Dirac gases for all temperatures. In the vicinity of Bose Einstein condensation (BEC) temperature, g(r) becomes long ranged and remains so in the condensed phase. In the dilute gas limit, g(r) of bosons and fermions do not coincide with Maxwell-Boltzmann gas but exhibit bunching and anti-bunching effect respectively. The width of these functions depends on the temperature and is scaled as {radical}(inverse atomic mass). Our numerical results provide the precise quantitative values of suppression/increase (antibunching and bunching) of the density fluctuations at small distances in ideal quantum gases in qualitative agreement with the experimental observation for almost non-trapped dilute gases.

Bosse, J. [Institute for Theoretical Physics, Freie Universitaet Berlin (Germany); Pathak, K. N. [Department of Physics, Panjab University, Chandigarh (India); Singh, G. S. [Department of Physics, Indian Institute of Technology, Roorkee (India)

2011-12-12

240

Remarks on the thermodynamics and the vacuum energy of a quantum Maxwell gas on compact and closed manifolds  

NASA Astrophysics Data System (ADS)

The quantum Maxwell theory at finite temperature at equilibrium is studied on compact and closed manifolds in both the functional integral and Hamiltonian formalism. The aim is to shed some light onto the interrelation between the topology of the spatial background and the thermodynamic properties of the system. The quantization is not unique and gives rise to inequivalent quantum theories which are classified by ?-vacua. Based on explicit parametrizations of the gauge orbit space in the functional integral approach and of the physical phase space in the canonical quantization scheme, the Gribov problem is resolved and the equivalence of both quantization schemes is elucidated. Using zeta-function regularization the free energy is determined and the effect of the topology of the spatial manifold on the vacuum energy and on the thermal gauge field excitations is clarified. The general results are then applied to a quantum Maxwell gas on an n-dimensional torus providing explicit formulae for the main thermodynamic functions in the low- and high-temperature regimes, respectively.

Kelnhofer, Gerald

2013-02-01

241

Structure and conformational properties of N-pentafluorosulfur(sulfuroxide difluoride imide) SF5N=S(O)F2: vibrational analysis, gas electron diffraction, and quantum chemical calculations.  

PubMed

The molecular structure and conformational properties of N-pentafluorosulfur(sulfuroxide difluoride imide), SF5N=S(O)F2, have been studied by vibrational spectroscopy (IR (gas) and Raman (liquid)), by gas electron diffraction (GED), and by quantum chemical calculations (MP2 and B3LYP with (6-31G(d) and 6-311+G(2df) basis sets). According to GED, the prevailing conformer possesses a syn structure (N-SF5 bond synperiplanar with respect to the bisector of the SF2 group). Splitting of the symmetric N=S=O stretching vibration in gas and liquid spectra demonstrates the presence of a second conformer (11(5)%) with anticlinal orientation of the N-SF5 bond according to quantum chemical calculations. The geometric structure, conformational properties, and vibrational frequencies are well reproduced by quantum chemical calculations. PMID:17388270

Alvarez, Rosa M S; Cutin, Edgardo H; Mews, Rüdiger; Oberhammer, Heinz

2007-02-23

242

Dicke quantum phase transition with a superfluid gas in an optical cavity.  

PubMed

A phase transition describes the sudden change of state of a physical system, such as melting or freezing. Quantum gases provide the opportunity to establish a direct link between experiments and generic models that capture the underlying physics. The Dicke model describes a collective matter-light interaction and has been predicted to show an intriguing quantum phase transition. Here we realize the Dicke quantum phase transition in an open system formed by a Bose-Einstein condensate coupled to an optical cavity, and observe the emergence of a self-organized supersolid phase. The phase transition is driven by infinitely long-range interactions between the condensed atoms, induced by two-photon processes involving the cavity mode and a pump field. We show that the phase transition is described by the Dicke Hamiltonian, including counter-rotating coupling terms, and that the supersolid phase is associated with a spontaneously broken spatial symmetry. The boundary of the phase transition is mapped out in quantitative agreement with the Dicke model. Our results should facilitate studies of quantum gases with long-range interactions and provide access to novel quantum phases. PMID:20428162

Baumann, Kristian; Guerlin, Christine; Brennecke, Ferdinand; Esslinger, Tilman

2010-04-29

243

Monitoring derivation of the quantum linear Boltzmann equation  

SciTech Connect

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.

Hornberger, Klaus; Vacchini, Bassano [Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universitaet Muenchen, Theresienstrasse 37, 80333 Munich (Germany); Dipartimento di Fisica, Universita di Milano and INFN Sezione di Milano, Via Celoria 16, 20133 Milano (Italy)

2008-02-15

244

Vortex Quantum Creation and Winding Number Scaling in a Quenched Spinor Bose Gas  

SciTech Connect

Motivated by a recent experiment, we study nonequilibrium quantum phenomena taking place in the quench of a spinor Bose-Einstein condensate through the zero-temperature phase transition separating the polar paramagnetic and planar ferromagnetic phases. We derive the typical spin domain structure (correlations of the effective magnetization) created by the quench arising due to spin-mode quantum fluctuations, and we establish a sample-size scaling law for the creation of spin vortices, which are topological defects in the transverse magnetization.

Uhlmann, Michael; Schuetzhold, Ralf [Institut fuer Theoretische Physik, Technische Universitaet Dresden, D-01062 Dresden (Germany); Fischer, Uwe R. [Eberhard-Karls-Universitaet Tuebingen, Institut fuer Theoretische Physik, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2007-09-21

245

Dielectric-environment mediated quantum screening of two-dimensional electron gas  

NASA Astrophysics Data System (ADS)

Electronic screening is a many-body phenomenon that strongly depends on the electron-electron interaction in an electron gas. Here, relaxing the assumption of ``infinite and homogeneous background,'' we show that the dielectric environment surrounding the electron gas alters the electron-electron interaction leading to substantial re-normalization of static and dynamic response of the electron gas. The re-normalization of static screening function by dielectric environment impacts experimentally measurable mobility as shown for Si-inversion layer for illustration. Results are analytical and can be used for accurate prediction of transport quantity for any two dimensional gas system with inhomogeneous dielectric environment.

Konar, Aniruddha; Bajaj, Mohit; Pandey, Rajan K.; Murali, K. V. R. M.

2013-09-01

246

A quantum mechanical model of interference  

Microsoft Academic Search

In this paper an ideal quantum mechanical model of interference is constructed, in particular, the role of the quantum mechanical phase difference of two harmonic modes on the interference picture is investigated.

A. Shalom; J. Zak

1973-01-01

247

Heterodyne gas cell measurements at 2.9 THz using a quantum cascade laser as local oscillator  

NASA Astrophysics Data System (ADS)

High-resolution heterodyne spectrometers operating at above 2 THz are crucial for detecting, e.g., the HD line at 2.7 THz and oxygen OI line at 4.7 THz in astronomy. The potential receiver technology is a combination of a hot electron bolometer (HEB) mixer and a THz quantum cascade laser (QCL) local oscillator (LO).Here we report the first highresolution heterodyne spectroscopy measurement of a gas cell using such a HEB-QCL receiver. The receiver employs a 2.9 THz free-running QCL as local oscillator and a NbN HEB as a mixer. By using methanol (CH3OH) gas as a signal source, we successfully recorded the methanol emission line at 2.92195 THz. Spectral lines at IF frequency at different pressures were measured using a FFTS and well fitted with a Lorentzian profile. Our gas cell measurement is a crucial demonstration of the QCL as LO for practical heterodyne instruments. Together with our other experimental demonstrations, such as using a QCL at 70 K to operate a HEB mixer and the phase locking of a QCL such a receiver is in principle ready for a next step, which is to build a real instrument for any balloon-, air-, and space-borne observatory.

Ren, Y.; Gao, J. R.; Hovenier, J. N.; Higgins, R.; Zhang, W.; Bell, A.; Klein, B.; Klapwijk, T. M.; Shi, S. C.; Kao, T.-Y.; Kumar, S.; Hu, Q.; Reno, J. L.

2010-07-01

248

Detonation Failure in Ideal and Non-Ideal Explosives  

NASA Astrophysics Data System (ADS)

In this paper we revisit and extend the classic treatment of detonation failure developed by Eyring et al. [1]. We recently published a development of this theory [2] in which a pressure dependant rate law was substituted for the Arrhenius temperature dependant law originally considered. Here we show that by assuming a 2-component rate law based upon a temperature dependant ignition phase and a pressure dependant growth phase we are able to rationalise the very different failure characteristics (critical diameter and velocity decrement at failure) of ideal and non-ideal explosives.

Haskins, Peter J.; Cook, Malcolm D.

2007-12-01

249

The Dicke Quantum Phase Transition in a Superfluid Gas Coupled to an Optical Cavity  

NASA Astrophysics Data System (ADS)

A fundamental approach to collective matter-light interaction is given by the Dicke model which has been predicted to show an intriguing quantum phase transition. We have realized the Dicke quantum phase transition in an open system formed by a Bose-Einstein condensate coupled to an optical cavity, and observed the emergence of a self-organized supersolid phase [1]. The phase transition is driven by infinitely long-ranged interactions between the condensed atoms. We show that the phase transition is described by the Dicke Hamiltonian, including counter-rotating coupling terms, and that the supersolid phase is associated with a spontaneously broken spatial symmetry. The boundary of the phase transition is mapped out in quantitative agreement with the Dicke model. [4pt] [1] K. Baumann, C. Guerlin, F. Brennecke, T. Esslinger, arXiv 0912.2361, 2009

Guerlin, Christine; Baumann, Kristian; Brennecke, Ferdinand; Esslinger, Tilman

2010-03-01

250

Evidence for Efimov quantum states in an ultracold gas of cesium atoms  

Microsoft Academic Search

A landmark theoretical advance in few-body quantum physics is Efimov's prediction of weakly bound three-body states occuring close to a two-body scattering resonance. Among the amazing properties predicted for Efimov states is the existence of weakly bound trimer states even when the interaction does not support a weakly bound dimer state. Since the Efimov problem originally occured 35 years ago

B. Engeser; T. Kraemer; P. Waldburger; J. G. Danzl; A. D. Lange; K. Pilch; A. Jaakkola; H.-C. Nägerl; R. Grimm

2006-01-01

251

Adiabatic quantum motors.  

PubMed

When parameters are varied periodically, charge can be pumped through a mesoscopic conductor without applied bias. Here, we consider the inverse effect in which a transport current drives a periodic variation of an adiabatic degree of freedom. This provides a general operating principle for adiabatic quantum motors which we discuss here in general terms. We relate the work performed per cycle on the motor degree of freedom to characteristics of the underlying quantum pump and discuss the motors' efficiency. Quantum motors based on chaotic quantum dots operate solely due to quantum interference, and motors based on Thouless pumps have ideal efficiency. PMID:23971547

Bustos-Marún, Raúl; Refael, Gil; von Oppen, Felix

2013-08-05

252

Quantum dynamics studies of gas-surface reactions and use of complex absorbing potentials in wave-packet calculations  

NASA Astrophysics Data System (ADS)

In this thesis, quantum dynamics studies are conducted on gas-surface reactions and complex absorbing potentials. Through a three-dimensional model, dissociation probabilities for O2 on both (110) and (100) surfaces of copper are calculated for ground state as well as rovibrationally excited oxygen molecules. Specifically, the reason for the difference in calculated dissociation probabilities of oxygen on two surfaces is explained. Then the thermal effect of the surface on the dissociation probability is studied by a one dimensional fluctuating barrier. It is observed that the quantum mechanical tunneling probability exhibits a maximum as a function of the oscillating frequency between the low and the high frequency limits. The physical origin and process underlying this resonantlike phenomenon are proposed. In the second part of this thesis, the complex absorbing potential (CAP) is introduced and studied. Exact numerical calculation shows that use of optimized CAP significantly improves the efficiency of wavefunction absorption over that of negative imaginary potential (NIP) in scattering applications. The CAP is optimized by an efficient time-dependent propagation approach. Application to the prototype inelastic scattering of He + H2 demonstrates the accuracy and efficiency of the channel-dependent CAP for extracting state-to-state scattering information.

Ge, Jiuyuan

1999-11-01

253

Anisotropic scattering of elongated GaSb/GaAs quantum dots embedded near two-dimensional electron gas.  

PubMed

Geometrically anisotropic GaSb/GaAs quantum dots elongated along [110] direction, with a lateral aspect ratio of 2-3, are embedded in the vicinity of AIGaAs/GaAs two-dimensional electron gas, using the molecular beam epitaxy by carefully controlling the Sb4 beam flux and As4 background pressure. The electron mobilities micro parallel, micro perpendicular parallel and perpendicular to the direction of dot elongation axis are measured as functions of electron concentration n(2D) at 4.2 K, respectively. As the increase of n(2D), the mobility discrepancy (micro parallel-micro perpendicular) is found to be getting larger. This mobility difference is believed to be due to the anisotropic scattering potential of the elongated GaSb quantum dots. Under Born approximation, we propose a model with the constant squared-barrier potential to calculate the n(2D) dependence of mobility and reasonable agreement is achieved between the experimental results and theoretical simulation. PMID:22408997

Li, Guodong; Jiang, Chao; Sakaki, Hiroyuki

2011-12-01

254

Quantum-tunneling dynamics of a spin-polarized Fermi gas in a double-well potential  

SciTech Connect

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.

Salasnich, L.; Mazzarella, G.; Toigo, F. [Dipartimento di Fisica 'Galileo Galilei' and CNISM, Universita di Padova, Via Marzolo 8, I-35122 Padua (Italy); Salerno, M. [Dipartimento di Fisica 'E.R. Caianiello', CNISM and INFN-Gruppo Collegato di Salerno, Universita di Salerno, Via Ponte don Melillo, I-84084 Fisciano(Italy)

2010-02-15

255

Sensitive trace gas detection with cavity enhanced absorption spectroscopy using a continuous wave external-cavity quantum cascade laser  

NASA Astrophysics Data System (ADS)

Trace gas sensing in the mid-infrared using quantum cascade lasers (QCLs) promises high specificity and sensitivity. We report on the performance of a simple cavity enhanced absorption spectroscopy (CEAS) sensor using a continuous wave external-cavity QCL at 7.4 ?m. A noise-equivalent absorption coefficient ?min of 2.6 × 10-8 cm-1 in 625 s was achieved, which corresponds to a detection limit of 6 +/- 1 ppb of CH4 in 15 millibars air for the R(3) transition at 1327.074 cm-1. This is the highest value of noise-equivalent absorption and among the longest effective path length (1780 m) reported to date with QCL-based CEAS.

van Helden, J. H.; Lang, N.; Macherius, U.; Zimmermann, H.; Röpcke, J.

2013-09-01

256

[Mid-infrared distributed-feedback quantum cascade laser-based photoacoustic detection of trace methane gas].  

PubMed

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

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

257

Dynamics of uniform quantum gases, I: Density and current correlations  

NASA Astrophysics Data System (ADS)

A unified approach valid for any wavenumber q, frequency ?, and temperature T is presented for uniform ideal quantum gases allowing for a comprehensive study of number density and particle-current density response functions. Exact analytical expressions are obtained for spectral functions in terms of polylogarithms. Also, particle-number and particle-current static susceptibilities are presented which, for fugacity less than unity, additionally involve Kummer functions. The q- and T-dependent transverse-current static susceptibility is used to show explicitly that current correlations are of long range in a Bose-condensed uniform ideal gas but for bosons at T>Tc and for Fermi and Boltzmann gases at all temperatures these correlations are of short range. Contact repulsive interactions for systems of neutral quantum particles are considered within the random phase approximation. The expressions for particle-number and transverse-current susceptibilities are utilized to discuss the existence or nonexistence of superfluidity in the systems under consideration.

Bosse, J.; Pathak, K. N.; Singh, G. S.

2010-02-01

258

Molecular structures of tetrabromothiophene and -selenophene as determined by gas-phase electron diffraction and high-level quantum chemical calculations  

NASA Astrophysics Data System (ADS)

The molecular structures of tetrabromothiophene and tetrabromoselenophene were studied by gas-phase electron diffraction and quantum chemical calculations. Calculations at the DFT/B3LYP and MP2 levels of theory confirm that the molecules possess a planar structure in the gas phase. MD simulations were performed for both molecules. Definitive gas-phase molecular structures of tetrabromothiophene and tetrabromoselenophene are reported, based on refinements of electron diffraction data starting from different input geometries. The single-crystal structure of tetrabromoselenophene is also reported. Geometries of all tetrabromochalcogenophenes, C4Br4X (X = O, S, Se, Te), were calculated and trends in the geometrical parameters along the series are discussed.

Zhabanov, Yuriy A.; Vande Velde, Christophe M. L.; Blockhuys, Frank; Shlykov, Sergey A.

2012-12-01

259

Ideal n-body correlations with massive particles  

NASA Astrophysics Data System (ADS)

In 1963 Glauber introduced the modern theory of quantum coherence, which extended the concept of first-order (one-body) correlations, describing phase coherence of classical waves, to include higher-order (n-body) quantum correlations characterizing the interference of multiple particles. Whereas the quantum coherence of photons is a mature cornerstone of quantum optics, the quantum coherence properties of massive particles remain largely unexplored. To investigate these properties, here we use a uniquely correlated source of atoms that allows us to observe n-body correlations up to the sixth-order at the ideal theoretical limit (n!). Our measurements constitute a direct demonstration of the validity of one of the most widely used theorems in quantum many-body theory--Wick's theorem--for a thermal ensemble of massive particles. Measurements involving n-body correlations may play an important role in the understanding of thermalization of isolated quantum systems and the thermodynamics of exotic many-body systems, such as Efimov trimers.

Dall, R. G.; Manning, A. G.; Hodgman, S. S.; Rugway, Wu; Kheruntsyan, K. V.; Truscott, A. G.

2013-06-01

260

Coherent Propagation of Spin Helices in a Quantum-Well Confined Electron Gas  

NASA Astrophysics Data System (ADS)

We use phase-resolved transient grating spectroscopy to measure the propagation of spin helices in a high mobility n-GaAs/AlGaAs quantum well with an applied in-plane electric field. At relatively low fields helical modes crossover from overdamped excitations where the spin-precession period exceeds the spin lifetime, to a regime of coherent propagation where several spin-precession periods can be observed. We demonstrate that the envelope of a spin polarization packet reaches a current-driven velocity of 107cms-1 in an applied field of 70Vcm-1.

Yang, Luyi; Koralek, J. D.; Orenstein, J.; Tibbetts, D. R.; Reno, J. L.; Lilly, M. P.

2012-12-01

261

Quantum Computation of Fluid Dynamics.  

National Technical Information Service (NTIS)

Presented is a quantum lattice gas for Navier-Stokes fluid dynamics simulation. The quantum lattice-gas transport equation at the microscopic scale is presented as a generalization of the classical lattice-gas transport equation. A special type of quantum...

J. Yepez

1998-01-01

262

Steady Non-Ideal Detonation  

Microsoft Academic Search

Highly non-ideal explosives, such as commercial ammonium nitrate based explosives used in mining and blasting, have critical charge diameters of several centimetres and relatively low detonation speeds. Shock polar match analyses between these explosives and confining inert materials give two main types of interactions. For the first type (denoted here by case I), the detonation drives an oblique shock into

G. J. Sharpe; M. Y. Luheshi; M. Braithwaite; S. A. E. G. Falle

2009-01-01

263

STEADY NON-IDEAL DETONATION  

Microsoft Academic Search

Highly non-ideal explosives, such as commercial ammonium nitrate based explosives used in mining and blasting, have critical charge diameters of several centimetres and relatively low detonation speeds. Shock polar match analyses between these explosives and confining inert materials give two main types of interactions. For the first type (denoted here by case I), the detonation drives an oblique shock into

G. J. Sharpe; M. Y. Luheshi; M. Braithwaite; S. A. E. G. Falle

2009-01-01

264

Ideal Multipartite Secret Sharing Schemes  

NASA Astrophysics Data System (ADS)

Multipartite secret sharing schemes are those having a multipartite access structure, in which the set of participants is divided into several parts and all participants in the same part play an equivalent role. Several particular families of multipartite schemes, such as the weighted threshold schemes, the hierarchical and the compartmented schemes, and the ones with bipartite or tripartite access structure have been considered in the literature. The characterization of the access structures of ideal secret sharing schemes is one of the main open problems in secret sharing. In this work, the characterization of ideal multipartite access structures is studied with all generality. Our results are based on the well-known connections between ideal secret sharing schemes and matroids. One of the main contributions of this paper is the application of discrete polymatroids to secret sharing. They are proved to be a powerful tool to study the properties of multipartite matroids. In this way, we obtain some necessary conditions and some sufficient conditions for a multipartite access structure to be ideal.

Farràs, Oriol; Martí-Farré, Jaume; Padró, Carles

265

Ideal Hierarchical Secret Sharing Schemes  

Microsoft Academic Search

Hierarchical secret sharing is among the most natural generalizations of threshold secret sharing, and it has attracted a lot of attention since the invention of secret sharing until nowadays. Several constructions of ideal hierarchical secret sharing schemes have been proposed, but it was not known what access structures admit such a scheme. We solve this problem by providing a natural

Oriol Farras; Carles Padro

2012-01-01

266

The genesis of ideal theory  

Microsoft Academic Search

This paper deals with the development of the theory of ideal factorization of algebraic integers, from the first discovery of KUMMER that such a theory is necessary and possible in the case of the cyclotomic integers to the final general theories of DEDEKIND and KRONECKER. DEDEKIND'S theory used what he called \\

Harold M. Edwards

1980-01-01

267

Quantum field theory for the three-body constrained lattice Bose gas. I. Formal developments  

SciTech Connect

We develop a quantum field theoretical framework to analytically study the three-body constrained Bose-Hubbard model beyond mean field and noninteracting spin wave approximations. It is based on an exact mapping of the constrained model to a theory with two coupled bosonic degrees of freedom with polynomial interactions, which have a natural interpretation as single particles and two-particle states. The procedure can be seen as a proper quantization of the Gutzwiller mean field theory. The theory is conveniently evaluated in the framework of the quantum effective action, for which the usual symmetry principles are now supplemented with a ''constraint principle'' operative on short distances. We test the theory via investigation of scattering properties of few particles in the limit of vanishing density, and we address the complementary problem in the limit of maximum filling, where the low-lying excitations are holes and diholes on top of the constraint-induced insulator. This is the first of a sequence of two papers. The application of the formalism to the many-body problem, which can be realized with atoms in optical lattices with strong three-body loss, is performed in a related work [S. Diehl, M. Baranov, A. Daley, and P. Zoller, Phys. Rev. B 82, 064510 (2010)].

Diehl, S.; Daley, A. J.; Zoller, P. [Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, A-6020 Innsbruck (Austria); Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Baranov, M. [Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, A-6020 Innsbruck (Austria); Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); RRC 'Kurchatov Institute', Kurchatov Square 1, 123182 Moscow (Russian Federation)

2010-08-01

268

Modified Coulomb gas construction of quantum Hall states from nonunitary conformal field theories  

SciTech Connect

Some fractional quantum Hall states observed in experiments may be described by first-quantized wavefunctions with special clustering properties such as the Moore-Read Pfaffian for filling factor {nu}=5/2. This wavefunction has been constructed by constructing correlation functions of a two-dimensional conformal field theory (CFT) involving a free boson and a Majorana fermion. By considering other CFTs many other clustered states have been proposed as candidate fractional quantum Hall states under appropriate circumstances. It is believed that the underlying CFT should be unitary if one wants to describe an incompressible, i.e., gapped liquid state. We show that by changing the way one derives the wavefunction from its parent CFT it is possible to obtain an incompressible candidate state when starting from a nonunitary parent. The construction mimics a global change in parameters in the phase space of the electron system. We explicit our construction in the case of the so-called Gaffnian state (a state for filling factor 2/5) and also for the Haldane-Rezayi state (a spin-singlet state at filling 1/2). We note that there are obstructions along this path in the case of the permanent spin-singlet state of Read and Rezayi which can be characterized as a robust gapless state.

Milovanovic, M. V.; Vidanovic, I. [Institute of Physics, P.O. Box 68, 11080 Belgrade (Serbia); Jolicoeur, Th. [Laboratoire de Physique Theorique et Modeles Statistiques, Universite Paris-Sud, 91405 Orsay (France)

2009-10-15

269

Quantum mechanics of the fractional-statistics gas: Random-phase approximation  

NASA Astrophysics Data System (ADS)

A description of the fractional-statistics gas based on the complete summation of Hartree, Fock, ladder and bubble diagrams is presented. The superfluid properties identified previously in the random-phase-approximation (RPA) calculation of Fetter, Hanna, and Laughlin [Phys. Rev. B 39, 9679 (1989)] are substantially confirmed. The discrepancy between the RPA sound speed and the Hartree-Fock bulk modulus is found to be eliminated. The unusual Hall-effect behavior is found to vanish for the Bose gas test case but not for the fractional-statistics gas, implying that it is physically correct. Excellent agreement is obtained with the collective-mode dispersion obtained numerically by Xie, He, and Das Sarma [Phys. Rev. Lett. 65, 649 (1990)].

Dai, Q.; Levy, J. L.; Fetter, A. L.; Hanna, C. B.; Laughlin, R. B.

1992-09-01

270

Synthesis and Gas Sensing Properties of ZnO Quantum Dots  

Microsoft Academic Search

\\u000a ZnO nanocrystals were prepared by a wet chemical method based on alkaline-activated 10 hydrolysis and condensation of zinc\\u000a acetate solutions. With this procedure, the mean crystallite size of the obtained powders was found in the range from 2.5\\u000a to 4.5 nm. Drop casting of the nanocrystals onto alumina substrates allowed the fabrication of gas sensing devices. These\\u000a Q-ZnO based gas

A. Forleo; L. Francioso; S. Capone; P. Siciliano; P. Lommens; Z. Hens

271

Application of quantum cascade lasers to high-precision atmospheric trace gas measurements  

NASA Astrophysics Data System (ADS)

We review our recent results in development of high-precision laser spectroscopic instrumentation using midinfrared quantum cascade lasers (QCLs). Some of these instruments have been directed at measurements of atmospheric trace gases where a fractional precision of 10-3 or better of ambient concentration may be required. Such high precision is needed in measurements of fluxes of stable atmospheric gases and measurements of isotopic ratios. Instruments that are based on thermoelectrically cooled midinfrared QCLs and thermoelectrically cooled detectors have been demonstrated that meet the requirements of high-precision atmospheric measurements, without the need for cryogens. We also describe the design of and results from a new dual QCL instrument with a 200-m path-length absorption cell. This instrument has demonstrated 1-s noise of 32 ppt for formaldehyde (HCHO) and 9 ppt for carbonyl sulfide (OCS).

McManus, J. Barry; Zahniser, Mark S.; Nelson, David D.; Shorter, Joanne H.; Herndon, Scott; Wood, Ezra; Wehr, Rick

2010-11-01

272

Quantum dynamics of an excited alkali atom in a noble gas cluster: lithium attached to a helium cluster.  

PubMed

An alkali atom-noble gas cluster system is considered as a model for solvation effects in optical spectra, within a quantum-classical description based on the density operator of a many-atom system and its partial Wigner transform. This leads to an eikonal-time-dependent molecular orbital treatment suitable for a time-dependent description of the coupling of light emission and atom dynamics in terms of the time-dependent electric dipole of the whole system. As an application, we consider an optically excited lithium atom as the dopant in a helium cluster at 0.5 K. We describe the motions of the excited Li atom interacting with a cluster of He atoms and calculate the time-dependent electric dipole of the Li-He(99) system during the dynamics. The electronic Hamiltonian is taken as a sum of three-body Li-He diatomic potentials including electronic polarization and repulsion, with l-dependent atomic pseudopotentials for Li and He, while we use a modified pair potential for He-He. The calculations involve the coupling of 12 quantum states with 300 classical degrees of freedom. We present results for the dynamics and spectra of a Li atom interacting with a model cluster surface of He atoms and also interacting with a droplet of He. We have found that the Li atom is attracted or repulsed from the He surface, depending on the orientation of its 2p orbitals. The spectra and dynamics of Li inside and at the surface of a cluster are found to be strongly dependent on its electronic states, its velocity direction, and whether light is present during emission or not. PMID:18163688

Pacheco, Alexander B; Thorndyke, Brian; Reyes, Andrés; Micha, David A

2007-12-28

273

The Challenge of Non-Ideal Detonation  

Microsoft Academic Search

This paper will compare and contrast detonation in ideal and in highly non-ideal explosives. Ideal explosives, represented here by a TATB \\/ binder system, have relatively flat velocity of detonation (VoD) versus inverse charge diameter relationships, and fail at VoDs only slightly below their ideal CJ values. Highly non-ideal explosives, such as the physically heterogeneous composites used both in Naval

D. L. Kennedy

1995-01-01

274

Steady non-ideal detonations  

Microsoft Academic Search

Theories for determining the velocity of detonation (VoD) in highly non-ideal explosives, e.g. commercial explosives used in mining, are discussed. Such explosives have critical charge diameters of several centimetres. An analysis of the interaction between detonations and confining materials along the explosive-confiner interface reveals there a two main types of interaction. In the first (denoted here by case 1) the

Gary Sharpe

2009-01-01

275

Ideal Hierarchical Secret Sharing Schemes  

Microsoft Academic Search

\\u000a Hierarchical secret sharing is among the most natural generalizations of threshold secret sharing, and it has attracted a\\u000a lot of attention from the invention of secret sharing until nowadays. Several constructions of ideal hierarchical secret sharing\\u000a schemes have been proposed, but it was not known what access structures admit such a scheme. We solve this problem by providing\\u000a a natural

Oriol Farràs; Carles Padró

2010-01-01

276

Flexibility of ideal zeolite frameworks.  

PubMed

We explore the flexibility windows of the 194 presently-known zeolite frameworks. The flexibility window represents a range of densities within which an ideal zeolite framework is stress-free. Here, we consider the ideal zeolite to be an assembly of rigid corner-sharing perfect tetrahedra. The corner linkages between tetrahedra are hard-sphere oxygen atoms, which are presumed to act as freely-rotating, force-free, spherical joints. All other inter-tetrahedral forces, such as coulomb interactions, are ignored. Thus, the flexibility window represents the null-space of the kinematic matrix that governs the allowable internal motions of the ideal zeolite framework. We show that almost all of the known aluminosilicate or aluminophosphate zeolites exhibit a flexibility window. Consequently, the presence of flexibility in a hypothetical framework topology promises to be a valuable indicator of synthetic feasibility. We describe computational methods for exploring the flexibility window, and discuss some of the exceptions to this flexibility rule. PMID:20589266

Kapko, V; Dawson, C; Treacy, M M J; Thorpe, M F

2010-06-29

277

Singlet Oxygen in Microporous Silica Xerogel: Quantum Yield and Oxidation at the Gas–Solid Interface  

Microsoft Academic Search

2 lifetimes (tD) at the gas-solid interface in silica gel material are determined. Different photosensitizers (PS) are encapsulated in parallelepipedic xerogel monoliths (PS-SG). PS were chosen ac- cording to their known photooxidation properties: 9,10-dicya- noanthracene (DCA), 9,10-anthraquinone (ANT), and a benzophe- none derivative, 4-benzoyl benzoic acid (4BB). These experiments are mainly based on time-resolved 1O2 phosphorescence detec- tion, and the

Christophe Cantau; Thierry Pigot; Narayanapillai Manoj; Esther Oliveros; Sylvie Lacombe

2007-01-01

278

Quantum Phase Transition Between a Luttinger Liquid and a Gas of Cold Molecules  

SciTech Connect

We consider cold polar molecules confined in a helical optical lattice similar to those used in holographic microfabrication. An external electric field polarizes molecules along the axis of the helix. The large-distance intermolecular dipolar interaction is attractive but the short-scale interaction is repulsive due to geometric constraints and thus prevents collapse. The interaction strength depends on the electric field. We show that a zero-temperature second-order liquid-gas transition occurs at a critical field. It can be observed under experimentally accessible conditions.

Law, K. T.; Feldman, D. E. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States)

2008-08-29

279

Baryon-number violation in a quantum gas of W and Higgs bosons  

NASA Astrophysics Data System (ADS)

Use of a coherent-state representation of the sphaleron allows a direct calculation of its production rate in a thermal gas of W and Higgs bosons Technical considerations permit a straightforward calculation only in the case ?/g2~=1 (MH~=3MW), where ? is the Higgs-boson quartic coupling, and g is the SU(2) gauge coupling. For this case it is found that the rate is unsuppressed for temperatures T>=2.4MW(0), where MW(0) is the zero-temperature W mass. Thus anomalous B+L violation is also unsuppressed above this temperature.

Goldberg, Haim

1989-04-01

280

Quantum phases of a Feshbach-resonant atomic Bose gas in one dimension  

SciTech Connect

We study an atomic Bose gas with an s-wave Feshbach resonance in one dimension. Most of the parameter region is occupied by a phase in which the superfluid fluctuations of atoms and molecules are the predominant ones, due to the phase fluctuations of atoms and molecules being locked by a Josephson coupling between them. When the density difference between atoms and molecules is close to zero, two additional phases may exist: the two-component Luttinger liquid, which contains two branches of gapless excitations, and the interchannel charge density wave where the relative density fluctuations between atoms and molecules are frozen at low energy.

Lee, Y.-W.; Lee, Y.-L. [Physics Department, Tunghai University, Taichung, Taiwan, Republic of China (China); Physics Department, National Changhua University of Education, Changhua, Taiwan (China)

2006-04-15

281

Quantum corrections to the semiclassical Hartree-Fock theory of a harmonically trapped Bose gas  

NASA Astrophysics Data System (ADS)

Using the phase-space expansion of the thermodynamical distribution functions we provide a general and systematic method for including effects beyond the local-density approximation to the semiclassical Hartree-Fock theories. We illustrate the method by applying it to the case of a strictly two-dimensional, harmonically trapped Bose gas. Thereby, we address the ambiguous prediction of the Hartree-Fock approximation, namely, whether a fixed number of trapped atoms undergoes Bose-Einstein condensation or not. We also investigate the dependence of the critical temperature on the interaction strength.

Schumayer, D.; Cormack, S.; van Zyl, B. P.; Farry, J.; Collin, A.; Zaremba, E.; Hutchinson, D. A. W.

2012-08-01

282

Voltage-controlled electron tunneling from a single self-assembled quantum dot embedded in a two-dimensional-electron-gas-based photovoltaic cell  

Microsoft Academic Search

We perform high-resolution photocurrent (PC) spectroscopy to investigate resonantly the neutral exciton ground-state (X0) in a single InAs\\/GaAs self-assembled quantum dot (QD) embedded in the intrinsic region of an n-i-Schottky photodiode based on a two-dimensional electron gas (2DEG), which was formed from a Si ?-doped GaAs layer. Using such a device, a single-QD PC spectrum of X0 is measured by

J. D. Mar; X. L. Xu; J. J. Baumberg; A. C. Irvine; D. A. Williams

2011-01-01

283

Quantum yield of Cl* ( 2 P 1\\/2 ) production in the gas phase photolysis of CCl 4 in the ultraviolet  

Microsoft Academic Search

In this paper, we have probed the dynamics of chlorine atom production from the gas phase photodissociation of carbon tetrachloride\\u000a at 222 and 235 nm. The quantum yield, ?* of Cl* (2P1\\/2) production has been determined by probing the nascent concentrations of both excited (2P1\\/2) and ground state (2P3\\/2) chlorine atoms by suitable resonance-enhanced multiphoton ionization (REMPI) detection schemes. Although

Manish Tak; Manabendra Chandra; Dulal Senapati; Puspendu K. Das

2006-01-01

284

Correlated angular and quantum state-resolved CO2 scattering dynamics at the gas-liquid interface.  

PubMed

Molecular beam scattering dynamics at the gas-liquid interface are investigated for CO2 (E(inc) = 10.6(8) kcal/mol) impinging on liquid perfluoropolyether (PFPE), with quantum state (v, J) populations measured as a function of incident (theta(inc)) and final (theta(scat)) scattering angles. The internal state distributions are well-characterized for both normal and grazing incident angles by a two-component Boltzmann model for trapping desorption (TD) and impulsive scattering (IS) at rotational temperatures T(rot)(TD/IS), where the fractional TD probability for CO2 on the perfluorinated surface is denoted by TD and IS densities (rho) as alpha = rhoTD/(rhoTD + rhoIS). On the basis of an assumed cos(theta(scat)) scattering behavior for the TD flux component, the angular dependence of the IS flux at normal incidence (theta(inc) = 0 degrees) is surprisingly well-modeled by a simple cos(n)(theta(scat)) distribution with n = 1.0 +/- 0.2, while glancing incident angles (theta(inc) = 30 degrees, 45 degrees, and 60 degrees) result in lobular angular IS distributions scattered preferentially in the forward direction. This trend is also corroborated in the TD fraction alpha, which decreases rapidly under non-normal incident conditions as a function of backward versus forward scattering direction. Furthermore, the extent of rotational excitation in the IS channel increases dramatically with increasing angle of incidence, consistent with an increasing rotational torque due to surface roughness at the gas-liquid interface. PMID:18767785

Perkins, Bradford G; Nesbitt, David J

2008-09-04

285

Quad quantum cascade laser spectrometer with dual gas cells for the simultaneous analysis of mainstream and sidestream cigarette smoke  

NASA Astrophysics Data System (ADS)

A compact, fast response, infrared spectrometer using four pulsed quantum cascade (QC) lasers has been applied to the analysis of gases in mainstream (MS) and sidestream (SS) cigarette smoke. QC lasers have many advantages over the traditional lead-salt tunable diode lasers, including near room temperature operation with thermoelectric cooling and single mode operation with improved long-term stability. The new instrument uses two 36 m, 0.3 l multiple pass absorption gas cells to obtain a time response of 0.1 s for the MS smoke system and 0.4 s for the SS smoke system. The concentrations of ammonia, ethylene, nitric oxide, and carbon dioxide for three different reference cigarettes were measured simultaneously in MS and SS smoke. A data rate of 20 Hz provides sufficient resolution to determine the concentration profiles during each 2 s puff in the MS smoke. Concentration profiles before, during and after the puffs also have been observed for these smoke constituents in SS smoke. Also, simultaneous measurements of CO 2 from a non-dispersive infrared (NDIR) analyzer are obtained for both MS and SS smoke. In addition, during this work, nitrous oxide was detected in both the MS and SS smoke for all reference cigarettes studied.

Baren, Randall E.; Parrish, Milton E.; Shafer, Kenneth H.; Harward, Charles N.; Shi, Quan; Nelson, David D.; McManus, J. Barry; Zahniser, Mark S.

2004-12-01

286

Atomic Fermi gas in the unitary limit by quantum Monte Carlo methods: Effects of the interaction range  

NASA Astrophysics Data System (ADS)

We calculate the ground-state properties of an unpolarized two-component Fermi gas with the aid of the diffusion quantum Monte Carlo (DMC) methods. Using an extrapolation to the zero effective range of the attractive two-particle interaction, we find E/Efree in the unitary limit to be 0.212(2), 0.407(2), 0.409(3), and 0.398(3) for 4, 14, 38, and 66 atoms, respectively. Our calculations indicate that the dependence of the total energy on the effective range of the interaction Reff is sizable and the extrapolation to Reff=0 is therefore important for reaching the true unitary limit. To test the quality of nodal surfaces and to estimate the impact of the fixed-node approximation, we perform released-node DMC calculations for 4 and 14 atoms. Analysis of the released-node and the fixed-node results suggests that the main sources of the fixed-node errors are long-range correlations, which are difficult to sample in the released-node approaches due to the fast growth of the bosonic noise. Besides energies, we evaluate the two-body density matrix and the condensate fraction. We find that the condensate fraction for the 66-atom system converges to 0.56(1) after the extrapolation to the zero interaction range.

Li, Xin; Koloren?, Jind?ich; Mitas, Lubos

2011-08-01

287

Light absorption during alkali atom-noble gas atom interactions at thermal energies: a quantum dynamics treatment.  

PubMed

The absorption of light during atomic collisions is treated by coupling electronic excitations, treated quantum mechanically, to the motion of the nuclei described within a short de Broglie wavelength approximation, using a density matrix approach. The time-dependent electric dipole of the system provides the intensity of light absorption in a treatment valid for transient phenomena, and the Fourier transform of time-dependent intensities gives absorption spectra that are very sensitive to details of the interaction potentials of excited diatomic states. We consider several sets of atomic expansion functions and atomic pseudopotentials, and introduce new parametrizations to provide light absorption spectra in good agreement with experimentally measured and ab initio calculated spectra. To this end, we describe the electronic excitation of the valence electron of excited alkali atoms in collisions with noble gas atoms with a procedure that combines l-dependent atomic pseudopotentials, including two- and three-body polarization terms, and a treatment of the dynamics based on the eikonal approximation of atomic motions and time-dependent molecular orbitals. We present results for the collision induced absorption spectra in the Li-He system at 720 K, which display both atomic and molecular transition intensities. PMID:17059261

Pacheco, Alexander B; Reyes, Andrés; Micha, David A

2006-10-21

288

Atomic Fermi gas in the unitary limit by quantum Monte Carlo methods: Effects of the interaction range  

SciTech Connect

We calculate the ground-state properties of an unpolarized two-component Fermi gas with the aid of the diffusion quantum Monte Carlo (DMC) methods. Using an extrapolation to the zero effective range of the attractive two-particle interaction, we find E/E{sub free} in the unitary limit to be 0.212(2), 0.407(2), 0.409(3), and 0.398(3) for 4, 14, 38, and 66 atoms, respectively. Our calculations indicate that the dependence of the total energy on the effective range of the interaction R{sub eff} is sizable and the extrapolation to R{sub eff}=0 is therefore important for reaching the true unitary limit. To test the quality of nodal surfaces and to estimate the impact of the fixed-node approximation, we perform released-node DMC calculations for 4 and 14 atoms. Analysis of the released-node and the fixed-node results suggests that the main sources of the fixed-node errors are long-range correlations, which are difficult to sample in the released-node approaches due to the fast growth of the bosonic noise. Besides energies, we evaluate the two-body density matrix and the condensate fraction. We find that the condensate fraction for the 66-atom system converges to 0.56(1) after the extrapolation to the zero interaction range.

Li Xin; Mitas, Lubos [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Kolorenc, Jindrich [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Institut fuer Theoretische Physik, Universitaet Hamburg, Jungiusstrasse 9, 20355 Hamburg (Germany)

2011-08-15

289

Chemical Laws, Idealization and Approximation  

NASA Astrophysics Data System (ADS)

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.

Tobin, Emma

2013-07-01

290

Trions, excitons, and scattering states in multiple quantum wells with a variable-concentration electron gas  

NASA Astrophysics Data System (ADS)

CdTe/Cd1-xZnxTe multiple quantum wells were modulation doped with indium donors compensated by nitrogen acceptors so that the two-dimensional electron concentration in the wells (ne) could be varied from near 0 up to ?1011 cm-2 by optical pumping. In zero field at T=2 K, the optical absorption spectra show trion (X-) and exciton (X) resonance peaks at low ne, with an electron-exciton scattering wing extending to high energy from the exciton resonance. At the highest ne, the spectrum evolves towards the single asymmetric peak traditionally associated with the many-body “Fermi edge singularity” but its total integrated intensity remains almost constant, in agreement with recent few-body theories of the optical response at ne?1/a2B. Under magnetic field B=8 T at T=2 K, sharp X- and X resonance peaks are seen as well as a broad band Z situated about ??ce (the electron cyclotron energy) higher in energy. Band Z is attributed to a known exciton-electron scattering process [Yakovlev et al., Phys. Rev. Lett. 79, 3974 (1997)] where the electrons are magnetically quantized. In ?+ circular polarization, the X resonance attenuates rapidly with ne but the X- resonance grows almost as rapidly (“intensity sharing”) so that their intensity sum falls only slowly. In ?- the X resonance also attenuates rapidly with ne and the Z band grows to compensate, with the intensity sum again falling only slowly. It is concluded that the spectrum evolution as ne varies from 0 to 1011 cm-2 in CdTe is due to intensity sharing between the X and X- resonances and between these resonances and scattering processes. This is a low ne (and low B) model of the excitonic properties, where screening and phase-space filling contribute only to the <10% decrease of the oscillator strength sums. As regards the samples’ luminescence properties, two series of phonon peaks seen in emission spectra are attributed to recombination of two-dimensional electrons with nitrogen acceptors that have migrated close to and into the wells.

Cox, R. T.; Miller, R. B.; Saminadayar, K.; Baron, T.

2004-06-01

291

Pairing, Off-Diagonal Long-Range Order, and Quantum Phase Transition in Strongly Attracting Ultracold Bose Gas Mixtures in Tight Waveguides  

SciTech Connect

A model of two 1D ideal Bose gases A and B with strong odd-wave AB attractions induced by a p-wave AB Feshbach resonance is studied. The model is solved exactly by a Bose-Bose duality mapping, and it is shown that there is no A-component or B-component Bose-Einstein condensation and no AB-pair off-diagonal long-range order (ODLRO), but both AA-pair and BB-pair ODLRO. After generalization by adding even-wave AA and BB repulsions and reducing the strength of the odd-wave AB attraction by Feshbach resonance detuning, a quantum phase transition occurs between a phase with AB contact nodes and one with no such nodes.

Girardeau, M. D. [College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States)

2009-06-19

292

Nonlinear Lagrangian MFE method for ideal MHD.  

National Technical Information Service (NTIS)

A nonlinear moving finite element method (MFE) for ideal magnetohydrodynamics (MHD) is developed and tested. The method is based on a variational principle in Lagrangian formulation of ideal MHD. A set of various FEM discretization based on this method is...

M. Benda A Bondeson L. O. Pekkari

1990-01-01

293

Unpolarized Fermi gas in squeezed anisotropic harmonic trap by Quantum Monte Carlo methods  

NASA Astrophysics Data System (ADS)

Using diffusion Monte Carlo (DMC) method, we calculate the ground state properties of unpolarized Fermi gas at unitarity regime in both isotropic and anisotropic harmonic potentials. We study the effects of anisotropy by increasing the frequency in z direction ?z of the harmonic potential while keeping the frequency in x and y direction unchanged. The true unitarity regime is obtained by extrapolating the interaction range to zero and the calculations are done using the fixed-node diffusion Monte Carlo method. The trial function is of the BCS form with the pairing function expanded in appropriate linear combinations of the anisotropic oscillator eigenstates. We evaluate the binding energies for varying particle numbers and we estimate its behavior in the limit of large number of atoms. We estimate dependence of projected density profile and momentum distribution on the X-Y plane with respect to ?z. Our results can be readily used as a benchmark for the cold atom experiment with similar experimental set-up. Supported by ARO and NSF.

Li, Xin; Mitas, Lubos

2012-02-01

294

ONE SIDED IDEALS AND CARLSON'S THEOREM  

Microsoft Academic Search

Using left ideals, right ideals, and the smallest two sided ideal in a compact right topological semigroup, we derive an extension of the Main Lemma to Carlson's Theorem. This extension involves an innite sequence of variable words over a nite alphabet, some of which are required to have the variable as the rst letter and others of which are required

NEIL HINDMAN; RANDALL MCCUTCHEON

295

The Changing Figure Ideal in Fashion Illustration  

Microsoft Academic Search

The purpose of this study was to examine the changing fashion figure ideal as represented in fashion illustration during the twentieth century. The ideal body forms and other appearance traits associated with fashionable women have varied notably during this time span. These changes have been documented and analyzed extensively in current literature. The related ideals presented for instruction in fashion

Donna R. Danielson

1989-01-01

296

Ideal Secret Sharing Schemes from Permutations  

Microsoft Academic Search

The work presents a new method for the design of ideal secret sharing. The method uses regular mappings that are well suited for construction of perfect secret sharing. The restriction of regular mappings to permutations gives a convenient tool for investigation of the relation between permutations and ideal secret sharing generated by them. Keywords: Ideal secret sharing schemes, perfect secret

Josef Pieprzyk; Xian-mo Zhang

2006-01-01

297

Recharging Our Sense of Idealism: Concluding Thoughts  

ERIC Educational Resources Information Center

|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…

D'Andrea, Michael; Dollarhide, Colette T.

2011-01-01

298

Informational derivation of quantum theory  

SciTech Connect

We derive quantum theory 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 standard. One postulate - purification - singles out quantum theory within this class.

Chiribella, Giulio; D'Ariano, Giacomo Mauro; Perinotti, Paolo [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Ontario, N2L 2Y5 (Canada); QUIT Group, Dipartimento di Fisica ''A. Volta'' and INFN Sezione di Pavia, via Bassi 6, I-27100 Pavia (Italy)

2011-07-15

299

The Quantum Spin Hall Effect  

Microsoft Academic Search

We show that the intrinsic spin orbit interaction in a single plane of graphene converts the ideal two dimensional semi metallic groundstate of graphene into a quantum spin Hall (QSH) state [1]. This novel electronic phase shares many similarities with the quantum Hall effect. It has a bulk excitation gap, but supports the transport of spin and charge in gapless

Charles Kane

2006-01-01

300

Quantum optics of dielectric media  

Microsoft Academic Search

We discuss the quantum fluctuations of the fields associated with a broad class of optical scattering and transmission problems by developing the quantum electrodynamics of an idealized linear, but nonuniform, dielectric medium. We present and compare two quantization schemes for this purpose. The first is based on the expansion of the field in terms of a set of single-frequency solutions

Roy J. Glauber; M. L. Lewenstein

1991-01-01

301

[The ideal body: media pedagogy].  

PubMed

We present enunciations that circulate in the media regarding the body, discussing the ways in which the speeches related with the maintenance of health and aesthetics invest in its improvement. Therefore, we used the Caderno Vida, a weekly insert of Zero Hora, for we understand it as owner of a proper speech that has the power of subjectivate people The analysis is part of Cultural Studies and it is based on the ideas of Michel Foucault. The methodological strategy used was the speech analysis of subjects about body care. The periodical questions its readers using speeches that point to beauty health and success The constructed categories were: how is the ideal body, what to do to have such body and why we must have this body Balanced feeding, practice of regular physical activities and the accomplishment of plastic surgeries are recommendations recurrently found in weekly inserts. PMID:19653558

Ribeiro, Rubia Guimarães; da Silva, Karen Schein; Kruse, Maria Henriqueta Luce

2009-03-01

302

Steady non-ideal detonations  

NASA Astrophysics Data System (ADS)

Theories for determining the velocity of detonation (VoD) in highly non-ideal explosives, e.g. commercial explosives used in mining, are discussed. Such explosives have critical charge diameters of several centimetres. An analysis of the interaction between detonations and confining materials along the explosive-confiner interface reveals there a two main types of interaction. In the first (denoted here by case 1) the detonation drives an oblique shock into the confiner. For the second (case 2), a wave propagates in the confiner ahead of the detonation in the explosive. Shock polar interactions are examined for commercial explosives and rocks, which shows that a significant proportion of problems are case 2 in mining. For case 1, numerical simulations show that for a given explosive model there is a unique relationship (valid for all charge diameters and confinements) between the VoD and the curvature of the detonation shock at the charge axis. This relationship is shown to be well predicted by a quasi-one-dimensional type analysis. A simple detonation shock dynamics method which uses this relationships predicts well the VoD even in highly non-ideal cases, provided the explosive is sufficiently confined (usually the case in mining), but which is inaccurate in the limit of an unconfined charge. Preliminary results of a novel variational method for solving the unconfined situation are also discussed. Numerical simulations are performed to investigate the coupling mechanisms in case 2 situations, including the influence on diameter effects. It is shown that, in agreement with an approximate theory, the detonation is driven up to VoDs above the confiner's sound speed, and the wave in the confiner weakly pre-compresses the explosive ahead of the detonation front.

Sharpe, Gary

2009-06-01

303

Pharmacytes: an ideal vehicle for targeted drug delivery.  

PubMed

An ideal nanotechnology-based drug delivery system is a pharmacyte--a self-powered, computer-controlled medical nanorobot system capable of digitally precise transport, timing, and targeted delivery of pharmaceutical agents to specific cellular and intracellular destinations within the human body. Pharmacytes may be constructed using future molecular manufacturing technologies such as diamond mechanosynthesis which are currently being investigated theoretically using quantum ab initio and density-functional computational methods. Pharmacytes will have many applications in nanomedicine such as initiation of apoptosis in cancer cells and direct control of cell signaling processes. PMID:17048481

Freitas, Robert A

304

Diameter effect and detonation front curvature of ideal and non-ideal explosives  

Microsoft Academic Search

Diameter effect and detonation front curvature data are presented for several representative ideal and non-ideal explosives, including cast TNT, Tritonal, urea nitrate (UN), ANFO, and two variants of ammonium nitrate (AN)\\/solid fuel explosives. The ideal vs. non-ideal detonation characteristics of these various explosives are compared and contrasted with respect to particle size and chemical composition.

F. W. Sandstrom; R. L. Abernathy; M. G. Leone; M. L. Banks

2000-01-01

305

Diameter effect and detonation front curvature of ideal and non-ideal explosives  

Microsoft Academic Search

Diameter effect and detonation front curvature data are presented for several representative ideal and non-ideal explosives, including cast TNT, Tritonal, urea nitrate (UN), ANFO, and two variants of ammonium nitrate (AN)\\/solid fuel explosives. The ideal vs. non-ideal detonation characteristics of these various explosives are compared and contrasted with respect to particle size and chemical composition. .

F. W. Sandstrom; R. L. Abernathy; M. G. Leone; M. L. Banks

2000-01-01

306

Diameter effect and detonation front curvature of ideal and non-ideal explosives  

NASA Astrophysics Data System (ADS)

Diameter effect and detonation front curvature data are presented for several representative ideal and non-ideal explosives, including cast TNT, Tritonal, urea nitrate (UN), ANFO, and two variants of ammonium nitrate (AN)/solid fuel explosives. The ideal vs. non-ideal detonation characteristics of these various explosives are compared and contrasted with respect to particle size and chemical composition. .

Sandstrom, F. W.; Abernathy, R. L.; Leone, M. G.; Banks, M. L.

2000-04-01

307

Linear and nonlinear quantum ion acoustic waves in a plasma with positive, negative ions and Fermi electron gas  

SciTech Connect

Linear and nonlinear propagations of quantum ion acoustic waves in positive, negative ions and electron plasma have been vetted via the dispersion relation and Korteweg-de Vries equation, where the ions are inertial and electrons are inertialess. The quantum mechanical effects arising due to the quantum diffraction and Fermi-Dirac statistics for this system are taken into account. The existence, as well as the type (compressive/rarefactive) of solitary wave propagating in the system, is strongly dependent on the numerical value of dimensionless quantum parameter H{sub e}. It is observed that negative ion population and ion mass ratio have emphatic influence on the phase velocity of ion acoustic wave and the propagation of localized coherent solitary structures at quantum scale in the system.

Saeed-ur-Rehman [Theoretical Plasma Physics Division, PINSTECH, Nilore, Islamabad 44000 (Pakistan)

2010-06-15

308

Performance analysis of a micro-scaled quantum Stirling refrigeration cycle  

NASA Astrophysics Data System (ADS)

The cycle model of a general micro-scaled regenerative quantum refrigerator working with an ideal Bose or Fermi gas is established. The combined effects of quantum boundary and degeneracy on the performance of the cycle are investigated based on the thermodynamic properties of a confined ideal Bose or Fermi gas. The inherent regenerative losses of the cycle are analyzed and calculated. Expressions for several important performance parameters, such as the refrigeration load, work input, and coefficient of performance (COP), are derived under the cases of the gas degeneracy, weak gas degeneracy, high temperature limit, and thermodynamic limit. The curves of the refrigeration load and coefficient of performance versus the volume and surface area ratios of the cycle and the refrigeration load versus the coefficient of performance are represented. The effects of the size effect on the refrigeration load and coefficient of performance are discussed. The general performance characteristics of the cycle are revealed. It is found that both the refrigeration load and coefficient of performance of the micro-scaled quantum Stirling refrigeration cycle depend on the surface area of the cyclic system besides the temperature of the heat reservoirs, the volume of cyclic system, and other parameters, while those of the macro-scaled refrigerator are independent of the surface area of a cyclic system. The results obtained here are more general and significant than those in the current literature.

Lin, Bihong; Huang, Zhifu; Chen, Jincan

2012-09-01

309

"Additive" cooperativity of hydrogen bonds in complexes of catechol with proton acceptors in the gas phase: FTIR spectroscopy and quantum chemical calculations.  

PubMed

Experimental study of hydrogen bond cooperativity in hetero-complexes in the gas phase was carried out by IR-spectroscopy method. Stretching vibration frequencies of O-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. O-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. PMID:22366617

Varfolomeev, Mikhail A; Klimovitskii, Alexander E; Abaidullina, Dilyara I; Madzhidov, Timur I; Solomonov, Boris N

2012-02-02

310

Steady Non-Ideal Detonation  

NASA Astrophysics Data System (ADS)

Highly non-ideal explosives, such as commercial ammonium nitrate based explosives used in mining and blasting, have critical charge diameters of several centimetres and relatively low detonation speeds. Shock polar match analyses between these explosives and confining inert materials give two main types of interactions. For the first type (denoted here by case I), the detonation drives an oblique shock into the confiner. For the second type (case II), a wave propagates in the confiner ahead of the detonation wave in the explosive. In case I, numerical simulations show that for a given explosive model there is a unique relationship (valid for all charge diameters and confinements) between the velocity of detonation (VoD) and the curvature of the detonation shock at the charge axis. This relationship is shown to be well predicted by a quasi-one-dimensional analysis. A simple detonation shock dynamics method which uses this relationship predicts the VoD provided the explosive is sufficiently confined (usually the case in mining), but is inaccurate in the limit of an unconfined charge. For commercial explosives confined by rocks, a significant proportion of problems are case II. Numerical simulations are performed to investigate the coupling mechanisms in these situations. It is found that, in agreement with an approximate theory, the detonation is driven up to VoDs near the confiner's sound speed, and the wave in the confiner weakly pre-compresses the explosive ahead of the detonation front.

Sharpe, G. J.; Luheshi, M. Y.; Braithwaite, M.; Falle, S. A. E. G.

2009-12-01

311

Gas permeability and ideal selectivity of poly[bis-(phenoxy)phosphazene], poly[bis-(4- tert-butylphenoxy)phosphazene], and poly[bis-(3,5-di- tert-butylphenoxy) 1.2(chloro) 0.8phosphazene  

Microsoft Academic Search

Described in this paper is the synthesis and gas permeability characterization of poly[bis-(4-tert-butylphenoxy)phosphazene], and poly[bis-(3,5-di-tert-butylphenoxy)1.2(chloro)0.8phosphazene]. In general, linear chloro-containing polyphosphazenes are hydrolytically unstable. However, in this work, a novel polymer, poly[bis-(3,5-di-tert-butylphenoxy)1.2(chloro)0.8phosphazene], was observed to have an unusually high degree of hydrolytic stability and excellent membrane formation characteristics. Data derived from these polymers were compared to that of the more common

Christopher J. Orme; John R. Klaehn; Frederick F. Stewart

2004-01-01

312

Anomalous spin-orbit coupling in high-density two-dimensional electron gas confined in InGaAs/InAlAs quantum well  

NASA Astrophysics Data System (ADS)

We study the magnetotransport property of a high-density two-dimensional electron gas confined in InGaAs/InAlAs quantum well. Both beating pattern in the Shubnikov-de Hass oscillation of resistivity and weak antilocalization effect are observed. From these two effects, Rashba spin-splitting energy is extracted. The extracted Rashba spin-splitting energy shows a nonmonotonic dependence on Fermi wave vector, contrary to the prevailing linear Rashba model. This anomalous behavior can be attributed to the nonlinear Rashba spin-splitting mechanism [Yang et al., Phys. Rev. B 74 (2006) 193314].

Gao, K. H.; Lin, T.; Wei, L. M.; Liu, X. Z.; Chen, X.; Yu, G.; Gu, Y.; Zhang, Y. G.; Dai, N.; Chu, J. H.

2012-06-01

313

Voltage-controlled electron tunneling from a single self-assembled quantum dot embedded in a two-dimensional-electron-gas-based photovoltaic cell  

Microsoft Academic Search

We perform high-resolution photocurrent (PC) spectroscopy to investigate resonantly the neutral exciton ground-state (X0) in a single InAs\\/GaAs self-assembled quantum dot (QD) embedded in the intrinsic region of an n-i-Schottky photodiode based on a two-dimensional electron gas (2DEG), which was formed from a Si delta-doped GaAs layer. Using such a device, a single-QD PC spectrum of X0 is measured by

J. D. Mar; X. L. Xu; J. J. Baumberg; A. C. Irvine; D. A. Williams

2011-01-01

314

Novel Electron Gas Systems  

NASA Astrophysics Data System (ADS)

We review recent progress on the physics of electrons in the bilayered electron gas, relevant to coupled quantum wells in GaAs/AlGaAs heterostructures. First, we focus on the phase diagram of a symmetric bilayer at T=B=0, obtained by diffusion Monte Carlo simulations. It is found that inter-layer correlations stabilize crystalline structures at intermediate inter-layer separation, while favouring a liquid phase at smaller distance. Also, the available DMC evidence is in contrast with the recently (Hartree-Fock) predicted total charge transfer (TCT), whereby all the electron spontaneously jump in one layer. In fact, one can show that such a TCT state is never stable in the ideal bilayer with no tunneling. We finally comment on ongoing DMC investigations on the electron-hole bilayer, where excitonic condensation is expected to take place.

Senatore, Gaetano; Rapisarda, F.; Conti, S.

315

On the Optical Potential of AN Attractive Nonrelativistic Degenerate Electron Gas Interacting with Nuclear Matter  

NASA Astrophysics Data System (ADS)

The optical potential of an attractive nonrelativistic electron gas interacting with nuclear matter is determined on the basis of the concept of degenerate Fermi gas. In fact, the involved electrons are treated as three-dimensional quantum harmonic oscillators confined at the surface of a spherical (approximately ideal) potential well. Within this picture, the Fermi velocity is calculated as well as the spatial electron density at the surface of the potential well and the attractive force between the electron gas and the nuclear matter. In addition, considerations related to the Lippmann-Schwinger model are made.

Grado-Caffaro, M. A.; Grado-Caffaro, M.

2012-12-01

316

Inherent contradictions in the ego ideal.  

PubMed

The author puts forth a concept of the ego ideal as the fantasied self that the child believes will bring it gratification and happiness. He then shows how the ego ideal's content evolves through the various stages of psychosexual development in accordance with its mission. A picture emerges of an ego ideal in inherent conflict because it is shaped by contradictory wishes, as well as contradictory fantasies of how to make those wishes come true. A section on romantic love points to a second contradiction within the ego ideal, beyond its contradictory content: a contradiction of aim. PMID:21141785

Dendy, Errol B

2010-10-01

317

Trapped atoms in cavity QED for quantum optics and quantum information  

Microsoft Academic Search

One of the requirements for the physical implementation of many protocols in quantum information science is the ability to convert quantum information from stationary to travelling form and transmit it over long distances. The strong coupling domain of cavity quantum electrodynamics (QED) provides a near-ideal setting for the pursuit of these goals. In addition, cavity QED is a unique system

Jason McKeever

2004-01-01

318

Quantum light emission from cavity enhanced LEDs  

Microsoft Academic Search

A particularly promising approach to realize optoelectronic devices based on semiconductor nanostructures are quantum dots coupled to an optical microcavity. Those quantum dot based light emitters are ideal sources for deterministic quantum light emission with tunable photon statistics. This paper investigates the theory of InAs\\/GaAs quantum dots (QDs) embedded in a two dimensional wetting layer (WL).To simulate realistic operating points

Alexander Carmele; M. Dachner; J. Wolters; M. Richter; A. Knorr

2010-01-01

319

Ideal Shrinking and Expansion of Discrete Sequences.  

National Technical Information Service (NTIS)

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 sm...

A. B. Watson

1986-01-01

320

Ideals and bands in principal modules  

Microsoft Academic Search

Introduction. We prove a monotone approximation theorem in principal modules extending thus a result of de Pagter on the monotone approximation of the elementary components of an operator. We consider also the inclusion of the order ideal into the algebraic ideal generated by an operator and we give a characterization of the band generated by an element in a principal

Dan Vuza

1985-01-01

321

Effect of quantum tunneling on single strand breaks in a modeled gas phase cytidine nucleotide induced by low energy electron: a theoretical approach.  

PubMed

Effect of quantum mechanical tunneling on single strand breaks induced by low energy electron (LEE) has been investigated in a modeled gas phase system, 2'-deoxycytidine-3'-monophosphate (3'-dCMPH). The potential energy curves for the sugar-phosphate C-O (3' C-O) bond cleavage have been generated using second order Møller-Plesset perturbation theory at the 6-31+G(d) accuracy level. Results from the electronic structure theory calculations in conjunction with our time dependent calculations for the 3' C-O bond rupture in 3'-dCMPH using local complex potential based time dependent wave packet approach show significant quantum tunneling of the 3' C-O bond from the bound vibrational states above 1 eV of the anionic potential energy curve. A comparison of the fragmentation profile with that of our earlier gas phase investigations based on Hartree-Fock and density functional theory--Becke, 3-parameter, Lee-Yang-Parr methods with 6-31+G(d) basis set is also provided. Further, inspection of the singly occupied molecular orbitals generated at different 3' C-O bond lengths clearly indicates the electron transfer from the low lying base-?(?) shape resonance state to the phosphate P = O ?(?) orbital of the DNA backbone during the strand breaks. The decisive step during LEE induced strand breaks follows via "charge induced dissociation" (CID) for the metastable anion formed below 1 eV, whereas quantum mechanical tunnel-ing is out-weighted the CID mechanism for the LEE above 1 eV. PMID:23902028

Bhaskaran, Renjith; Sarma, Manabendra

2013-07-28

322

Kirkwood-Buff integrals for ideal solutions  

PubMed Central

The Kirkwood–Buff (KB) theory of solutions is a rigorous theory of solution mixtures which relates the molecular distributions between the solution components to the thermodynamic properties of the mixture. Ideal solutions represent a useful reference for understanding the properties of real solutions. Here, we derive expressions for the KB integrals, the central components of KB theory, in ideal solutions of any number of components corresponding to the three main concentration scales. The results are illustrated by use of molecular dynamics simulations for two binary solutions mixtures, benzene with toluene, and methanethiol with dimethylsulfide, which closely approach ideal behavior, and a binary mixture of benzene and methanol which is nonideal. Simulations of a quaternary mixture containing benzene, toluene, methanethiol, and dimethylsulfide suggest this system displays ideal behavior and that ideal behavior is not limited to mixtures containing a small number of components.

Ploetz, Elizabeth A.; Bentenitis, Nikolaos; Smith, Paul E.

2010-01-01

323

Two Quantum Polytropic Cycles  

NASA Astrophysics Data System (ADS)

In this work we follow the Bender et al paper [1] to study the quantum analogues of the Stirling and Ericsson polytropic cycles. In the context of the classical thermodynamics, the Stirling and Ericsson cycles correspond to reversible heat engines with two isothermal processes joined by two polytropic branches which occur in a device called regenerator. If this device is an ideal one, the efficiency of these cycles is the Carnot efficiency. Here, we introduce the quantum analogues of the Stirling and Ericsson cycles, the first one based on a double square potential well with a finite potential barrier, since in this system the tunnel effect could be the analogue to the regeneration classical process, therefore the isochoric quantum branches would really correspond to an internal energy storage, and the last one with an unknown system where the isobaric quantum processes don't induce changes in its quantum state. With these systems the quantum engines have cycles consisting of polytropic and isothermal quantum processes analogues to the corresponding classical processes. We show that in both cases the quantum cycles have an efficiency given by ?CQM = 1 - EC/EH, which is the same expression for the quantum analogue of the Carnot cycle studied by Bender.

Arias-Hernández, L. A.; Morales-Serrano, A. F.

2002-11-01

324

Thermodynamical Properties of a Trapped Interacting Bose Gas  

NASA Astrophysics Data System (ADS)

The thermodynamical properties of interacting Bose atoms in a harmonic potential are studied within the mean-field approximation. For weak interactions, the quantum statistics is equivalent to an ideal gas in an effective mean-field potential. The eigenvalue of the Gross-Pitaevskii equation is identified as the chemical potential of the ideal gas. The condensation temperature and density profile of atoms are calculated. It is found that the critical temperature Tc decreases as the interactions increase. Below the critical point, the condensation fraction exhibits a universal relation of N0/N = 1-(T/Tc)?, with the index ? ? 2.3 independent of the interaction strength, the chemical potential, as well as the frequency of the confining potential.

Yang, Shi-Jie; Liu, Yuechan; Feng, Shiping

325

Purification of noisy quantum measurements  

SciTech Connect

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)].

Dall'Arno, Michele; D'Ariano, Giacomo Mauro [Quit Group, Dipartimento di Fisica 'A. Volta', via Bassi 6, I-27100 Pavia (Italy); Istituto Nazionale di Fisica Nucleare, Gruppo IV, via Bassi 6, I-27100 Pavia (Italy); Sacchi, Massimiliano F. [Quit Group, Dipartimento di Fisica 'A. Volta', via Bassi 6, I-27100 Pavia (Italy); Istituto di Fotonica e Nanotecnologie (IFN-CNR), Piazza Leonardo da Vinci 32, I-20133 Milano (Italy)

2010-10-15

326

Gate-Controlled Spin-Orbit Effects in a 2D Electron Gas and in Quantum Dots  

NASA Astrophysics Data System (ADS)

This talk present results of recent experimental studies of spin-orbit coupling in macroscopic GaAs/AlGaAs heterostructure 2DEG samples [1] and micron-scale gate-confined quantum dots [2], including comparisons to theory presented by others in this session. In the 2D system, we consider the regime of sufficiently high mobility and spin-orbit strength that significant spin precision occurs during a transport scattering time. By changing a top gate voltage, a crossover from antilocalization to weak localization is observed. Comparison to theory allows separate values for linear and cubic Dresselhaus contributions and Rashba contribution to be extracted from the gate-dependence of magnetoconductivity. In the quantum dots, we demonstrate antilocalization as a signature of strong spin-orbit coupling, a suppression of antilocalization as the dot area is reduced, the effects of an in-plane magnetic field, and a gate-control of antilocalization. [1] J. B. Miller, D. M. Zumbuhl, C. M. Marcus, Y. B. Lyanda-Geller, D. Goldhaber-Gordon, K. Campman, A. C. Gossard, Gate-Controlled Spin-Orbit Quantum Interference Effects in Lateral Transport, cond-mat/0206375 (2002). [2] D. M. Zumbuhl, J. B. Miller, C. M. Marcus, K. Campman, A. C. Gossard, Spin-Orbit Coupling, Antilocalization, and Parallel Magnetic Fields in Quantum Dots Phys. Rev. Lett. 89, 276803 (2002).

Marcus, Charles

2003-03-01

327

Predicting film genres with implicit ideals.  

PubMed

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

Olney, Andrew McGregor

2013-01-07

328

Predicting Film Genres with Implicit Ideals  

PubMed Central

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.

Olney, Andrew McGregor

2013-01-01

329

Charged particle flows in an explosively generated non-ideal plasma  

NASA Astrophysics Data System (ADS)

Non-ideal plasmas occur as a result of the stimulation of matter by strong shocks, detonation waves, or concentrated laser irradiation. Since all of these methods of generating non-ideal plasmas are already in use to address other problems, we focus on a detailed understanding of this plasma. In particular, we study the flow of charged particles in a non-ideal plasma generated using an explosive to compress the gas into the non- ideal plasma state. The shock wave in the gas is generated by an explosive located at one end of a guide tube filled with the gas. The detonation produces a shock wave strong enough to ionize the gas. Spectral line emission profiles, recorded with a streak emission spectroscopy system, are used to ascertain neutral and ionized gas properties. The electric and magnetic fields are measured by electrostatic probes and magnetic induction coils which permit the measurement of the temperature, density, and electric potential of the non-ideal plasma; as well as the flow of net electric charges respectively. The results demonstrate that a separation of the positive and negative charges occurs in the vicinity of the shock wave.

Boswell, C. J.; Carney, J. R.; Wilkinson, J.; Pangilinan, G. I.; Whitley, V. H.

2007-06-01

330

Optimal minimum-cost quantum measurements for imperfect detection  

NASA Astrophysics Data System (ADS)

Knowledge of optimal quantum measurements is important for a wide range of situations, including quantum communication and quantum metrology. Quantum measurements are usually optimized with an ideal experimental realization in mind. Real devices and detectors are, however, imperfect. This has to be taken into account when optimizing quantum measurements. In this paper, we derive the optimal minimum-cost and minimum-error measurements for a general model of imperfect detection.

Andersson, Erika

2012-07-01

331

Linear Waves and Stability in Ideal Magnetohydrodynamics.  

National Technical Information Service (NTIS)

Linear waves superimposed on an arbitrary basic state in ideal magnetohydrodynamics are studied by an asymptotic expansion valid for short wavelengths. The theory allows for a gravitational potential, and it may therefore be applied both in astrophysics a...

K. S. Eckhoff

1987-01-01

332

Ideals and Realities of the Olympic Games  

ERIC Educational Resources Information Center

With the growth of professionalism and the emphasis on money in sports, modern society is losing sight of the ideals of style and grace that were of primary importance in the early Olympic games. nJD)

Hibler, Richard W.

1976-01-01

333

Medical learning curves and the Kantian ideal.  

PubMed

A hitherto unexamined problem for the "Kantian ideal" that one should always treat patients as ends in themselves, and never only as a means to other ends, is explored in this paper. The problem consists of a prima facie conflict between this Kantian ideal and the reality of medical practice. This conflict arises because, at least presently, medical practitioners can only acquire certain skills and abilities by practising on live, human patients, and given the inevitability and ubiquity of learning curves, this learning requires some patients to be treated only as a means to this end. A number of ways of attempting to establish the compatibility of the Kantian Ideal with the reality of medical practice are considered. Each attempt is found to be unsuccessful. Accordingly, until a way is found to reconcile them, we conclude that the Kantian ideal is inconsistent with the reality of medical practice. PMID:16131552

Le Morvan, P; Stock, B

2005-09-01

334

Output Performance of Idealized Microwave Power Amplifiers.  

National Technical Information Service (NTIS)

Output power, efficiency, power dissipation and optimum load resistance expressions for idealized microwave class A and class B power amplifiers are derived based on a waveform analysis. The effects of device transconductance variation with bias and circu...

L. J. Kushner

1989-01-01

335

Medical learning curves and the Kantian ideal  

PubMed Central

A hitherto unexamined problem for the "Kantian ideal" that one should always treat patients as ends in themselves, and never only as a means to other ends, is explored in this paper. The problem consists of a prima facie conflict between this Kantian ideal and the reality of medical practice. This conflict arises because, at least presently, medical practitioners can only acquire certain skills and abilities by practising on live, human patients, and given the inevitability and ubiquity of learning curves, this learning requires some patients to be treated only as a means to this end. A number of ways of attempting to establish the compatibility of the Kantian Ideal with the reality of medical practice are considered. Each attempt is found to be unsuccessful. Accordingly, until a way is found to reconcile them, we conclude that the Kantian ideal is inconsistent with the reality of medical practice.

Le Morvan, P; Stock, B

2005-01-01

336

Kinetic modeling of non-ideal explosives  

Microsoft Academic Search

We have implemented a Wood-Kirkwood kinetic detonation model based on multi-species equations of state and multiple reaction rate laws. Finite rate laws are used for the slowest chemical reactions, while other reactions are given infinite rates and are kept in constant thermodynamic equilibrium. We model a wide range of ideal and non-ideal composite energetic materials. In addition, we develop an

L E Fried; W M Howard; P C Souers

1999-01-01

337

Countably generated prime ideals in H ?  

Microsoft Academic Search

We confirm a twenty year old conjecture by showing that a nonzero prime ideal P in the algebra H? of bounded analytic functions in the open unit disk is countably generated if and only if it is either a principal ideal generated by the polynomial z?z0, |z0|P is generated by the n-th roots of an atomic inner function. The case

Pamela Gorkin; Raymond Mortini

2005-01-01

338

Time Dependent Measurements of Nitrous Oxide - Foreign Gas Collisional Relaxation Processes Using a Frequency Down-Chirped 7.84 Microns Quantum Cascade Laser  

NASA Astrophysics Data System (ADS)

Intra-pulse quantum cascade laser (QCL) spectrometers are able to produce both saturation and molecular alignment of the gas sample. This is due to the rapid sweep of the radiation through the absorption features. The intra-pulse time domain spectra closely resemble those recorded in coherent optical nutation experiments. In this presentation the frequency down-chirped technique is employed to investigate nitrous oxide - foreign gas collisions. We have demonstrated that the measurements may be characterised by the induced polarization dominated and collision dominated measurement limits. The first of these is directly related to the time dependence of the long range collision cross sections. Among the collisional partners considered, carbon dioxide shows a very unusual behaviour of rapid polarization damping, resulting in the production of symmetrical line shapes at very low gas buffer pressures. The carbon dioxide absorptions are modelled by solving the coupled Maxwell - Bloch equations and the role played by the low transition dipole moment of the {}{16}{O}{}{12}{C}{}{18}{O} isotopomer is discussed.

Hay, K. G.; Duxbury, G.; Langford, N.; Tasinato, N.

2010-06-01

339

Iowa's ideal homes: innovative designs for energy affordable living  

SciTech Connect

New home buyers in Iowa are looking for energy performance because of rising natural gas costs. The ideal home now requires thermal comfort at affordable prices as well as location and size criteria. The four key design elements are superinsulation, air tight construction, air-to-air exchangers, and passive solar orientation. The book includes design and construction details, cost estimates and comparisons, and a collection of available floor plans. The Iowa Energy Policy Council will provide information for both new homes and modifications of existing home plans. 25 figures, 2 tables.

Not Available

1986-01-01

340

Guiding center equations for ideal magnetohydrodynamic modes  

NASA Astrophysics Data System (ADS)

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 ?Bvec =?×(?vec ×Bvec ), 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 ?vec 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.

White, R. B.

2013-04-01

341

Collective Recombination of Two-Dimensional Electron Gas with Bound Holes and Density Dependent Band-Gap Renormalization in GaInAs/A1IAs Single Quantum Wells.  

National Technical Information Service (NTIS)

Due to the k-conservation restriction the intrinsic luminescence from the two-dimensional electron gas (2DEG) in modulation-doped (MD) quantum wells (QWs) of high structural perfection consists of a sharp peak centered around the band gap instead of a ste...

Y. H. Zhang M. Potemski R. Cingolani K. Kern J. C. Maan

1992-01-01

342

Roton-type mode softening in a quantum gas with cavity-mediated long-range interactions.  

PubMed

Long-range interactions in quantum gases are predicted to give rise to an excitation spectrum of roton character, similar to that observed in superfluid helium. We investigated the excitation spectrum of a Bose-Einstein condensate with cavity-mediated long-range interactions, which couple all particles to each other. Increasing the strength of the interaction leads to a softening of an excitation mode at a finite momentum, preceding a superfluid-to-supersolid phase transition. We used a variant of Bragg spectroscopy to study the mode softening across the phase transition. The measured spectrum was in very good agreement with ab initio calculations and, at the phase transition, a diverging susceptibility was observed. The work paves the way toward quantum simulation of long-range interacting many-body systems. PMID:22604724

Mottl, R; Brennecke, F; Baumann, K; Landig, R; Donner, T; Esslinger, T

2012-05-17

343

Anisotropic transport of two-dimensional electron gas modulated by embedded elongated GaSb\\/GaAs quantum dots  

Microsoft Academic Search

Geometrically anisotropic GaSb\\/GaAs quantum dots (QDs) that are elongated along the [110] direction are embedded in the vicinity of a modulation-doped AlGaAs\\/GaAs heterointerface. At 4.2 K, the electron mobilities mu|| and mu?, which are parallel and perpendicular to the QD elongation axis, respectively, are systematically investigated as a function of the electron concentration NS by both experimental measurements and theoretical

Guodong Li; Chao Jiang; Qinsheng Zhu; Hiroyuki Sakaki

2011-01-01

344

Heterodyne gas cell measurements at 2.9 THz using a quantum cascade laser as local oscillator  

Microsoft Academic Search

High-resolution heterodyne spectrometers operating at above 2 THz are crucial for detecting, e.g., the HD line at 2.7 THz and oxygen OI line at 4.7 THz in astronomy. The potential receiver technology is a combination of a hot electron bolometer (HEB) mixer and a THz quantum cascade laser (QCL) local oscillator (LO).Here we report the first highresolution heterodyne spectroscopy measurement

Y. Ren; J. R. Gao; J. N. Hovenier; R. Higgins; W. Zhang; A. Bell; B. Klein; T. M. Klapwijk; S. C. Shi; T.-Y. Kao; S. Kumar; Q. Hu; J. L. Reno

2010-01-01

345

Quantum nature of two-dimensional electron gas confinement at LaAlO3/SrTiO3 interfaces.  

PubMed

We perform density functional calculations to understand the mechanism controlling the confinement width of the two-dimensional electron gas (2DEG) at LaAlO_{3}/SrTiO_{3} interfaces. We find that the 2DEG confinement can be explained by the formation of metal induced gap states (MIGS) in the band gap of SrTiO3. These states are formed as the result of quantum-mechanical tunneling of the charge created at the interface due to electronic reconstruction. The attenuation length of the MIGS into the insulator is controlled by the lowest-decay-rate evanescent states of SrTiO3, as determined by its complex band structure. Our calculations predict that the 2DEG is confined in SrTiO3 within about 1 nm at the interface. PMID:19392142

Janicka, Karolina; Velev, Julian P; Tsymbal, Evgeny Y

2009-03-10

346

Zeeman-gap anomaly in photoluminescence from a two-dimensional electron gas in CdTe/(Cd, Mg)Te quantum wells  

NASA Astrophysics Data System (ADS)

We have investigated photoluminescence spectra from a two-dimensional electron gas in a n-type CdTe/Cd0.865Mg0.135Te single quantum well in magnetic fields up to 14 T at low temperatures. High-mobility two-dimensional carriers in this system exhibited photoluminescence oscillation and splitting in accordance with the Landau filling factor. The pronounced spectral anomaly especially near at odd filling factor suggests the importance of the spin degree of freedom. The observed spectra exhibited the behavior predicted by a calculation by Hawrylak and Potemski [Phys. Rev. B 56, 12 386 (1997)] taking account of Auger and spin-flip recombination processes. Temperature as well as excitation power dependence of this anomalous photoluminescence peaks was investigated.

Takeyama, S.; Karczewski, G.; Wojtowicz, T.; Kossut, J.; Kunimatsu, H.; Uchida, K.; Miura, N.

1999-03-01

347

Gas-Phase Spectroscopy of Biomolecular Building Blocks  

NASA Astrophysics Data System (ADS)

Gas-phase spectroscopy lends itself ideally to the study of isolated molecules and provides important data for comparison with theory. In recent years, we have seen enormous progress in the study of biomolecular building blocks in the gas phase. The motivation for such work is threefold: (a) It is important to distinguish between intrinsic molecular properties and properties that result from the biological environment. (b) Gas-phase spectroscopy of clusters provides insights into fundamental interactions and into microsolvation. (c) Gas-phase data support quantum-chemical calculations. This review focuses on the current status of (poly)amino acids and DNA bases. Recent results help elucidate structure and hydrogen-bonded interactions, as well as showcase a successful interplay between theory and experiment.

de Vries, Mattanjah S.; Hobza, Pavel

2007-05-01

348

Analytic Idealizations and the Disavowed: Winnicott, His Patients, and Us  

Microsoft Academic Search

This paper explores the dynamics of mutual idealization within the analytic dyad. While the subject of idealization is not a new one, very little has been written about the analyst's own participation in patients' idealizations or her vulnerability to idealizing the patient. I use both published and unpublished materials to muse about coconstructed idealizations as they appear to have coalesced

Joyce Slochower

2011-01-01

349

Graphene and the Quantum Spin Hall Effect  

Microsoft Academic Search

We show that the intrinsic spin orbit interaction in a single plane of graphene converts the ideal two dimensional semi metallic groundstate of graphene into a quantum spin Hall (QSH) state. This novel electronic phase shares many similarities with the quantum Hall effect. It has a bulk excitation gap, but supports the transport of spin and charge in gapless \\

C. L. Kane

2007-01-01

350

Quantum optics and cavity QED Quantum network with individual atoms and photons  

NASA Astrophysics Data System (ADS)

Quantum physics allows a new approach to information processing. A grand challenge is the realization of a quantum network for long-distance quantum communication and large-scale quantum simulation. This paper highlights a first implementation of an elementary quantum network with two fibre-linked high-finesse optical resonators, each containing a single quasi-permanently trapped atom as a stationary quantum node. Reversible quantum state transfer between the two atoms and entanglement of the two atoms are achieved by the controlled exchange of a time-symmetric single photon. This approach to quantum networking is efficient and offers a clear perspective for scalability. It allows for arbitrary topologies and features controlled connectivity as well as, in principle, infinite-range interactions. Our system constitutes the largest man-made material quantum system to date and is an ideal test bed for fundamental investigations, e.g. quantum non-locality.

Rempe, G.

2013-08-01

351

Simple correlation for predicting detonation velocity of ideal and non-ideal explosives  

Microsoft Academic Search

This paper describes a simple method for prediction of detonation velocity of ideal and non-ideal explosives. A non-ideal aluminized and nitrated explosive can have Chapman–Jouguet detonation velocity significantly different from that expected from existing thermodynamic computer codes for equilibrium and steady-state calculations. Detonation velocity of explosives with general formula CaHbNcOdAle can be predicted only from values of a, b, c,

Mohammad Hossein Keshavarz

2009-01-01

352

Quantum Computers and Quantum Control  

Microsoft Academic Search

Quantum computation is an excercise in quantum control: for a quantum system to compute, its dynamics must be controlled to a high degree of precision. Quantum control, in turn, is an excercise in quantum computation: control can be thought of in terms of how information is represented and processed. This talk reviews recent developments in quantum computation and quantum control

Seth Lloyd

2001-01-01

353

The condensation of ideal Bose gas in a gravitational field  

NASA Astrophysics Data System (ADS)

Bose-Einstein condensation of two- and three-dimensional boson gases confined in the one-dimensional gravitational field is investigated. Using the semiclassical approximation method, the expressions for the BEC transition temperature, condensate fraction, heat capacity and the entropy of the system are obtained. The heat capacities of the systems with D=1, 2, 3 (D is the dimension) at the critical temperature are discussed. We find that for the 1-D and 2-D boson systems, the heat capacities are continuous, but for the 3-D case there is a gap at the critical temperature Tc. The entropies of the systems with D=1, 2, 3 are also studied in detail. It is found that the entropies increase with the increasing of the temperature T.

Du, Cong-Fei; Li, Hong; Lin, Zhen-Quan; Kong, Xiang-Mu

2012-11-01

354

Towards scalable quantum communication using atomic ensembles and light  

Microsoft Academic Search

One of the challenges in experimental quantum information science involves reliable transport (communication) of quantum bits over long distances under realistic conditions involving decoherence and noise. Photons are the fastest and simplest carriers of quantum information since they interact weakly with environment, but they are difficult to localize and store. It appears that an ideal solution would be to store

Mikhail Lukin

2002-01-01

355

Quantum Shock Waves and Domain Walls in the Real-Time Dynamics of a Superfluid Unitary Fermi Gas  

SciTech Connect

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.

Bulgac, Aurel; Luo, Yuan-Lung; Roche, Kenneth J.

2012-04-10

356

Quantum shock waves and domain walls in the real-time dynamics of a superfluid unitary Fermi gas.  

PubMed

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 ? 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 appear to collide elastically. PMID:22587233

Bulgac, Aurel; Luo, Yuan-Lung; Roche, Kenneth J

2012-04-10

357

Reality television and the muscular male ideal.  

PubMed

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

Dallesasse, Starla L; Kluck, Annette S

2013-03-21

358

Entropic inflation of ideal zeolitic frameworks  

NASA Astrophysics Data System (ADS)

Ideal zeolites can be viewed as flexible networks of rigid, corner-sharing tetrahedra. Recent studies have shown that such systems can exist at a range of densities (termed the "flexibility window") without breaking topology or deforming the comprising tetrahedra. They also have shown that densities of real zeolites almost always correspond to the lowest densities within this range. This anomalous behavior is usually attributed to coulombic repulsion between oxygen atoms in framework cavities and channels. In this paper we show that the inflation of ideal zeolites can be driven by entropy. This effect is closely related to displacive phase transitions often observed in zeolites and related materials like quartz, which cannot be explained by potential energy minimization alone. We show that periodicity and high symmetry in ideal zeolites is a result of entropy maximization. An estimation of entropy using a harmonic oscillator model with a realistic force field is given.

Kapko, Vitaliy; Dawson, Colby; Treacy, Michael

2011-03-01

359

Quantum Kinematics of Bosonic Vortex Loops  

SciTech Connect

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.

Goldin, G.A.; Owczarek, R.; Sharp, D.H.

1999-05-06

360

Quantum particle-number fluctuations in a two-component Bose gas in a double-well potential  

SciTech Connect

A two-component Bose gas in a double-well potential with repulsive interactions may undergo a phase separation transition if the interspecies interactions outweigh the intraspecies ones. We analyze the transition in the strong interaction limit within the two-mode approximation. Numbers of particles in each potential well are equal and constant. However, at the transition point, the ground state of the system reveals huge fluctuations of numbers of particles belonging to the different gas components; that is, the probability for observation of any mixture of particles in each potential well becomes uniform.

Zin, Pawel [Soltan Institute for Nuclear Studies, Hoza 69, PL-00-681 Warsaw (Poland); Oles, Bartlomiej; Sacha, Krzysztof [Instytut Fizyki imienia Mariana Smoluchowskiego and Mark Kac Complex Systems Research Center, Uniwersytet Jagiellonski, ulica Reymonta 4, PL-30-059 Krakow (Poland)

2011-09-15

361

Quantum master equation for collisional dynamics of massive particles with internal degrees of freedom  

SciTech Connect

We address the microscopic derivation of a quantum master equation in Lindblad form for the dynamics of a massive test particle with internal degrees of freedom, interacting through collisions with a background ideal gas. When either internal or center-of-mass degrees of freedom can be treated classically, previously established equations are obtained as special cases. If in an interferometric setup the internal degrees of freedom are not detected at the output, the equation can be recast in the form of a generalized Lindblad structure, which describes non-Markovian effects. The effect of internal degrees of freedom on center-of-mass decoherence is considered in this framework.

Smirne, Andrea; Vacchini, Bassano [Universita degli Studi di Milano, Dipartimento di Fisica, Via Celoria 16, I-20133 Milano (Italy) and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy)

2010-10-15

362

Simple correlation for predicting detonation velocity of ideal and non-ideal explosives.  

PubMed

This paper describes a simple method for prediction of detonation velocity of ideal and non-ideal explosives. A non-ideal aluminized and nitrated explosive can have Chapman-Jouguet detonation velocity significantly different from that expected from existing thermodynamic computer codes for equilibrium and steady-state calculations. Detonation velocity of explosives with general formula C(a)H(b)N(c)O(d)Al(e) can be predicted only from values of a, b, c, d, e and a specific structural parameter without using any assumed detonation products, heat of formation and experimental data. Predicted detonation velocities by this procedure for ideal and non-ideal explosives show good agreement with respect to experimental values as compared to computed results of BKWR and BKWS equations of state. PMID:19135789

Keshavarz, Mohammad Hossein

2008-12-06

363

Theory of an Ideal Jet Thrust Augmentor  

Microsoft Academic Search

A theory of the ideal jet thrust augmentor is presented. The conditions of optimal outflow of the active (primary) and passive (secondary) jets from the device under consideration are obtained by solving the variational problem of maximum average thrust realization. The inlet values of the mass and total enthalpy fluxes for both flows, their entropies, and the inlet value of

N. L. Efremov; A. N. Kraiko

2004-01-01

364

Beauty Ideals & Body Image: Suva, Fiji  

Microsoft Academic Search

Fiji is a country rich with traditions and culture. For many decades, the two dominant ethnic groups in Fiji- Indo-Fijians and Indigenous Fijians- have maintained their distinct cultural values and practices. As a country that is currently experiencing westernization, technological advancement, and the influx of mass media, cultural traditions, lifestyles, and ideals are changing rapidly. One such change from the

Melissa Kong

2007-01-01

365

The Ideal Science Student and Problem Solving  

Microsoft Academic Search

We examined the nature of students' social mental models of the ideal science student, whether or not these models vary with student ethnicity, and the relationship of these models to problem solving strategies used, and problem solving ability in a robotics challenge. Participants were twenty-six, academically advanced, eleven and twelve year olds. Two social mental models were identified, a traits-based

Florence R. Sullivan; Xiaodong Lin

366

Nuclear and trace ideals in tensored ?-categories  

Microsoft Academic Search

We generalize the notion of nuclear maps from functional analysis by defining nuclear ideals in tensored ?-categories. The motivation for this study came from attempts to generalize the structure of the category of relations to handle what might be called “probabilistic relations”. The compact closed structure associated with the category of relations does not generalize directly, instead one obtains nuclear

Samson Abramsky; Richard Blute; Prakash Panangaden

1999-01-01

367

Dworkin's prudent insurance ideal: two revisions.  

PubMed

This article offers two revisions to Dworkin's 'prudent insurance ideal', which aims to account for justice in the distribution of healthcare so that (a) it can deal with market failures in healthcare and (b) when applied to unjust societies it addresses health problems caused by injustice in a fair manner. PMID:22108579

Kurtulmus, A Faik

2011-11-21

368

Street Children Draw the Ideal Person.  

ERIC Educational Resources Information Center

|Forty-three adolescents (11-16 years of age) attending a health care program, Project Alternatives, for "street children" in Tegucigalpa, Honduras, drew randomly assigned pictures of either the ideal man or woman, engaged in some activity. These drawings were compared to samples from adolescents in various parts of the world to assess the global…

DiCarlo, Margaret A.; And Others

369

Ideal spatial adaptation by wavelet shrinkage  

Microsoft Academic Search

SUMMARY With ideal spatial adaptation, an oracle furnishes information about how best to adapt a spatially variable estimator, whether piecewise constant, piecewise polynomial, variable knot spline, or variable bandwidth kernel, to the unknown function. Estimation with the aid of an oracle offers dramatic advantages over traditional linear estimation by nonadapt- ive kernels; however, it is a priori unclear whether such

DAVID L. DON; IAIN M. JOHNSTONE

1993-01-01

370

CALIBRATED THIN 1 1 -IDEALS ARE G  

Microsoft Academic Search

Let E be a compact metric space, and let I K ( E) be a calibrated thin 1 1 -ideal. Then I is . This solves an open problem, which was posed by Kechris, Louveau and Woodin. Using our result we obtain a new proof of Kaufman's theorem concerning U-sets and U0-sets.

MIROSLAV ZELEN

371

Water: The Ideal Early Learning Environment  

ERIC Educational Resources Information Center

|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.…

Grosse, Susan J.

2008-01-01

372

Ideal thermal efficiency for geothermal binary plants  

Microsoft Academic Search

The Carnot cycle is reviewed as to its appropriateness to serve as the ideal model for geothermal binary power plants. It is shown that the Carnot cycle sets an unrealistically high upper limit on the thermal efficiency of these plants. A more useful model is the triangular (or trilateral) cycle because binary plants operating on geothermal hot water use a

Ronald DiPippo

2007-01-01

373

Contesting Domestic Ideals: queering the Australian home  

Microsoft Academic Search

The Australian home is a crucial site for both normalising and contesting acceptable modes of sexual identity, desire and behaviour. Social norms and government policies have imbricated the detached suburban dwelling with the heterosexual nuclear family form, consequently heterosexualising the ideal Australian home. But this discourse is simultaneously challenged by the domestic practices of gay men and lesbians, who use

Andrew Gorman-Murray

2007-01-01

374

Critical Reflection as a Rationalistic Ideal  

ERIC Educational Resources Information Center

|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…

van Woerkom, Marianne

2010-01-01

375

Blast Waves From Non-ideal Explosives  

NASA Astrophysics Data System (ADS)

The non-ideal behavior of explosives comes from different ways which retard the energy release from the explosive. These include a lack of oxygen balance which results in energy being released after the shock wave from the detonation has gone into the surrounding air and the detonation products react with this fresh source of oxygen as it is included within the shock wave. Also included are slow and/or multiple reactions which cause energy to be released late in the reaction zone of the detonation when the pressure of the detonations has dropped until the local sound speed has fallen below the detonation velocity. All energy released after this point cannot keep up with the detonation shock wave and must wait to catch up with the blast wave that propagates into the air. Both of these non-ideal characteristics of the explosive reduce the irreversible losses to the air close to the explosive charge by reducing the peak pressure, and therefore, the temperature compressive heating of the air. Less irreversible losses to the air means more energy propagates to greater distance. This presentation covers the research conducted into the influence of these non-ideal effects upon the propagation of peak pressures and the positive and negative impulses from non-ideal explosives.

Romero, Van D.; Williams, Pharis E.

1997-07-01

376

Blast waves from non-ideal explosives  

NASA Astrophysics Data System (ADS)

The non-ideal behavior of explosives comes from different ways which retard the energy release from the explosive. These include a lack of oxygen balance which results in energy being released after the shock wave from the detonation has gone into the surrounding air and the detonation products react with this fresh source of oxygen as it is included within the shock wave. Also included are slow and/or multiple reactions which cause energy to be released late in the reaction zone of the detonation when the pressure of the detonations has dropped until the local sound speed has fallen below the detonation velocity. All energy released after this point cannot keep up with the detonation shock wave and must wait to catch up with the blast wave that propagates into the air. Both of these non-ideal characteristics of the explosive reduce the irreversible losses to the air close to the explosive charge by reducing the peak pressure, and therefore, the temperature compressive heating of the air. Less irreversible losses to the air means more energy propagates to greater distance. This presentation covers the research conducted into the influence of these non-ideal effects upon the propagation of peak pressures and the positive and negative impulses from non-ideal explosives.

Romero, Van; Williams, Pharis E.

1998-07-01

377

Exact map through ideal bends (again?)  

SciTech Connect

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.

Michelotti, L.

1995-06-01

378

The World Grant Ideal and Engagement Scholarship  

ERIC Educational Resources Information Center

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…

Fitzgerald, Hiram E.; Simon, Lou Anna K.

2012-01-01

379

Towards designing an ideal patent system  

Microsoft Academic Search

An ideal patent system balances the returns to inventors and the dissemination of new technologies. This article examines legal policy instruments – encompassing duration, scope and strength of patent protection, as well as invention disclosure and novelty requirements – and R&D subsidies that help sustain growth in GDP. The paper studies the issues associated with designing an effective patent system,

Alexei G. Orlov

2004-01-01

380

Counting integral ideals in a number field  

Microsoft Academic Search

Let K be an algebraic number field. We discuss the problem of counting the number of integral ideals below a given norm and obtain effective error estimates. The approach is elementary and follows a classical line of argument of Dedekind and Weber. The novelty here is that explicit error estimates can be obtained by fine tuning this classical argument without

M. Ram Murty; Jeanine Van Order

2007-01-01

381

Anisotropic transport of two-dimensional electron gas modulated by embedded elongated GaSb/GaAs quantum dots  

NASA Astrophysics Data System (ADS)

Geometrically anisotropic GaSb/GaAs quantum dots (QDs) that are elongated along the [110] direction are embedded in the vicinity of a modulation-doped AlGaAs/GaAs heterointerface. At 4.2 K, the electron mobilities ?? and ??, which are parallel and perpendicular to the QD elongation axis, respectively, are systematically investigated as a function of the electron concentration NS by both experimental measurements and theoretical simulations. In the experiments, the mobility ratio ??/?? increased with increasing NS. The mobility anisotropy, attributed to the anisotropic scattering potential of the elongated GaSb QDs, is calculated under the theoretical model of a rectangular scattering potential of GaSb QDs.

Li, Guodong; Jiang, Chao; Zhu, Qinsheng; Sakaki, Hiroyuki

2011-01-01

382

Eigenanalysis of Ideal Hall MHD Turbulence  

NASA Astrophysics Data System (ADS)

Ideal, incompressible, homogeneous, Hall magnetohydrodynamic (HMHD) turbulence may be investigated through a Fourier spectral method. In three-dimensional periodic geometry, the independent Fourier coefficients represent a canonical ensemble described by a Gaussian probability density. The canonical ensemble is based on the conservation of three invariants: total energy, generalized helicity, and magnetic helicity. Generalized helicity in HMHD takes the place of cross helicity in MHD. The invariants determine the modal probability density giving the spectral structure and equilibrium statistics of ideal HMHD, which are compared to known MHD results. New results in absolute equilibrium ensemble theory are derived using a novel approach that involves finding the eigenvalues of a Hermitian covariance matrix for each modal probability density. The associated eigenvectors transform the original phase space variables into eigenvariables through a special unitary transformation. These are the normal modes which facilitate the analysis of ideal HMHD non-linear dynamics. The eigenanalysis predicts that the low wavenumber modes with very small eigenvalues may have mean values that are large compared to their standard deviations, contrary to the ideal ensemble prediction of zero mean values. (Expectation values may also be relatively large at the highest wave numbers, but the addition of even small levels of dissipation removes any relevance this may have for real-world turbulence.) This behavior is non-ergodic over very long times for a numerical simulation and is termed 'broken ergodicity'. For fixed values of the ideal invariants, the effect is seen to be enhanced with increased numerical grid size. Broken ergodicity at low wave number modes gives rise to large-scale, quasi-stationary, coherent structure. Physically, this corresponds to plasma relaxation to force-free states. For real HMHD turbulence with dissipation, broken ergodicity and coherent structure are still expected to occur at low wave numbers, i.e. largest scales, where dissipation is least. We will discuss the relevant eigenanalysis and present numerical examples.

Fu, T.; Shebalin, J. V.

2011-12-01

383

The ideal subject distance for passport pictures.  

PubMed

In an age of global combat against terrorism, the recognition and identification of people on document images is of increasing significance. Experiments and calculations have shown that the camera-to-subject distance - not the focal length of the lens - can have a significant effect on facial proportions. Modern passport pictures should be able to function as a reference image for automatic and manual picture comparisons. This requires a defined subject distance. It is completely unclear which subject distance, in the taking of passport photographs, is ideal for the recognition of the actual person. We show here that the camera-to-subject distance that is perceived as ideal is dependent on the face being photographed, even if the distance of 2m was most frequently preferred. So far the problem of the ideal camera-to-subject distance for faces has only been approached through technical calculations. We have, for the first time, answered this question experimentally with a double-blind experiment. Even if there is apparently no ideal camera-to-subject distance valid for every face, 2m can be proposed as ideal for the taking of passport pictures. The first step would actually be the determination of a camera-to-subject distance for the taking of passport pictures within the standards. From an anthropological point of view it would be interesting to find out which facial features allow the preference of a shorter camera-to-subject distance and which allow the preference of a longer camera-to-subject distance. PMID:18450396

Verhoff, Marcel A; Witzel, Carsten; Kreutz, Kerstin; Ramsthaler, Frank

2008-05-02

384

Quantum kinematics of spacetime. II. A model quantum cosmology with real clocks  

Microsoft Academic Search

Nonrelativistic model quantum cosmologies are studied in which the basic time variable is the position of a clock indicator and the time parameter of the Schroedinger equation is an unobservable label. Familiar Schroedinger-Heisenberg quantum mechanics emerges if the clock is ideal: arbitrarily accurate for arbitrarily long times. More realistically, however, the usual formulation emerges only as an approximation appropriate to

J. Hartle

1988-01-01

385

Thermodynamic properties and ideal-gas enthalpies of formation for dicyclohexyl sulfide, diethylenetriamine, di-n-octyl sulfide, dimethyl carbonate, piperazine, hexachloroprop-1-ene, tetrakis(dimethylamino)ethylene, N,N{prime}-bis-(2-hydroxyethyl)ethylenediamine, and 1,2,4-triazolo[1,5-a]pyrimidine  

SciTech Connect

The results of the study are aimed at improvement of group-contribution methodology for estimation of thermodynamic properties of organic substances. 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 (DSC) heat-capacity measurements. Ideal-gas enthalpies of formation of hexachloroprop-1-ene, N,N{prime}-bis(2-hydroxyethyl)ethylenediamine, dimethyl carbonate, di-n-octyl sulfide, dicyclohexyl sulfide, diethylenetriamine, tetrakis(dimethylamino)ethylene, piperazine, and 1,2,4-triazolo[1,5-a]pyrimidine are reported. Enthalpies of fusion were determined for N,N{prime}-bis(2-hydroxyethyl)ethylenediamine, piperazine and 1,2,4-triazolo[1,5-a]pyrimidine. Two-phase (solid + vapor) or (liquid + vapor) heat capacities were determined from 300 K to the critical region or earlier decomposition temperature for each compound studied. Liquid-phase densities along the saturation line were measured for N,N{prime}-bis(2-hydroxyethyl)ethylenediamine, dimethyl carbonate, and dicyclohexyl sulfide. For dimethyl carbonate and piperazine, 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 hexachloroprop-1-ene, di-n-octyl sulfide, dicyclohexyl sulfide, and diethylenetriamine. Group-additivity parameters and 1,4-interaction terms useful in the application of group-contribution correlations were derived.

Steele, W.V.; Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Smith, N.K. [National Inst. for Petroleum and Energy Research, Bartlesville, OK (United States)

1997-11-01

386

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Remote laser detection of natural gas leakages from pipelines  

Microsoft Academic Search

A differential absorption lidar based on a tunable TEA CO2 laser emitting at 42 lines of the 'hot' 0111 --- 1110 band in the range from 10.9 to 11.4 mum is developed for detecting natural gas leakages from oil pipelines by measuring the ethane content in the atmosphere. The ethane detection sensitivity is 0.9 ppm km. The presence of methane

V. O. Petukhov; V. A. Gorobets; Yu M. Andreev; G. V. Lanskii

2010-01-01

387

Quantum virial expansion approach to thermodynamics of 4He adsorbates in carbon nanotube materials: Interacting Bose gas in one dimension  

Microsoft Academic Search

I demonstrate that 4He adsorbates in carbon nanotube materials can be treated as one-dimensional interacting gas of spinless bosons for temperatures below 8 K and for coverages such that all the adsorbates are in the groove positions of the carbon nanotube bundles. The effects of adsorbate-adsorbate interactions are studied within the scheme of the virial expansion approach. The theoretical predictions

Antonio Siber

2003-01-01

388

Optimal control of quantum revival  

NASA Astrophysics Data System (ADS)

Increasing fidelity is the ultimate challenge of quantum information technology. In addition to decoherence and dissipation, fidelity is affected by internal imperfections such as impurities in the system. Here we show that the quality of quantum revival, i.e., periodic recurrence in the time evolution, can be restored almost completely by coupling the distorted system to an external field obtained from quantum optimal control theory. We demonstrate the procedure with wave-packet calculations in both one- and two-dimensional quantum wells, and analyze the required physical characteristics of the control field. Our results generally show that the inherent dynamics of a quantum system can be idealized at an extremely low cost.

Räsänen, Esa; Heller, Eric J.

2013-01-01

389

Quantum Tetrahedra  

NASA Astrophysics Data System (ADS)

We discuss in details the role of Wigner 6j symbol as the basic building block unifying such different fields as state sum models for quantum geometry, topological quantum field theory, statistical lattice models and quantum computing. The apparent 2-fold nature of the 6j symbol displayed in quantum field theory and quantum computing -a quantum tetrahedron and a computational gate- is shown to merge together in a unified quantum-computational SU(2)-state sum framework.

Carfora, Mauro; Marzuoli, Annalisa; Rasetti, Mario

2009-11-01

390

The Ideal Man and Woman According to University Students  

ERIC Educational Resources Information Center

|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…

Weinstein, Lawrence; Laverghetta, Antonio V.; Peterson, Scott A.

2009-01-01

391

A multiwave approximate Riemann solver for ideal MHD based on relaxation. I: theoretical framework  

Microsoft Academic Search

We present a relaxation system for ideal magnetohydrodynamics (MHD) that is an extension of the Suliciu relaxation system\\u000a for the Euler equations of gas dynamics. From it one can derive approximate Riemann solvers with three or seven waves, that\\u000a generalize the HLLC solver for gas dynamics. Under some subcharacteristic conditions, the solvers satisfy discrete entropy\\u000a inequalities, and preserve positivity of

François Bouchut; Christian Klingenberg; Knut Waagan

2007-01-01

392

A Comparison of Two Intermediate State HLLC Solvers for Ideal Magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

This paper compares a solver based on the HLLC (Harten-Lax-van Leer-contact wave) approximate nonlinear Riemann solver for gas dynamics for ideal magnetohydrodynamics (MHD) with the HLL, Roe, Linde, and Li solvers. Simulation results are given for three one-dimensional test cases not previously shown in the original paper presenting the smooth HLLC solver for MHD.

Gurski, K. F.

2008-04-01

393

The behaviour of non-ideal explosives in the Ballistic Mortar  

Microsoft Academic Search

An analysis has been developed for the Ballistic Mortar test based on classical mechanics and a two stage chemical reaction rate model. Non-ideal behaviour of the composition was modelled by partial energy release during the detonation phase and secondary exothermic processes during the expansion phase. Erosive grain burning and time delayed reactions were both considered. Gas loss from the mortar

Graeme A. Leiper

1989-01-01

394

Polariton Quantum Optics  

NASA Astrophysics Data System (ADS)

I will give an overview of our recent studies on polariton quantum optics. I will show how polaritons can be produced in quantum entangled states, thanks to parametric scattering. By combining a time-dependent density-matrix model of the coherent polaritons, with a Boltzmann kinetics of the surrounding incoherent polariton gas in interaction with a thermal bath of phonons, the degree of entanglement can be quantified. It turns out that large entanglement is expected under realistic experimental conditions. I will further show how the polariton nonlinearity can be exploited to design quantum devices. As an example, I will model a system of coupled polariton modes, that operates as an efficient source of single photons by exploiting quantum interference between different pathways in the time evolution of the quantum field.

Savona, Vincenzo

2010-10-01

395

Quantum field theory for the three-body constrained lattice Bose gas. II. Application to the many-body problem  

SciTech Connect

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).]. 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.

Diehl, S.; Daley, A. J.; Zoller, P. [Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, A-6020 Innsbruck (Austria); Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Baranov, M. [Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, A-6020 Innsbruck (Austria); Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); RRC 'Kurchatov Institute', Kurchatov Square 1, 123182 Moscow (Russian Federation)

2010-08-01

396

Regular shock refraction in planar ideal MHD  

NASA Astrophysics Data System (ADS)

We study the classical problem of planar shock refraction at an oblique density discontinuity, separating two gases at rest, in planar ideal (magneto)hydrodynamics. In the hydrodynamical case, 3 signals arise and the interface becomes Richtmyer-Meshkov unstable due to vorticity deposition on the shocked contact. In the magnetohydrodynamical case, on the other hand, when the normal component of the magnetic field does not vanish, 5 signals will arise. The interface then typically remains stable, since the Rankine-Hugoniot jump conditions in ideal MHD do not allow for vorticity deposition on a contact discontinuity. We present an exact Riemann solver based solution strategy to describe the initial self similar refraction phase. Using grid-adaptive MHD simulations, we show that after reflection from the top wall, the interface remains stable.

Delmont, P.; Keppens, R.

2010-03-01

397

Modeling of non-ideal aluminized explosives  

NASA Astrophysics Data System (ADS)

We have implemented a Wood-Kirkwood kinetic detonation model based on multi-species equations of state and multiple reaction rate laws. Finite rate laws are used for the slowest chemical reactions, while other reactions are given infinite rates and are kept in constant thermodynamic equilibrium. Within the context of WK theory, we study the chemical interaction between Al and HMX detonation products in non-ideal explosives. We develop a kinetic rate law for the combustion of Al in a condensed detonation that depends on the pressure and the detonation product gases. We use a Murnaghan form for the equation of state of the solid and liquid Al and Al2O3. We find that we can replicate experimental detonation velocities for HMX/Al composites to within a few percent for a wide range of aluminum content. We discuss the uncertainties in our model and the implications of our results on the modeling of other non-ideal explosives ??? .

Howard, W. M.; Fried, L. E.; Souers, P. C.

2000-04-01

398

Kinetic modeling of non-ideal explosives  

SciTech Connect

We have implemented a Wood-Kirkwood kinetic detonation model based on multi-species equations of state and multiple reaction rate laws. Finite rate laws are used for the slowest chemical reactions, while other reactions are given infinite rates and are kept in constant thermodynamic equilibrium. We model a wide range of ideal and non-ideal composite energetic materials. In addition, we develop an exp-6 equation of state for the product fluids that reproduces a wide range experimental shock Hugoniot and static compression data. For unreacted solids, including solid and liquid Al and Al{sub 2}O{sub 3}, we use a Murnaghan form for the equation of state. We find that we can replicate experimental detonation velocities to within a few per cent for a wide range of explosives, while obtaining good agreement with estimated reaction zone lengths. The detonation velocity as a function of charge radius is also correctly reproduced.

Fried, L E; Howard, W M; Souers, P C

1999-03-01

399

Ideal MHD Stability of the QPS Stellarator  

NASA Astrophysics Data System (ADS)

The ideal MHD stability properties of the Quasi-Poloidal Stellarator (QPS) are examined. QPS is an ultra-low aspect ratio stellarator (A=2.7) with a quasi-poloidal symmetric magnetic field strength in Boozer coordinates and which has been proposed by ORNL. Variation of the external coil currents provides a useful tool for testing ideal MHD stability limits of QPS plasmas. Here, variation of external coil currents is shown to modify ballooning stability limits from an optimized case (? > 2% ) to a degraded case (? ˜ 1% ). This flexible coil set will allow QPS to test numerical predictions of ballooning stability. In addition, QPS will have the capability to drive Ohmic current. Plasma current magnitude and profile (from both Ohmic and bootstrap current) are shown to impact ballooning stability limits as well as possibly inducing kink or vertical instability.

Todd, L.; Ware, A. S.; Berry, L. A.; Hirshman, S. P.; Lyon, J. F.; Spong, D. A.; Strickler, D. J.; Sanchez, R.

2002-11-01

400

Variations in task and the ideal observer  

SciTech Connect

In most previous studies involving the ideal observer, the task considered has been that of simple detection where it is assumed that there is complete a priori knowledge of the background and of the possible object's shape, amplitude, and position. It is shown that redefining the detection task to include the possibility of an unknown, slowly varying background reduces the importance of the low-frequency components in the image for the ideal observer. More complicated tasks than object detection are also considered, such as determination of an object's position and width and the resolution of two objects. These higher-order tasks further enhance the importance of the high-frequency information content of the image.

Hanson, K.M.

1983-01-01

401

Max Weber's methodology: an ideal-type.  

PubMed

Weber dealt-in contrast to the textbook image of his method-with rational and nonempathetic explanatory interpretation. His ideal-type for social action emerged in a very formative period, as a mediation between history and theory and can be characterized as releasing what was inherent in a historicist tradition in crisis. Theoretical elements from Austrian marginalism provided Weber with the prototype for developing contrafactual schemes into ideal-types. Weber as a scholar at the crossroads resolved the problem of uncontrolled value-intrusion in a way that provided rational evidence and limited objectivity, in the form of instrumental means-end analysis. His methodology was coherent over time but gradually emerged when contemporary polemics called for his voice to be heard. PMID:10898889

Eliaeson, S

2000-01-01

402

Extracting the chern number from the dynamics of a fermi gas: implementing a quantum Hall bar for cold atoms.  

PubMed

We propose a scheme to measure the quantized Hall conductivity of an ultracold Fermi gas initially prepared in a topological Chern insulating phase and driven by a constant force. We show that the time evolution of the center of mass, after releasing the cloud, provides a direct and clear signature of the topologically invariant Chern number. We discuss the validity of this scheme, highlighting the importance of driving the system with a sufficiently strong force to displace the cloud over measurable distances while avoiding band-mixing effects. The unusual shapes of the driven atomic cloud are qualitatively discussed in terms of a semiclassical approach. PMID:24116789

Dauphin, Alexandre; Goldman, Nathan

2013-09-26

403

Electronic structures of mixed sandwich ansa -complexes of chromium as studied by gas-phase absorption spectroscopy and quantum chemistry  

Microsoft Academic Search

Gas-phase electronic absorption spectra of ansa-(cycloheptatrienylcyclopentadienyl)-chromium complexes with silicon- and germanium-containing bridges were recorded for the\\u000a first time. The spectrum of the —(SiMe2)2— bridged compound exhibits a Rydberg structure arising from the transitions originating at HOMO. Shortening of the bridge\\u000a causes the Rydberg bands to broaden beyond detection. Density functional calculations were performed to investigate the electron\\u000a density distribution in

S. Yu. Ketkov; N. A. Isachenkov; H. Braunschweig; T. Kupfer

2009-01-01

404

Diffusion thermopower of a two-dimensional hole gas in SiGe in a quantum Hall insulating state.  

PubMed

Both the temperature dependence of resistivity and thermopower of a two-dimensional hole gas in SiGe show a reentrant metal-insulator transition at filling factor nu=1.5, but with strikingly different behavior of the two coefficients. As the temperature is decreased in the insulating state, the resistivity diverges exponentially while the thermopower decreases rapidly, suggesting that the insulating state is due to the presence of a mobility edge rather than a gap at the Fermi energy. PMID:12786087

Possanzini, C; Fletcher, R; Coleridge, P T; Feng, Y; Williams, R L; Maan, J C

2003-04-28

405

Trace gas sensing using quantum cascade lasers and a fiber-coupled optoacoustic sensor: Application to formaldehyde  

NASA Astrophysics Data System (ADS)

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.

Elia, A.; Spagnolo, V.; Di Franco, C.; Lugarà, P. M.; Scamarcio, G.

2010-03-01

406

Scaling property of ideal granitic sequences  

Microsoft Academic Search

Quantification of granite textures and structures using a mathematical model for characterization of granites has been a long-term attempt of mathematical geologists over the past four decades. It is usually difficult to determine the influence of magma properties on mineral crystallization forming fined-grained granites due to its irregular and fine-grained textures. The ideal granite model was originally developed for modeling

D. Xu; Q. Cheng; F. Agterberg

2007-01-01

407

The ideal politician: Impact of voters’ ideology  

Microsoft Academic Search

The present study explores the relationship between voters’ ideology and their image of politicians’ ideal personality in terms of the Five-Factor Model and political leadership dimensions. Substantial differences between left- and right-wing voters emerged, indicating that left-wing voters preferred politicians to be higher in agreeableness and openness to experience than right-wing voters. Regardless of voters’ ideology, conscientiousness proved to be

Arne Roets; Alain Van Hiel

2009-01-01

408

Ideal equilibria in noncooperative multicriteria games  

Microsoft Academic Search

.   Pareto equilibria in multicriteria games can be computed as the Nash equilibria of scalarized games, obtained by assigning\\u000a weights to the separate criteria of a player. To analysts, these weights are usually unknown. This paper therefore proposes\\u000a ideal equilibria, strategy profiles that are robust against unilateral deviations of the players no matter what importance\\u000a is assigned to the criteria.

Mark Voorneveld; Sofia Grahn; Martin Dufwenberg

2000-01-01

409

Preserving idealism in global health promotion.  

PubMed

If the field of global health is to evolve in the second decade of the new millennium, we need to revive the idealistic spirit and by using the lens of health equity work toward improved health status around the world. Morality and empathy are considered by-products of our evolutionary history as a human species. Idealism may be a trait that we may choose to preserve in our modern evolutionary history. PMID:21513081

Franco-Paredes, Carlos; Zeuli, Julia; Hernández-Ramos, Isabel; Santos-Preciado, Jose I

2010-12-01

410

The magnetized d-dimensional ideal paragas  

Microsoft Academic Search

The magnetic properties of a d-dimensional uncharged ideal paragas in a uniform magnetic field are examined. For parastatistics parameter p = ? (bosons) there is Bose-Einstein condensation for d\\/alpha > 1 with spontaneous magnetization, and for 1

H. O. Frota; A. C. R. Bittencourt

1989-01-01

411

Equilibrium contact angles of liquid droplets on ideal rough solids.  

PubMed

This work proposes a theoretical model for predicting the apparent equilibrium contact angle of a liquid on an ideal rough surface that is homogeneous and has a negligible body force, line tension, or contact angle hysteresis between solid and liquid. The model is derived from the conservation equations and the free-energy minimization theory for the changes of state of liquid droplets. The work of adhesion is expressed as the contact angles in the wetting process of the liquid droplets. Equilibrium contact angles of liquid droplets for rough surfaces are expressed as functions of the area ratios for the solid, liquid, and surrounding gas and the roughness ratio and wetting ratio of the liquid on the solid for the partially and fully wet states. It is found that the ideal critical angle for accentuating the contact angles by the surface roughness is 48°. The present model is compared with existing experimental data and the classical Wenzel and Cassie-Baxter models and agrees with most of the experimental data for various surfaces and liquids better than does the Wenzel model and accounts for trends that the Wenzel model cannot explain. PMID:22053925

Kang, Hie Chan; Jacobi, Anthony M

2011-11-23

412

Searching Out the Ideal: Awareness of Ideal Body Standards Predicts Lower Global Self-esteem in Women  

Microsoft Academic Search

Does awareness of female body ideals affect women's global self-esteem? We measured awareness of ideal standards for beauty via two approaches. As one approach, participants (55 undergraduate women) self-reported their general propensity to be aware of society's thin ideal standard. As a second approach, we measured visual attention orienting to ideal standards; we covertly measured participants' eye movements to peers'

Emily Balcetis; Shana Cole; Marie B. Chelberg; Mark Alicke

2012-01-01

413

Quantum Computers and Quantum Control  

NASA Astrophysics Data System (ADS)

Quantum computation is an excercise in quantum control: for a quantum system to compute, its dynamics must be controlled to a high degree of precision. Quantum control, in turn, is an excercise in quantum computation: control can be thought of in terms of how information is represented and processed. This talk reviews recent developments in quantum computation and quantum control with an emphasis on their theoretical and experimental overlap.

Lloyd, Seth

2001-03-01

414

The direct effect of thin ideal focused adult television on young girls’ ideal body figure  

Microsoft Academic Search

The present study tested the direct effect of watching thin ideal focused television aimed at (young) adults on body dissatisfaction in preadolescent girls (9–12 years old). A within-subject design was used in which the girls (N=60) were tested three times. They watched three movie clips in random order that were either focused explicitly (thin ideal program) or indirectly (soap opera)

Doeschka J. Anschutz; Donna Spruijt-Metz; Tatjana Van Strien; Rutger C. M. E. Engels

2011-01-01

415

Gröbner Bases of Ideals Defined by Functionals with an Application to Ideals of Projective Points  

Microsoft Academic Search

In this paper we study 0-dimensional polynomial ideals defined by a dual basis, i.e. as the set of polynomials which are in the kernel of a set of linear morhpisms from the polynomial ring to the base field. For such ideals, we give polynomial complexity algorithms to compute a Gršbner basis, generalizing the Buchberger-Mšller algorithm for computing a basis of

Maria Grazia Marinari; H. Michael Möller; Teo Mora

1993-01-01

416

Classification of Universally Ideal Homomorphic Secret Sharing Schemes and Ideal BlackBox Secret Sharing Schemes  

Microsoft Academic Search

\\u000a A secret sharing scheme (SSS) is homomorphic, if the products of shares of secrets are shares of the product of secrets. For\\u000a a finite abelian group G, an access structure A{\\\\mathcal A} is G-ideal homomorphic, if there exists an ideal homomorphic SSS realizing the access structure A{\\\\mathcal A} over the secret domain G. An access structure A{\\\\mathcal A} is universally

Zhanfei Zhou

2005-01-01

417

Word recognition using ideal word patterns  

NASA Astrophysics Data System (ADS)

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.

Zhao, Sheila X.; Srihari, Sargur N.

1994-03-01

418

Non-Ideal Behavior in Solvent Extraction  

SciTech Connect

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.

Peter Zalupski

2011-09-01

419

Elastin: a representative ideal protein elastomer.  

PubMed

During the last half century, identification of an ideal (predominantly entropic) protein elastomer was generally thought to require that the ideal protein elastomer be a random chain network. Here, we report two new sets of data and review previous data. The first set of new data utilizes atomic force microscopy to report single-chain force-extension curves for (GVGVP)(251) and (GVGIP)(260), and provides evidence for single-chain ideal elasticity. The second class of new data provides a direct contrast between low-frequency sound absorption (0.1-10 kHz) exhibited by random-chain network elastomers and by elastin protein-based polymers. Earlier composition, dielectric relaxation (1-1000 MHz), thermoelasticity, molecular mechanics and dynamics calculations and thermodynamic and statistical mechanical analyses are presented, that combine with the new data to contrast with random-chain network rubbers and to detail the presence of regular non-random structural elements of the elastin-based systems that lose entropic elastomeric force upon thermal denaturation. The data and analyses affirm an earlier contrary argument that components of elastin, the elastic protein of the mammalian elastic fibre, and purified elastin fibre itself contain dynamic, non-random, regularly repeating structures that exhibit dominantly entropic elasticity by means of a damping of internal chain dynamics on extension. PMID:11911774

Urry, D W; Hugel, T; Seitz, M; Gaub, H E; Sheiba, L; Dea, J; Xu, J; Parker, T

2002-02-28

420

Quantum walks, quantum gates, and quantum computers  

SciTech Connect

The physics of quantum walks on graphs is formulated in Hamiltonian language, both for simple quantum walks and for composite walks, where extra discrete degrees of freedom live at each node of the graph. It is shown how to map between quantum walk Hamiltonians and Hamiltonians for qubit systems and quantum circuits; this is done for both single-excitation and multiexcitation encodings. Specific examples of spin chains, as well as static and dynamic systems of qubits, are mapped to quantum walks, and walks on hyperlattices and hypercubes are mapped to various gate systems. We also show how to map a quantum circuit performing the quantum Fourier transform, the key element of Shor's algorithm, to a quantum walk system doing the same. The results herein are an essential preliminary to a Hamiltonian formulation of quantum walks in which coupling to a dynamic quantum environment is included.

Hines, Andrew P. [Pacific Institute of Theoretical Physics and Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia, V6T 1Z1 (Canada); Pacific Institute for the Mathematical Sciences, 1933 West Mall, University of British Columbia, Vancouver, British Columbia, V6T 1Z2 (Canada); Stamp, P. C. E. [Pacific Institute of Theoretical Physics and Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia, V6T 1Z1 (Canada)

2007-06-15

421

Quantum communication  

Microsoft Academic Search

Quantum communication, and indeed quantum information in general, has changed the way we think about quantum physics. In 1984 and 1991, the first protocol for quantum cryptography and the first application of quantum non-locality, respectively, attracted interest from a diverse field of researchers in theoretical and experimental physics, mathematics and computer science. Since then we have seen a fundamental shift

Nicolas Gisin; Rob Thew

2007-01-01

422

Quantum imaging  

Microsoft Academic Search

One of the most surprising consequences of quantum mechanics is the entan- glement of two or more distant particles. Although questions regarding fundamental issues of quantum theory still exist, quantum entanglement has started to play important roles in practical engineering applications. Quantum imaging is one of these exciting areas. Quantum imaging has demonstrated two peculiar features: (1) reproducing \\

Yanhua Shih

2005-01-01

423

Quantum Imaging  

Microsoft Academic Search

One of the most surprising consequences of quantum mechanics is the entanglement of two or more distant particles. Although questions regarding fundamental issues of quantum theory still exist, quantum entanglement has started to play important roles in practical engineering applications. Quantum imaging is one of these exciting areas. Quantum imaging has demonstrated two peculiar features: 1) reproducing \\

Yanhua Shih

2007-01-01

424

Quantum computing  

Microsoft Academic Search

The subject of quantum computing brings together ideas from classical information theory, computer science, and quantum physics. This review aims to summarise not just quantum computing, but the whole subject of quantum information theory. It turns out that information theory and quantum mechanics fit together very well. In order to explain their relationship, the review begins with an introduction to

Andrew Steane

1998-01-01

425

Ionization equilibrium and partition functions of high-temperature weakly non-ideal Flibe gasMuch of this work has been presented at the 15th ANS Topical Meeting on the Technology of Fusion Energy (TOFE) (Washington, DC, November 2002)  

Microsoft Academic Search

A model for the ionization equilibrium of weakly non-ideal Flibe plasma is presented in terms of a set of coupled non-linear Saha equations supplemented by electro-neutrality and conservation of nuclei. Non-ideality effects have been taken into account in terms of lowering of the ionization potentials and truncated partition functions. A simple formulation and solution strategy of the Saha equations for

Mofreh R Zaghloul

2003-01-01

426

Increased body satisfaction after exposure to thin ideal children's television in young girls showing thin ideal internalisation.  

PubMed

This study tested the direct effect of watching thin ideal children's television on body satisfaction in preadolescent girls (6-8 years old). A within-subject design was used in which girls (N?=?51) were tested three times. They watched television clips in random order containing either (1) thin ideal animated characters or (2) animated characters with no thin ideal features or (3) 'real' human actors with no thin ideal features. After watching, their state body satisfaction was measured. Girls with higher levels of thin ideal internalisation showed higher body satisfaction after exposure to the thin ideal characters than after exposure to animated or real characters featuring no thin ideal features. No differences on body satisfaction between the exposure conditions were found in girls with lower levels of thin ideal internalisation. The results might suggest that young girls who internalised the thin ideal are inspired by thin ideal characters in children's media. PMID:22512700

Anschutz, Doeschka J; Engels, Rutger C M E; Van Strien, Tatjana

2012-01-01

427

Semi-insulating InP:Fe for buried-heterostructure strain-compensated quantum-cascade lasers grown by gas-source molecular-beam epitaxy  

NASA Astrophysics Data System (ADS)

We describe the realization of buried-heterostructure strain-compensated quantum-cascade lasers that incorporate a very high degree of internal strain and are grown on InP substrates using gas-source molecular-beam epitaxy (GSMBE). The active region of the lasers contains AlAs layers up to 1.6nm thick with 3.7% tensile strain; restricting any post-growth processing to temperatures below 600°C to avoid relaxation. We demonstrate that buried-heterostructure devices can be realized by using GSMBE to over-grow the etched laser ridge with insulating InP:Fe at temperatures low enough to preserve the crystal quality of the strain-compensated active region. Two distinct growth techniques are described, both leading to successful device realization: selective regrowth at 550°C and non-selective regrowth at 470°C. The resulting buried-heterostructure lasers are compared to a reference laser from the same wafer, but with SiO2 insulation; all three have very similar threshold current densities, operational thermal stability, and waveguide losses.

Semtsiv, M. P.; Aleksandrova, A.; Elagin, M.; Monastyrskyi, G.; Kischkat, J.-F.; Flores, Y. V.; Masselink, W. T.

2013-09-01

428

Energy relaxation rate of the two-dimensional hole gas in a GaAs/InGaAs/GaAs quantum well  

NASA Astrophysics Data System (ADS)

The nonohmic conductivity of two-dimensional hole gas (2DHG) in single GaAsIn0.2Ga0.8AsGaAs quantum-well structures within the temperature range of 1.4-4.2 K, the carrier’s densities p=(1.5-8)×1015m-2 and a wide range of conductivities (10-4-100)G0 (G0=e2/?h) was investigated. It was shown that at conductivity ?>G0 the energy relaxation rate P(Th,TL) is well described by the conventional theory [P. J. Price, J. Appl. Phys.JAPIAU0021-897910.1063/1.330026 53, 6863 (1982)], which takes into account scattering on acoustic phonons with both piezoelectric and deformational potential coupling to holes. At the conductivity range 0.01G0

Soldatov, I. V.; Germanenko, A. V.; Minkov, G. M.; Rut, O. E.; Sherstobitov, A. A.

2011-02-01

429

High resolution Dopplerimetry of correlated angular and quantum state-resolved CO(2) scattering dynamics at the gas-liquid interface.  

PubMed

Full three dimensional (3D) translational distributions for quantum state-resolved scattering dynamics at the gas-liquid interface are presented for experimental and theoretical studies of CO(2) + perfluorinated surfaces. Experimentally, high resolution absorption profiles are measured as a function of incident (?(inc)) and scattering (?(scat)) angles for CO(2) that has been scattered from a 300 K perfluorinated polyether surface (PFPE) with an incident energy of E(inc) = 10.6(8) kcal mol(-1). Line shape analysis of the absorption profiles reveals non-equilibrium dynamics that are characterized by trapping-desorption (TD) and impulsive scattering (IS) components, with each channel simply characterized by an effective "temperature" that compares very well with previous results from rotational state analysis [Perkins and Nesbitt, J. Phys. Chem. A, 2008, 112, 9324]. From a theoretical perspective, molecular dynamics (MD) simulations of CO(2) + fluorinated self-assembled monolayer surface (F-SAMs) yield translational probability distributions that are also compared with experimental results. Trajectories are parsed by ?(scat) and J, with the results rigorously corrected by flux-to-density transformation and providing comparisons in near quantitative agreement with experiment. 3D flux and velocity distributions obtained from MD simulations are also presented to illustrate the role of in- and out-of-plane scattering. PMID:20890492

Perkins, Bradford G; Nesbitt, David J

2010-10-01

430

Time-resolved gas-phase kinetic, quantum chemical, and RRKM studies of reactions of silylene with alcohols.  

PubMed

Time-resolved kinetic studies of silylene, SiH(2), generated by laser flash photolysis of 1-silacyclopent-3-ene and phenylsilane, have been carried out to obtain rate constants for its bimolecular reactions with methanol, ethanol, 1-propanol, 1-butanol, and 2-methyl-1-butanol. The reactions were studied in the gas phase over the pressure range 1-100 Torr in SF(6) bath gas, at room temperature. In the study with methanol several buffer gases were used. All five reactions showed pressure dependences characteristic of third body assisted association reactions. The rate constant pressure dependences were modeled using RRKM theory, based on E(0) values of the association complexes obtained by ab initio calculation (G3 level). Transition state models were adjusted to fit experimental fall-off curves and extrapolated to obtain k(?) values in the range (1.9-4.5) × 10(-10) cm(3) molecule(-1) s(-1). These numbers, corresponding to the true bimolecular rate constants, indicate efficiencies of between 16% and 67% of the collision rates for these reactions. In the reaction of SiH(2) + MeOH there is a small kinetic component to the rate which is second order in MeOH (at low total pressures). This suggests an additional catalyzed reaction pathway, which is supported by the ab initio calculations. These calculations have been used to define specific MeOH-for-H(2)O substitution effects on this catalytic pathway. Where possible our experimental and theoretical results are compared with those of previous studies. PMID:21469721

Becerra, Rosa; Cannady, J Pat; Walsh, Robin

2011-04-06

431

Quantum memory in quantum cryptography  

Microsoft Academic Search

[Shortened abstract:] This thesis investigates the importance of quantum memory in quantum cryptography, concentrating on quantum key distribution schemes. In the hands of an eavesdropper -- a quantum memory is a powerful tool, putting in question the security of quantum cryptography; Classical privacy amplification techniques, used to prove security against less powerful eavesdroppers, might not be effective when the eavesdropper

Tal Mor

1999-01-01

432

Experimental signature of programmable quantum annealing  

NASA Astrophysics Data System (ADS)

Quantum annealing is a general strategy for solving difficult optimization problems with the aid of quantum adiabatic evolution. Both analytical and numerical evidence suggests that under idealized, closed system conditions, quantum annealing can outperform classical thermalization-based algorithms such as simulated annealing. Current engineered quantum annealing devices have a decoherence timescale which is orders of magnitude shorter than the adiabatic evolution time. Do they effectively perform classical thermalization when coupled to a decohering thermal environment? Here we present an experimental signature which is consistent with quantum annealing, and at the same time inconsistent with classical thermalization. Our experiment uses groups of eight superconducting flux qubits with programmable spin-spin couplings, embedded on a commercially available chip with >100 functional qubits. This suggests that programmable quantum devices, scalable with current superconducting technology, implement quantum annealing with a surprising robustness against noise and imperfections.

Boixo, Sergio; Albash, Tameem; Spedalieri, Federico M.; Chancellor, Nicholas; Lidar, Daniel A.

2013-06-01

433

Quantum mechanics of cluster melting  

SciTech Connect

We present here prototype studies of the effects of quantum mechanics on the melting of clusters. Using equilibrium path integral methods, we examine the melting transition for small rare gas clusters. Argon and neon clusters are considered. We find the quantum-mechanical effects on the melting and coexistence properties of small neon clusters to be appreciable.

Beck, T.L.; Doll, J.D.; Freeman, D.L.

1989-05-15

434

Quantumness beyond quantum mechanics  

NASA Astrophysics Data System (ADS)

Bohmian mechanics allows us to understand quantum systems in the light of other quantum traits than the well-known ones (coherence, diffraction, interference, tunnelling, discreteness, entanglement, etc.). Here the discussion focusses precisely on two of these interesting aspects, which arise when quantum mechanics is thought within this theoretical framework: the non-crossing property, which allows for distinguishability without erasing interference patterns, and the possibility to define quantum probability tubes, along which the probability remains constant all the way. Furthermore, taking into account this hydrodynamic-like description as a link, it is also shown how this knowledge (concepts and ideas) can be straightforwardly transferred to other fields of physics (for example, the transmission of light along waveguides).

Sanz, Ángel S.

2012-05-01

435

I, Quantum Robot: Quantum Mind control on a Quantum Computer  

Microsoft Academic Search

The logic which describes quantum robots is not orthodox quantum logic, but a deductive calculus which reproduces the quantum tasks (computational processes, and actions) taking into account quantum superposition and quantum entanglement. A way toward the realization of intelligent quantum robots is to adopt a quantum metalanguage to control quantum robots. A physical implementation of a quantum metalanguage might be

Paola Zizzi

2008-01-01

436

Ideal Magnetohydrodynamic Stability of the NCSX  

SciTech Connect

The ideal magnetohydrodynamic (MHD) stability of the National Compact Stellarator Experiment (NCSX) is extensively analyzed using the most advanced three-dimensional MHD codes. It is shown that the NCSX is stable to finite-n MHD modes, including the vertical mode, external kink modes and ballooning modes. However, high-n external kink modes that peak near the plasma edge are found to be weakly unstable. A global calculation shows that finite-n ballooning modes are significantly more stable than the local infinite-n modes.

Fu, GuoYong [Princeton Plasma Physics Laboratory (PPPL); Isaev, Maxim Yu [Kurchatov Institute, Moscow, Russia; Ku, Long-Poe [Princeton Plasma Physics Laboratory (PPPL); Mikhailov, M [Kurchatov Institute, Moscow, Russia; Redi, M H [Princeton Plasma Physics Laboratory (PPPL); Sanchez, Raul [ORNL; Subbotin, A [Kurchatov Institute, Moscow, Russia; Hirshman, Steven Paul [ORNL; Cooper, W Anthony [CRPP/EPFL, Association Euratom-Suisse, Lausanne, Switzerland; Monticello, D. [Princeton Plasma Physics Laboratory (PPPL); Reiman, A H [Princeton Plasma Physics Laboratory (PPPL); Zarnstorff, M. C. [Princeton Plasma Physics Laboratory (PPPL)

2007-01-01

437

Identification of ideal peptides for heterovalent ligands.  

PubMed

Recent use of hetero-dimerization to improve the affinity of peptide ligands has made peptides an attractive alternative to small molecules and proteins. Using this strategy, we have developed peptides with affinities comparable to antibodies and specificities often better than small molecules or antibodies. These peptides can be used as a delivery vehicle for drugs or diagnostics, especially in the case of tumor targeting cytotoxic drugs or targeted diagnostics. We describe here an assay to identify an ideal pair of peptides suitable for heterovalent ligands. PMID:24146399

Shrivastava, Ajay; von Wronski, Matthew; Tweedle, Michael F; Nunn, Adrian D

2014-01-01

438

Quantum Singularity of Quasiregular Spacetimes  

NASA Astrophysics Data System (ADS)

A quasiregular spacetime is a spacetime with a classical quasiregular singularity, the mildest form of true singularity [G.F.R. Ellis and B.G. Schmidt, Gen. Rel. Grav. 8, 915 (1977)]. The definition of G.T. Horowitz and D. Marolf [Phys. Rev. D52, 5670 (1995)] for a quantum-mechanically singular spacetime is one in which the spatial-derivative operator in the Klein-Gordon equation for a massive scalar field is not essentially self-adjoint. In such a quantum-mechanically singular spacetime, the time evolution of a quantum test particle is not uniquely determined. Horowitz and Marolf showed that a two-dimensional spacetime with a classical conical singularity (i.e., a two-dimensional quasiregular singularity) is also quantum-mechanically singular. Here we show that a class of static quasiregular spacetimes possessing disclinations and dislocations [R.A.Puntigam and H.H. Soleng , Class. Quantum Grav. 14, 1129 (1997)] is quantum-mechanically singular, since the scalar wave operator is not essentially self-adjoint. These spacetimes include an idealized cosmic string spacetime, i.e., a four-dimensional spacetime with conical singularity, and a Galtsov/Letelier/Tod spacetime featuring a screw dislocation [K.P. Tod, Class. Quantum Grav. 11, 1331 (1994); D.V. Galtsov and P.S. Letelier, Phys. Rev. D47, 4273 (1993)]. In addition, we show that the definition of quantum-mechanically singular spacetimes can be extended to include Maxwell and Dirac fields.

Konkowski, Deborah A.; Helliwell, Thomas M.

2001-04-01

439

Modeling of non-ideal aluminized explosives  

SciTech Connect

We have implemented a Wood-Kirkwood kinetic detonation model based on multi-species equations of state and multiple reaction rate laws. Finite rate laws are used for the slowest chemical reactions, while other reactions are given infinite rates and are kept in constant thermodynamic equilibrium. Within the context of WK theory, we study the chemical interaction between Al and HMX detonation products in non-ideal explosives. We develop a kinetic rate law for the combustion of Al in a condensed detonation that depends on the pressure and the detonation product gases. We use a Murnaghan form for the equation of state of the solid and liquid Al and Al{sub 2}O{sub 3}. We find that we can replicate experimental detonation velocities for HMX/Al composites to within a few percent for a wide range of aluminum content. We discuss the uncertainties in our model and the implications of our results on the modeling of other non-ideal explosives.

Fried, L E; Howard, W M; Souers, P C

1999-06-01

440

Modeling of Non-Ideal Aluminized Detonations  

NASA Astrophysics Data System (ADS)

We have implemented a Wood-Kirkwood (WK) kinetic detonation model based on multi-species equations of state and multiple reaction rate laws. Finite rate laws are used for the slowest chemical reactions, while other reactions are given infinite rates and are kept in constant thermodynamic equilibrium. Within the context of WK theory, we study the chemical interaction between Al and HMX detonation products in non-ideal explosives. We develop a kinetic rate law for the burning of Al in condensed detonation that depends on the surface properties of the Al grains and the detonation product gases. Moreover, we use an exp-6 equation of state for the product fluids that reproduces a wide range experimental shock hugoniot and static compression data. We use a Murnaghan form for the equation of state of the solid and liquid Al and Al_2O_3. We find that we can replicate experimental detonation velocities to within a few per cent for a wide range of aluminum content. We discuss the uncertainties in our model and the implications of our results on the modeling of other non-ideal explosives. This work was performed under the auspices of the U. S. Department of Energy under Contract No. W-7405-ENG-48.

Howard, W. Michael; Fried, Laurence E.; Souers, P. Clark

1999-06-01

441

Developing antitussives: the ideal clinical trial.  

PubMed

Antitussive drugs are amongst the most widely used medications worldwide; however no new class of drugs have been introduced into the market for many years. Trials showing patient benefit are scarce and have been hampered by the lack of objective and validated outcome measures. Recent improvements in the assessment of cough will facilitate better trials and aid the development of antitussive drugs. When conducting a trial, patient selection is of paramount importance. Patients with unexplained chronic cough and sub-acute cough following upper respiratory tract infection are ideal because they represent an unmet clinical need and an untapped market for pharmaceutical companies. Patients with asthma and chronic obstructive pulmonary disease are less suitable since cough suppression is not always desirable and the findings of trials may not be generalisable to all patients with cough. Randomized, placebo-controlled, double-blind clinical trials are obviously the gold standard. The choice of placebo, whether inert or active, depends on the incidence and severity of drug side-effects. The primary outcome measure should be objective and cough monitors are the ideal tool. Subjective outcome measures should be used to assess symptoms and health related quality of life. Properly conducted clinical trials are an opportunity to evaluate the benefits of currently available therapies and aid advances in the antitussive drug market. PMID:19041729

Birring, Surinder S

2008-11-13

442

Nonlinear stability of ideal fluid equilibria  

SciTech Connect

The Lyapunov method for establishing stability is related to well- known energy principles for nondissipative dynamical systems. A development of the Lyapunov method for Hamiltonian systems due to Arnold establishes sufficient conditions for Lyapunov stability by using the energy plus other conserved quantities, together with second variations and convexity estimates. When treating the stability of ideal fluid dynamics within the Hamiltonian framework, a useful class of these conserved quantities consists of the Casimir functionals, which Poisson-commute with all functionals of the dynamical fluid variables. Such conserved quantities, when added to the energy, help to provide convexity estimates that bound the growth of perturbations. These convexity estimates, in turn, provide norms necessary for establishing Lyapunov stability under the nonlinear evolution. In contrast, the commonly used second variation or spectral stability arguments only prove linearized stability. As ideal fluid examples, in these lectures we discuss planar barotropic compressible fluid dynamics, the three-dimensional hydrostatic Boussinesq model, and a new set of shallow water equations with nonlinear dispersion due to Basdenkov, Morosov, and Pogutse(1985). Remarkably, all three of these samples have the same Hamiltonian structure and, thus, possess the same Casimir functionals upon which their stability analyses are based. We also treat stability of modified quasigeostrophic flow, a problem whose Hamiltonian structure and Casimirs closely resemble Arnold's original example. Finally, we discuss some aspects of conditional stability and the applicability of Arnold's development of the Lyapunov technique. 100 refs.

Holm, D.D.

1988-01-01

443

Conservative regularization of ideal hydrodynamics and magnetohydrodynamics  

NASA Astrophysics Data System (ADS)

Inviscid, incompressible hydrodynamics and incompressible ideal magnetohydrodynamics (MHD) share many properties such as time-reversal invariance of equations, conservation laws, and certain topological features. In three dimensions, these systems may lead to singular solutions (involving vortex and current sheets). While dissipative (viscoresistive) effects can regularize the equations leading to bounded solutions to the initial-boundary value (Cauchy) problem which presumably exist uniquely, the time-reversal symmetry and associated conservation properties are certainly destroyed. The present work is analogous to (and suggested by) the Korteweg-de Vries regularization of the one-dimensional, nonlinear kinematic wave equation. Thus the regularizations applied to the original equations of hydrodynamics and ideal MHD retain conservation properties and the symmetries of the original equations. Integral invariants which generalize those known for the original systems are shown to imply bounded enstrophy. The regularization developed can also be applied to the corresponding dissipative models (such as the Navier-Stokes equations and the viscoresistive MHD equations) and may imply interesting regularity properties for the solutions of the latter as well. The models developed thus have intrinsic mathematical interest as well as possible applications to large-scale numerical simulations in systems where dissipative effects are extremely small or even absent.

Thyagaraja, A.

2010-03-01

444

Thermodynamics of an idealized hydrologic cycle  

NASA Astrophysics Data System (ADS)

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.

Konings, Alexandra G.; Feng, Xue; Molini, Annalisa; Manzoni, Stefano; Vico, Giulia; Porporato, Amilcare

2012-05-01

445

Conservative regularization of ideal hydrodynamics and magnetohydrodynamics  

SciTech Connect

Inviscid, incompressible hydrodynamics and incompressible ideal magnetohydrodynamics (MHD) share many properties such as time-reversal invariance of equations, conservation laws, and certain topological features. In three dimensions, these systems may lead to singular solutions (involving vortex and current sheets). While dissipative (viscoresistive) effects can regularize the equations leading to bounded solutions to the initial-boundary value (Cauchy) problem which presumably exist uniquely, the time-reversal symmetry and associated conservation properties are certainly destroyed. The present work is analogous to (and suggested by) the Korteweg-de Vries regularization of the one-dimensional, nonlinear kinematic wave equation. Thus the regularizations applied to the original equations of hydrodynamics and ideal MHD retain conservation properties and the symmetries of the original equations. Integral invariants which generalize those known for the original systems are shown to imply bounded enstrophy. The regularization developed can also be applied to the corresponding dissipative models (such as the Navier-Stokes equations and the viscoresistive MHD equations) and may imply interesting regularity properties for the solutions of the latter as well. The models developed thus have intrinsic mathematical interest as well as possible applications to large-scale numerical simulations in systems where dissipative effects are extremely small or even absent.

Thyagaraja, A. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

2010-03-15

446

What constitutes an ideal dental restorative material?  

PubMed

Intense environmental concerns recently have prompted dentistry to evaluate the performance and environmental impact of existing restoration materials. Doing so entices us to explore the 'what if?' innovation in materials science to create more ideal restorative materials. Articulating a specification for our design and evaluation methods is proving to be more complicated than originally anticipated. Challenges exist not only in specifying how the material should be manipulated and perform clinically but also in understanding and incorporating implications of the skill of the operator placing the restoration, economic considerations, expectations patients have for their investment, cost-effectiveness, influences of the health care system on how and for whom restorations are to be placed, and global challenges that limit the types of materials available in different areas of the world. The quandary is to find ways to actively engage multiple stakeholders to agree on priorities and future actions to focus future directions on the creation of more ideal restorative materials that can be available throughout the world. PMID:24129813

Rekow, E D; Bayne, S C; Carvalho, R M; Steele, J G

2013-11-01

447

THE EISENBUD-GREEN-HARRIS CONJECTURE FOR IDEALS OF POINTS  

Microsoft Academic Search

It has been conjectured by Eisenbud, Green, and Harris that lex-plus-powers ideals exhibit extremal conditions among all homogeneous ideals containing a regular sequence of forms in fixed degrees. In this paper we give a \\

SUSAN MARIE COOPER

448

Purification of noisy quantum measurements  

NASA Astrophysics Data System (ADS)

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.OPLEDP0146-959210.1364/OL.12.000789 12, 789 (1987)].

Dall'Arno, Michele; D'Ariano, Giacomo Mauro; Sacchi, Massimiliano F.

2010-10-01

449

Experimental one-way quantum computing.  

PubMed

Standard quantum computation is based on sequences of unitary quantum logic gates that process qubits. The one-way quantum computer proposed by Raussendorf and Briegel is entirely different. It has changed our understanding of the requirements for quantum computation and more generally how we think about quantum physics. This new model requires qubits to be initialized in a highly entangled cluster state. From this point, the quantum computation proceeds by a sequence of single-qubit measurements with classical feedforward of their outcomes. Because of the essential role of measurement, a one-way quantum computer is irreversible. In the one-way quantum computer, the order and choices of measurements determine the algorithm computed. We have experimentally realized four-qubit cluster states encoded into the polarization state of four photons. We characterize the quantum state fully by implementing experimental four-qubit quantum state tomography. Using this cluster state, we demonstrate the feasibility of one-way quantum computing through a universal set of one- and two-qubit operations. Finally, our implementation of Grover's search algorithm demonstrates that one-way quantum computation is ideally suited for such tasks. PMID:15758991

Walther, P; Resch, K J; Rudolph, T; Schenck, E; Weinfurter, H; Vedral, V; Aspelmeyer, M; Zeilinger, A

2005-03-10

450

Accurate molecular structure of nickel phthalocyanine (NiN8C32H16): Gas-phase electron diffraction and quantum-chemical calculations  

NASA Astrophysics Data System (ADS)

The molecular structure of the nickel phthalocyanine (NiPc) was determined using the combination of gas-phase electron diffraction (GED), mass spectrometry and quantum chemical calculations. The DFT calculations with employing different functionals and basis sets found the molecular structure with D4h symmetry that agrees satisfactorily to the one found in experiment at 776 ± 5 K. The important bond lengths and bond angles according to GED (total errors in parentheses) are: rh1(Ni-N) = 1.913(5) Å, rh1(N-Cp) = 1.385(4) Å, rh1(Cp-Nm) = 1.327(5) Å, rh1(Cp-Cp) = 1.462(6) Å, rh1(Cp-C) = 1.399(3) Å, rh1(C-C) = 1.395(3) Å, ?NiNCp = 126.6(2)°, ?NCpNm = 128.4(4)°, ?CpNmCp = 120.1(5)°, ?NCpCp = 110.0(4)°, ?CpCpC = 121.2(1)°. The nickel-nitrogen bond distance obtained is by 0.04 Å longer than the one found for this compound in the literature. The structures of the crystalline and gaseous NiPc complex are compared. The effect of the metal (Ni, Cu, Zn) on structural features of the MPc complexes is discussed. Using NBO-analysis, the correlation between the metal-ligand bond distance and the total energy of donor-acceptor orbital interactions per one M-N bond was found in the MPc complexes.

Tverdova, Natalya V.; Pimenov, Oleg A.; Girichev, Georgiy V.; Shlykov, Sergey A.; Giricheva, Nina I.; Mayzlish, Vladimir E.; Koifman, Oscar I.

2012-09-01

451

Poset resolutions and lattice-linear monomial ideals  

Microsoft Academic Search

We introduce the class of lattice-linear monomial ideals and use the lcm-lattice to give an explicit construction for their minimal free resolution. The class of lattice-linear ideals includes (among others) the class of monomial ideals with a linear free resolution and the class of Scarf monomial ideals. Our main tool is a new construction by Tchernev that produces from a

Timothy B. P. Clark

2010-01-01

452

B(H) lattices, density and arithmetic mean ideals  

Microsoft Academic Search

This part of a multi-paper project studies the lattice properties of the arithmetic mean ideals of B(H) introduced by Dykema, Figiel, Weiss, and Wodzicki. We prove: the lattices of all principal ideals, of arithmetic mean or arithmetic mean at infinity stable principal ideals or of principal ideals with a generator that satisfies the Delta_1\\/2 condition, are all both upper and

Victor Kaftal; Gary Weiss

2007-01-01

453

Quantum information dynamics  

NASA Astrophysics Data System (ADS)

Presented is a study of quantum entanglement from the perspective of the theory of quantum information dynamics. We consider pairwise entanglement and present an analytical development using joint ladder operators, the sum of two single-particle fermionic ladder operators. This approach allows us to write down analytical representations of quantum algorithms and to explore quantum entanglement as it is manifested in a system of qubits. We present a topological representation of quantum logic that views entangled qubit spacetime histories (or qubit world lines) as a generalized braid, referred to as a super-braid. The crossing of world lines may be either classical or quantum mechanical in nature, and in the latter case most conveniently expressed with our analytical expressions for entangling quantum gates. At a quantum mechanical crossing, independent world lines can become entangled. We present quantum skein relations that allow complicated superbraids to be recursively reduced to alternate classical histories. If the superbraid is closed, then one can decompose the resulting superlink into an entangled superposition of classical links. Also, one can compute a superlink invariant, for example the Jones polynomial for the square root of a knot. We present measurement-based quantum computing based on our joint number operators. We take expectation values of the joint number operators to determine kinetic-level variables describing the quantum information dynamics in the qubit system at the mesoscopic scale. We explore the issue of reversibility in quantum maps at this scale using a quantum Boltzmann equation. We then present an example of quantum information processing using a qubit system comprised of nuclear spins. We also discuss quantum propositions cast in terms of joint number operators. We review the well known dynamical equations governing superfluidity, with a focus on self-consistent dynamics supporting quantum vortices in a Bose-Einstein condensate (BEC). Furthermore, we review the mutual vortex-vortex interaction and the consequent Kelvin wave instability. We derive an effective equation of motion for a Fermi condensate that is the basis of our qubit representation of superfluidity. We then present our quantum lattice gas representation of a superfluid. We explore aspects of our model with two qubits per point, referred to as a Q2 model, particularly its usefulness for carrying out practical quantum fluid simulations. We find that it is perhaps the simplest yet most comprehensive model of superfluid dynamics. As a prime application of Q2, we explore the power-law regions in the energy spectrum of a condensate in the low-temperature limit. We achieved the largest quantum simulations to date of a BEC and, for the first time, Kolmogorov scaling in superfluids, a flow regime heretofore only obtainably by classical turbulence models. Finally, we address the subject of turbulence regarding information conservation on the small scales (both mesoscopic and microscopic) underlying the flow dynamics on the large hydrodynamic (macroscopic) scale. We present a hydrodynamic-level momentum equation, in the form of a Navier-Stokes equation, as the basis for the energy spectrum of quantum turbulence at large scales. Quantum turbulence, in particular the representation of fluid eddies in terms of a coherent structure of polarized quantum vortices, offers a unique window into the heretofore intractable subject of energy cascades.

Yepez, Jeffrey

454

Quantum memory  

Microsoft Academic Search

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

Jean-Louis Le Gouët; Sergey Moiseev

2012-01-01

455

Quantum Noise  

Microsoft Academic Search

Quantum Noise is advertised as a handbook, and this is indeed how it functions for me these days: it is a book that I keep within hand's reach, ready to be consulted on the proper use of quantum stochastic methods in the course of my research on quantum dots. I should point out that quantum optics, the target field for

C W J Beenakker

2005-01-01

456

Why Education in Public Schools Should Include Religious Ideals  

ERIC Educational Resources Information Center

This article aims to open a new line of debate about religion in public schools by focusing on religious ideals. The article begins with an elucidation of the concept "religious ideals" and an explanation of the notion of reasonable pluralism, in order to be able to explore the dangers and positive contributions of religious ideals and their…

de Ruyter, Doret J.; Merry, Michael S.

2009-01-01

457

Promoting Spiritual Ideals through Design Thinking in Public Schools  

ERIC Educational Resources Information Center

|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…

Tan, Charlene; Wong, Yew-Leong

2012-01-01

458

Susceptibility for thin ideal media and eating styles  

Microsoft Academic Search

This study examined the relations between susceptibility for thin ideal media and restrained, emotional and external eating, directly and indirectly through body dissatisfaction. Thin ideal media susceptibility, body dissatisfaction and eating styles were measured in a sample of 163 female students. Structural equation modelling was used for analyses, controlling for BMI. Higher susceptibility for thin ideal media was directly related

Doeschka J. Anschutz; Rutger C. M. E. Engels; Tatjana Van Strien

2008-01-01

459

The Ideal Structure of Cuntz-Krieger Algebras  

Microsoft Academic Search

We construct a universal Cuntz-Krieger algebra AO A , which isisomorphic to the usual Cuntz-Krieger algebra O A when A satises thecondition (I) of Cuntz and Krieger. Cuntz's classication of ideals inO A when A satises condition (II) extends to a classication of thegauge invariant ideals in AO A . We use this to describe the topologyon the primitive ideal

Astrid An Huef; Iain Raeburn

1996-01-01

460

Why Education in Public Schools Should Include Religious Ideals  

ERIC Educational Resources Information Center

|This article aims to open a new line of debate about religion in public schools by focusing on religious ideals. The article begins with an elucidation of the concept "religious ideals" and an explanation of the notion of reasonable pluralism, in order to be able to explore the dangers and positive contributions of religious ideals and their…

de Ruyter, Doret J.; Merry, Michael S.

2009-01-01

461

Examples for Non-Ideal Solution Thermodynamics Study  

ERIC Educational Resources Information Center

|A mathematical model of a non-ideal solution is presented, where it is shown how and where the non-ideality manifests itself in the standard thermodynamics tableau. Examples related to the non-ideal solution thermodynamics study are also included.|

David, Carl W.

2004-01-01

462

The management of ideals: a political perspective on ethics  

Microsoft Academic Search

Both bureaucratic and democratic ideals are essential elements of the public administration ethos, yet these two sets of ideals have not been effectively integrated in an ethic of public administration. Ethics has been approached primarily from a rule-oriented bureaucratic perspective that gives little guidance to administrators who wish to promote democratic ideals and function ethically in an increasingly political administrative

Kathryn G. Denhardt

1997-01-01

463

Quantum Blobs  

NASA Astrophysics Data System (ADS)

Quantum blobs are the smallest phase space units of phase space compatible with the uncertainty principle of quantum mechanics and having the symplectic group as group of symmetries. Quantum blobs are in a bijective correspondence with the squeezed coherent states from standard quantum mechanics, of which they are a phase space picture. This allows us to propose a substitute for phase space in quantum mechanics. We study the relationship between quantum blobs with a certain class of level sets defined by Fermi for the purpose of representing geometrically quantum states.

de Gosson, Maurice A.

2013-04-01

464