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1

?-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.

2

Ideal Gas Laws  

NSDL National Science Digital Library

This lab manual contains descriptions of a series of laboratories covering the ideal gas laws and ideal gas processes. These experiments are designed for introductory high school and college introductory physics, chemistry, and engineering courses. Each experiment includes the intended audience, learning goals, and a short introduction to the physics. The experiments include Boyleâs Law, work done in an isothermal process, adiabatic processes, thermodynamic cycles, and the heat capacity of a gas. These labs are designed for an adiabatic gas law apparatus developed at Andrews University.

Kutzner, Mickey; Wong, Peter

2011-11-18

3

Ideal theory of quantum well solar cells  

Microsoft Academic Search

An ideal model for quantum well solar cells is developed and is used to theoretically explore the dependence of terminal characteristics on the host cell and quantum well properties. The model, which explicitly treats carrier generation and recombination in the quantum wells, is described and compared with an analogous ideal model for bulk homojunction cells. Open-circuit voltages, short-circuit current densities,

Neal G. Andersona

1995-01-01

4

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.

5

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

6

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

7

Quantum Darwinism in non-ideal environments  

Microsoft Academic Search

Quantum Darwinism provides an information-theoretic framework for the emergence of the objective, classical world from the quantum substrate. The key to this emergence is the proliferation of redundant information throughout the environment where observers can then intercept it. We study this process for a purely decohering interaction when the environment, E, is in a non-ideal (e.g., mixed) initial state. In

Michael Zwolak; H. T. Quan; Wojciech H. Zurek

2009-01-01

8

Quantum Darwinism in non-ideal environments  

Microsoft Academic Search

Quantum Darwinism provides an information-theoretic framework for the\\u000aemergence of the objective, classical world from the quantum substrate. The key\\u000ato this emergence is the proliferation of redundant information throughout the\\u000aenvironment where observers can then intercept it. We study this process for a\\u000apurely decohering interaction when the environment, E, is in a non-ideal (e.g.,\\u000amixed) initial state. In

Michael Zwolak; H. T. Quan; Wojciech H. Zurek

2009-01-01

9

STP Ideal Fermi Gas Integral Program  

NSDL National Science Digital Library

The STP IdealFermiGasIntegral program numerically determines the value of the chemical potential of an ideal Fermi gas for a given temperature and density. STP IdealFermiGasIntegral is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp_IdealFermiGasIntegral.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2009-02-19

10

STP Temperature Measurement Ideal Gas Program  

NSDL National Science Digital Library

The STP DemonIdealGas program displays a histogram of the energy of a demon that exchanges energy with an ideal gas of particles. The purpose of this simulation is to understand why the demon acts as a perfect thermometer and why its mean energy is a measure of the temperature of the gas. The default system is a one-dimensional ideal gas of N=40 particles. Additional states and parameters can be specified using the Display|Switch GUI menu item. STP DemonIdealGas is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double-clicking the stp_DemonIdealGas.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2008-05-28

11

Cutoff Energy Behavior for an Ideal Gas  

Microsoft Academic Search

The energy distribution for an ideal gas is important to dynamical astronomy because it is used as the statistical basis for modeling relaxed dynamical systems. This presentation deals with some fundamental aspects of this distribution. The microcanonical distribution for a monatomic ideal gas gives the probability that a particle's energy is in a specified range simply as $ dpsi =c1(

M. Cahill

2003-01-01

12

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

13

Modelling ideal gas fluorides laser plasmas  

Microsoft Academic Search

A model of spatially homogeneous ideal gas fluorides discharges is developed for estimation of charge carrier densities, electron energies and drift, and their time dependence is a function of gas composition, partial pressure, geometry and electrical input data. The calculations were based on the Boltzmann equation and the transport equation with the density, impulsion and energy of the electron gas.

Karin Stein

1991-01-01

14

STP Ideal Gas Number Of States Program  

NSDL National Science Digital Library

The STP IdealGasNumberOfStates program numerically evaluates the number of states of an ideal gas and demonstrates finite size effects by plotting the actual number of states and the asymptotic expression. The default is two-dimensional system (d=2). STP IdealGasNumberOfStates is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double clicking the stp_IdealGasNumberOfStates.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2009-02-17

15

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

16

Ideal shear strength of a quantum crystal.  

PubMed

Using path-integral Monte Carlo simulations, we compute the ideal shear strength (ISS) on the basal plane of hcp (4)He. The failure mode upon reaching the ISS limit is characterized by the homogeneous nucleation of a stacking fault and it is found to be anisotropic, consistent with Schmid's law of resolved shear stress. Comparing the ISS of hcp (4)He to a large set of classical crystals shows that it closely fits the approximately universal modified Frenkel model of ideal strength. In addition to giving quantitative stress levels for the homogeneous nucleation of extended defects in hcp (4)He, our findings lend support to assumptions in the literature that inherently classical models remain useful for the description of mechanical behavior in quantum crystals. PMID:24785047

Borda, Edgar Josué Landinez; Cai, Wei; de Koning, Maurice

2014-04-18

17

Ideal Shear Strength of a Quantum Crystal  

NASA Astrophysics Data System (ADS)

Using path-integral Monte Carlo simulations, we compute the ideal shear strength (ISS) on the basal plane of hcp He4. The failure mode upon reaching the ISS limit is characterized by the homogeneous nucleation of a stacking fault and it is found to be anisotropic, consistent with Schmid's law of resolved shear stress. Comparing the ISS of hcp He4 to a large set of classical crystals shows that it closely fits the approximately universal modified Frenkel model of ideal strength. In addition to giving quantitative stress levels for the homogeneous nucleation of extended defects in hcp He4, our findings lend support to assumptions in the literature that inherently classical models remain useful for the description of mechanical behavior in quantum crystals.

Borda, Edgar Josué Landinez; Cai, Wei; de Koning, Maurice

2014-04-01

18

Equation of State - Ideal Gas  

NSDL National Science Digital Library

Gases have various observable properties, such as pressure (p), temperature (T), mass (m), and volume (V). Careful scientific observation has determined that these variables are related to one another, and the values of these properties determine the state of the gas. Users can read an explanation of the three laws (Boyle's Law, Charles' Law, and Gay-Lussac's Law) that describe the properties of gases and observe how gases behave under changing conditions.

2001-06-01

19

Joule–Thomson coefficients of quantum ideal-gases  

Microsoft Academic Search

The temperature drop of a gas divided by its pressure drop under constant enthalpy conditions is called the Joule–Thomson coefficient (JTC) of the gas. The JTC of an ideal gas is equal to zero since its enthalpy depends on only temperature. On the other hand, this is only true for classical ideal gas which obeys the classical ideal gas equation

Hasan Sayg?n; Altu? ?i?man

2001-01-01

20

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

21

Structural Arrest in an Ideal Gas  

Microsoft Academic Search

We report a molecular dynamics study of a simple model system that has the static properties of an ideal gas, yet exhibits nontrivial ``glassy'' dynamics behavior at high densities. The constituent molecules of this system are constructs of three infinitely thin hard rods of length L, rigidly joined at their midpoints. The crosses have random but fixed orientation. The static

Willem van Ketel; Chinmay Das; Daan Frenkel

2005-01-01

22

Single fireball and fireball ideal gas  

Microsoft Academic Search

Summary  In this paper we study the partition function of a macroscopic hadron system with two models. In one model the mathematical\\u000a fireball appears as a fundamental particle in a Boltzmann ideal gas occupying a volumeV. In a second model the macroscopic volumeV is divided in noninteracting boxes of volumeV\\u000a 0, each one containing an interacting-pion gas. Both cases show the

R. Fiore; R. Page; L. Sertorio

1977-01-01

23

Thermodynamics of an ideal generalized gas: I. Thermodynamic laws.  

PubMed

The equations of state for an ideal relativistic, or generalized, gas, like an ideal quantum gas, are expressed in terms of power laws of the temperature. In contrast to an ideal classical gas, the internal energy is a function of volume at constant temperature, implying that the ideal generalized gas will show either attractive or repulsive interactions. This is a necessary condition in order that the third law be obeyed and for matter to have an electromagnetic origin. The transition from an ideal generalized to a classical gas occurs when the two independent solutions of the subsidiary equation to Lagrange's equation coalesce. The equation of state relating the pressure to the internal energy encompasses the full range of cosmological scenarios, from the radiation to the matter dominated universes and finally to the vacuum energy, enabling the coefficient of proportionality, analogous to the Grüeisen ratio, to be interpreted in terms of the degrees of freedom related to the temperature exponents of the internal energy and the absolute temperature expressed in terms of a power of the empirical temperature. The limit where these exponents merge is shown to be the ideal classical gas limit. A corollary to Carnot's theorem is proved, asserting that the ratio of the work done over a cycle to the heat absorbed to increase the temperature at constant volume is the same for all bodies at the same volume. As power means, the energy and entropy are incomparable, and a new adiabatic potential is introduced by showing that the volume raised to a characteristic exponent is also the integrating factor for the quantity of heat so that the second law can be based on the property that power means are monotonically increasing functions of their order. The vanishing of the chemical potential in extensive systems implies that energy cannot be transported without matter and is equivalent to the condition that Clapeyron's equation be satisfied. PMID:16231132

Lavenda, B H

2005-11-01

24

Thermodynamics of an ultrarelativistic ideal Bose gas  

NASA Astrophysics Data System (ADS)

The properties of an ideal relativistic Bose gas with nonzero chemical potential mu are analyzed with allowance for the effects of antiparticles. The high-temperature expansion is obtained and it is shown that massless particles can have net charge density even though mu = 0 and no condensation takes place. The expansions obtained are then used to study the properties of Bose-Einstein condensation for both massless and massive bosons in d space dimensions.

Haber, H. E.; Weldon, H. A.

1981-06-01

25

Ideal gas provides q-entropy  

NASA Astrophysics Data System (ADS)

A mathematical procedure is suggested to obtain deformed entropy formulas of type K(SK)=?PiK(-lnPi), by requiring zero mutual K(SK)-information between a finite subsystem and a finite reservoir. The use of this method is first demonstrated on the ideal gas equation of state with finite constant heat capacity, C, where it delivers the Rényi and Tsallis formulas. A novel interpretation of the q?=2-q duality arises from the comparison of canonical subsystem and total microcanonical partition approaches. In the sequel a new, generalized deformed entropy formula is constructed for the linear C(S)=C0+C1S relation.

Biró, T. S.

2013-08-01

26

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

27

How is the Ideal Gas Law Explanatory?  

NASA Astrophysics Data System (ADS)

Using the ideal gas law as a comparative example, this essay reviews contemporary research in philosophy of science concerning scientific explanation. It outlines the inferential, causal, unification, and erotetic conceptions of explanation and discusses an alternative project, the functional perspective. In each case, the aim is to highlight insights from these investigations that are salient for pedagogical concerns. Perhaps most importantly, this essay argues that science teachers should be mindful of the normative and prescriptive components of explanatory discourse both in the classroom and in science more generally. Giving attention to this dimension of explanation not only will do justice to the nature of explanatory activity in science but also will support the development of robust reasoning skills in science students while helping them understand an important respect in which science is more than a straightforward collection of empirical facts, and consequently, science education involves more than simply learning them.

Woody, Andrea I.

2013-07-01

28

Information, Entropy, and the Classical Ideal Gas  

NASA Astrophysics Data System (ADS)

The physical basis of the canonical and grand canonical distributions is questioned. In particular, we question the usual methods by which these distributions are derived, namely that fluctuations in entropy around energy and particle number are assumed to occur when the entropy depends only on variables which cannot themselves fluctuate. We show, starting from the Maxwellian velocity distribution, that the probability that a classical ideal gas at a fixed temperature occupies a given energy state corresponds not to the canonical ensemble of classical statistical mechanics but to the Gamma distribution. Computer simulations of a hard-sphere fluid demonstrate the principles. The analysis is extended to open systems in which the number of particles fluctuates and we show that for a system connected to a particle reservoir the Poisson distribution governs the probability of finding a given number of particles. The resulting probability distributions are used to calculate the Shannon information entropy which is then compared with the thermodynamic entropy. We argue that information theoretic entropy and thermodynamic entropy, whilst related, are not necessarily identical and that the information entropy contains non-thermodynamic components.

Sands, David; Dunning-Davies, Jeremy

2013-09-01

29

Local thermal equilibrium and ideal gas Stephani universes  

Microsoft Academic Search

The Stephani universes that can be interpreted as an ideal gas evolving in local thermal equilibrium are determined. Five classes of thermodynamic schemes are admissible, which give rise to five classes of regular models and three classes of singular models. No Stephani universes exist representing an exact solution to a classical ideal gas (one for which the internal energy is

Bartolomé Coll; Joan Josep Ferrando

2005-01-01

30

Joule-Thomson Coefficients of Confined Ideal Quantum Gases  

NASA Astrophysics Data System (ADS)

By using the pressure and entropy of a system obtained from the grand potential of ideal quantum gases confined in a long tube with a fixed transverse cross section of area and the fundamental relations of thermodynamics, expression for the heat capacity at given longitudinal pressure and area of cross section is derived, from which the linear expansion coefficient and the Joule-Thomson coefficient (JTC) of the system are obtained. Moreover, the effects of the finite size on the heat capacity, expansion coefficient and JTC of the system are discussed in detail. It is significant to find that the absolute values of the JTCs of confined ideal quantum gases increase with the decrease of the systemic size and temperature.

Guo, Juncheng; Su, Guozhen; Chen, Jincan

2011-04-01

31

Lorentz covariant statistical mechanics and thermodynamics of the relativistic ideal gas and preferred frame  

NASA Astrophysics Data System (ADS)

The Lorentz covariant classical and quantum statistical mechanics and thermodynamics of an ideal relativistic gas of bradyons (particles slower than light), luxons (particles moving with the speed of light), and tachyons (hypothetical particles faster than light) is discussed. The Lorentz covariant formulation is based on the preferred frame approach which among others enables a consistent, free of paradoxes description of tachyons. The thermodynamic functions within the covariant approach are obtained both in the classical and quantum case.

Kowalski, K.; Rembieli?ski, J.; Smoli?ski, K. A.

2007-08-01

32

Lorentz covariant statistical mechanics and thermodynamics of the relativistic ideal gas and preferred frame  

SciTech Connect

The Lorentz covariant classical and quantum statistical mechanics and thermodynamics of an ideal relativistic gas of bradyons (particles slower than light), luxons (particles moving with the speed of light), and tachyons (hypothetical particles faster than light) is discussed. The Lorentz covariant formulation is based on the preferred frame approach which among others enables a consistent, free of paradoxes description of tachyons. The thermodynamic functions within the covariant approach are obtained both in the classical and quantum case.

Kowalski, K.; Rembielinski, J.; Smolinski, K. A. [Department of Theoretical Physics, University of Lodz, ul. Pomorska 149/153, 90-236 Lodz (Poland)

2007-08-15

33

Do the Particles of an Ideal Gas Collide?  

ERIC Educational Resources Information Center

Describes the collisional properties as a logically essential component of the ideal gas model since an actual intraparticle process cannot support observable anisotropic velocity distributions without collisions taken into account. (CC)

Lesk, Arthur M.

1974-01-01

34

Theory of relativistic ideal gas for quasi and ordinary particles  

NASA Astrophysics Data System (ADS)

A theory of relativistic ideal gas (RIG), fluxons and electrons is presented. A distribution function of velocities (FRS) and the equation of state of the RIG are found, together with the distribution function of the observed frequencies.

Jumaev, Mustaqim

35

Ideal Gas gluon plasma with medium dependent dispersion relation.  

National Technical Information Service (NTIS)

An '' ideal gas '' model with temperature dependent particle mass is constructed for the gluon plasma equation of state. This simple model gives us an example of a system with temperature dependent effective Hamiltonian. To satisfy thermodynamical relatio...

M. I. Gorenstein Shin Nan Yang

1995-01-01

36

Computer program for calculation of ideal gas thermodynamic data  

NASA Technical Reports Server (NTRS)

Computer program calculates ideal gas thermodynamic properties for any species for which molecular constant data is available. Partial functions and derivatives from formulas based on statistical mechanics are provided by the program which is written in FORTRAN 4 and MAP.

Gordon, S.; Mc Bride, B. J.

1968-01-01

37

Exact solutions of Einstein's equations with ideal gas sources  

Microsoft Academic Search

We derive a new class of exact solutions characterized by the Szekeres-Szafron metrics (of class I), admitting in general no isometries. The source is a fluid with viscosity but zero heat flux (adiabatic but irreversible evolution) whose equilibrium state variables satisfy the equations of state of: (a) an ultra-relativistic ideal gas; (b) a non-relativistic ideal gas; (c) a mixture of

R. A. Sussman; Josep Triginer

1999-01-01

38

Boston University Physics Applets: The Ideal Gas Law  

NSDL National Science Digital Library

This web page is an interactive physics simulation on the ideal gas law. The page states the assumptions behind the law, and the cases when it works. The formula is provided, and the attached Java applet illustrates how the gas particle collisions are modeled. This is part of a collection of similar simulation-based student activities.

Duffy, Andrew

2008-08-01

39

Hierarchy of free heat convection models for an ideal gas  

Microsoft Academic Search

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

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

1989-01-01

40

Optimising an intercooled compressor for an ideal gas model  

Microsoft Academic Search

Many of the conventional results obtained when optimising the performance of an intercooler during compression using a perfect gas model can be obtained when the restrictions of the model are relaxed to an ideal gas. That is, we now have temperature-dependent specific heat capacities but retain the equation of state pV = RT. This note illustrates the theme. Working in

Jeffery D. Lewins

41

Similarity of ideal gas flow at different scales  

Microsoft Academic Search

The similarity of ideal gas flow at different scales is investigated analytically and numerically. With the compressible and\\u000a rarefied effects considered, two dimensionless parameters, Mach number and Knudsen number, are proposed as the similarity\\u000a criterions, because the Reynolds number can be expressed by the Mach number and the Knudsen number of ideal gases. A DSMC\\u000a method is used to simulate

Moran Wang; Zhixin Li

2003-01-01

42

Direct simulation methods for compressible inviscid ideal-gas flow  

Microsoft Academic Search

Two novel schemes are proposed for the calculation of compressible flow of an ideal fluid. One method is the equilibrium analog of the well-known discrete-particle direct simulation Monte Carlo method for the treatment of nonequilibrium ideal-gas flows. The second follows from an analytical treatment of the model inertial-transport mechanisms inherent in the first scheme. Accounts of the methods are presented

D. I. Pullin

1980-01-01

43

Effective Dynamics of a Tracer Particle Interacting with an Ideal Bose Gas  

NASA Astrophysics Data System (ADS)

We study a system consisting of a heavy quantum particle, called the tracer particle, coupled to an ideal gas of light Bose particles, the ratio of masses of the tracer particle and a gas particle being proportional to the gas density. All particles have non-relativistic kinematics. The tracer particle is driven by an external potential and couples to the gas particles through a pair potential. We compare the quantum dynamics of this system to an effective dynamics given by a Newtonian equation of motion for the tracer particle coupled to a classical wave equation for the Bose gas. We quantify the closeness of these two dynamics as the mean-field limit is approached (gas density ). Our estimates allow us to interchange the thermodynamic with the mean-field limit.

Deckert, Dirk-André; Fröhlich, Jürg; Pickl, Peter; Pizzo, Alessandro

2014-06-01

44

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

45

Adiabatic motion of an ideal gas in Lagrangian coordinates  

Microsoft Academic Search

A model is presented which describes the adiabatic motion of an ideal gas using Lagrangian variables. The model describes the state of a continuous medium using a minimum number of unknown functions: not more than three functions in the general case and only one or two functions in the case of symmetry. Geometrical assumptions about the motion can readily be

V. A. Vinokurov

1987-01-01

46

Microeconomics of the ideal gas like market models  

Microsoft Academic Search

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

Anindya S. Chakrabarti; Bikas K. Chakrabarti

2009-01-01

47

Analyzing money distributions in `ideal gas' models of markets  

Microsoft Academic Search

We analyze an ideal gas like models of a trading market. We propose a new fit for the money distribution in the fixed or uniform saving market. For the marketwith quenched random saving factors for its agents we show that the steady state income ($m$) distribution $P(m)$ in the model has a power law tail with Pareto index $\\\

Arnab Chatterjee; Bikas K. Chakrabarti; Robin B. Stinchcombe

2005-01-01

48

The pressure exerted by a confined ideal gas  

Microsoft Academic Search

In this paper, we study the pressure exerted by a confined ideal gas on the container boundary and we introduce a surface force in gases. First, the general expression for the local surface pressure tensor is obtained. We find, by examples, that the pressure vanishes at the edges of a box, peaks at the middle of the surface and its

Hai Pang; Wu-Sheng Dai; Mi Xie

2011-01-01

49

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

50

David Maloney's Physics Examples: Thermo Example 3-Ideal Gas Behavior  

NSDL National Science Digital Library

This item is an annotated homework problem involving an ideal gas contained in a cylinder with a movable piston. The author provides explicit explanations of isothermal, adiabatic, isobaric, and isochoric processes to guide users in solving for a number of unknowns. This item is part of a larger collection of introductory physics homework examples.

Maloney, David

2008-10-03

51

Shock wave structure in an ideal dissociating gas  

NASA Technical Reports Server (NTRS)

Composition changes within the shock layer due to chemical reactions are considered. The Lighthill ideal dissociating gas model was used in an effort to describe the oxygen type molecule. First, the two limiting cases, when the chemical reaction rates are very slow and very fast in comparison to local convective rates, are investigated. Then, the problem is solved for arbitrary chemical reaction rates.

Liu, K. H.

1975-01-01

52

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

53

Volume exclusion correction to the ideal gas with a lattice gas model  

Microsoft Academic Search

The thermodynamic properties of the classical ideal gas are well known and documented. The departure of real gases from ideal behavior requires modification of the ideal equation of state. We derive an exact solution for an ``excluded volume'' system in which the constituent particles have nonzero volume and only one particle may occupy a specific region in space. To incorporate

J. M. Pimbley

1986-01-01

54

Molecular structure, conformation, potential to internal rotation, and ideal gas thermodynamic properties of 3-fluoroanisole and 3,5-difluoroanisole as studied by gas-phase electron diffraction and quantum chemical calculations  

NASA Astrophysics Data System (ADS)

3-Fluoroanisole (3-FA) and 3,5-difluoroanisole (3,5-DFA) have been studied by gas-phase electron diffraction, ab initio (HF and MP2), and density functional theory (B3LYP) calculations. Both molecules have a planar heavy atom skeleton. 3,5-DFA exists as a single conformer of Cs symmetry, whereas 3-FA exists as a mixture of two planar conformers of Cs symmetry with the syn form (the O-CH 3 bond is oriented toward the fluorine atom) being 0.1-0.2 kcal/mol lower in energy than the anti form (the O-CH 3 bond is oriented away from the fluorine atom). From the experimental scattering intensities the following geometric parameters ( ra distances and ? ? angles with 3? uncertainties) were derived for 3,5-DFA: r(C-C) av=1.391(2) Å, r(C Ph-O)=1.359(13) Å, r(C Me-O)=1.427(19) Å, r(C-F) av=1.350(6) Å, ?C-C-C=116.0-123.6°, ?C-O-C=118.7(12)°, ?C2-C1-O=114.9(10)°, ?C6-C1-O=124.9(10)°, ?(C-C-F) av=118.4(17)°, and for 3-FA, syn conformer: r(C-C) av=1.393(3) Å, r(C Ph-O)=1.364(13) Å, r(C Me-O)=1.423(14) Å, r(C-F)=1.348(9) Å, ?C-C-C=117.7-123.1°, ?C-O-C=118.4(11)°, ?C2-C1-O=124.7(17)°, ?C6-C1-O=115.1(17)°, ?C2-C3-F=118.0(24)°. The mole fractions of the syn and anti conformers were found to be 0.55(17) and 0.45, respectively, in good agreement with the theoretical prediction. Ideal gas thermodynamic functions, S°( T), Cp°(T), H°( T)- H°(0), for anisole, 3-FA, and 3,5-DFA were obtained on the basis of B3LYP calculations. Enthalpies of formations, ? fH298°, were calculated using a Gaussian-3X (G3X) method and the method of isodesmic reactions. Calculated values of Cp°(T) and ? fH298° for anisole are in good agreement with experimental data.

Dorofeeva, Olga V.; Vishnevskiy, Yuriy V.; Rykov, Anatolii N.; Karasev, Nikolai M.; Moiseeva, Natalia F.; Vilkov, Lev V.; Oberhammer, Heinz

2006-05-01

55

Ideal-Gas Like Markets: Effect of Savings  

Microsoft Academic Search

We discuss the ideal gas like models of a trading market. The effect of savings on the distribution have been thoroughly reviewed.\\u000a The market with fixed saving factors leads to a Gamma-like distribution. In a market with quenched random saving factors for\\u000a its agents we show that the steady state income (m) distribution P(m) in the model has a power

Arnab Chatterjee; Bikas K Chakrabarti

2005-01-01

56

Relativistic ideal Fermi gas at zero temperature and preferred frame  

SciTech Connect

We discuss the limit T{yields}0 of the relativistic ideal Fermi gas of luxons (particles moving with the speed of light) and tachyons (hypothetical particles faster than light) based on observations of our recent paper: K. Kowalski, J. Rembielinski, and K. A. Smolinski, Phys. Rev. D 76, 045018 (2007). For bradyons this limit is in fact the nonrelativistic one and therefore it is not studied herein.

Kowalski, K.; Rembielinski, J.; Smolinski, K. A. [Department of Theoretical Physics, University of Lodz, ul. Pomorska 149/153, 90-236 Lodz (Poland)

2007-12-15

57

Spectral Stability of Ideal-Gas Shock Layers  

Microsoft Academic Search

Extending recent results in the isentropic case, we use a combination of asymptotic ODE estimates and numerical Evans-function\\u000a computations to examine the spectral stability of shock-wave solutions of the compressible Navier–Stokes equations with ideal\\u000a gas equation of state. Our main results are that, in appropriately rescaled coordinates, the Evans function associated with\\u000a the linearized operator about the wave (i) converges

Jeffrey Humpherys; Gregory Lyng; Kevin Zumbrun

2009-01-01

58

Computations of ideal and real gas high altitude plume flows  

NASA Technical Reports Server (NTRS)

In the present work, complete flow fields around generic space vehicles in supersonic and hypersonic flight regimes are studied numerically. Numerical simulation is performed with a flux-split, time asymptotic viscous flow solver that incorporates a generalized equilibrium chemistry model. Solutions to generic problems at various altitude and flight conditions show the complexity of the flow, the equilibrium chemical dissociation and its effect on the overall flow field. Viscous ideal gas solutions are compared against equilibrium gas solutions to illustrate the effect of equilibrium chemistry. Improved solution accuracy is achieved through adaptive grid refinement.

Feiereisen, William J.; Venkatapathy, Ethiraj

1988-01-01

59

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

60

Dynamics of a massive piston in an ideal gas  

NASA Astrophysics Data System (ADS)

This survey is a study of a dynamical system consisting of a massive piston in a cubic container of large size L filled with an ideal gas. The piston has mass M\\sim L^2 and undergoes elastic collisions with N\\sim L^3 non-interacting gas particles of mass m=1. It is found that under suitable initial conditions there is a scaling regime with time and space scaled by L in which the motion of the piston and the one-particle distribution of the gas satisfy autonomous coupled equations (hydrodynamic equations) such that in the limit L\\to\\infty the mechanical trajectory of the piston converges in probability to the solution of the hydrodynamic equations for a certain period of time. There is also a heuristic discussion of the dynamics of the system on longer intervals of time.

Chernov, N. I.; Lebowitz, J. L.; Sinai, Yakov G.

2002-12-01

61

Thermodynamical properties of a rotating ideal Bose gas  

NASA Astrophysics Data System (ADS)

In a recent experiment, a Bose-Einstein condensate was trapped in an anharmonic potential that is well approximated by a harmonic and a quartic part. The condensate was set into such a fast rotation that the centrifugal force in the corotating frame overcompensates the harmonic part in the plane perpendicular to the rotation axis. Thus, the resulting trap potential becomes sombrero shaped. We present an analysis for an ideal Bose gas that is confined in such an anharmonic rotating trap within a semiclassical approximation, where we calculate the critical temperature, the condensate fraction, and the heat capacity. In particular, we examine in detail how these thermodynamical quantities depend on the rotation frequency.

Kling, Sebastian; Pelster, Axel

2007-08-01

62

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

63

Boltzmann equations for a binary one-dimensional ideal gas.  

PubMed

We consider a time-reversal invariant dynamical model of a binary ideal gas of N molecules in one spatial dimension. By making time-asymmetric assumptions about the behavior of the gas, we derive Boltzmann and anti-Boltzmann equations that describe the evolution of the single-molecule velocity distribution functions for an ensemble of such systems. We show that for a special class of initial states of the ensemble one can obtain an exact expression for the N-molecule velocity distribution function, and we use this expression to rigorously prove that the time-asymmetric assumptions needed to derive the Boltzmann and anti-Boltzmann equations hold in the limit of large N. Our results clarify some subtle issues regarding the origin of the time asymmetry of Boltzmann's H theorem. PMID:22060348

Boozer, A D

2011-09-01

64

Thermal Boundary Resistance at Ideal Gas Solid-Fluid Interfaces  

NASA Astrophysics Data System (ADS)

We study the thermal boundary resistance at the interface between an ideal gas solid and another ideal gas fluid. In the solid side, heat is mostly carried by phonons, and thermal resistance occurs due to the partial reflection of phonons at the interface. In the fluid side, the sound waves can carry diffusive heat from the interface into the bulk of the liquid. We include both longitudinal and transverse sound modes of the fluid in the theory. The sound modes in the fluid and the reflected phonons in the solid have the same frequency as the phonon incident at the interface from the solid side. The wave vector for the sound modes is then calculated using the knowledge of the fluid pair distribution function in the bulk. The pair distribution function near the interface is modified due to the presence of the solid atoms. We solve coupled equations of motion for the atoms at the interface to obtain the phonon reflection coefficients. The Kapitza resistance is then obtained using the knowledge of these reflection coefficients. The calculation provides a method for extending the Young-Maris theory to the fluid-solid substances.

Neogi, Sanghamitra; Mahan, Gerald

2011-03-01

65

Lattice-Gas Quantum Computation  

Microsoft Academic Search

We present a quantum lattice-gas model for a quantum computer operating with continual wavefunction collapse; entanglement of the wavefunction occurs locally over small spatial regions between nearby qubits for only a short time period. The quantum lattice-gas is a noiseless method that directly models the lattice-gas particle dynamics at the mesoscopic scale. The system behaves like a viscous Navier-Stokes fluid.

Jeffrey Yepez

1998-01-01

66

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

67

Stability of the blast wave in ideal gas  

NASA Astrophysics Data System (ADS)

Stability of a point blast wave in an ideal gas is considered in the case when the initial gas density0 is a power function of radius r:0~r-k . We use a technique previously used in /1,2,3/. Small non-radial blast wave perturbations are expanded to spherical harmonics components of expansion being represented in a self-similar form. The cases of a constant initial gas density and of one being power function of radius are considered. Instability region on n- plane (herestands for a gas specific heat ratio and n stands for a harmonic number) is determined in all cases (k=0 - 12) considered. Critical values of c determining the blast wave stability are calculated. The results are calculated numerically in the general case of arbitrary , n and analytically in some special cases: n=1, n>>1, and -1<<1. The considered cases are modeling supernova explosion /4/ as well as simulating astrophysical phenomena in laboratory experiments /5/. REFERENCES 1. V.M.Ktitorov, Voprosy Atomnoi Nauki i Tekhniki, Ser.Teoreticheskaya i Prikladnaya.Fizika (Atomic Science and Technique Issues, Ser. Theoretical and Applied Physics), No2, p.28, (1984); 2. D.Ryu and E.T.Vishniac, Astrophys.J. 313, 820 (1987); 3. V.M.Ktitorov, Khimicheskaya Fizika (Chemical Physics Issues) V.14, No 2-3, p.169, (1995); 4. R.P.Drake et al., Physics of Plasma, V.8, No 5, p.1804, (2001); 5. R.G.Chevalier, Astrophys.J. 259, p.302 (1982);

Ktitorov, V.

68

D-dimensional ideal gas in parastatistics: thermodynamic properties  

SciTech Connect

The authors consider a parastatistics ideal gas with energy spectrum epsilon proportional to absolute value k/sup ..cap alpha../ (..cap alpha.. > 0) or even more generally in a d-dimensional box with volume V (periodic boundary conditions), the number N of the gas particles being well determined (real particles) or not (quasiparticles). They calculate the main thermodynamic quantities (chemical potential, internal energy, specific heat C, equation of state, latent heat, average numbers of particles) for arbitrary d, ..cap alpha.., T (temperature), and p (maximal number of particles per state allowed in the parastatistics). The main asymptotic regimes are worked out explicitly. In particular, the Bose-Einstein condensation for fixed density N/V appears as a nonuniform convergence in the p ..-->.. infinity limit, in complete analogy with the standard critical phenomena that appear in interacting systems in the N ..-->.. infinity limit. The system behaves essentially like a Fermi-Dirac one for all finite values of p, and reveals a Bose-Einstein behavior only in the p ..-->.. infinity limit. For instance, at low temperatures C proportional to T if p < infinity and C proportional to T/sup d/..cap alpha../ if p ..-->.. infinity. Finally, the Sommerfeld integral and its expansion are generalized to an arbitrary, finite p.

de Sousa Vieira, M.C.; Tsallis, C.

1987-07-01

69

Persistent spectral hole-burning: ideal memory for quantum computers?  

NASA Astrophysics Data System (ADS)

After a brief summary of characteristics of persistent hole-burning of mesoporphyrin in polyvinylalcohol, its use for the recording of quantum computation with optical processes is discussed. It will be shown that not only quasi-cw single-frequency recording but also photon-echo-type recording is possible with single photons.

Sakoda, Kazuaki

2002-12-01

70

High School Forum. The Solution: "Derivation of the Ideal Gas Law."  

ERIC Educational Resources Information Center

Presents responses to an earlier report concerning a procedure for the derivation of the Ideal Gas Law from Charles', Boyle's, and other gas laws. Logic errors and solutions that work are discussed. (CS)

Herron, J. Dudley, Ed.

1980-01-01

71

Senior High School Students' Mental Models of Mix-Gas in the Particulate Model of Ideal Gas  

Microsoft Academic Search

As research about the particulate nature of gas shows, students have many misconceptions about gas volume, gas pressure, and the spread of gas (Benson, Wittrock, & Baur, 1993; Chiu, in press). Our research focuses mainly on senior high school students' mental models and the consistency of conceptions about mix-gas in the particulate model of ideal gas. Our study is based

Shiao-Lan Chung; Mei-Hung Chiu

72

Ideal gas thermodynamic properties for the phenyl, phenoxy, and o-biphenyl radicals  

NASA Technical Reports Server (NTRS)

Ideal gas thermodynamic properties of the phenyl and o-biphenyl radicals, their deuterated analogs and the phenoxy radical were calculated to 5000 K using estimated vibrational frequencies and structures. The ideal gas thermodynamic properties of benzene, biphenyl, their deuterated analogs and phenyl were also calculated.

Burcat, A.; Zeleznik, F. J.; Mcbride, B. J.

1985-01-01

73

Shock dynamics of weak imploding cylindrical and spherical shock waves with non-ideal gas effects  

NASA Astrophysics Data System (ADS)

The author (Anand 2012 Astrophys. Space Sci. 342 377-88) recently obtained jump relations across a shock front in non-ideal gas flow taking into consideration the equation of state for a non-ideal gas as given by Landau and Lifshitz. In this paper an analytical solution for one-dimensional adiabatic flow behind weak converging shock waves propagating in a non-ideal gas is obtained by using Whitham's (1974 Linear and Nonlinear Waves (New York: Wiley)) geometrical shock dynamics approach. The effects of an increase in (i) the propagation distance from the centre of convergence, (ii) the non-idealness parameter and (iii) the adiabatic index of the gas, on the shock velocity, pressure, density, particle velocity, adiabatic compressibility and the change in entropy across the shock front, are analyzed. The results provided a clear picture of whether and how the non-idealness parameter and the adiabatic index affect the flow field behind the imploding shock front.

Anand, R. K.

2013-06-01

74

Ideal Gas-Like Distributions in Economics: Effects of Saving Propensity  

Microsoft Academic Search

We consider the ideal-gas models of trading markets, where each agent is identified with a gas molecule and each trading as an elastic or money-conserving (two-body) collision. Unlike in the ideal gas, we introduce saving propensity $\\\\lambda$ of agents, such that each agent saves a fraction $\\\\lambda$ of its money and trades with the rest. We show the steady-state money

Bikas K. Chakrabarti; Arnab Chatterjee

2003-01-01

75

MODELLING AND SIMULATION OF SOLITONS AND DISCONTINUITIES IN ADIABATIC AND IDEAL GAS AND ELECROSTATIC PLASMA ONE DIMENSIONAL SYSTEMA  

Microsoft Academic Search

Four models of gas and electrostatic plasma are stu died viz ideal gas and adiabatic gas and ideal plasma and adiabatic plasma. These models are fluid equations (continuity ,momentum and energy) of gas and electrostatic plas ma with initial conditions which give rise to soliton and shock formation and examine the effe cts of the ideal and adiabatic thermodynamic assumptions,

R. NAIDOO

76

Application of Ideal Gas Theory to the Gaseous Expansion from an Electric Spark  

Microsoft Academic Search

The gaseous expansion from an electric spark is described in this paper in terms of ideal gas theory. The assumption is made that a quantity of energy is injected into a small gas volume in an infinitesimally short time and that the initial volume of gas then expands until it reaches the pre-spark pressure at an elevated temperature. Experimental results

R. B. Edmonson; H. L. Olsen; E. L. Gayhart

1954-01-01

77

Possible realization of an ideal quantum computer in Josephson junction array  

NASA Astrophysics Data System (ADS)

We introduce a class of Josephson arrays which have nontrivial topology and exhibit a novel state at low temperatures. This state is characterized by long-range order in a two Cooper pair condensate and by a discrete topological order parameter. These arrays have degenerate ground states with this degeneracy ``protected'' from the external perturbations (and noise) by the topological order parameter. We show that in ideal conditions the low order effect of the external perturbations on this degeneracy is exactly zero and that deviations from ideality lead to only exponentially small effects of perturbations. We argue that this system provides a physical implementation of an ideal quantum computer with a built-in error correction and show that even a small array exhibits interesting physical properties such as superconductivity with double charge, 4e, and extremely long decoherence times.

Ioffe, L. B.; Feigel'Man, M. V.

2002-12-01

78

On The Impact of the Ideal Gas Assumption to High-Pressure Combustion Phenomena in Engines  

Microsoft Academic Search

The effect of the ideal gas law assumption on auto-ignition and NOx-formation in a rapid compression machine is studied. For both processes the simulations are compared to a reference simulation using a Redlich-Kwong equation-of-state based on the critical properties of all constituents.Auto-ignition is studied for several n-heptane\\/air mixtures and the results show that the ideal gas assumption can impose large

A. Evlampiev; L. M. T. Somers; R. S. G. Baert; L. P. H. de Goey

2007-01-01

79

Observation of deviations from ideal gas thermodynamics in a trapped Bose-Einstein condensed gas  

Microsoft Academic Search

We have investigated experimentally the finite-temperature properties of a\\u000aBose-Einstein condensed cloud of $^{87}$Rb atoms in a harmonic trap. Focusing\\u000aprimarily on condensed fraction and expansion energy, we measure unambiguous\\u000adeviations from ideal-gas thermodynamics, and obtain good agreement with a\\u000aHartree-Fock description of the mixed cloud. Our results offer for the first\\u000atime clear evidence of the mutual interaction between

Fabrice Gerbier; Joseph H. Thywissen; Simon Richard; Mathilde Hugbart; Philippe Bouyer; Alain Aspect

2004-01-01

80

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

Microsoft Academic Search

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,

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

2006-01-01

81

Ideal Gas of Particle-Like Excitations at Low Temperatures  

NASA Astrophysics Data System (ADS)

A phenomenological approach to the description of the equilibrium characteristics of "kink" gas is proposed, which is based on model of lattice gas. A general simple technique for obtaining the dynamical structure factors (DSF) of solitions and bions in the "gas" approximation is developed. The DSF defined by soliton excitations in the framework of the Klein-Gordon equation are obtained and discussed. It is shown that at low temperatures the bion type excitations dominate the contribution to the central peak (CP) as well as give rise to the satellites to appear at harmonics of the main bion frequency. Both the frequency of bions, ? and their average density are defined by the temperature of a system. A possibility is discussed to generalize the results to (2 + 1) and (3 + 1) dimensional models.

Fedyanin, V. K.; Makhankov, V. G.

1983-08-01

82

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

83

On the structure of MHD shock waves in a viscous non-ideal gas  

NASA Astrophysics Data System (ADS)

The structure of one-dimensional magnetohydrodynamics (MHD) shock waves is studied using the Navier-Stokes equations for the non-ideal gas phase. The exact solutions are obtained for the flow variables (i.e. particle velocity, temperature, pressure and change-in-entropy) within the shock transition region. The equation of state for a non-ideal gas is considered as given by Landau and Lifshitz. The effects of the non-idealness parameter and coefficient of viscosity of the gas are analysed on the flow variables assuming the magnetic field having only constant axial component. The findings confirm that the thickness of MHD shock front increases with decreasing values of the non-idealness parameter.

Anand, R. K.; Yadav, Harish C.

2014-06-01

84

A probabilistic model for the equilibration of an ideal gas  

Microsoft Academic Search

I present a generalization of the Ehrenfest urn model that is aimed at simulating the approach to equilibrium in a dilute gas. The present model differs from the original one in two respects: (1) the two boxes have different volumes and are divided into identical cells with either multiple or single occupancy; (2) particles, which carry also a velocity vector,

Santi Prestipino

2004-01-01

85

An Enskog based Monte Carlo method for high Knudsen number non-ideal gas flows  

Microsoft Academic Search

A Monte Carlo method based on the Enskog equation for dense gas is developed by considering high density effect on collision rates and both repulsive and attractive molecular interactions for a Lennard–Jones fluid. The appropriate internal energy exchange model is introduced with consistency with the collision model. The equation of state for a non-ideal gas is therefore derived involving the

Moran Wang; Zhixin Li

2007-01-01

86

EXACT THREE-DIMENSIONAL EQUATIONS OF NONLINEAR ACOUSTIC WAVES IN IDEAL GAS  

Microsoft Academic Search

Propagation of acoustic waves in ideal barotropic gas is considered. It is shown that the complete system of the three-dimensional equations of gas dynamics for the arbitrary amplitude of sound wave can be reduced to one nonlinear equation for potential of a velocity. The equation of nonlinear acoustics contains both quadratic and cubic terms of wave amplitude. At small wave

Nizhny Novgorod

2007-01-01

87

Time asymmetry in a dynamical model of the one-dimensional ideal gas  

Microsoft Academic Search

We present a simple dynamical model of the one-dimensional ideal gas and show how it can be used to introduce a number of fundamental ideas in statistical mechanics. We use the model to illustrate the role of initial conditions in explaining time asymmetry and show that although the dynamical model is time-reversal invariant, the macroscopic behavior of the gas can

A. D. Boozer

2008-01-01

88

Real-gas effects 1: Simulation of ideal gas flow by cryogenic nitrogen and other selected gases  

NASA Technical Reports Server (NTRS)

The thermodynamic properties of nitrogen gas do not thermodynamically approximate an ideal, diatomic gas at cryogenic temperatures. Choice of a suitable equation of state to model its behavior is discussed and the equation of Beattie and Bridgeman is selected as best meeting the needs for cryogenic wind tunnel use. The real gas behavior of nitrogen gas is compared to an ideal, diatomic gas for the following flow processes: isentropic expansion; normal shocks; boundary layers; and shock wave boundary layer interactions. The only differences in predicted pressure ratio between nitrogen and an ideal gas that may limit the minimum operating temperatures of transonic cryogenic wind tunnels seem to occur at total pressures approaching 9atmospheres and total temperatures 10 K below the corresponding saturation temperature, where the differences approach 1 percent for both isentropic expansions and normal shocks. Several alternative cryogenic test gases - air, helium, and hydrogen - are also analyzed. Differences in air from an ideal, diatomic gas are similar in magnitude to those of nitrogen. Differences for helium and hydrogen are over an order of magnitude greater than those for nitrogen or air. Helium and hydrogen do not approximate the compressible flow of an ideal, diatomic gas.

Hall, R. M.

1980-01-01

89

A Unified Theory of Non-Ideal Gas Lattice Boltzmann Models  

NASA Technical Reports Server (NTRS)

A non-ideal gas lattice Boltzmann model is directly derived, in an a priori fashion, from the Enskog equation for dense gases. The model is rigorously obtained by a systematic procedure to discretize the Enskog equation (in the presence of an external force) in both phase space and time. The lattice Boltzmann model derived here is thermodynamically consistent and is free of the defects which exist in previous lattice Boltzmann models for non-ideal gases. The existing lattice Boltzmann models for non-ideal gases are analyzed and compared with the model derived here.

Luo, Li-Shi

1998-01-01

90

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

91

The effect of the reference frame on the thermophysical properties of an ideal gas  

NASA Astrophysics Data System (ADS)

The effect that the frame of reference has on the thermophysical properties of an ideal gas is examined from a fundamental theoretical standpoint based on the Boltzmann equation. In continuum mechanics, the principle of material frame-indifference forbids the thermophysical properties of a fluid or solid to depend in any way on the motion of the reference frame. It is demonstrated that the Boltzmann equation is only consistent with material frame-indifference in a strong approximate sense provided that the gas is not highly rarefied and, thus, well within the limits of classical continuum mechanics. Estimates of the mean free times for which material frame-indifference can be invoked in the modeling of gas flows are provided from an analysis of the problem of heat conduction in a rigidly rotating gas. Applications of these results in obtaining asymptotic solutions of the Boltzmann equation for the continuum description of an ideal gas are discussed briefly.

Speziale, C. G.

1986-01-01

92

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

Microsoft Academic Search

We revisit the paradigm of an ideal gas under isothermal conditions. A moving\\u000apiston performs work on an ideal gas in a container that is strongly coupled to\\u000aa heat reservoir. The thermal coupling is modelled by stochastic scattering at\\u000athe boundaries. In contrast to recent studies of an adiabatic ideal gas with a\\u000apiston [R.C. Lua and A.Y. Grosberg,

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

2006-01-01

93

Experimental Demonstration of Quantum Lattice Gas Computation  

Microsoft Academic Search

We report an ensemble nuclear magnetic resonance (NMR) implementation of a quantum lattice gas algorithm for the diffusion equation. The algorithm employs an array of quantum information processors sharing classical information, a novel architecture referred to as a type-II quantum computer. This concrete implementa-tion provides a test example from which to probe the strengths and limitations of this new computation

Marco A. Pravia; Zhiying Chen; Jeffrey Yepez; David G. Cory

2003-01-01

94

Experimental Demonstration of Quantum Lattice Gas Computation  

Microsoft Academic Search

We report an ensemble nuclear magnetic resonance (NMR) implementation of a quantum lattice gas algorithm for the diffusion equation. The algorithm employs an array of quantum information processors sharing classical information, a novel architecture referred to as a type-II quantum computer. This concrete implementation provides a test example from which to probe the strengths and limitations of this new computation

Marco A. Pravia; Zhiying Chen; Jeffrey Yepez; David G. Cory

2003-01-01

95

Simple Ideal Gas Model of the Pavlovskii High-Explosive Opening Switch.  

National Technical Information Service (NTIS)

The behavior of the Pavlovskii type high-explosive opening switch is modeled using an ideal gas formulation. It is shown that this simple 1-D model agrees with experiment during early arc compression but that at later times the process exhibits a more com...

T. J. Tucker

1983-01-01

96

Ideal-gas like market models with savings: quenched and annealed cases  

Microsoft Academic Search

We analyze the ideal gas like models of markets and review the different cases where a `savings' factor changes the nature and shape of the distribution of wealth. These models can produce similar distribution of wealth as observed across varied economies. We present a more realistic model where the saving factor can vary over time (annealed savings) and yet produces

Arnab Chatterjee; Bikas K Chakrabarti

2006-01-01

97

Three-dimensional supersonic flow of ideal gas past a body with tail fins  

Microsoft Academic Search

The results are given of numerical and experimental investigations of the steady supersonic flow of an ideal gas past a model of a body with + and X fins. The angle of attack varied from 0 to 20 °. A study is made of the physical structure of the flow, and the pressure distributions, the coefficients of the normal force

A. V. Rozin

1983-01-01

98

Modeling shock waves in an ideal gas: Combining the Burnett approximation and Holian's conjecture  

Microsoft Academic Search

We model a shock wave in an ideal gas by combining the Burnett approximation and Holian's conjecture. We use the temperature in the direction of shock propagation rather than the average temperature in the Burnett transport coefficients. The shock wave profiles and shock thickness are compared with other theories. The results are found to agree better with the nonequilibrium molecular

Yi-Guang He; Xiu-Zhang Tang; Yi-Kang Pu

2008-01-01

99

Effect of feedback and inter-particle collisions in an idealized gas–liquid annular flow  

Microsoft Academic Search

An idealized gas–liquid annular flow in a vertical rectangular channel was considered. Point sources of solid spheres were located on the walls to represent an atomizing wall film. The decrease in the deposition coefficient with increasing volume fraction, observed in laboratory studies, was examined by using a direct numerical simulation, which does not fully resolve scales of the size of

Yoichi Mito; Thomas J. Hanratty

2006-01-01

100

Ideal-gas-like market models with savings: Quenched and annealed cases  

Microsoft Academic Search

We analyze the ideal-gas-like models of markets and review the different cases where a ‘savings’ factor changes the nature and shape of the distribution of wealth. These models can produce similar distribution of wealth as observed across varied economies. We present a more realistic model where the saving factor can vary over time (annealed savings) and yet produce Pareto distribution

Arnab Chatterjeeand; Bikas K. Chakrabarti

2007-01-01

101

The effect of the reference frame on the thermophysical properties of an ideal gas  

Microsoft Academic Search

The effect that the frame of reference has on the thermophysical properties of an ideal gas is examined from a fundamental theoretical standpoint based on the Boltzmann equation. In continuum mechanics, the principle of material frame-indifference forbids the thermophysical properties of a fluid or solid to depend in any way on the motion of the reference frame. It is demonstrated

C. G. Speziale

1986-01-01

102

The BGK model for an ideal gas with an internal degree of freedom  

Microsoft Academic Search

The BGK model for an ideal gas with an internal degree of freedom introduces two characteristic times into the Boltzmann equation, accounting for the times between elastic and inelastic collisions, respectively. Moment equations are derived from the Boltzmann equation and the influence of the characteristic times is studied for some processes, such as heating, sound waves and shocks.

Henning Struchtrup

1999-01-01

103

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

104

Modeling shock waves in an ideal gas: Going beyond the Navier-Stokes level  

Microsoft Academic Search

We model a shock wave in an ideal gas by solving a modified version of the compressible Navier-Stokes equations of hydrodynamics, where, following an earlier conjecture by Holian [Phys. Rev. A 37, 2562 (1988)], we use the temperature in the direction of shock propagation [ital T][sub [ital x][ital x

B. L. Holian; C. W. Patterson; M. Mareschal; E. Salomons

1993-01-01

105

How Incorrect Is the Classical Partition Function for the Ideal Gas?  

ERIC Educational Resources Information Center

Discussed is the classical partition function for the ideal gas and how it differs from the exact value for bosons or fermions in the classical regime. The differences in the two values are negligible hence the classical treatment leads in the end to correct answers for all observables. (Author/DS)

Kroemer, Herbert

1980-01-01

106

Simple ideal gas model of the Pavlovskii high-explosive opening switch  

Microsoft Academic Search

The behavior of the Pavlovskii type high-explosive opening switch is modeled using an ideal gas formulation. It is shown that this simple 1 dimensional model agrees with experiment during early arc compression but that at later times the process exhibits a more complex behavior, resulting from turbulent mixing.

T. J. Tucker

1983-01-01

107

Inverse Chapman-Enskog Derivation of the Thermohydrodynamic Lattice-BGK Model for the Ideal Gas  

Microsoft Academic Search

A thermohydrodynamic lattice-BGK model for the ideal gas was derived by Alexander et al. in 1993, and generalized by McNamara et al. in the same year. In these works, particular forms for the equilibrium distribution function and the transport coefficients were posited and shown to work, thereby establishing the sufficiency of the model. In this paper, we rederive the model

Bruce M. Boghosian; Peter V. Coveney

1998-01-01

108

A UNIFIED THEORY OF NON-IDEAL GAS LATTICE BOLTZMANN MODELS  

Microsoft Academic Search

A non-ideal gas lattice Boltzmann model is directly derived, in an a priori fashion, from the Enskog equation for dense gases. The model is rigorously obtained by a systematic procedure to discretize the Enskog equation (in the presence of an external force) in both phase space and time. The lattice Boltzmann model derived here is thermodynamically consistent and is free

LI-SHI LUO

109

Student understanding of the ideal gas law, Part II: A microscopic perspective  

Microsoft Academic Search

Evidence from research indicates that many undergraduate science and engineering majors have seriously flawed microscopic models for the pressure and temperature in an ideal gas. In the investigation described in this paper, some common mistaken ideas about microscopic processes were identified. Examples illustrate the use of this information in the design of instruction that helped improve student understanding of the

Christian H. Kautz; Paula R. L. Heron; Peter S. Shaffer; Lillian C. McDermott

2005-01-01

110

THE EXACT PENETRATION MODEL OF DIFFUSION IN MULTICOMPONENT IDEAL GAS MIXTURES. ANALYTICAL AND NUMERICAL SOLUTIONS  

Microsoft Academic Search

An exact analytical solution is derived for the penetration model of diffusion in multicomponent ideal gas mixtures at constant pressure and temperature. It takes the form of a matrizant solution to the continuity and Maxwell-Stefan equations transformed by introduction of a similarity variable, and includes as special cases the corresponding binary and linearized theory solutionsDirect numerical implementation of the analytical

CLAUDIO OLIVERA-FUENTES; JOAQUÍN PASQUEL-GUERRA

1987-01-01

111

The Ideal Gas Thermodynamics of Diesel Fuel Ingredients. I. Naphthalene Derivatives and Their Radicals  

Microsoft Academic Search

The molecular fundamentals of 21 naphthalene derivatives were investigated, calculated and evaluated, and their ideal gas thermodynamic properties were calculated, for the sake of simulating the combustion properties of diesel fuel. Ten of these species are stable molecules and 11 are radicals. The molecular fundamentals are calculated using Gaussian 94 ab initio and MOPAC 6 semiempirical programs. The results can

Henry Curran; Christine Wu; Nick Marinov; William J. Pitz; Charles. K. Westbrook; Alexander Burcat

2000-01-01

112

Simple ideal gas model of the Pavlovskii high-explosive opening switch  

NASA Astrophysics Data System (ADS)

The behavior of the Pavlovskii type high-explosive opening switch is modeled using an ideal gas formulation. It is shown that this simple 1 dimensional model agrees with experiment during early arc compression but that at later times the process exhibits a more complex behavior, resulting from turbulent mixing.

Tucker, T. J.

1983-08-01

113

Calculation of the swirling flow of an ideal gas in a laval nozzle  

Microsoft Academic Search

The numerical solution of the problem of the motion of a swirling flow of an ideal gas in a Laval nozzle in axisymmetric formulation is obtained by the method of stabilization. As a result, a number of effects appear that are essentially not one-dimensional, in particular, the drawing-in of the sonic line into the nozzle, an effect that leads to

Ao D. Rychkov

1971-01-01

114

Kinetic Models for Adiabatic Reversible Expansion of a Monatomic Ideal Gas.  

ERIC Educational Resources Information Center

A fixed amount of an ideal gas is confined in an adiabatic cylinder and piston device. The relation between temperature and volume in initial/final phases can be derived from the first law of thermodynamics. However, the relation can also be derived based on kinetic models. Several of these models are discussed. (JN)

Chang, On-Kok

1983-01-01

115

Application of quantum cascade lasers to trace gas analysis  

NASA Astrophysics Data System (ADS)

Quantum cascade (QC) lasers are virtually ideal mid-infrared sources for trace gas monitoring. They can be fabricated to operate at any of a very wide range of wavelengths from ˜ 3 ?m to ˜ 24 ?m. Seizing the opportunity presented by mid-infrared QC lasers, several groups world-wide are actively applying them to trace gas sensing. Real world applications include environmental monitoring, industrial process control and biomedical diagnostics. In our laboratory we have explored the use of several methods for carrying out absorption spectroscopy with these sources, which include multipass absorption spectroscopy, cavity ring down spectroscopy (CRDS), integrated cavity output spectroscopy (ICOS), and quartz-enhanced photoacoustic spectroscopy (QEPAS).

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

2008-02-01

116

Ballistic and diffusive dynamics in a two-dimensional ideal gas of macroscopic chaotic Faraday waves  

NASA Astrophysics Data System (ADS)

We have constructed a macroscopic driven system of chaotic Faraday waves whose statistical mechanics, we find, are surprisingly simple, mimicking those of a thermal gas. We use real-time tracking of a single floating probe, energy equipartition, and the Stokes-Einstein relation to define and measure a pseudotemperature and diffusion constant and then self-consistently determine a coefficient of viscous friction for a test particle in this pseudothermal gas. Because of its simplicity, this system can serve as a model for direct experimental investigation of nonequilibrium statistical mechanics, much as the ideal gas epitomizes equilibrium statistical mechanics.

Welch, Kyle J.; Hastings-Hauss, Isaac; Parthasarathy, Raghuveer; Corwin, Eric I.

2014-04-01

117

Ballistic and diffusive dynamics in a two-dimensional ideal gas of macroscopic chaotic Faraday waves.  

PubMed

We have constructed a macroscopic driven system of chaotic Faraday waves whose statistical mechanics, we find, are surprisingly simple, mimicking those of a thermal gas. We use real-time tracking of a single floating probe, energy equipartition, and the Stokes-Einstein relation to define and measure a pseudotemperature and diffusion constant and then self-consistently determine a coefficient of viscous friction for a test particle in this pseudothermal gas. Because of its simplicity, this system can serve as a model for direct experimental investigation of nonequilibrium statistical mechanics, much as the ideal gas epitomizes equilibrium statistical mechanics. PMID:24827228

Welch, Kyle J; Hastings-Hauss, Isaac; Parthasarathy, Raghuveer; Corwin, Eric I

2014-04-01

118

Using Rubber-Elastic Material-Ideal Gas Analogies To Teach Introductory Thermodynamics. Part II: The Laws of Thermodynamics.  

ERIC Educational Resources Information Center

Describes the laws of thermodynamics as a supplement to an introductory thermodynamics undergraduate course. Uses rubber-elastic materials (REM) which have strong analogies to the concept of ideal gas. Provides examples of the analogies between ideal gas and REM and mathematical analogies. (YDS)

Smith, Brent

2002-01-01

119

Oscillatory conductive heat transfer for a fiber in an ideal gas  

NASA Technical Reports Server (NTRS)

A description of the thermal effects created by placing a cylindrical fiber in an inviscid, ideal gas, through which an acoustic wave propagates, is presented. The fibers and the gas have finite heat capacities and thermal conductivities. Expressions for the temperature distribution in the gas and in the material are determined. The temperature distribution is caused by pressure oscillations in the gas which, in turn, are caused by the passage of an acoustic wave. The relative value of a dimensionless parameter is found to be indicative of whether the exact or approximate equations should be used in the solution. This parameter is a function of the thermal conductivities and heat capacities of the fiber and gas, the acoustic frequency, and the fiber diameter.

Kuntz, H. L.; Perreira, N. D.

1985-01-01

120

Thermodynamic instability and first-order phase transition in an ideal Bose gas  

SciTech Connect

We conduct a rigorous investigation into the thermodynamic instability of an ideal Bose gas confined in a cubic box, without assuming a thermodynamic limit or a continuous approximation. Based on the exact expression of the canonical partition function, we perform numerical computations up to 10{sup 6} particles. We report that if the number of particles is equal to or greater than a certain critical value, which turns out to be 7616, the ideal Bose gas subject to the Dirichlet boundary condition reveals a thermodynamic instability. Accordingly, we demonstrate that a system consisting of a finite number of particles can exhibit a discontinuous phase transition that features a genuine mathematical singularity, provided we keep not volume but pressure constant. The specific number, 7616, can be regarded as a characteristic number of a ''cube,'' which is the geometric shape of the box.

Park, Jeong-Hyuck [Department of Physics and Center for Quantum Spacetime Sogang University, Mapo-gu, Seoul 121-742 (Korea, Republic of); Kim, Sang-Woo [High Energy Accelerator Research Organization (KEK) Tsukuba, Ibaraki 305-0801 (Japan)

2010-06-15

121

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

122

Modeling shock waves in an ideal gas: Going beyond the Navier-Stokes level  

Microsoft Academic Search

We model a shock wave in an ideal gas by solving a modified version of the compressible Navier-Stokes equations of hydrodynamics, where, following an earlier conjecture by Holian [Phys. Rev. A 37, 2562 (1988)], we use the temperature in the direction of shock propagation Txx, rather than the average temperature T=(Txx+Tyy+Tzz)\\/3, in the evaluation of the linear transport coefficients. The

B. L. Holian; C. W. Patterson; M. Mareschal; E. Salomons

1993-01-01

123

Generic features of the wealth distribution in ideal-gas-like markets  

Microsoft Academic Search

We provide an exact solution to the ideal-gas-like models studied in econophysics to understand the microscopic origin of Pareto law. In these classes of models the key ingredient necessary for having a self-organized scale-free steady-state distribution is the trading or collision rule where agents or particles save a definite fraction of their wealth or energy and invest the rest for

P. K. Mohanty

2006-01-01

124

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

Microsoft Academic Search

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

Vitaly V. Kocharovsky; Vladimir V. Kocharovsky

2010-01-01

125

Free boundary value problem of the one-dimensional model of polytropic ideal gas  

Microsoft Academic Search

In this paper the free boundary value problem of the one-dimensional model of polytropic ideal gas is discussed. Under some\\u000a smallness assumption on the initial data, the global weak solution of our problem is obtained. Furthermore the solution decays\\u000a inL\\u000a ?-sense as time goes to infinity (Theorem 2.1).

Sadamu Inaishi

1991-01-01

126

Micro and nanoscale non-ideal gas Poiseuille flows in a consistent Boltzmann algorithm model  

Microsoft Academic Search

The direct simulation Monte Carlo method in the consistent Boltzmann algorithm model has been developed and expanded for non-ideal gas predictions. The enhanced collision rate factor is determined by considering the excluded molecular volume and shadowing\\/screening effects based on the Enskog theory. The parameter for the attraction strength is also determined by comparison with the classical thermodynamics theory. Different pressure-driven

Moran Wang; Zhixin Li

2004-01-01

127

Two-level trap model of BEC in an ideal gas  

Microsoft Academic Search

We consider a two-energy-level trap with arbitrary degeneracy of an upper level and find an analytical solution for the condensate statistics in a mesoscopic ideal gas with arbitrary number of atoms and any temperature, including a critical region. The solution is a cut-off negative binomial distribution that tends to a cut-off gamma distribution in the thermodynamic limit. We show how

Konstantin Dorfman; Vitaly Kocharovsky; Vladimir Kocharovsky

2009-01-01

128

The ideal gas as an urn model: derivation of the entropy formula  

Microsoft Academic Search

The approach of an ideal gas to equilibrium is simulated through a generalization of the Ehrenfest ball-and-box model. In the present model, the interior of each box is discretized, i.e., balls\\/particles live in cells whose occupation can be either multiple or single. Moreover, particles occasionally undergo random, but elastic, collisions between each other and against the container walls. I show,

Santi Prestipino; Contrada Papardo

2005-01-01

129

Cooking Under Pressure Applying the Ideal Gas Law in the Kitchen  

NSDL National Science Digital Library

The Clarksons are making dinner for friends and decide to try out their new pressure cooker. As students read the dialogue that ensues, they learn about how the boiling point of water is directly related to external pressure, apply the ideal gas law, and relate chemical reaction rates with temperatures in addition to learning about the conservation of energy. Designed for a non-majors’ general chemistry course, the case could be extended to other disciplines, including physics, nutrition, and microbiology.

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

2009-01-01

130

Theory of Critical Temperature Adiabatic Change for Ideal Gas Bose-Einstein Condensation in Optical Lattices  

Microsoft Academic Search

We present a scheme of analytical calculations determining the critical temperature and the number of condensed atoms of ideal gas Bose-Einstein condensation in external potentials with 1D, 2D or 3D periodicity. In particular we show that the width of the lowest energy band appears as the main parameter determining the critical temperature of condensation. Is obtained a very simple, proportional

G. A. Muradyan; A. Zh. Muradyan

2006-01-01

131

Theory of Critical Temperature Adiabatic Change for Ideal Gas Bose-Einstein Condensation in Optical Lattices  

Microsoft Academic Search

We present a scheme of analytical calculations determining the critical\\u000atemperature and the number of condensed atoms of ideal gas Bose-Einstein\\u000acondensation in external potentials with 1D, 2D or 3D periodicity. In\\u000aparticular we show that the width of the lowest energy band appears as the main\\u000aparameter determining the critical temperature of condensation. Is obtained a\\u000avery simple, proportional

G. A. Muradyan; A. Zh

2006-01-01

132

Effect of the Minimal Length on the Thermodynamics of Ultra-Relativistic Ideal Fermi Gas  

NASA Astrophysics Data System (ADS)

Based on the generalized uncertainty principle, the thermodynamics of Fermi gas in high density, high pressure and high temperature are calculated. As the temperature and density increases, the energy and entropy becomes saturated and the pressure blows up without any bound. Using the conservation equation of the Robertson—Walker cosmology, we find that, when the energy exceeds the EH = ?0?1/2c2Mp, the expansion cannot be driven by the photon gas and the fermion gas. This requires some new physical mechanism related to quantum gravity, such as tachyons and dilatons.

Zhang, Xiu-Ming; Sun, Jiu-Xun; Yang, Li

2014-04-01

133

Quantum lattice gas representation for vector solitons  

Microsoft Academic Search

Quantum lattice gas algorithms are developed for the coupled-nonlinear Schrodinger (coupled-NLS) equations, equations that describe the propagation of pulses in birefringent fibers. When the cross-phase modulation factor is unity, the coupled-NLS reduce to the Manakov equations. The quantum lattice gas algorithm yields vector solitons for the fully integrable Manakov system that are in excellent agreement with exact results. Simulations are

George Vahala; Linda Vahala; Jeffrey Yepez

2003-01-01

134

Equation of state of an ideal gas with nonergodic behavior in two connected vessels  

NASA Astrophysics Data System (ADS)

We consider a two-dimensional collisionless ideal gas in the two vessels connected through a small hole. One of them is a well-behaved chaotic billiard, another one is known to be nonergodic. A significant part of the second vessel's phase space is occupied by an island of stability. In the works of Zaslavsky and coauthors, distribution of Poincaré recurrence times in similar systems was considered. We study the gas pressure in the vessels; it is uniform in the first vessel and not uniform in second one. An equation of the gas state in the first vessel is obtained. Despite the very different phase-space structure, behavior of the second vessel is found to be very close to the behavior of a good ergodic billiard but of different volume. The equation of state differs from the ordinary equation of ideal gas state by an amendment to the vessel's volume. Correlation of this amendment with a share of the phase space under remaining intact islands of stability is shown.

Naplekov, D. M.; Semynozhenko, V. P.; Yanovsky, V. V.

2014-01-01

135

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. Presented in this talk is a quantum computing algorithm called a quantum lattice gas. An analytical treatment of the microscopic quantum lattice-gas system is summarized and the predicted effective field theory of the quantum system, at the mesoscopic and macroscopic scales, is given. At the mesoscopic

Jeffrey Yepez

2000-01-01

136

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 specifically, 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

Jeffrey Yepez

2001-01-01

137

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) cancellation of perturbation terms that appear with opposite signs in the model moment expressions. PMID:24105525

Ben-David, Avishai; Davidson, Charles E

2013-08-26

138

Generic features of the wealth distribution in ideal-gas-like markets  

Microsoft Academic Search

We provide an exact solution to the ideal-gas-like models studied in\\u000aeconophysics to understand the microscopic origin of Pareto-law. In these class\\u000aof models the key ingredient necessary for having a self-organized scale-free\\u000asteady-state distribution is the trading or collision rule where agents or\\u000aparticles save a definite fraction of their wealth or energy and invests the\\u000arest for trading.

P. K. Mohanty; AF Bidhan Nagar

2006-01-01

139

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

140

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

141

Gas-Kinetic Theory Based Flux Splitting Method for Ideal Magnetohydrodynamics  

NASA Technical Reports Server (NTRS)

A gas-kinetic solver is developed for the ideal magnetohydrodynamics (MHD) equations. The new scheme is based on the direct splitting of the flux function of the MHD equations with the inclusion of "particle" collisions in the transport process. Consequently, the artificial dissipation in the new scheme is much reduced in comparison with the MHD Flux Vector Splitting Scheme. At the same time, the new scheme is compared with the well-developed Roe-type MHD solver. It is concluded that the kinetic MHD scheme is more robust and efficient than the Roe- type method, and the accuracy is competitive. In this paper the general principle of splitting the macroscopic flux function based on the gas-kinetic theory is presented. The flux construction strategy may shed some light on the possible modification of AUSM- and CUSP-type schemes for the compressible Euler equations, as well as to the development of new schemes for a non-strictly hyperbolic system.

Xu, Kun

1998-01-01

142

Rapid distortion analysis of compressible turbulence in ideal gas: Part 2 - Density averaged moments  

NASA Astrophysics Data System (ADS)

We perform rapid distortion analysis of linearized, inviscid Favre-averaged Navier Stokes equation. This study - Favre-averaged Rapid Distortion Theory (F-RDT)- investigates the evolution of density weighted fluctuating moments. The fluid is assumed to be an ideal gas. The F-RDT formulation comprises of a closed set of 65 ordinary differential equations for the case of homogenous mean shear field. With S / S RT . - RT as compressibility parameter (S=magnitude of mean shear, R=gas constant, T=density weighted mean temperature), the versatility of the formulation is demonstrated by recovering both the incompressible and Burgers limit behaviors. Results for several intermediate cases-between the above two extreme limits-are also obtained. Favre-averaged Reynolds stresses, temperature variance, density variance and various cross-correlations will be discussed.

Suman, Sawan; Yu, Huidan; Girimaji, Sharath; Lavin, Tucker

2006-11-01

143

Collision of BEC dark matter structures and comparison with the collision of ideal gas structures  

SciTech Connect

In this work we present an important feature of the Bose Einstein Condensate (BEC) dark matter model, that is, the head-on collision of BEC dark matter virialized structures. This model of dark matter is assumed to be ruled by the Schroedinger-Poisson system of equations, which is interpreted as the Gross-Pitaevskii equation with a gravitational potential sourced by the density of probability. It has been shown recently that during the collision of two structures a pattern formation in the density of probability appears. We explore the pattern formation for various initial dynamical conditions during the collision. In order to know whether or not the pattern formation is a particular property of the BEC dark matter, we compare with the collision of two structures of virialized ideal gas under similar dynamical initial conditions, which is a model more consistent with usual models of dark matter. In order to do so, we also solve Euler's equations using a smoothed particle hydrodynamics approach. We found that the collision of the ideal gas structures does not show interference patterns, which in turn implies that the pattern formation is a property of the BEC dark matter.

Guzman, F. S.; Gonzalez, J. A. [Instituto de Fisica y Matematicas, Universidad Michoacana de San Nicolas de Hidalgo. Edificio C-3, Cd. Universitaria, 58040 Morelia, Michoacan (Mexico)

2010-12-07

144

Experimental Demonstration of Quantum Lattice Gas Computation  

Microsoft Academic Search

We report an ensemble nuclear magnetic resonance (NMR) implementation of a\\u000aquantum lattice gas algorithm for the diffusion equation. The algorithm employs\\u000aan array of quantum information processors sharing classical information, a\\u000anovel architecture referred to as a type-II quantum computer. This concrete\\u000aimplementation provides a test example from which to probe the strengths and\\u000alimitations of this new computation

Marco A. Pravia; Zhiying Chen; David G. Cory; Jeffrey Yepez

2003-01-01

145

Unitary Quantum Lattice Gas Algorithms for Quantum to Classical Turbulence  

Microsoft Academic Search

Using a set of interleaved unitary collision-stream operators, a three-dimensional (3D) quantum lattice gas algorithm is devised which, on taking moments, recovers the Gross-Pitaevskii (GP) equation. If a zerotemperature Bose-Einstein condensate (BEC) is trapped in an a magnetic well, the evolution of the ground-state wave function satisfies the scalar GP equation; while if the BEC is trapped in an optical

George Vahala; Jeffrey Yepez; Min Soe; Linda Vahala; Sean Ziegeler

2010-01-01

146

Dephasing Length and Coherence of a Quantum Soliton in an Ideal Long Josephson Junction  

Microsoft Academic Search

We study the internal dephasing of a quantum soliton (fluxon) via its interaction with thermal plasmons. We show that dephasing occurs even when the excitations of the system are completely decoupled and there is no dissipation. The dephasing length of the fluxon (below which quantum coherence is maintained) is evaluated. It is found to be much longer than the width

Ziv Hermon; Alexander Shnirman; Eshel Ben-Jacob

1995-01-01

147

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

148

Determination of ideal-gas enthalpies of formation for key compounds:  

SciTech Connect

The results of a study aimed at improvement of group-contribution methodology for estimation of thermodynamic properties of organic and organosilicon substances are reported. Specific weaknesses where particular group-contribution terms were unknown, or estimated because of lack of experimental data, are addressed by experimental studies of enthalpies of combustion in the condensed phase, vapor-pressure measurements, and differential scanning calorimetric (d.s.c.) heat-capacity measurements. Ideal-gas enthalpies of formation of ({plus minus})-butan-2-ol, tetradecan-1-ol, hexan-1,6-diol, methacrylamide, benzoyl formic acid, naphthalene-2,6-dicarboxylic acid dimethyl ester, and tetraethylsilane are reported. A crystalline-phase enthalpy of formation at 298.15 K was determined for naphthalene-2,6-dicarboxylic acid, which decomposed at 695 K before melting. The combustion calorimetry of tetraethylsilane used the proven fluorine-additivity methodology. Critical temperature and critical density were determined for tetraethylsilane with differential scanning calorimeter and the critical pressure was derived. Group-additivity parameters useful in the application of group- contribution correlations are derived. 112 refs., 13 figs., 19 tabs.

Steele, W.V.; Chirico, R.D.; Nguyen, A.; Hossenlopp, I.A.; Smith, N.K.

1991-10-01

149

Thermodynamics of an ideal generalized gas: II. Means of order alpha.  

PubMed

The property that power means are monotonically increasing functions of their order is shown to be the basis of the second laws not only for processes involving heat conduction, but also for processes involving deformations. This generalizes earlier work involving only pure heat conduction and underlines the incomparability of the internal energy and adiabatic potentials when expressed as powers of the adiabatic variable. In an L-potential equilibration, the final state will be one of maximum entropy, whereas in an entropy equilibration, the final state will be one of minimum L. Unlike classical equilibrium thermodynamic phase space, which lacks an intrinsic metric structure insofar as distances and other geometrical concepts do not have an intrinsic thermodynamic significance in such spaces, a metric space can be constructed for the power means: the distance between means of different order is related to the Carnot efficiency. In the ideal classical gas limit, the average change in the entropy is shown to be proportional to the difference between the Shannon and Rényi entropies for nonextensive systems that are multifractal in nature. The L potential, like the internal energy, is a Schur convex function of the empirical temperature, which satisfies Jensen's inequality, and serves as a measure of the tendency to uniformity in processes involving pure thermal conduction. PMID:16228240

Lavenda, B H

2005-11-01

150

Ideal-gas heat capacities and virial coefficients of HFC refrigerants  

SciTech Connect

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 (C{sub p}{sup 0}) and virial coefficients derived from the experimental data are of particular interest, since they are directly related to the intramolecular and intermolecular potentials through the statistical mechanical procedure. There have been some discrepancies reported in the observed and theoretical C{sub p}{sup 0} for HFC compounds. The authors have performed new calculations for C{sub p}{sup 0} for several HFCs. The present results are consistent with the selected experimental values. The second (B) and Third (C) virial coefficients have been reported for these HFC refrigerants from speed of sound data and Burnett PVT data. Often, a square well-type intermolecular potential is employed to correlate the data. However, the model potential cannot account consistently for both B and C coefficients with the same potential parameters. They have analyzed the data with the Stockmayer potential and obtained self-consistent results for various HFC (R-23, R-32, R-125, R-134a, R-143a, and R-152a) compounds with physically reasonable potential parameters.

Yokozeki, A.; Sato, H.; Watanabe, K. [Keio Univ., Yokohama (Japan)] [Keio Univ., Yokohama (Japan)

1998-01-01

151

Rapid distortion analysis of compressible turbulence in ideal gas: Part 1 -- Reynolds averaged moments  

NASA Astrophysics Data System (ADS)

We solve the inviscid, compressible linearized Reynolds-averaged Navier-Stokes equations, invoking the ideal gas law rather than employing the simpler but less practical isentropic assumption. The formulation involves 26 ordinary differential equations. At the zero-Mach number limit, the incompressible RDT solutions are recovered for various mean velocity gradients. At the high-Mach number limit, the Burgers solution is recovered for the homogeneous mean shear case. For intermediate Mach numbers the pressure dilatation term is found to be influential in transferring energy between the kinetic and internal modes. The exchange causes high frequency oscillations in Reynolds stresses which are absent in the incompressible limit. The effects of compressible initial conditions are also examined. Initially compressible velocity field is found to be more conducive to internal energy conversion. Nearly half of the total energy is in the form of internal energy at large times. In comparison about 25 percent of energy is in the form of internal energy for the case of the initially- incompressible field.

Lavin, Tucker; Yu, Huidan; Girimaji, Sharath

2006-11-01

152

The ideal relativistic rotating gas as a perfect fluid with spin  

SciTech Connect

We show that the ideal relativistic spinning gas at complete thermodynamical equilibrium is a fluid with a non-vanishing spin density tensor {sigma}{sub {mu}{nu}}. After having obtained the expression of the local spin-dependent phase-space density f(x, p){sub {sigma}{tau}} in the Boltzmann approximation, we derive the spin density tensor and show that it is proportional to the acceleration tensor {Omega}{sub {mu}{nu}} constructed with the Frenet-Serret tetrad. We recover the proper generalization of the fundamental thermodynamical relation, involving an additional term -(1/2){Omega}{sub {mu}{nu}{sigma}}{sup {mu}{nu}}. We also show that the spin density tensor has a non-vanishing projection onto the four-velocity field, i.e. t{sup {mu}} = {sigma}{sub {mu}}{nu}u{sup {nu}} {ne} 0, in contrast to the common assumption t{sup {mu}} = 0, known as Frenkel condition, in the thus-far proposed theories of relativistic fluids with spin. We briefly address the viewpoint of the accelerated observer and inertial spin effects.

Becattini, F., E-mail: becattini@fi.infn.i [Universita di Firenze, Florence (Italy); INFN Sezione di Firenze, Florence (Italy); Tinti, L. [Universita di Firenze, Florence (Italy)

2010-08-15

153

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

Microsoft Academic Search

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

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

2002-01-01

154

Self-similar adiabatic flow headed by a magnetogasdynamic cylindrical shock wave in a rotating non-ideal gas  

Microsoft Academic Search

Similarity solutions are obtained for one-dimensional adiabatic flow behind a magnetogasdynamic cylindrical shock wave propagating in a rotating non-ideal gas in presence of an azimuthal magnetic field. The density of the medium ahead of the shock is assumed to be constant. In order to obtain the similarity solutions the angular velocity of the ambient medium is assumed to be obeying

J. P. Vishwakarma; Anil Kumar Maurya; K. K. Singh

2007-01-01

155

University Students Explaining Adiabatic Compression of an Ideal Gas---A New Phenomenon in Introductory Thermal Physics  

Microsoft Academic Search

This study focuses on second-year university students' explanations and reasoning related to adiabatic compression of an ideal gas. The phenomenon was new to the students, but it was one which they should have been capable of explaining using their previous upper secondary school knowledge. The students' explanations and reasoning were investigated with the aid of paper and pencil tests (n

Risto Leinonen; Mervi A. Asikainen; Pekka E. Hirvonen

2011-01-01

156

Flow pattern induced by the plane piston moving in a non-ideal gas with weak gravitational field  

Microsoft Academic Search

A systematic perturbation scheme is used to analyze the flow pattern induced by the motion of a plane piston moving with constant velocity in a non-ideal gas with weak gravitational field. The flow variables are expanded as a series of small parameter ?, which is the ratio of the typical escape velocity to the plasma velocity. The zeroth order solution

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

2011-01-01

157

Effect of ideal-gas flow swirl on the optimum supersonic contour of an axisymmetric nozzle with break  

Microsoft Academic Search

The effect of swirling the flow at the nozzle inlet on the shape of the optimum supersonic section with a break at the point of intersection of the limiting characteristic and the contour is investigated within the framework of the ideal (inviscid and non-heat-conducting) gas model. A direct method based on reduction to a problem of nonlinear programming is used

G. I. Afonin; V. G. Butov

1989-01-01

158

University Students Explaining Adiabatic Compression of an Ideal Gas--A New Phenomenon in Introductory Thermal Physics  

ERIC Educational Resources Information Center

This study focuses on second-year university students' explanations and reasoning related to adiabatic compression of an ideal gas. The phenomenon was new to the students, but it was one which they should have been capable of explaining using their previous upper secondary school knowledge. The students' explanations and reasoning were…

Leinonen, Risto; Asikainen, Mervi A.; Hirvonen, Pekka E.

2012-01-01

159

Ideal quantum nondemolition measurement of a flux qubit at variable bias  

NASA Astrophysics Data System (ADS)

We propose a scheme to realize a quantum nondemolition (QND) measurement of a superconducting flux qubit by a Josephson bifurcation amplifier. Our scheme can implement a perfect QND measurement for a qubit subject to a variable magnetic bias. Measurement back-action-induced qubit relaxation can be suppressed and hence the QND fidelity is expected to be high over a wide range of bias conditions.

Wang, Ying-Dan; Zhu, Xiaobo; Bruder, Christoph

2011-04-01

160

Quantum lattice-gas model for computational fluid dynamics.  

PubMed

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 specifically, 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 behavior at the mesoscopic scale. At the mesoscopic scale, a lattice Boltzmann equation with a nonlocal collision term that depends on the entire system wave function, governs the dynamical system. Numerical results obtained from an exact simulation of a one-dimensional quantum lattice model are included to illustrate the formalism. A symbolic mathematical method is used to implement the quantum mechanical model on a conventional workstation. The numerical simulation indicates that classical viscous damping is not present in the one-dimensional quantum lattice-gas system. PMID:11308976

Yepez, J

2001-04-01

161

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

162

Propagation of weak shock waves in a non-ideal gas  

Microsoft Academic Search

This paper investigates the problem of propagation of planar and non-planar weak shock waves in a non-ideal medium. The mathematical\\u000a formulation developed in this work leads to a closed system of coupled transport equations which efficiently describes the\\u000a strength of a shock wave and the first order discontinuities induced behind it. The influence of the parameter of non-idealness\\u000a and the

Lal. P. Singh; Dheerendra B. Singh; Subedar Ram

2011-01-01

163

Jack Polynomials as Fractional Quantum Hall States and the Betti Numbers of the ( k + 1)-Equals Ideal  

NASA Astrophysics Data System (ADS)

We show that for Jack parameter ? = -( k + 1)/( r - 1), certain Jack polynomials studied by Feigin-Jimbo-Miwa-Mukhin vanish to order r when k + 1 of the coordinates coincide. This result was conjectured by Bernevig and Haldane, who proposed that these Jack polynomials are model wavefunctions for fractional quantum Hall states. Special cases of these Jack polynomials include the wavefunctions of Laughlin and Read-Rezayi. In fact, along these lines we prove several vanishing theorems known as clustering properties for Jack polynomials in the mathematical physics literature, special cases of which had previously been conjectured by Bernevig and Haldane. Motivated by the method of proof, which in the case r = 2 identifies the span of the relevant Jack polynomials with the S n -invariant part of a unitary representation of the rational Cherednik algebra, we conjecture that unitary representations of the type A Cherednik algebra have graded minimal free resolutions of Bernstein-Gelfand-Gelfand type; we prove this for the ideal of the ( k + 1)-equals arrangement in the case when the number of coordinates n is at most 2 k + 1. In general, our conjecture predicts the graded S n -equivariant Betti numbers of the ideal of the ( k + 1)-equals arrangement with no restriction on the number of ambient dimensions.

Zamaere, Christine Berkesch; Griffeth, Stephen; Sam, Steven V.

2014-08-01

164

Jack Polynomials as Fractional Quantum Hall States and the Betti Numbers of the (k + 1)-Equals Ideal  

NASA Astrophysics Data System (ADS)

We show that for Jack parameter ? = -(k + 1)/(r - 1), certain Jack polynomials studied by Feigin-Jimbo-Miwa-Mukhin vanish to order r when k + 1 of the coordinates coincide. This result was conjectured by Bernevig and Haldane, who proposed that these Jack polynomials are model wavefunctions for fractional quantum Hall states. Special cases of these Jack polynomials include the wavefunctions of Laughlin and Read-Rezayi. In fact, along these lines we prove several vanishing theorems known as clustering properties for Jack polynomials in the mathematical physics literature, special cases of which had previously been conjectured by Bernevig and Haldane. Motivated by the method of proof, which in the case r = 2 identifies the span of the relevant Jack polynomials with the S n -invariant part of a unitary representation of the rational Cherednik algebra, we conjecture that unitary representations of the type A Cherednik algebra have graded minimal free resolutions of Bernstein-Gelfand-Gelfand type; we prove this for the ideal of the (k + 1)-equals arrangement in the case when the number of coordinates n is at most 2k + 1. In general, our conjecture predicts the graded S n -equivariant Betti numbers of the ideal of the (k + 1)-equals arrangement with no restriction on the number of ambient dimensions.

Zamaere, Christine Berkesch; Griffeth, Stephen; Sam, Steven V.

2014-03-01

165

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

166

University Students Explaining Adiabatic Compression of an Ideal Gas—A New Phenomenon in Introductory Thermal Physics  

Microsoft Academic Search

This study focuses on second-year university students’ explanations and reasoning related to adiabatic compression of an ideal\\u000a gas. The phenomenon was new to the students, but it was one which they should have been capable of explaining using their\\u000a previous upper secondary school knowledge. The students’ explanations and reasoning were investigated with the aid of paper\\u000a and pencil tests (n?=?86)

Risto Leinonen; Mervi A. Asikainen; Pekka E. Hirvonen

167

Sound velocity and ideal-gas specific heat of gaseous 1,1,1,2-tetrafluoroethane (R134a)  

Microsoft Academic Search

A cylindrical, variable-path acoustic interferometer operating at 156.252kHz is developed for determining ideal-gas specific heats. Results of validation measurements with argon are very satisfactory, with the maximum deviation of the speed of sound equal to 3×10-4. The sound velocity of gaseous R134a has been measured at low temperatures and low pressures. The specific heat was then calculated from the results.

M. S. Zhu; L. Z. Han; K. Z. Zhang; T. Y. Zhou

1993-01-01

168

Quantum Lattice Gas Algorithm for the Coupled Nonlinear Schrodinger Equation  

Microsoft Academic Search

Quantum computers hold the promise of exponential speed-up over classical computers when quantum entanglement plays a significant role in the algorithm. Here we extend our quantum lattice gas algorithm for the nonlinear Schrodinger equation (NLS) to the Manakov equations. Under certain conditions, the Manakov equations describe the nonlinear interaction between the orthogonal polarization components of an electromagnetic wave propagating in

George Vahala; Linda Vahala; Jeffrey Yepez

2003-01-01

169

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

170

Ideal-gas heat capacities of dimethylsiloxanes from speed-of-sound measurements and ab initio calculations  

Microsoft Academic Search

A two-pronged approach has been used to obtain accurate ideal-gas heat capacities of cyclic and linear dimethylsiloxanes that are useful for thermodynamic modeling of several processes involving these compounds. Acoustic resonance measurements were made on gas-phase octamethylcyclotetrasiloxane (D4, [(CH3)2–Si–O]4) and decamethylcyclopentasiloxane (D5, [(CH3)2–Si–O]5) over the temperature range 450–510?K. These new data, along with previously published molecular vibrational frequency data for

N. R. Nannan; P. Colonna; C. M. Tracy; R. L. Rowley; J. J. Hurly

2007-01-01

171

Quantum Lattice-Gas Model for the Diffusion Equation  

Microsoft Academic Search

Presented is a factorized quantum lattice-gas algorithm to model the diffusion equation. It is a minimal model with two qubits per node of a one-dimensional lattice and it is suitable for implementation on a large array of small quantum computers interconnected by nearest-neighbor classical communication channels. The quantum lattice-gas system is described at the mesoscopic scale by a lattice-Boltzmann equation

Jeffrey Yepez

2001-01-01

172

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

173

The Role of Multiple Representations in the Understanding of Ideal Gas Problems  

ERIC Educational Resources Information Center

This study examined the representational competence of students as they solved problems dealing with the temperature-pressure relationship for ideal gases. Seven students enrolled in a first-semester general chemistry course and two advanced undergraduate science majors participated in the study. The written work and transcripts from videotaped…

Madden, Sean P.; Jones, Loretta L.; Rahm, Jrene

2011-01-01

174

Interferograms, Schlieren, and Shadowgraphs Constructed from Real- and Ideal-Gas, Two- and Three-Dimensional Computed Flowfields  

NASA Technical Reports Server (NTRS)

The construction of interferograms, schlieren, and shadowgraphs from computed flowfield solutions permits one-to-one comparisons of computed and experimental results. A method for constructing these images from both ideal- and real-gas, two- and three-dimensional computed flowfields is described. The computational grids can be structured or unstructured, and multiple grids are an option. Constructed images are shown for several types of computed flows including nozzle, wake, and reacting flows; comparisons to experimental images are also shown. In addition, the sensitivity of these images to errors in the flowfield solution is demonstrated, and the constructed images can be used to identify problem areas in the computations.

Yates, Leslie A.

1992-01-01

175

Interferograms, schlieren, and shadowgraphs constructed from real- and ideal-gas, two- and three-dimensional computed flowfields  

NASA Technical Reports Server (NTRS)

The construction of interferograms, schlieren, and shadowgraphs from computed flowfield solutions permits one-to-one comparisons of computed and experimental results. A method of constructing these images from both ideal- and real-gas, two and three-dimensional computed flowfields is described. The computational grids can be structured or unstructured, and multiple grids are an option. Constructed images are shown for several types of computed flows including nozzle, wake, and reacting flows; comparisons to experimental images are also shown. In addition, th sensitivity of these images to errors in the flowfield solution is demonstrated, and the constructed images can be used to identify problem areas in the computations.

Yates, Leslie A.

1993-01-01

176

Idealized gas turbine combustor for performance research and validation of large eddy simulations  

Microsoft Academic Search

This paper details the design of a premixed, swirl-stabilized combustor that was designed and built for the express purpose of obtaining validation-quality data for the development of large eddy simulations (LES) of gas turbine combustors. The combustor features nonambiguous boundary conditions, a geometrically simple design that retains the essential fluid dynamics and thermochemical processes that occur in actual gas turbine

Timothy C. Williams; Robert W. Schefer; Joseph C. Oefelein; Christopher R. Shaddix

2007-01-01

177

Vibrational frequencies and ideal-gas heat capacities as calculated by a modified Urey-Bradley force field. Fluorochloroderivatives of methane  

Microsoft Academic Search

Ideal-gas heat capacities are required to estimate caloric properties of fluids. Relationships between ideal-gas and molecular properties are given by statistical thermodynamics. For many molecules the required molecular data, i.e. vibrational frequencies, or heat capacity data from different references are contradictory or still lacking. Here a method is applied, which is able to predict the vibrational frequencies for many molecules

Uwe Delfs; Klaus Lucas

1997-01-01

178

Quantum lattice gas representation of some classical solitons  

Microsoft Academic Search

A quantum lattice gas representation is determined for both the non-linear Schrödinger (NLS) and Korteweg–de Vries (KdV) equations. There is excellent agreement with the solutions from these representations to the exact soliton–soliton collisions of the integrable NLS and KdV equations. These algorithms could, in principle, be simulated on a hybrid quantum-classical computer.

George Vahala; Jeffrey Yepez; Linda Vahala

2003-01-01

179

Highly covariant quantum lattice gas model of the Dirac equation  

Microsoft Academic Search

We revisit the quantum lattice gas model of a spinor quantum field theory-the smallest scale particle dynamics is partitioned into unitary collide and stream operations. The construction is covariant (on all scales down to a small length {\\\\ell} and small time {\\\\tau} = c {\\\\ell}) with respect to Lorentz transformations. The mass m and momentum p of the modeled Dirac

Jeffrey Yepez

2011-01-01

180

Towards a NMR implementation of a quantum lattice gas algorithm  

Microsoft Academic Search

Recent theoretical results suggest that an array of quantum information processors communicating via classical channels can be used to solve fluid dynamics problems. Quantum lattice-gas algorithms (QLGA) running on such architectures have been shown to solve the diffusion equation and the nonlinear Burgers equations. In this report, we describe progress towards an ensemble nuclear magnetic resonance (NMR) implementation of a

Marco A. Pravia; Zhiying Chen; Jeffrey Yepez; David G. Cory

2002-01-01

181

Quantum Lattice-Gas Model for the Diffusion Equation.  

National Technical Information Service (NTIS)

Presented is a factorized quantum lattice-gas algorithm to model the diffusion equation. It is a minimal model with two qubits per node of a one- dimensional lattice and it is suitable for implementation on a large array of small quantum computers interco...

J. Yepez

2001-01-01

182

FRW quantum cosmology with a generalized Chaplygin gas  

Microsoft Academic Search

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

Mariam Bouhmadi-López; Paulo Vargas Moniz

2005-01-01

183

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

184

Condensation of ideal Bose gas confined in a box within a canonical ensemble  

SciTech Connect

We set up recursion relations for the partition function and the ground-state occupancy for a fixed number of noninteracting bosons confined in a square box potential and determine the temperature dependence of the specific heat and the particle number in the ground state. A proper semiclassical treatment is set up which yields the correct small-T behavior in contrast to an earlier theory in Feynman's textbook on statistical mechanics, in which the special role of the ground state was ignored. The results are compared with an exact quantum-mechanical treatment. Furthermore, we derive the finite-size effect of the system.

Glaum, Konstantin; Kleinert, Hagen; Pelster, Axel [Institut fuer Theoretische Physik, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin (Germany); Fachbereich Physik, Universitaet Duisburg-Essen, Campus Duisburg, Lotharstrasse 1, 47048 Duisburg (Germany)

2007-12-15

185

Theoretical study of the swirling flows of an ideal gas in a Laval nozzle  

Microsoft Academic Search

Using the finite-difference equations of Godunov [1, 2], the problem of the behavior of an arbitrarily swirling gas flow in a Laval nozzle is solved. Numerical calculations relating to a variety of flows indicate that the integrated parameter of the swirling intensity of the flow e, obtained by solving the linearized equations [3] of radially balanced, slightly swirling gases, provides

N. N. Slavyanov

1973-01-01

186

Quantum Joule-Thomson Effect in a Saturated Homogeneous Bose Gas  

NASA Astrophysics Data System (ADS)

We study the thermodynamics of Bose-Einstein condensation in a weakly interacting quasihomogeneous atomic gas, prepared in an optical-box trap. We characterize the critical point for condensation and observe saturation of the thermal component in a partially condensed cloud, in agreement with Einstein's textbook picture of a purely statistical phase transition. Finally, we observe the quantum Joule-Thomson effect, namely isoenthalpic cooling of an (essentially) ideal gas. In our experiments this cooling occurs spontaneously, due to energy-independent collisions with the background gas in the vacuum chamber. We extract a Joule-Thomson coefficient ?JT>109 K /bar, about 10 orders of magnitude larger than observed in classical gases.

Schmidutz, Tobias F.; Gotlibovych, Igor; Gaunt, Alexander L.; Smith, Robert P.; Navon, Nir; Hadzibabic, Zoran

2014-01-01

187

Idealized gas turbine combustor for performance research and validation of large eddy simulations  

NASA Astrophysics Data System (ADS)

This paper details the design of a premixed, swirl-stabilized combustor that was designed and built for the express purpose of obtaining validation-quality data for the development of large eddy simulations (LES) of gas turbine combustors. The combustor features nonambiguous boundary conditions, a geometrically simple design that retains the essential fluid dynamics and thermochemical processes that occur in actual gas turbine combustors, and unrestrictive access for laser and optical diagnostic measurements. After discussing the design detail, a preliminary investigation of the performance and operating envelope of the combustor is presented. With the combustor operating on premixed methane/air, both the equivalence ratio and the inlet velocity were systematically varied and the flame structure was recorded via digital photography. Interesting lean flame blowout and resonance characteristics were observed. In addition, the combustor exhibited a large region of stable, acoustically clean combustion that is suitable for preliminary validation of LES models.

Williams, Timothy C.; Schefer, Robert W.; Oefelein, Joseph C.; Shaddix, Christopher R.

2007-03-01

188

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

189

Quantum lattice-gas model of spinor superfluids  

Microsoft Academic Search

Spinor Bose Einstein Condensates are intriguing because of their vast range of different topological vortices. These states occur when a BEC gas is trapped in an optical lattice rather than in a magnetic well (which would result in scalar BEC vortices). A spinor BEC states also occur in a quantum gas when several hyperfine states of the atom co-exist in

Jeffrey Yepez; George Vahala; Linda Vahala; Min Soe

2010-01-01

190

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

Microsoft Academic Search

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

Raphael Lamonand; Andreas J. Wöhr

2010-01-01

191

Nonlinear quantum hydrodynamical model of the electron gas  

Microsoft Academic Search

It is well known that the hydrodynamical model of the electron gas is suitable when the electron density can be considered as the fundamental quantity, small wavelength effects being less important. This is the case when the electron gas is excited by the passage of swift charged particles. In this paper we make use of the quantum hydrodynamical model of

A. Bergara; J. M. Pitarke; R. H. Ritchie

1996-01-01

192

Development Of Excel Add-in Modules For Use In Thermodynamics Curriculum: Steam And Ideal Gas Properties  

NSDL National Science Digital Library

For engineering graduates entering the job market, experience with appropriate computational tools and techniques is increasingly necessary. Therefore, the University of Alabama's Mechanical Engineering Department is introducing students to computational problem solving earlier in their college careers by developing Microsoft Excel-based modules to be used as teaching tools in the sophomore and junior-level thermodynamics and heat transfer courses. The MS Excel package was chosen as a software platform for this purpose because of its ubiquitous nature and its ability to utilize Visual Basic for Applications (VBA) macros in a spreadsheet format. In the sophomore-level thermodynamics course, much of the class material focuses on the properties of steam and ideal gases. Therefore, a suite of Microsoft Excel functions to compute steam and ideal gas properties and assist in analyzing properties of states and processes has been developed. A number of Excel packages that pertained to the computation of steam properties were already available in the public domain. In a companion paper1, these packages were compared and Magnus Holmgrens Xsteam functions were chosen as a starting point for the current project.

Huguet, Jesse; Taylor, Robert; Woodbury, Keith

2011-05-09

193

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

194

Unified First Principles Description from Warm Dense Matter to Ideal Ionized Gas Plasma: Electron-Ion Collisions Induced Friction  

SciTech Connect

Electron-ion interactions are central to numerous phenomena in the warm dense matter (WDM) regime and at higher temperature. The electron-ion collisions induced friction at high temperature is introduced in the procedure of ab initio molecular dynamics using the Langevin equation based on density functional theory. In this framework, as a test for Fe and H up to 1000 eV, the equation of state and the transition of electronic structures of the materials with very wide density and temperature can be described, which covers a full range of WDM up to high energy density physics. A unified first principles description from condensed matter to ideal ionized gas plasma is constructed.

Dai Jiayu; Hou Yong; Yuan Jianmin [Department of Physics, College of Science, National University of Defense Technology, Changsha 410073 (China)

2010-06-18

195

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

196

Speed-of-sound measurements and ideal-gas heat capacity for 1,1,1,2-tetrafluoroethane and difluoromethane  

SciTech Connect

The speed of sound in gaseous 1,1,1,2-tetrafluoroethane (R-134a, CF{sub 3}CH{sub 2}F) and difluoromethane (R-32, CH{sub 2}F{sub 2}) has been measured by using a spherical resonator. The measurements for R-134a have been carried out along two isotherms at 323 K and 343 K and at pressures up to 400 kPa for a total of 26 values. For R-32 the measurements were made at 308 K, 323 K, 333 K, and 343 K and at pressures up to 500 kPa for a total of 44 measurements. The experimental uncertainties for R-134a in temperature, pressure, and speed of sound are estimated to be not greater than {+-}6 mK, {+-}0.2 kPa, and {+-}0.0061%, respectively. The experimental uncertainties for R-32 in temperature, pressure, and speed of sound are estimated to be not greater than {+-}8 mK, {+-}0.2 kPa, and {+-}0.0061%, respectively. The purities of the R-134a and R-32 samples were better than 99.95% and 99.99% of area percent of the gas chromatography, respectively. The authors have determined the ideal-gas heat capacities and the second acoustic virial coefficients from the speed-of-sound measurements.

Hozumi, T.; Sato, H.; Watanabe, K. [Keio Univ., Yokohama (Japan)] [Keio Univ., Yokohama (Japan)

1996-09-01

197

Quantum Control of Molecular Gas Hydrodynamics  

NASA Astrophysics Data System (ADS)

We demonstrate that strong impulsive gas heating or heating suppression at standard temperature and pressure can occur from coherent rotational excitation or deexcitation of molecular gases using a sequence of nonionizing laser pulses. For the case of excitation, subsequent collisional decoherence of the ensemble leads to gas heating significantly exceeding that from plasma absorption under the same laser focusing conditions. In both cases, the macroscopic hydrodynamics of the gas can be finely controlled with ˜40 fs temporal sensitivity.

Zahedpour, S.; Wahlstrand, J. K.; Milchberg, H. M.

2014-04-01

198

Quantum control of molecular gas hydrodynamics.  

PubMed

We demonstrate that strong impulsive gas heating or heating suppression at standard temperature and pressure can occur from coherent rotational excitation or deexcitation of molecular gases using a sequence of nonionizing laser pulses. For the case of excitation, subsequent collisional decoherence of the ensemble leads to gas heating significantly exceeding that from plasma absorption under the same laser focusing conditions. In both cases, the macroscopic hydrodynamics of the gas can be finely controlled with ?40??fs temporal sensitivity. PMID:24765959

Zahedpour, S; Wahlstrand, J K; Milchberg, H M

2014-04-11

199

Rigorous investigation of the reduced density matrix for the ideal Bose gas in harmonic traps by a loop-gas-like approach  

NASA Astrophysics Data System (ADS)

In this paper, we rigorously investigate the reduced density matrix (RDM) associated to the ideal Bose gas in harmonic traps. We present a method based on a sum-decomposition of the RDM allowing to treat not only the isotropic trap, but also general anisotropic traps. When focusing on the isotropic trap, the method is analogous to the loop-gas approach developed by Mullin ["The loop-gas approach to Bose-Einstein condensation for trapped particles," Am. J. Phys. 68(2), 120 (2000)]. Turning to the case of anisotropic traps, we examine the RDM for some anisotropic trap models corresponding to some quasi-1D and quasi-2D regimes. For such models, we bring out an additional contribution in the local density of particles which arises from the mesoscopic loops. The close connection with the occurrence of generalized-Bose-Einstein condensation is discussed. Our loop-gas-like approach provides relevant information which can help guide numerical investigations on highly anisotropic systems based on the Path Integral Monte Carlo method.

Beau, Mathieu; Savoie, Baptiste

2014-05-01

200

Prediction of dew points of semicontinuous natural gas and petroleum mixtures. 1. Characterization by use of an effective carbon number and ideal solution predictions  

Microsoft Academic Search

The effective carbon number (ECN) is used as the distribution variable in a gamma distribution function to characterize natural gas and petroleum mixtures containing many components. The ECN offers the advantage over more conventional continuous distribution variables in that it can distinguish between isomers. The resulting function is combined with an ideal-solution theory to develop a simple method to predict

Bert Willman; Amyn S. Teja

1987-01-01

201

Effect of the swirling of an ideal gas flow on the shape of the supersonic part of an optimal axisymmetric nozzle profile with a bend  

Microsoft Academic Search

The effect of inlet flow swirling on the shape of an optimal supersonic nozzle section with a bend is investigated using an ideal (nonviscous and non-heat-conducting) gas model. The corresponding variational problem is solved by a direct method whereby the problem is reduced to a nonlinear programming problem. Two types of optimal nozzle profiles are constructed as an example.

G. I. Afonin; V. G. Butov

1989-01-01

202

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

203

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

Microsoft Academic Search

An ideal-reactor-network model has been developed to describe the fluid flow and mixing observed in pyrometallurgical channel\\u000a reactors with countercurrent liquid flow and high-strength bottom gas injection. Experiments were performed in a cold model\\u000a under various operating conditions to determine the effects of liquid density, viscosity, flow rate, gas injection rates,\\u000a injector diameter, and injector spacing on the residence time

Kumar M. Iyer; H. Y. Sohn

1994-01-01

204

Strongly interacting quantum excitations of a cold atomic gas  

NASA Astrophysics Data System (ADS)

Strong interactions of Rydberg atoms in a mesoscopic ensemble can be employed for fast preparation of desired many-particle states. In this work, Rydberg excitations are generated in an ultra-cold atomic Rb gas and are converted into light. As the principal quantum number n is increased beyond ˜ 70, no more than a single excitation is retrieved from a mesoscopic ensemble. These results hold promise for studies of dynamics and disorder in many-body systems with tunable interactions and for scalable quantum information networks.

Dudin, Yaroslav; Kuzmich, Alex

2012-06-01

205

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

206

Similarity solution for the flow behind a shock wave in a non-ideal gas with heat conduction and radiation heat-flux in magnetogasdynamics  

NASA Astrophysics Data System (ADS)

The propagation of a spherical (or cylindrical) shock wave in a non-ideal gas with heat conduction and radiation heat-flux, in the presence of a spacially decreasing azimuthal magnetic field, driven out by a moving piston is investigated. The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be of the diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient ?R are assumed to vary with temperature and density. The gas is assumed to have infinite electrical conductivity and to obey a simplified van der Waals equation of state. The shock wave moves with variable velocity and the total energy of the wave is non-constant. Similarity solutions are obtained for the flow-field behind the shock and the effects of variation of the heat transfer parameters, the parameter of the non-idealness of the gas, both, decreases the compressibility of the gas and hence there is a decrease in the shock strength. Further, it is investigated that with an increase in the parameters of radiative and conductive heat transfer the tendency of formation of maxima in the distributions of heat flux, density and isothermal speed of sound decreases. The pressure and density vanish at the inner surface (piston) and hence a vacuum is form at the center of symmetry. The shock waves in conducting non-ideal gas with conductive and radiative heat fluxes can be important for description of shocks in supernova explosions, in the study of central part of star burst galaxies, nuclear explosion, chemical detonation, rupture of a pressurized vessels, in the analysis of data from exploding wire experiments, and cylindrically symmetric hypersonic flow problems associated with meteors or reentry vehicles, etc. The findings of the present works provided a clear picture of whether and how the non-idealness parameter, conductive and radiative heat transfer parameters and the magnetic field affect the flow behind the shock front.

Nath, G.; Vishwakarma, J. P.

2014-05-01

207

Thermodynamic properties of H 4SiO 4 in the ideal gas state as evaluated from experimental data  

NASA Astrophysics Data System (ADS)

Solid phases of silicon dioxide react with water vapor with the formation of hydroxides and oxyhydroxides of silica. Recent transpiration and mass-spectrometric studies convincingly demonstrate that H 4SiO 4 is the predominant form of silica in vapor phase at water pressure in excess of 10 -2 MPa. Available literature transpiration and solubility data for the reactions of solid SiO 2 phases and low-density water, extending from 424 to 1661 K, are employed for the determination of ?fG0, ?fH0 and S0 of H 4SiO 4 in the ideal gas state at 298.15 K, 0.1 MPa. In total, there are 102 data points from seven literature sources. The resulting values of the thermodynamic functions of H 4SiO 4(g) are: ?fG0 = -1238.51 ± 3.0 kJ mol -1, ?fH0 = -1340.68 ± 3.5 kJ mol -1 and S0 = 347.78 ± 6.2 J K -1 mol -1. These values agree quantitatively with one set of ab initio calculations. The relatively large uncertainties are mainly due to conflicting Cp0 data for H 4SiO 4(g) from various sources, and new determinations of Cp0 would be helpful. The thermodynamic properties of this species, H 4SiO 4(g), are necessary for realistic modeling of silica transport in a low-density water phase. Applications of this analysis may include the processes of silicates condensation in the primordial solar nebula, the precipitation of silica in steam-rich geothermal systems and the corrosion of SiO 2-containing alloys and ceramics in moist environments.

Plyasunov, Andrey V.

2011-07-01

208

Equation of state and ideals-gas heat capacity of a gaseous mixture of 1,1,1,2-tetrafluoroethane, pentafluoroethane, and difluoromethane  

Microsoft Academic Search

We present the gas-phase equation of state and ideal-gas heat capacity of a ternary mixture (nominal molar concentration)\\u000a of 1,1,1,2-tetrafluoroethane (35%), pentafluoroethane (30%), and difluoromethane (35%) for temperatures between 260 and 453\\u000a K and pressures between 0.05 and 7.7 MPa. These results were based on two very different measurement techniques. The first\\u000a technique measured the gas density of the mixture

J. J. Hurly; J. W. Schmidt; K. A. Gillis

1997-01-01

209

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

2013-06-13

210

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

211

Distance-scaled, finite ideal-gas reference state improves structure-derived potentials of mean force for structure selection and stability prediction  

Microsoft Academic Search

The distance-dependent structure-derived potentials developed so far all employed a reference state that can be characterized as a residue (atom)-averaged state. Here, we establish a new reference state called the distance-scaled, finite ideal-gas reference (DFIRE) state. The reference state is used to construct a residue- specific all-atom potential of mean force from a database of 1011 nonhomologous (less than 30%

Hongyi Zhou; Yaoqi Zhou

2002-01-01

212

Prediction of dew points of semicontinuous natural gas and petroleum mixtures. 1. Characterization by use of an effective carbon number and ideal solution predictions  

SciTech Connect

The effective carbon number (ECN) is used as the distribution variable in a gamma distribution function to characterize natural gas and petroleum mixtures containing many components. The ECN offers the advantage over more conventional continuous distribution variables in that it can distinguish between isomers. The resulting function is combined with an ideal-solution theory to develop a simple method to predict dew points of natural gas condensates. The simple method is compared with the modified equation of state approach of other authors and, although it is less accurate in its predictions, is shown to work surprisingly well.

Willman, B.; Teja, A.S.

1987-05-01

213

Equation of state and ideal-gas heat capacity of a gaseous mixture of 1,1,1,2-tetrafluoroethane, pentafluoroethane, and difluoromethane  

SciTech Connect

The authors present the gas-phase equation of state and ideal-gas heat capacity of a ternary mixture of 1,1,1,2-tetrafluoroethane (35%), pentafluoroethane (30%), and difluoromethane (35%) for temperatures between 260 and 453 K and pressures between 0.05 and 7.7 MPa. These results were based on two very different measurement techniques. The first technique measured the gas density of the mixture in a Burnett apparatus from 313 to 453 K and from 0.2 to 7.7 MPa. The second technique deduced the gas density and ideal-gas heat capacity from high-accuracy speed-of-sound measurements in the mixture at temperatures between 260 and 400 K and at pressures between 0.05 and 1.0 MPa. The data from the two techniques were analyzed together to obtain an equation of state that reproduced the densities from the Burnett technique with a fractional RMS deviation of 0.038%, and it also reproduced the sound speeds with a fractional RMS deviation of 0.003%. Finally, the results are compared to a predictive model based on the properties of the pure fluids.

Hurly, J.J.; Schmidt, J.W.; Gillis, K.A. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

1997-05-01

214

Quantum scalar-metric cosmology with Chaplygin gas  

NASA Astrophysics Data System (ADS)

A spatially flat Friedmann-Robertson-Walker (FRW) cosmological model with generalized Chaplygin gas is studied in the context of scalar-metric formulation of cosmology. Schutz's mechanism for the perfect fluid is applied with generalized Chaplygin gas and the classical and quantum dynamics for this model is studied. It is found that the only surviving matter degree of freedom played the role of cosmic time. For the quantum mechanical description it is possible to find the wave packet which resulted from the linear superposition of the wave functions of the Schrödinger-Wheeler-DeWitt (SWD) equation, which is a consequence of the above formalism. The wave packets show two distinct dominant peaks and propagate in the direction of increasing scale factor. It may happen that our present universe originated from one of those peaks. The many-world and ontological interpretation of quantum mechanics is applied to investigate about the behavior of the scale factor and the scalar field (considered for this model). In both the cases the scale factor avoids singularity and a bouncing non-singular universe is found.

Majumder, Barun

2011-02-01

215

Quantum Simulation using Next Generation Degenerate Fermi Gas Apparatus  

NASA Astrophysics Data System (ADS)

Ultracold neutral atoms in optical lattices are a perfect toy model to simulate and study Hubbard model physics relevant to high temperature superconductivity and other exotic phases of matter. We present the design and construction of a novel apparatus to study these exciting condensed matter systems. We also investigate the viability of a various transport schemes to transport a quantum-degenerate Fermi gas of ultracold lithium atoms into a Science Chamber. The high optical access of the science chamber permits innovative probing and manipulation of BECs.

Wooley-Brown, Kate; Huber, Florian; Setiawan, Widagdo; Greiner, Markus

2010-03-01

216

Spin dynamics in a two-dimensional quantum gas  

NASA Astrophysics Data System (ADS)

We have investigated spin dynamics in a two-dimensional quantum gas. Through spin-changing collisions, two clouds with opposite spin orientations are spontaneously created in a Bose-Einstein condensate. After ballistic expansion, both clouds acquire ring-shaped density distributions with superimposed angular density modulations. The density distributions depend on the applied magnetic field and are well explained by a simple Bogoliubov model. We show that the two clouds are anticorrelated in momentum space. The observed momentum correlations pave the way towards the creation of an atom source with nonlocal Einstein-Podolsky-Rosen entanglement.

Pedersen, Poul L.; Gajdacz, Miroslav; Deuretzbacher, Frank; Santos, Luis; Klempt, Carsten; Sherson, Jacob F.; Hilliard, Andrew J.; Arlt, Jan J.

2014-05-01

217

Umklapp superradiance with a collisionless quantum degenerate fermi gas.  

PubMed

The quantum dynamics of the electromagnetic light mode of an optical cavity filled with a coherently driven Fermi gas of ultracold atoms strongly depends on the geometry of the Fermi surface. Superradiant light generation and self-organization of the atoms can be achieved at low pumping threshold due to resonant atom-photon umklapp processes, where the fermions are scattered from one side of the Fermi surface to the other by exchanging photon momenta. The cavity spectrum exhibits sidebands that, despite strong atom-light coupling and cavity decay, retain narrow linewidth, due to absorptionless transparency windows outside the atomic particle-hole continuum and the suppression of broadening and thermal fluctuations in the collisionless Fermi gas. PMID:24765951

Piazza, Francesco; Strack, Philipp

2014-04-11

218

Finite-Difference Solution for Laminar or Turbulent Boundary Layer Flow over Axisymmetric Bodies with Ideal Gas, CF4, or Equilibrium Air Chemistry  

NASA Technical Reports Server (NTRS)

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.

1992-01-01

219

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

220

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

2013-02-01

221

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

222

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 spa- tial 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

Jeffrey Yepez

2000-01-01

223

Universal Quantum Viscosity in a Unitary Fermi Gas  

NASA Astrophysics Data System (ADS)

Unitary Fermi gases, first observed in 2002, have been widely studied as they provide model systems for tabletop research on a variety of strongly coupled systems, including the high temperature superconductors, quark-gluon plasmas and neutron stars. A two component 6Li unitary Fermi gas is created through a collisional Feshbach resonance centered around 834G, using all-optical trapping and cooling methods. In the vicinity of the Feshbach resonance, the atoms are strongly interacting and exhibit universal behaviors, where the equilibrium thermodynamic properties and transport coefficients are universal functions of the density n and temperature T. Thus, unitary Fermi gases provide a paradigm to study nonperturbative many-body physics, which is of fundamental significance and field-crossing interests. This dissertation reports the measurement of the quantum shear viscosity in a 6Li unitary Fermi gas, which is the first measurement of transport coefficients for unitary Fermi gases. Two hydrodynamic experiments are employed to measure the shear viscosity eta in different temperature regimes: the anisotropic expansion for the high temperature regime and the radial breathing mode for the low temperature regime. In order to consistently and quantitatively extract the shear viscosity from these two experiments, the hydrodynamic theory is utilized to derive the universal hydrodynamic equations, which include both friction force and heating arising from frictions. These equations are simplified and solved, considering the universal properties of unitary Fermi gases as well as the specific conditions for each experiment. Using these universal hydrodynamic equations, shear viscosity is extracted from the anisotropic expansion conducted at high temperatures and the predicted eta ? T3/2 scaling is demonstrated. The demonstration of the high temperature scaling sets a benchmark for measuring viscosity at low temperatures. For the low temperature breathing mode experiment, the shear viscosity is directly related to the damping rate of an oscillating cloud, through the same universal hydrodynamic equations. The raw data from the previously measured radial breathing experiments are carefully analyzed to extract the shear viscosity. The low temperature data join with the high temperature data smoothly, which presents the full measurement of the quantum shear viscosity from nearly the ground state to the two-body Boltzmann regime. The possible effects of the bulk viscosity in the high temperature anisotropic expansion experiment is also studied and found to be consistent with the predicted vanishing bulk viscosity in the normal fluid phase at unitarity. Using the measured shear viscosity eta and the previously measured entropy density s, the ratio of eta/s is estimated and therefore compared to a string theory limit, which conjectures eta/ s ? h/4pikB for any fluid and defines a perfect fluid when the equality is satisfied. It is found that eta/s, for a unitary Fermi gas at the normal-superfluid transition point, is about 5 times the string limit. This shows that our unitary Fermi gas exhibit nearly perfect fluidity at low temperatures. In addition to the quantum shear viscosity measurement, consistent and accurate methods of calibrating the energy and temperature for unitary Fermi gases is also developed in this thesis. While the energy is calculated from the cloud dimensions by exploiting the virial theorem, the temperature is determined using different methods for different temperature regimes. At high temperatures, the second virial coefficient approximation is applied to the energy density, from which a variety of thermodynamic quantities, including the temperature, are derived. For the low temperatures, the previous calibration from the energy E and entropy S measurement is improved by using a better calculation on the entropy and adding more constraints at higher temperatures using the second virial approximation. A power law curve with discontinues heat capacity is then fitted to the E-S curve and the temperature is obtained us

Cao, Chenglin

224

Highly efficient counter-propagation-beams narrow-band ultraviolet frequency conversion in a quantum gas.  

PubMed

We show that highly efficient ultraviolet frequency up conversion can be established in a single-component quantum gas in the counter-propagating weak pump beam geometry where no frequency up conversion can occur in a normal gas. We also show that all light-wave mixing and scattering processes in quantum gases originating from elementary excitations characterized by efficient collective atomic recoil motion are stimulated Raman/hyper-Raman in nature. PMID:23938922

Zhu, Chengjie; Deng, L; Hagley, E W

2013-05-15

225

Relaxation dynamics in a lattice gas: A test of the mode-coupling theory of the ideal glass transition  

NASA Astrophysics Data System (ADS)

By means of computer simulations we investigate the dynamical behavior of a binary lattice-gas mixture with short-range interactions in order to provide a stringent test of mode-coupling theory (MCT). The dynamics of the particles is given by Monte Carlo-like moves that change the positions of the particles and binary collisions that change the velocities. By monitoring the self part of the van Hove correlation function we find the low-temperature dynamics to be glasslike. In accordance with MCT the imaginary part of the dynamic susceptibility ?'' shows a well-defined ? peak whose high-frequency wing follows a von Schweidler law with an exponent that is independent of temperature. The low-frequency wing of the peak follows a different power-law dependence that corresponds to a power law of the form -P+A/t? (A,P,?>0) in the self part of the intermediate scattering function Fs1(k,t). In agreement with MCT we find that the diffusion constant for one of the two types of particles, the relaxation times of Fs1(k,t), the location of the ? peak in the susceptibility, and the prefactor of the von Schweidler law all have a power-law dependence on temperature, (T-Tc)?, for T>Tc at constant density. As predicted by the theory the critical temperatures Tc for the different quantities are the same within the statistical error. However, in contradiction to MCT, the critical exponents ? vary from one quantity to another. The value of the Lamb-Mössbauer factor shows qualitatively the wave-vector dependence predicted by MCT. The self part of a second kind of correlation function exhibits the two power laws predicted by MCT for the high- and low-frequency wings of the ? relaxation. We show that in the vicinity of the minimum of the susceptibility the scaling behavior predicted by MCT holds. However, the location of this minimum at a given temperature depends on the quantity investigated, contrary to the predictions of MCT. Moreover, the value of ?'' at this minimum exhibits a power-law dependence on temperature with an exponent that is significantly larger than the one predicted by MCT. We also find that the height of the ? peak as well as the total energy per particle have a power-law dependence on temperature and that the corresponding critical temperatures are close to those obtained for the other quantities.

Kob, Walter; Andersen, Hans C.

1993-05-01

226

Analytical Model for Super-Ideal Gases.  

National Technical Information Service (NTIS)

The equations of state for the ideal classical gas are generalized with two characteristic constants known as the state indices. A simple and complete representation is developed for the super-ideal gas, with explicit results which are general enough to c...

Y. K. Huang

1973-01-01

227

Quantum Lattice Gas Algorithms for MHD and Solitons  

Microsoft Academic Search

While classical computers work on bits '0' and '1', quantum computers can form superposition of the qubits | 0 > and | 1 >. In geometric terms, the classical computer's operational space consists of two points, while that of the quantum computer is the Bloch sphere - the surface manifold of a unit sphere. It is this greater geometric freedom

George Vahala; Linda Vahala; Jeffrey Yepez

2003-01-01

228

Distance-scaled, finite ideal-gas reference state improves structure-derived potentials of mean force for structure selection and stability prediction  

PubMed Central

The distance-dependent structure-derived potentials developed so far all employed a reference state that can be characterized as a residue (atom)-averaged state. Here, we establish a new reference state called the distance-scaled, finite ideal-gas reference (DFIRE) state. The reference state is used to construct a residue-specific all-atom potential of mean force from a database of 1011 nonhomologous (less than 30% homology) protein structures with resolution less than 2 ?. The new all-atom potential recognizes more native proteins from 32 multiple decoy sets, and raises an average Z-score by 1.4 units more than two previously developed, residue-specific, all-atom knowledge-based potentials. When only backbone and C? atoms are used in scoring, the performance of the DFIRE-based potential, although is worse than that of the all-atom version, is comparable to those of the previously developed potentials on the all-atom level. In addition, the DFIRE-based all-atom potential provides the most accurate prediction of the stabilities of 895 mutants among three knowledge-based all-atom potentials. Comparison with several physical-based potentials is made.

Zhou, Hongyi; Zhou, Yaoqi

2002-01-01

229

Engineering Light: Quantum Cascade Lasers  

ScienceCinema

Quantum cascade lasers are ideal for environmental sensing and medical diagnostic applications. Gmachl discusses how these lasers work, and their applications, including their use as chemical trace gas sensors. As examples of these applications, she briefly presents results from her field campaign at the Beijing Olympics, and ongoing campaigns in Texas, Maryland, and Ghana.

Claire Gmachl

2010-09-01

230

Engineering Light: Quantum Cascade Lasers  

SciTech Connect

Quantum cascade lasers are ideal for environmental sensing and medical diagnostic applications. Gmachl discusses how these lasers work, and their applications, including their use as chemical trace gas sensors. As examples of these applications, she briefly presents results from her field campaign at the Beijing Olympics, and ongoing campaigns in Texas, Maryland, and Ghana.

Claire Gmachl

2010-03-17

231

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

2013-09-01

232

I-stable ideals  

NASA Astrophysics Data System (ADS)

We define the concept of I-stable ideals in the ring of commutative polynomials over a field, generalizing the so-called stable ideals, which arise as ideals of higher terms under general linear changes of variables. The interest in ideals of this type is motivated by the fact that certain problems concerning homogeneous ideals (for example, the problem of obtaining upper estimates for the graded Betti numbers) can be reduced to the study of stable ideals. I-stable ideals retain many interesting properties of stable ideals. In particular, the minimal resolutions of I-stable ideals constructed in this paper enable us to obtain an explicit formula for the graded Betti numbers, which turn out to be independent of the characteristic of the ground field. Factor rings by I-stable ideals generated by monomials of degree >=2 are Golod rings. We also consider other analogues of stable ideals (strongly and weakly I-stable ideals) and give conditions sufficient for the factor ring by an I-stable ideal to be Cohen-Macaulay or Gorenstein.

Shakin, D. A.

2002-06-01

233

Satyendranath Bose: Co-Founder of Quantum Statistics  

ERIC Educational Resources Information Center

Satyendranath Bose was first to prove Planck's Law by using ideal quantum gas. Einstein credited Bose for this first step in the development of quantum statistical mechanics. Bose did not realize the importance of his work, perhaps because of peculiar academic settings in India under British rule. (PS)

Blanpied, William A.

1972-01-01

234

Modeling an adiabatic quantum computer via an exact map to a gas of particles.  

PubMed

We map adiabatic quantum evolution on the classical Hamiltonian dynamics of a 1D gas (Pechukas gas) and simulate the latter numerically. This approach turns out to be both insightful and numerically efficient, as seen from our example of a CNOT gate simulation. For a general class of Hamiltonians we show that the escape probability from the initial state scales no faster than |lambda|gamma, where |lambda| is the adiabaticity parameter. The scaling exponent for the escape probability is gamma=1/2 for all levels, except the edge (bottom and top) ones, where gamma approximately < 1/3. In principle, our method can solve arbitrarily large adiabatic quantum Hamiltonians. PMID:17501105

Zagoskin, A M; Savel'ev, S; Nori, Franco

2007-03-23

235

Chaplygin gas quantum universe in the presence of the cosmological constant  

Microsoft Academic Search

We present a Chaplygin gas Friedmann-Robertson-Walker quantum cosmological model in the presence of the cosmological constant.\\u000a We apply the Schutz’s variational formalism to recover the notion of time, and this gives rise to Wheeler-DeWitt equation\\u000a for the scale factor. We study the early and late time universes and show that the presence of the Chaplygin gas leads to\\u000a an effective

Pouria Pedram; Shahram Jalalzadeh

2010-01-01

236

Exactly solvable three-level quantum dissipative systems via bosonization of fermion gas-impurity models  

NASA Astrophysics Data System (ADS)

We study the relationship between one-dimensional fermion gas-impurity models and quantum dissipative systems, via the method of constructive bosonization and unitary transformation. Starting from an anisotropic Coqblin-Schrieffer model, a new, exactly solvable, three-level quantum dissipative system is derived as a generalization of the standard spin-{\\frac{1}{2}} spin-boson model. The new system has two environmental oscillator baths with ohmic coupling, and admits arbitrary detuning between the three levels. All tunnelling matrix elements are equal, up to one complex phase which is itself a function of the longitudinal and transverse couplings in the integrable limit. Our work underlines the importance of re-examining the detailed structure of fermion-gas impurity models and spin chains, in the light of connections to models for quantum dissipative systems.

Jacobsen, Sol H.; Jarvis, P. D.

2010-06-01

237

Quantum FRW cosmological solutions in the presence of Chaplygin gas and perfect fluid  

NASA Astrophysics Data System (ADS)

We present a Friedmann Robertson Walker quantum cosmological model in the presence of Chaplygin gas and perfect fluid for early and late time epochs. In this work, we consider perfect fluid as an effective potential and apply Schutz's variational formalism to the Chaplygin gas which recovers the notion of time. These give rise to Schrödinger Wheeler DeWitt equation for the scale factor. We use the eigenfunctions in order to construct wave packets and study the time dependent behavior of the expectation value of the scale factor using the many-worlds interpretation of quantum mechanics. We show that contrary to the classical case, the expectation value of the scale factor avoids singularity at quantum level. Moreover, this model predicts that the expansion of Universe is accelerating for the late times.

Pedram, P.; Jalalzadeh, S.

2008-01-01

238

A Analysis of Petrov-Galerkin Techniques Applied to Lattice Gas Models for Quantum Transport Processes in Open Systems  

Microsoft Academic Search

Quantum transport processes in open systems are analyzed in terms of generalized master equations using a representation-independent operator approach and projection superoperators. Boundary conditions associated with ideal reservoirs are imposed to derive simplified master equations in the steady state limit. Conserved quantities and corresponding rate observables are defined for interacting subsystems. Galerkin techniques for finite element models are extended to

Robert Geoffrey Byrnes

1996-01-01

239

Gotzmann Edge Ideals  

Microsoft Academic Search

Let P = k[x_1, ..., x_n] be the polynomial ring in n variables. A homogeneous ideal I of P generated in degree d is called Gotzmann if it has the smallest possible Hilbert function out of all homogeneous ideals with the same dimension in degree d. The edge ideal of a simple graph G on vertices x_1, ..., x_n is

Andrew H. Hoefel

2009-01-01

240

Gotzmann Edge Ideals  

Microsoft Academic Search

Let P = 𝕜[x1,…, xn] be the polynomial ring in n variables. A homogeneous ideal I ? P generated in degree d is called Gotzmann if it has the smallest possible Hilbert function out of all homogeneous ideals with the same dimension in degree d. The edge ideal of a simple graph G on vertices x1,…, xn is the quadratic square-free monomial

Andrew H. Hoefel

2012-01-01

241

Idealization and psychoanalytic learning.  

PubMed

Idealization is an intrinsic part of psychological maturation, but it is also a potential barrier to psychoanalytic learning, and must to some degree be outgrown if an analyst is to develop a natural authority and individual style. Unrecognized idealizations stifle analysts' engagement in the transferences of their patients, and so compromise the ability to freely experience and analyze them. Attention to real life and the lessons it teaches counterbalances the tendency to idealize and encourages lifelong psychoanalytic growth. PMID:12718250

Glick, Robert Alan

2003-04-01

242

``Ideal'' Engineering Alloys  

NASA Astrophysics Data System (ADS)

A newly discovered group of alloys, called Gum Metals, approaches ideal strength in bulk form, exhibits significant plastic deformation prior to failure, and shows no indications of conventional-dislocation activity. Two conditions must be met for a material to exhibit this “ideal” behavior: (1) the stress required to trigger conventional-dislocation plasticity in the material must exceed its ideal strength, and (2) the material must be intrinsically ductile when stressed to ideal strength. Gum Metals satisfy both criteria, explaining their remarkable mechanical properties.

Li, Tianshu; Morris, J. W., Jr.; Nagasako, N.; Kuramoto, S.; Chrzan, D. C.

2007-03-01

243

GENERAL: Joule-Thomson Coefficient for Strongly Interacting Unitary Fermi Gas  

NASA Astrophysics Data System (ADS)

The Joule-Thomson effect reflects the interaction among constituent particles of macroscopic system. For classical ideal gas, the corresponding Joule-Thomson coefficient is vanishing while it is non-zero for ideal quantum gas due to the quantum degeneracy. In recent years, much attention is paid to the unitary Fermi gas with infinite two-body scattering length. According to universal analysis, the thermodynamical law of unitary Fermi gas is similar to that of non-interacting ideal gas, which can be explored by the virial theorem P = 2E/3V. Based on previous works, we further study the unitary Fermi gas properties. The effective chemical potential is introduced to characterize the nonlinear levels crossing effects in a strongly interacting medium. The changing behavior of the rescaled Joule-Thomson coefficient according to temperature manifests a quite different behavior from that for ideal Fermi gas.

Liao, Kai; Chen, Ji-Sheng; Li, Chao

2010-09-01

244

Exact quantum dynamics of yrast states in the finite 1D Bose gas  

NASA Astrophysics Data System (ADS)

We demonstrate that the quantum dynamics of yrast states in the one-dimensional (1D) Bose gas gives an illustrative example to equilibration of an isolated quantum many-body system. We first formulate the energy spectrum of yrast states in terms of the dressed energy by applying the method of finite-size corrections. We then review the exact time evolution of quantum states constructed from yrast states shown by the Bethe ansatz. In time evolution the density profile of an initially localized quantum state constructed from yrast states collapses into a flat profile in the case of a large particle number such as N = 1000, while recurrence of the localized state occurs in the case of a small particle number such as N = 20. We suggest that the dynamical relaxation behavior for the large N case is consistent with the viewpoint of typicality for generic quantum states: the expectation values of local operators evaluated in most of quantum states are very close to those of the micro-canonical ensemble.

Kaminishi, Eriko; Sato, Jun; Deguchi, Tetsuo

2014-04-01

245

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

246

Quantum-defect method and valence excitons in rare-gas solids  

NASA Astrophysics Data System (ADS)

In Resca's Comment on three of our papers (preceding paper), he attributes to us a much greater criticism of the quantum-defect method applied to valence excitons than we ourselves originally intended. In this Reply, we attempt to clarify the issue (i) by stating very explicitly where we differ with the original Resca-Resta quantum-defect model, and (ii) by recapitulating the experimental results which support our conclusions. In particular, we find ourselves in full agreement with the basic Resca-Resta nonstructural theory of rare-gas excitons. Unlike the original Resca-Resta quantum-defect model, however, we attribute nonatomic contributions to the exciton short-ranged potentials.

Saile, V.; Reininger, R.; Laporte, P.; Steinberger, I. T.; Findley, G. L.

1988-06-01

247

Many particle simulations of the quantum electron gas using momentum-dependent potentials  

SciTech Connect

A simple quasiclassical model of the quantum electron gas based on a quasiclassical dynamics with an effective momentum-dependent Hamiltonian is developed. The quantum mechanical effects corresponding to the Pauli and the Heisenberg principles are modeled by constraints in the Hamiltonian. By using the concept of minimum uncertainty wave packets, momentum-dependent effective potentials are derived. Monte Carlo and molecular dynamics calculations are carried out for ensembles of 64{endash}512 electrons and calculations of the internal energy at several temperatures are given. A comparison with quantum Monte Carlo calculations of the mean energy for low temperatures and with Pad{acute e} approximations for several finite temperatures show that at least in thermodynamic equilibrium our simple model yields reasonable results. {copyright} {ital 1997} {ital The American Physical Society}

Ebeling, W.; Schautz, F. [Institut fuer Physik, Humboldt-Universitaet zu Berlin, Invalidenstrasse 110, D-10115 Berlin (Germany)] [Institut fuer Physik, Humboldt-Universitaet zu Berlin, Invalidenstrasse 110, D-10115 Berlin (Germany)

1997-09-01

248

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

249

Conductance quantization of an ideal Sharvin contact  

NASA Astrophysics Data System (ADS)

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 ?F = 2 ?/ kF = 2 ?/(3 ?2n) 1/3 may be tens of nanometers. The theory of the conductance ?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 ?S on the variable kFa 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 ?S vs. kFa 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].

Bezák, Viktor

2007-11-01

250

Lattice Boltzmann and quantum lattice gas representations of one-dimensional magnetohydrodynamic turbulence  

Microsoft Academic Search

A simplified one-dimensional (1D) magnetohydrodynamics (MHD) is solved using a lattice Boltzmann and a quantum lattice gas model. It is shown that the magnetic field decreases the strength of the velocity shock fronts, with marked spikes in the magnetic field strength that gradually broaden in time. There is very good agreement between the lattice Boltzmann model—a representation of non-linear systems

Linda Vahala; George Vahala; Jeffrey Yepez

2003-01-01

251

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

252

Gas-source molecular beam epitaxy growth of an 8.5 µm quantum cascade laser  

Microsoft Academic Search

We demonstrate preliminary results for an 8.5 ?m laser emission from quantum cascade lasers grown in a single step by gas-source molecular beam epitaxy. 70 mW peak power per two facets is recorded for all devices tested at 79 K with 1 ?s pulses at 200 Hz. For a 3 mm cavity length, lasing persists up to 270 K with

S. Slivken; C. Jelen; A. Rybaltowski; J. Diaz; M. Razeghi

1997-01-01

253

Quantum scattering theory of rotational relaxation and spectral line shapes in H2He gas mixtures  

Microsoft Academic Search

A systematic study is presented of the rotational relaxation and spectral line shape properties of dilute gas mixtures of H2 in He, in an effort to determine the radial and angular dependence of the H2&sngbnd;He intermolecular potential. The quantum mechanical theory of relaxation in gases is reviewed, and we express the results in terms of a matrix of cross sections

Richard Shafer; Roy G. Gordon

1973-01-01

254

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

255

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.

256

Quantum-State Detection of Molecular Hydrogen in Gas-Gas and Gas-Surface Scattering Experiments.  

National Technical Information Service (NTIS)

We have used the technique of resonance-enhanced multiphoton ionization to detect molecular hydrogen in a quantum state specific manner. We report on the use of this technique to determine accurate ro-vibrational state populations in scattering experiment...

G. O. Sitz R. S. Blake T. A. Stephenson R. N. Zare

1986-01-01

257

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

258

Raman-dressed spin-1 spin-orbit-coupled quantum gas  

NASA Astrophysics Data System (ADS)

The recently realized spin-orbit-coupled quantum gases [Lin et al., Nature (London) 471, 83 (2011), 10.1038/nature09887; Wang et al., Phys. Rev. Lett. 109, 095301 (2012), 10.1103/PhysRevLett.109.095301; Cheuk et al., Phys. Rev. Lett. 109, 095302 (2012), 10.1103/PhysRevLett.109.095302] mark a breakthrough in the cold atom community. In these experiments, two hyperfine states are selected from a hyperfine manifold to mimic a pseudospin-1/2 spin-orbit-coupled system by the method of Raman dressing, which is applicable to both bosonic and fermionic gases. In this paper, we show that the method used in these experiments can be generalized to create any large pseudospin spin-orbit-coupled gas if more hyperfine states are coupled equally by the Raman lasers. As an example, we study, in detail, a quantum gas with three hyperfine states coupled by the Raman lasers and show, when the state-dependent energy shifts of the three states are comparable, triple-degenerate minima will appear at the bottom of the band dispersions, thus, realizing a spin-1 spin-orbit-coupled quantum gas. A novel feature of this three-minima regime is that there can be two different kinds of stripe phases with different wavelengths, which has an interesting connection to the ferromagnetic and polar phases of spin-1 spinor Bose-Einstein condensates without spin-orbit coupling.

Lan, Zhihao; Öhberg, Patrik

2014-02-01

259

Gotzmann Edge Ideals  

Microsoft Academic Search

Let P = k[x_1, ..., x_n] be the polynomial ring in n variables. A homogeneous\\u000aideal I of P generated in degree d is called Gotzmann if it has the smallest\\u000apossible Hilbert function out of all homogeneous ideals with the same dimension\\u000ain degree d. The edge ideal of a simple graph G on vertices x_1, ..., x_n is

Andrew H. Hoefel

2009-01-01

260

Ideal Gas Thermodynamic Properties of CH3, CD3, CD4, C2D2, C2D4, C2D6, C2H6, CH3N2CH3, and CD3N2CD3  

Microsoft Academic Search

Ideal gas thermodynamic properties, C°p,S°,(G°?H°298)\\/T,H°t ?H°298,?H°F,?G°F and log Kp of formation for CH3, CD3, CD4, C2D2, C2D4, C2D6, C2H6, CH3N2CH3 and CD3N2CD3 in the temperature range O–3000 K and at 1 atmosphere have calculated by statistical thermodynamic methods employing spectroscopic and other molecular constants. The rigid rotor-harmonic oscillator model has been used. Estimated uncertainties in the thermodynamic properties due to

Krishna M. Pamidimukkala; David Rogers; Gordon B. Skinner

1982-01-01

261

Quantum State-Resolved Reactive and Inelastic Scattering at Gas-Liquid and Gas-Solid Interfaces  

NASA Astrophysics Data System (ADS)

Quantum state-resolved reactive and inelastic scattering at gas-liquid and gas-solid interfaces has become a research field of considerable interest in recent years. The collision and reaction dynamics of internally cold gas beams from liquid or solid surfaces is governed by two main processes, impulsive scattering (IS), where the incident particles scatter in a few-collisions environment from the surface, and trapping-desorption (TD), where full equilibration to the surface temperature (T{TD}? T{s}) occurs prior to the particles' return to the gas phase. Impulsive scattering events, on the other hand, result in significant rotational, and to a lesser extent vibrational, excitation of the scattered molecules, which can be well-described by a Boltzmann-distribution at a temperature (T{IS}>>T{s}). The quantum-state resolved detection used here allows the disentanglement of the rotational, vibrational, and translational degrees of freedom of the scattered molecules. The two examples discussed are (i) reactive scattering of monoatomic fluorine from room-temperature ionic liquids (RTILs) and (ii) inelastic scattering of benzene from a heated (˜500 K) gold surface. In the former experiment, rovibrational states of the nascent HF beam are detected using direct infrared absorption spectroscopy, and in the latter, a resonace-enhanced multi-photon-ionization (REMPI) scheme is employed in combination with a velocity-map imaging (VMI) device, which allows the detection of different vibrational states of benzene excited during the scattering process. M. E. Saecker, S. T. Govoni, D. V. Kowalski, M. E. King and G. M. Nathanson Science 252, 1421, 1991. A. M. Zolot, W. W. Harper, B. G. Perkins, P. J. Dagdigian and D. J. Nesbitt J. Chem. Phys 125, 021101, 2006. J. R. Roscioli and D. J. Nesbitt Faraday Disc. 150, 471, 2011.

Grütter, Monika; Nelson, Daniel J.; Nesbitt, David J.

2012-06-01

262

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

263

Suppression of quantum collapse in an anisotropic gas of dipolar bosons  

NASA Astrophysics Data System (ADS)

In recent work [Sakaguchi and Malomed, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.83.013607 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 -(U0/2)r-2 was proposed, based on the replacement of the linear Schrödinger 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 Schrödinger 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 Schrödinger 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 (U0)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?0.

Sakaguchi, Hidetsugu; Malomed, Boris A.

2011-09-01

264

Electric field effects on the quantum efficiency of Cesium-iodide photocathodes in gas media  

NASA Astrophysics Data System (ADS)

We have measured the quantum efficiency (QE) of Cesium iodide photocathodes as a function of the electric field strength in a parallel-plate geometry, in CH4, C2H6, and i-C4H10 both in charge collection and multiplication modes. It was found that in the collection mode the QE value in gases is lower compared to that of vacuum and is independent on the field; in gas media the QE starts to increase at the transition between collection and multiplication modes and reaches the vacuum value at high gas gain. We explain this effect by a decrease of the electron-molecule elastic backscattering while entering the multiplication mode. We conclude that the electric field effects observed here would also apply for other photocathodes and gas mixtures. An enhancement of the QE after micro discharges was observed and is discussed in detail.

Breskin, A.; Buzulutskov, A.; Chechik, R.; Vartsky, D.; Malamud, G.; Mine, P.

1993-12-01

265

Optical spectral imaging of a single layer of a quantum gas with an ultranarrow optical transition  

NASA Astrophysics Data System (ADS)

We demonstrated high-sensitivity optical spectral imaging of a single layer of a quantum gas of ytterbium atoms in a two-dimensional optical lattice using the ultranarrow 1S0-3P2 transition. We successfully obtained a set of excitation-frequency-dependent fluorescence images with an excitation laser of the linewidth of 1 kHz (FWHM), and the overall features were well explained by considering the inhomogeneous light shift originating from the Gaussian beam shape of the optical lattice potential which provided the steepest potential gradient of 3.6 kHz/?m. This result is also the successful demonstration of the tunable local atom addressing along the equipotential contour depending on the excitation laser frequency with the frequency resolution of 8 kHz and the spatial resolution of approximately 2 ?m. The demonstrated technique will be useful for many purposes including the measurement of interaction shift in the study of a quantum gas and quantum information processing.

Shibata, Kosuke; Yamamoto, Ryuta; Seki, Yu; Takahashi, Yoshiro

2014-03-01

266

Gas detection with quantum cascade lasers: An adapted photoacoustic sensor based on Helmholtz resonance  

NASA Astrophysics Data System (ADS)

A photoacoustic gas sensor exploiting a quantum cascade laser as a radiation source is demonstrated. A detection limit of ~1 ppm with 1 ms response time is found using a Peltier-cooled Fabry-Pérot InGaAs-based quantum cascade laser emitting at 9.4 ?m, and a commercial microphone as a detector. The photoacoustic cell consists of a Helmholtz resonator preceeded by a low-pass acoustic filter. This geometry is well adapted to the shape of the laser beam and allows for an effective filtering of ambient acoustical noise. The relative simplicity of the system is particularly attractive for applications where sensitivity, robustness, and ease of fabrication are all fundamental requirements.

Barbieri, Stefano; Pellaux, Jean-Paul; Studemann, Eric; Rosset, Daniel

2002-06-01

267

Cyclotron resonance of an interacting polaron gas in a quantum well in a tilted magnetic field  

NASA Astrophysics Data System (ADS)

Cyclotron-resonance spectra of a gas of interacting polarons confined to a GaAs/AlAs quantum well in the presence of a tilted magnetic field are theoretically investigated taking into account the magnetoplasmon-phonon mixing. In a tilted magnetic field, the intersubband magnetoplasmon-phonon modes can participate in the CR optical absorption. It is confirmed theoretically, that the resonant magneto-polaron coupling in a high-density GaAs/AlAs quantum well occurs near the GaAs TO-phonon frequency rather than near the GaAs LO-phonon frequency. Calculated CR spectra are in agreement with recent experimental data. This work has been supported by the GOA BOF UA 2000, IUAP, FWO-V projects G.0274.01N, G.0435.03, the WOG WO.025.99 (Belgium) and the European Commission GROWTH Programme, NANOMAT project, contract No. G5RD-CT-2001-00545.

Klimin, S. N.; Devreese, J. T.

2004-03-01

268

Quantum Mechanical Limitations to Spin Diffusion in the Unitary Fermi Gas  

NASA Astrophysics Data System (ADS)

We compute spin transport in the unitary Fermi gas using the strong-coupling Luttinger-Ward theory. In the quantum degenerate regime the spin diffusivity attains a minimum value of Ds?1.3?/m approaching the quantum limit of diffusion for a particle of mass m. Conversely, the spin drag rate reaches a maximum value of ?sd?1.2kBTF/? in terms of the Fermi temperature TF. The frequency-dependent spin conductivity ?s(?) exhibits a broad Drude peak, with spectral weight transferred to a universal high-frequency tail ?s(???)=?1/2C/3?(m?)3/2 proportional to the Tan contact density C. For the spin susceptibility ?s(T) we find no downturn in the normal phase.

Enss, Tilman; Haussmann, Rudolf

2012-11-01

269

Kinetic lattice-gas model of cage effects in high-density liquids and a test of mode-coupling theory of the ideal-glass transition  

Microsoft Academic Search

We have devised a kinetic lattice-gas model of an atomic liquid that incorporates the physical features associated with the formation of cages around a particle at high density. The model has simple equilibrium statistics, with a maximum of one particle per lattice site, and simple dynamical rules, so that it is feasible to perform dynamical calculations of the fluctuations about

Walter Kob; Hans C. Andersen

1993-01-01

270

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

SciTech Connect

Quantum cascade lasers (QCLs) are increasingly being used to detect, identify, and measure levels of trace gases in the air. External cavity QCLs (ECQCLs) provide a broadly-tunable infrared source to measure absorption spectra of chemicals and provide high detection sensitivity and identification confidence. Applications include detecting chemical warfare agents and toxic industrial chemicals, monitoring building air quality, measuring greenhouse gases for atmospheric research, monitoring and controlling industrial processes, analyzing chemicals in exhaled breath for medical diagnostics, and many more. Compact, portable trace gas sensors enable in-field operation in a wide range of platforms, including handheld units for use by first responders, fixed installations for monitoring air quality, and lightweight sensors for deployment in unmanned aerial vehicles (UAVs). We present experimental demonstration of a new chemical sensing technique based on intracavity absorption in an external cavity quantum cascade laser (ECQCL). This new technique eliminates the need for an infrared photodetector and gas cell by detecting the intracavity absorption spectrum in the compliance voltage of the laser device itself. To demonstrate and characterize the technique, we measure infrared absorption spectra of chemicals including water vapor and Freon-134a. Sub-ppm detection limits in one second are achieved, with the potential for increased sensitivity after further optimization. The technique enables development of handheld, high-sensitivity, and high-accuracy trace gas sensors for in-field use.

Phillips, Mark C.; Taubman, Matthew S.

2013-06-04

271

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

2008-08-01

272

Broadband THz imaging in gas and multiple quantum-well media  

NASA Astrophysics Data System (ADS)

We discuss two schemes of ultrafast THz imaging, both constituting non-perturbative response of either gas or solidstate media to the THz bias fields and thus offering very sensitive detection of the latter. In the first approach, we utilize air-breakdown plasma for space-time mapping of the THz field. In the second approach, we THz-induce strong electroabsorption response in the multiple quantum-well sample of thickness much smaller than the wavelength of the THz bias. As such, ultrabroadband imaging of the quasi single-cycle THz pulses can be possible.

Li, Chia-Yeh; Seletskiy, Denis V.; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor

2014-03-01

273

Quantum Anomaly, Universal Relations, and Breathing Mode of a Two-Dimensional Fermi Gas  

NASA Astrophysics Data System (ADS)

In this Letter, we show that the classical SO(2,1) symmetry of a harmonically trapped Fermi gas in two dimensions is broken by quantum effects. The anomalous correction to the symmetry algebra is given by a two-body operator that is well known as the contact. Taking into account this modification, we are able to derive the virial theorem for the system and a universal relation for the pressure of a homogeneous gas. The existence of an undamped breathing mode is associated with the classical symmetry. We provide an estimate for the anomalous frequency shift of this oscillation at zero temperature and compare the result with a recent experiment by [E. Vogt , Phys. Rev. Lett.PRLTAO0031-9007 108, 070404 (2012)10.1103/PhysRevLett.108.070404]. Discrepancies are attributed to finite temperature effects.

Hofmann, Johannes

2012-05-01

274

Quantum anomaly, universal relations, and breathing mode of a two-dimensional Fermi gas.  

PubMed

In this Letter, we show that the classical SO(2,1) symmetry of a harmonically trapped Fermi gas in two dimensions is broken by quantum effects. The anomalous correction to the symmetry algebra is given by a two-body operator that is well known as the contact. Taking into account this modification, we are able to derive the virial theorem for the system and a universal relation for the pressure of a homogeneous gas. The existence of an undamped breathing mode is associated with the classical symmetry. We provide an estimate for the anomalous frequency shift of this oscillation at zero temperature and compare the result with a recent experiment by [E. Vogt et al., Phys. Rev. Lett. 108, 070404 (2012)]. Discrepancies are attributed to finite temperature effects. PMID:22681087

Hofmann, Johannes

2012-05-01

275

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

276

Ideal electrokinesis and dielectrophoresis  

NASA Astrophysics Data System (ADS)

Electrokinesis (EK) and dielectrophoresis (DEP) are electrostatic transport mechanisms of considerable practical importance in microfluidics. In general microsystems, these mechanisms are difficult to model, requiring the coupled solution of the Poisson-Boltzmann, Stokes (or Navier-Stokes), and unsteady species-transport equations, in addition to models of interfacial charges, electrochemical reactions, and material properties in high-electric fields. Fortunately, EK in many practical microfluidic devices approaches an ideal limit in which the flow velocity and electric fields are everywhere proportional by a constant electrokinetic mobility. However, this limit requires all bounding surfaces to be impermeable and insulating, which excludes systems that use embedded electrodes to drive DEP. Fortunately again, insulating obstacles and spatially non-uniform channels can produce non-uniform electric fields to drive DEP consistent with ideal EK. Moreover, insulators are generally simpler and cheaper to manufacture, less susceptible to fouling, and less electrochemically complicated than electrodes. Mixed EK and DEP in these non-uniform channels can be simulated efficiently in two uncoupled steps: 1) solving the Laplace equation for the electric field, and 2) simulating EK and DEP motion of point tracer particles in this field. These simulations require the particles represented by the tracers to affect fluid and surface properties and each other negligibly. This additional condition uncouples EK and DEP, allowing the phenomena to be linearly superimposed. The resulting transport can be called ideal EK and ``linear'' or ideal DEP. Experiments and simulations of these flows point to ``streaming'' and ``trapping'' flow regimes that are exploited in novel devices to concentrate, filter, and immobilize particles selectively.

Cummings, E. B.

2003-03-01

277

Computing ideal sceptical argumentation  

Microsoft Academic Search

We present two dialectic procedures for the sceptical ideal semantics for argumentation. The first procedure is defined in terms of dispute trees, for abstract argumentation frameworks. The second procedure is defined in dialectical terms, for assumption-based argumentation frameworks. The procedures are adapted from (variants of) corresponding procedures for computing the credulous admissible semantics for assumption-based argumentation, proposed in [P.M. Dung,

Phan Minh Dung; Paolo Mancarella; Francesca Toni

2007-01-01

278

An efficient and accurate quantum lattice-gas model for the many-body Schrödinger wave equation  

Microsoft Academic Search

Presented is quantum lattice-gas model for simulating the time-dependent evolution of a many-body quantum mechanical system of particles governed by the non-relativistic Schrödinger wave equation with an external scalar potential. A variety of computational demonstrations are given where the numerical predictions are compared with exact analytical solutions. In all cases, the model results accurately agree with the analytical predictions and

Jeffrey Yepez; Bruce Boghosian

2002-01-01

279

Unravelling the quantum-entanglement effect of noble gas coordination on the spin ground state of CUO.  

PubMed

The accurate description of the complexation of the CUO molecule by Ne and Ar noble gas matrices represents a challenging task for present-day quantum chemistry. Especially, the accurate prediction of the spin ground state of different CUO-noble-gas complexes remains elusive. In this work, the interaction of the CUO unit with the surrounding noble gas matrices is investigated in terms of complexation energies and dissected into its molecular orbital quantum entanglement patterns. Our analysis elucidates the anticipated singlet-triplet ground-state reversal of the CUO molecule diluted in different noble gas matrices and demonstrates that the strongest uranium-noble gas interaction is found for CUOAr4 in its triplet configuration. PMID:24263815

Tecmer, Pawe?; Boguslawski, Katharina; Legeza, Örs; Reiher, Markus

2014-01-14

280

Multi-quantum excitation in optically pumped alkali atom: rare gas mixtures  

NASA Astrophysics Data System (ADS)

Diode-pumped alkali laser (DPAL) technology offers a means of achieving high-energy gas laser output through optical pumping of the D-lines of Cs, Rb, and K. The exciplex effect, based on weak attractive forces between alkali atoms and polarizable rare gas atoms (Ar, Kr, Xe), provides an alternative approach via broadband excitation of exciplex precursors (XPAL). In XPAL configurations, we have observed multi-quantum excitation within the alkali manifolds which result in infrared emission lines between 1 and 4 ?m. The observed excited states include the 42FJ states of both Cs and Rb, which are well above the two-photon energy of the excitation laser in each case. We have observed fluorescence from multi-quantum states for excitation wavelengths throughout the exciplex absorption bands of Cs-Ar, Cs-Kr, and Cs-Xe. The intensity scaling is roughly first-order or less in both pump power and alkali concentration, suggesting a collisional energy pooling excitation mechanism. Collisional up-pumping appears to present a parasitic loss term for optically pumped atomic systems at high intensities, however there may also be excitation of other lasing transitions at infrared wavelengths.

Galbally-Kinney, K. L.; Rawlins, W. T.; Davis, S. J.

2014-03-01

281

Investigation of the full configuration interaction quantum Monte Carlo method using homogeneous electron gas models  

NASA Astrophysics Data System (ADS)

Using the homogeneous electron gas (HEG) as a model, we investigate the sources of error in the ``initiator'' adaptation to full configuration interaction quantum Monte Carlo (i-FCIQMC), with a view to accelerating convergence. In particular, we find that the fixed-shift phase, where the walker number is allowed to grow slowly, can be used to effectively assess stochastic and initiator error. Using this approach we provide simple explanations for the internal parameters of an i-FCIQMC simulation. We exploit the consistent basis sets and adjustable correlation strength of the HEG to analyze properties of the algorithm, and present finite basis benchmark energies for N = 14 over a range of densities 0.5 <= rs <= 5.0 a.u. A single-point extrapolation scheme is introduced to produce complete basis energies for 14, 38, and 54 electrons. It is empirically found that, in the weakly correlated regime, the computational cost scales linearly with the plane wave basis set size, which is justifiable on physical grounds. We expect the fixed-shift strategy to reduce the computational cost of many i-FCIQMC calculations of weakly correlated systems. In addition, we provide benchmarks for the electron gas, to be used by other quantum chemical methods in exploring periodic solid state systems.

Shepherd, James J.; Booth, George H.; Alavi, Ali

2012-06-01

282

Chaplygin gas quantum universe in the presence of the cosmological constant  

NASA Astrophysics Data System (ADS)

We present a Chaplygin gas Friedmann-Robertson-Walker quantum cosmological model in the presence of the cosmological constant. We apply the Schutz’s variational formalism to recover the notion of time, and this gives rise to Wheeler-DeWitt equation for the scale factor. We study the early and late time universes and show that the presence of the Chaplygin gas leads to an effective positive cosmological constant for the late times. This suggests the possibility of changing the sign of the effective cosmological constant during the transition from the early times to the late times. For the case of an effective negative cosmological constant for both epoches, we solve the resulting Wheeler-DeWitt equation using the Spectral Method and find the eigenvalues and eigenfunctions for positive, zero, and negative constant spatial curvatures. Then, we use the eigenfunctions in order to construct wave packets for each case and obtain the time-dependent expectation value of the scale factors, which are found to oscillate between finite maximum and minimum values. Since the expectation value of the scale factors never tend to the singular point, we have an initial indication that this model may not have singularities at the quantum level.

Pedram, Pouria; Jalalzadeh, Shahram

2010-04-01

283

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

284

Quantum linear Boltzmann equation with finite intercollision time  

SciTech Connect

Inconsistencies are pointed out in the usual quantum versions of the classical linear Boltzmann equation constructed for a quantized test particle in a gas. These are related to the incorrect formal treatment of momentum decoherence. We prove that ideal collisions with the molecules would result in complete momentum decoherence, the persistence of coherence is only due to the finite intercollision time. A corresponding quantum linear Boltzmann equation is proposed.

Diosi, Lajos [Research Institute for Particle and Nuclear Physics, P.O. Box 49, H-1525 Budapest 114 (Hungary)

2009-12-15

285

Coherent spin dynamics of different density high mobility two-dimensional electron gas in a GaAs quantum well  

NASA Astrophysics Data System (ADS)

We have addressed the dependence of quasi-two-dimensional electron spin dephasing time on the electron gas density in a 17-nm GaAs quantum well using the time-resolved magneto-optical Kerr effect. A superlinear increase in the electron dephasing time with decreasing electron density has been found. The degree of electron spin relaxation anisotropy has been measured and the dependence of spin-orbit splitting on electron gas density has been determined.

Larionov, A. V.; Zhuravlev, A. S.

2013-04-01

286

Quantum phase transition in the Frenkel-Kontorova chain: from pinned instanton glass to sliding phonon gas.  

PubMed

We study analytically and numerically the one-dimensional quantum Frenkel-Kontorova chain in the regime where the classical model is located in the pinned phase characterized by the gaped phonon excitations and devil's staircase. By extensive quantum Monte Carlo simulations, we show that for the effective Planck constant Planck smaller than the critical value Planck(c) the quantum chain is in the pinned instanton glass phase. In this phase, the elementary excitations have two branches: phonons, separated from zero energy by a finite gap, and instantons that have an exponentially small excitation energy. At Planck = Planck(c) the quantum phase transition takes place and for Planck > Planck(c) the pinned instanton glass is transformed into the sliding phonon gas with gapless phonon excitations. This transition is accompanied by the divergence of the spatial correlation length and appearance of sliding modes at Planck > Planck(c). PMID:12786252

Zhirov, O V; Casati, G; Shepelyansky, D L

2003-05-01

287

Ferromagnetism of a repulsive atomic Fermi gas in an optical lattice: a quantum Monte Carlo study.  

PubMed

Using continuous-space quantum Monte Carlo methods, we investigate the zero-temperature ferromagnetic behavior of a two-component repulsive Fermi gas under the influence of periodic potentials that describe the effect of a simple-cubic optical lattice. Simulations are performed with balanced and with imbalanced components, including the case of a single impurity immersed in a polarized Fermi sea (repulsive polaron). For an intermediate density below half filling, we locate the transitions between the paramagnetic, and the partially and fully ferromagnetic phases. As the intensity of the optical lattice increases, the ferromagnetic instability takes place at weaker interactions, indicating a possible route to observe ferromagnetism in experiments performed with ultracold atoms. We compare our findings with previous predictions based on the standard computational method used in material science, namely density functional theory, and with results based on tight-binding models. PMID:24483906

Pilati, S; Zintchenko, I; Troyer, M

2014-01-10

288

Thermal versus entanglement entropy: a measurement protocol for fermionic atoms with a quantum gas microscope  

NASA Astrophysics Data System (ADS)

We show how to measure the order-two Renyi entropy of many-body states of spinful fermionic atoms in an optical lattice in equilibrium and non-equilibrium situations. The proposed scheme relies on the possibility to produce and couple two copies of the state under investigation, and to measure the occupation number in a site- and spin-resolved manner, e.g. with a quantum gas microscope. Such a protocol opens the possibility to measure entanglement and test a number of theoretical predictions, such as area laws and their corrections. As an illustration we discuss the interplay between thermal and entanglement entropy for a one dimensional Fermi-Hubbard model at finite temperature, and its possible measurement in an experiment using the present scheme.

Pichler, Hannes; Bonnes, Lars; Daley, Andrew J.; Läuchli, Andreas M.; Zoller, Peter

2013-06-01

289

Fermi-edge superfluorescence from a quantum-degenerate electron-hole gas  

PubMed Central

Nonequilibrium can be a source of order. This rather counterintuitive statement has been proven to be true through a variety of fluctuation-driven, self-organization behaviors exhibited by out-of-equilibrium, many-body systems in nature (physical, chemical, and biological), resulting in the spontaneous appearance of macroscopic coherence. Here, we report on the observation of spontaneous bursts of coherent radiation from a quantum-degenerate gas of nonequilibrium electron-hole pairs in semiconductor quantum wells. Unlike typical spontaneous emission from semiconductors, which occurs at the band edge, the observed emission occurs at the quasi-Fermi edge of the carrier distribution. As the carriers are consumed by recombination, the quasi-Fermi energy goes down toward the band edge, and we observe a continuously red-shifting streak. We interpret this emission as cooperative spontaneous recombination of electron-hole pairs, or superfluorescence (SF), which is enhanced by Coulomb interactions near the Fermi edge. This novel many-body enhancement allows the magnitude of the spontaneously developed macroscopic polarization to exceed the maximum value for ordinary SF, making electron-hole SF even more “super” than atomic SF.

Kim, Ji-Hee; II, G. Timothy Noe; McGill, Stephen A.; Wang, Yongrui; Wojcik, Aleksander K.; Belyanin, Alexey A.; Kono, Junichiro

2013-01-01

290

Modulation potential effects on the quantum magnetotransport in a two-dimensional electron gas  

NASA Astrophysics Data System (ADS)

The quantum magnetotransport (QMT) coefficients of a two-dimensional electron gas (2DEG) in a perpendicular magnetic field for the 2D square array of modulated anti-dot (AD) and in quantum dot (QD)-limit potentials and 1D Quantum Wire (QW) are calculated in the low magnetic field region (<0.3 T) using the Kubo method. The model potential is modulated by controlling the steepness and its strength. The effect on the band part of all QMT coefficients are studied. Our analysis is based on how the sub Landau Level states sue to new magnetic Brillouin zone (MBZ) affect the QMT coefficients, how the cyclotron orbit and the scattering by the potential contribute to the QMT coefficients, and how the states near the Fermi level and below the Fermi level contribute to the QMT coefficients when the size and the strength of the modulated potential are changed. The results for 2D modulation show that (i) Oscillations associated with the filling of sub Landau levels occur in sigmasbsp{xx}{(0)} and sigmasbsp{yx}{(0)} for the low modulation case. (ii) The effect of scattering by the AD potential is quite different from that by the dot potential. (iii) For a strong lateral superlattice AD potential, the longitudinal resistivity rhosbsp{xx}{(0)} has a double peak structure which depends on both the strength of the modulation potential as well as its slope. (iv) For both the AD and QD potentials, rhosbsp{xy}{(0)} is quenched and is negative at low magnetic fields which depend on the size and the strength of the modulation. (v) For the strong dot potential, there are Aharanov-Bohm oscillations in rhosbsp{xx}{(0)} and rhosbsp{xy}{(0)} and large plus-to-minus oscillations. The double peak structure in rhosbsp{xx}{(0)} and the negative values and quenching of the Hall effect at low magnetic fields have been observed experimentally for AD in both the quasiclassical and quantum regimes. In 1D modulation, all the QMT coefficients of a 2DEG in a perpendicular magnetic field for the Short Quantum Wire are calculated in the low magnetic field region (<0.3 T) using the Kubo method. The Quantum Wire Channel is modulated by controlling the steepness and its strength of the potential barrier. Our studies show a step-like feature in transverse conductivities due to the Landau Level (LL) crossing for the weak modulation and low-field giant peaks in the transverse resistivities for the strong potential. And also, quenched Hall resistivities at low magnetic fields are presented. In longitudinal resistivities, some threshold peaks are shown. Our interesting feature is the negative Hall resistivities which are guessed as the result of the boundary back-scattering in the short Quantum Wire.

Park, Tae-Ik

291

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

292

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

NASA Astrophysics Data System (ADS)

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 success using detailed chemical kinetic modeling. This contribution provides examples from our own work of how computational quantum chemistry can be used in developing gas phase reaction mechanisms for modeling of high temperature materials processing. In the context of CVD of silicon from dichlorosilane, CVD of alumina from AlCl3/H2/CO2 mixtures, and particle nucleation from silane, this detailed chemical kinetic modeling has given us insight into gas phase reaction pathways that we would not likely have gained by other means.

Swihart, Mark T.

2005-02-01

293

Vortex-antivortex pair in a Bose-Einstein condensate. Type-II quantum lattice gas as a nonlinear ?4 theory of a complex field  

NASA Astrophysics Data System (ADS)

Presented is a type-II quantum algorithm for superfluid dynamics, used to numerically predict solutions of the GP equation for a complex scalar field (spinless bosons) in ?4 theory. The GP equation is a long wavelength effective field theory of a microscopic quantum lattice gas with nonlinear state reduction. The quantum lattice gas algorithm for modeling the dynamics of the one-body BEC state in 3+1 dimensions is presented. To demonstrate the method's strength as a computational physics tool, a difficult situation of filamentary singularities is simulated, the dynamics of solitary vortex-antivortex pairs, which are a basic building block of morphologies of quantum turbulence.

Yepez, J.; Vahala, G.; Vahala, L.

2009-04-01

294

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

SciTech Connect

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({theta}). 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 [Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Goettingen (Germany); Ueta, Hirokazu; Beck, Rainer D. [Laboratoire de Chimie Physique Moleculaire, Ecole Polytechnique Federale de Lausanne (Switzerland); Bisson, Regis [Aix-Marseille Universite, PIIM, CNRS, UMR 7345, 13397 Marseille (France)

2013-05-15

295

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

296

Quantum dots as mediators in gas sensing: A case study of CdS sensitized WO3 sensing composites  

NASA Astrophysics Data System (ADS)

In this study the proof of principle of the use of naked semiconductor directly generated on metal oxide surface as mediators in gas sensing is provided. Successive ionic layer absorption and reaction (SILAR) technique has been applied to sensitize a WO3 thin film with CdS quantum dots. Response to gases of bare WO3 is deeply modified: quantum dots dramatically increase the metal oxide conductance, otherwise rather poor, and modify the capability of detecting environmental pollutants, such as CO and NO2. A modified sensing mechanism is proposed to rationalize the mediation exerted by the semiconducting active layer on the interaction between gaseous species and WO3 surface.

Concina, Isabella; Comini, Elisabetta; Kaciulis, Saulius; Sberveglieri, Giorgio

2014-01-01

297

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.

298

Uncountably Generated Ideals of Functions  

ERIC Educational Resources Information Center

Maximal ideals in the ring of continuous functions on the closed interval [0, 1] are not finitely generated. This is well-known. What is not as well-known, but perhaps should be, is the fact that these ideals are not countably generated although the proof is not harder! We prove this here and use the result to produce some non-prime ideals in the…

Sury, B.

2011-01-01

299

The performance analysis of a micro-/nanoscaled quantum heat engine  

NASA Astrophysics Data System (ADS)

A new model of micro-/nanoscaled heat engines consisting of two thin long tubes with the same length but different sizes of cross section, which are filled up with ideal quantum gases and operated between two heat reservoirs, is put forward. The working fluid of the heat engine cycle goes through four processes, which include two isothermal processes and two isobaric processes with constant longitudinal pressure. General expressions for the power output and efficiency of the cycle are derived, based on the thermodynamic properties of confined ideal quantum gases. The influence of the size effect on the power output and efficiency is discussed. The differences between the heat engines working with the ideal Bose gas and Fermi gas are revealed. The performance of the heat engines operating at weak gas degeneracy and high temperatures is further analyzed. The results obtained are more general and significant than those in the current literature.

Guo, Juncheng; Zhang, Xiuqin; Su, Guozhen; Chen, Jincan

2012-12-01

300

Structure and IR spectrum of phenylalanyl-glycyl-glycine tripetide in the gas-phase: IR/UV experiments, ab initio quantum chemical calculations, and molecular dynamic simulations.  

PubMed

We investigated the potential-energy surface (PES) of the phenylalanyl-glycyl-glycine tripeptide in the gas phase by means of IR/UV double-resonance spectroscopy, and quantum chemical and statistical thermodynamic calculations. Experimentally, we observed four conformational structures and we recorded their IR spectra in the spectral region of 3000-4000 cm(-1). Computationally, we investigated the PES by a combination of molecular dynamics/quenching procedures with high-level correlated ab initio calculations. We found that neither empirical potentials nor various DFT functionals provide satisfactory results. On the other hand, the approximative DFT method covering the dispersion energy yields a reliable set of the most stable structures, which we subsequently investigated with an accurate, correlated ab initio treatment. The global minimum contains three moderately strong intramolecular hydrogen bonds and is mainly stabilized by London dispersion forces between the phenyl ring, the carboxylic acid group, and various peptide bonds. A proper description of the last type of interaction requires accurate correlated ab initio calculations, including the complete basis set limit of the MP2 method and CCSD(T) correction terms. Since in our beam experiments the conformations are frozen by cooling from a higher temperature, it is necessary to localize the most stable structures on the free-energy surface rather than on the PES. We used two different procedures (rigid rotor/harmonic oscillator/ideal gas approximation based on ab initio characteristics and evaluation of relative populations from the molecular dynamic simulations using the AMBER potential) and both yield four structures, the global minimum and three local minima. These four structures were among the 15 most energetically stable structures obtained from accurate ab initio optimization. The calculated IR spectra for these four structures agree well with the experimental frequencies, which validates the localization procedure. PMID:16092140

Reha, D; Valdés, H; Vondrásek, J; Hobza, P; Abu-Riziq, Ali; Crews, Bridgit; de Vries, Mattanjah S

2005-11-18

301

High-performance quantum cascade lasers grown by gas-source molecular beam epitaxy  

Microsoft Academic Search

Recent improvements in quantum cascade laser technology have led to a number of very impressive results. This paper is a brief summary of the technological development and state-of- the-art performance of quantum cascade lasers produced at the Center for Quantum Devices. Laser design will be discussed, as well as experimental details of device fabrication. Room temperature QCL operation has been

Manijeh Razeghi; Steven Slivken; Abbes Tahraoui; Anthony W. Matlis

2001-01-01

302

Quantum chaos in ultracold collisions of gas-phase erbium atoms  

NASA Astrophysics Data System (ADS)

Atomic and molecular samples reduced to temperatures below one microkelvin, yet still in the gas phase, afford unprecedented energy resolution in probing and manipulating the interactions between their constituent particles. As a result of this resolution, atoms can be made to scatter resonantly on demand, through the precise control of a magnetic field. For simple atoms, such as alkalis, scattering resonances are extremely well characterized. However, ultracold physics is now poised to enter a new regime, where much more complex species can be cooled and studied, including magnetic lanthanide atoms and even molecules. For molecules, it has been speculated that a dense set of resonances in ultracold collision cross-sections will probably exhibit essentially random fluctuations, much as the observed energy spectra of nuclear scattering do. According to the Bohigas-Giannoni-Schmit conjecture, such fluctuations would imply chaotic dynamics of the underlying classical motion driving the collision. This would necessitate new ways of looking at the fundamental interactions in ultracold atomic and molecular systems, as well as perhaps new chaos-driven states of ultracold matter. Here we describe the experimental demonstration that random spectra are indeed found at ultralow temperatures. In the experiment, an ultracold gas of erbium atoms is shown to exhibit many Fano-Feshbach resonances, of the order of three per gauss for bosons. Analysis of their statistics verifies that their distribution of nearest-neighbour spacings is what one would expect from random matrix theory. The density and statistics of these resonances are explained by fully quantum mechanical scattering calculations that locate their origin in the anisotropy of the atoms' potential energy surface. Our results therefore reveal chaotic behaviour in the native interaction between ultracold atoms.

Frisch, Albert; Mark, Michael; Aikawa, Kiyotaka; Ferlaino, Francesca; Bohn, John L.; Makrides, Constantinos; Petrov, Alexander; Kotochigova, Svetlana

2014-03-01

303

Quantum de Laval nozzle: Stability and quantum dynamics of sonic horizons in a toroidally trapped Bose gas containing a superflow  

Microsoft Academic Search

We study an experimentally realizable system containing stable black hole white hole acoustic horizons in toroidally trapped Bose-Einstein condensates---the quantum de Laval nozzle. We numerically obtain stationary flow configurations and assess their stability using Bogoliubov theory, finding both in hydrodynamic and nonhydrodynamic regimes there exist dynamically unstable regions associated with the creation of positive and negative energy quasiparticle pairs in

P. Jain; A. S. Bradley; C. W. Gardiner

2007-01-01

304

8.5-um room temperature quantum cascade lasers grown by gas-source molecular beam epitaxy  

Microsoft Academic Search

We report room-temperature pulsed-mode operation of 8.5 micrometers quantum cascade lasers grown by gas-source molecular beam epitaxy. The theory necessary to understand the operation of the laser is presented and current problems are analyzed. Very good agreement is shown to exist between theoretical and experimental emission wavelengths. The high- temperature operation is achieved with 1 microsecond(s) pulses at a repetition

Steven Slivken; Manijeh Razeghi

1998-01-01

305

NO trace gas sensor based on quartz-enhanced photoacoustic spectroscopy and external cavity quantum cascade laser  

NASA Astrophysics Data System (ADS)

A gas sensor based on quartz-enhanced photoacoustic detection and an external cavity quantum cascade laser was realized and characterized for trace nitric oxide monitoring using the NO R(6.5) absorption doublet at 1900.075 cm-1. Signal and noise dependence on gas pressure were studied to optimize sensor performance. The NO concentration resulting in a noise-equivalent signal was found to be 15 parts per billion by volume, with 100 mW optical excitation power and a data acquisition time of 5 s.

Spagnolo, V.; Kosterev, A. A.; Dong, L.; Lewicki, R.; Tittel, F. K.

2010-07-01

306

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

SciTech Connect

We have used the narrow 2S{sub 1/2}{yields}3P{sub 3/2} transition in the ultraviolet (uv) to laser cool and magneto-optically trap (MOT) {sup 6}Li atoms. Laser cooling of lithium is usually performed on the 2S{sub 1/2}{yields}2P{sub 3/2} (D2) transition, and temperatures of {approx}300 {mu}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 {mu}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 {sup 6}Li in the optical trap produces a quantum degenerate Fermi gas with 3x10{sup 6} 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. [Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, Texas 77005 (United States)

2011-12-15

307

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

308

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

309

Diffusion Monte Carlo study of a valley-degenerate electron gas and application to quantum dots  

NASA Astrophysics Data System (ADS)

A many-flavor electron gas (MFEG) in a semiconductor with a valley degeneracy ranging between 6 and 24 was analyzed using diffusion Monte Carlo (DMC) calculations. The DMC results compare well to an analytic expression derived by one of us [Phys. Rev. B 78, 035111 (2008)] for the total energy to within ±1% over an order of magnitude range of density, which increases with valley degeneracy. For Bi2Te3 (sixfold valley degeneracy) the applicable charge-carrier densities are between 7×1019cm-3 and 2×1020cm-3 . DMC calculations distinguished between an exact and a useful approximate expression for the 24-fold degenerate MFEG polarizability for wave numbers 2pFquantum dot.

Conduit, G. J.; Haynes, P. D.

2008-11-01

310

The degradation of quantum efficiency in negative electron affinity GaAs photocathodes under gas exposure  

NASA Astrophysics Data System (ADS)

The influence of O2, CO2, CO, N2, H2 and CH4 on the stability of the quantum efficiency (QE) of a negative electron affinity gallium arsenide (GaAs) photocathode activated with caesium (Cs) and oxygen (O) has been demonstrated for the first time under an extremely high vacuum condition, a base pressure of 1.5 × 10-11 mbar, where the influence of the background gas is minimized. It was found that exposure of a GaAs photocathode to N2, H2 and CH4 does not affect the QE, whereas exposure to O2, CO2 and CO leads to a substantial reduction in photocathode QE. It was also found that the QE of photocathodes which have been degraded under O2 exposure can be recovered to 95% of their initial QE level by the re-caesiation process, while those which have been degraded under exposure to CO and CO2 can only be partly restored to 60-70% of their initial QE levels.

Chanlek, N.; Herbert, J. D.; Jones, R. M.; Jones, L. B.; Middleman, K. J.; Militsyn, B. L.

2014-02-01

311

Molecular geometry of 2-nitrotoluene from gas phase electron diffraction and quantum chemical study  

NASA Astrophysics Data System (ADS)

The molecular geometry of 2-nitrotoluene has been determined by gas phase electron diffraction and quantum chemical computations at the MP2/6-31G? and Becke3-Lee-Yang-Parr (B3-LYP)/6-31G? levels of theory. Computed differences in C?C bond lengths were utilized as constraints in the electron diffraction structure analysis. The scaled B3-LYP/6-31G? force field was used to generate the initial set of vibrational amplitudes. The electron diffraction study yielded the following bond lengths ( rg) and bond angles: C 1?C 2, 1.405(8) Å; N?O, 1.231(3) Å; C 1?C 7, 1.508(8) Å; C?N, 1.490(9) Å; C 7?C 1?C 2, 127.3(7)°; N?C 2?C 3, 113.8(6)°; C 1?C 2?C 3, 124.2(9)°; C 6?C 1?C 2, 114.8(6)°; C 5?C 6?C 1, 123.1(10)°; O-N-O, 124.9(3)°; ?(C?N), 38(1)°. The structural features of the molecule point to steric interactions prevailing between the methyl and nitro groups.

Shishkov, Igor F.; Vilkov, Lev V.; Kovács, Attila; Hargittai, István

1998-04-01

312

On fuzzy ideals of BL-algebras.  

PubMed

In this paper we investigate further properties of fuzzy ideals of a BL-algebra. The notions of fuzzy prime ideals, fuzzy irreducible ideals, and fuzzy Gödel ideals of a BL-algebra are introduced and their several properties are investigated. We give a procedure to generate a fuzzy ideal by a fuzzy set. We prove that every fuzzy irreducible ideal is a fuzzy prime ideal but a fuzzy prime ideal may not be a fuzzy irreducible ideal and prove that a fuzzy prime ideal ? is a fuzzy irreducible ideal if and only if ?(0) = 1 and |Im(?)| = 2. We give the Krull-Stone representation theorem of fuzzy ideals in BL-algebras. Furthermore, we prove that the lattice of all fuzzy ideals of a BL-algebra is a complete distributive lattice. Finally, it is proved that every fuzzy Boolean ideal is a fuzzy Gödel ideal, but the converse implication is not true. PMID:24892085

Meng, Biao Long; Xin, Xiao Long

2014-01-01

313

On Fuzzy Ideals of BL-Algebras  

PubMed Central

In this paper we investigate further properties of fuzzy ideals of a BL-algebra. The notions of fuzzy prime ideals, fuzzy irreducible ideals, and fuzzy Gödel ideals of a BL-algebra are introduced and their several properties are investigated. We give a procedure to generate a fuzzy ideal by a fuzzy set. We prove that every fuzzy irreducible ideal is a fuzzy prime ideal but a fuzzy prime ideal may not be a fuzzy irreducible ideal and prove that a fuzzy prime ideal ? is a fuzzy irreducible ideal if and only if ?(0) = 1 and |Im?(?)| = 2. We give the Krull-Stone representation theorem of fuzzy ideals in BL-algebras. Furthermore, we prove that the lattice of all fuzzy ideals of a BL-algebra is a complete distributive lattice. Finally, it is proved that every fuzzy Boolean ideal is a fuzzy Gödel ideal, but the converse implication is not true.

Xin, Xiao Long

2014-01-01

314

Beyond the Quantum  

NASA Astrophysics Data System (ADS)

pt. A. Introductions. The mathematical basis for deterministic quantum mechanics / G.'t Hooft. What did we learn from quantum gravity? / A. Ashtekar. Bose-Einstein condensates and EPR quantum non-locality / F. Laloe. The quantum measurement process: lessons from an exactly solvable model / A.E. Allahverdyan, R. Balian and Th. M. Nieuwenhuizen -- pt. B. Quantum mechanics and quantum information. POVMs: a small but important step beyond standard quantum mechanics / W. M. de Muynck. State reduction by measurements with a null result / G. Nienhuis. Solving open questions in the Bose-Einstein condensation of an ideal gas via a hybrid mixture of laser and statistical physics / M. Kim, A. Svidzinsky and M.O. Scully. Twin-Photon light scattering and causality / G. Puentes, A. Aiello and J. P. Woerdman. Simultaneous measurement of non-commuting observables / G. Aquino and B. Mehmani. Quantum decoherence and gravitational waves / M.T. Jaekel ... [et al.]. Role of various entropies in the black hole information loss problem / Th. M. Nieuwenhuizen and I.V. Volovich. Quantum and super-quantum correlations / G.S. Jaeger -- pt. C. Long distance correlations and bell inequalities. Understanding long-distance quantum correlations / L. Marchildon. Connection of probability models to EPR experiments: probability spaces and Bell's theorem / K. Hess and W. Philipp. Fair sampling vs no-signalling principle in EPR experiments / G. Adenier and A. Yu. Khrennikov -- pt. D. Mathematical foundations. Where the mathematical structure of quantum mechanics comes from / G.M. D'Ariano. Phase space description of quantum mechanics and non-commutative geometry: Wigner-Moyal and Bohm in a wider context / B.J. Hiley. Quantum mechanics as simple algorithm for approximation of classical integrals / A. Yu. Khrennikov. Noncommutative quantum mechanics viewed from Feynman Formalism / J. Lages ... [et al.]. Beyond the quantum in Snyder space / J.F.S. van Huele and M. K. Transtrum -- pt. E. Stochastic electrodynamics. Some quantum experiments from the point of view of Stochastic electrodynamics / V. Spicka ... [et al.]. On the ergodic behaviour of atomic systems under the action of the zero-point radiation field / L. De La Peña and A. M. Cetto. Inertia and the vacuum-view on the emergence of the inertia reaction force / A. Rueda and H. Sunahata -- pt. F. Models for the electron. Rotating Hopf-Kinks: oscillators in the sense of de Broglie / U. Enz. Kerr-Newman particles: symmetries and other properties / H.I. Arcos and J.G. Pereira. Kerr geometry beyond the quantum theory / Th. M. Nieuwenhuizen -- pt. G. Philosophical considerations. Probability in non-collapse interpretations of a quantum mechanics / D. Dieks. The Schrödinger-Park paradox about the concept of "State" in quantum statistical mechanics and quantum information theory is still open: one more reason to go beyond? / G.P. Beretta. The conjecture that local realism is possible / E. Santos -- pt. H. The round table. Round table discussion / A.M. Cetto ... [et al.].

Nieuwenhuizen, Theo M.; Mehmani, Bahar; Špi?ka, Václav; Aghdami, Maryam J.; Khrennikov, Andrei Yu

2007-09-01

315

Quantum de Laval nozzle: Stability and quantum dynamics of sonic horizons in a toroidally trapped Bose gas containing a superflow  

Microsoft Academic Search

We study an experimentally realizable system containing stable black\\u000ahole-white hole acoustic horizons in toroidally trapped Bose-Einstein\\u000acondensates - the quantum de Laval nozzle. We numerically obtain stationary\\u000aflow configurations and assess their stability using Bogoliubov theory, finding\\u000aboth in hydrodynamic and non-hydrodynamic regimes there exist dynamically\\u000aunstable regions associated with the creation of positive and negative energy\\u000aquasiparticle pairs

P. Jain; A. S. Bradley; C. W. Gardiner

2007-01-01

316

Quantum de Laval nozzle: Stability and quantum dynamics of sonic horizons in a toroidally trapped Bose gas containing a superflow  

Microsoft Academic Search

We study an experimentally realizable system containing stable black hole-white hole acoustic horizons in toroidally trapped Bose-Einstein condensates--the quantum de Laval nozzle. We numerically obtain stationary flow configurations and assess their stability using Bogoliubov theory, finding both in hydrodynamic and nonhydrodynamic regimes there exist dynamically unstable regions associated with the creation of positive and negative energy quasiparticle pairs in analogy

P. Jain; A. S. Bradley; C. W. Gardiner

2007-01-01

317

Uranyl complexes with diamide ligands: a quantum mechanics study of chelating properties in the gas phase.  

PubMed

We report a quantum mechanical study on the complexes of UO(2)(2+) with diamide ligands L of malonamide and succinamide type, respectively, forming 6- and 7-chelate rings in their bidentate coordination to uranium. The main aims are to (i) assess how strong the chelate effect is (i.e., the preference for bi- versus monodentate binding modes of L), (ii) compare these ligands as a function of the chelate ring size, and (iii) assess the role of neutralizing counterions. For this purpose, we consider UO(2)L(2+), UO(2)L(2)(2+), UO(2)L(3)(2+), and UO(2)X(2)L type complexes with X(-) = Cl(-) versus NO(3)(-). Hartree-Fock and DFT calculations lead to similar trends and reveal the importance of saturation and steric repulsions ("strain") in the first coordination sphere. In the unsaturated UO(2)L(2+), UO(2)L(2)(2+), and UO(2)Cl(2)L complexes, the 7-ring chelate is preferred over the 6-ring chelate, and bidentate coordination is preferred over the monodentate one. However, in the saturated UO(2)(NO(3))(2)L complexes, the 6- and 7-chelating ligands have similar binding energies, and for a given ligand, the mono- and bidentate binding modes are quasi-isoenergetic. These conclusions are confirmed by the calculations of free energies of complexation in the gas phase. In condensed phases, the monodentate form of UO(2)X(2)L complexes should be further stabilized by coordination of additional ligands, as well as by interactions (e.g., hydrogen bonding) of the "free" carbonyl oxygen, leading to an enthalpic preference for this form, compared to the bidentate one. We also considered an isodesmic reaction exchanging one bidentate ligand L with two monoamide analogues, which reveals that the latter are clearly preferred (by 23-14 kcal/mol at the HF level and 24-12 kcal/mol at the DFT level). Thus, in the gas phase, the studied bidentate ligands are enthalpically disfavored, compared to bis-monodentate analogues. The contrast with trends observed in solution hints at the importance of "long range" forces (e.g., second shell interactions) and entropy effects on the chelate effect in condensed phases. PMID:12767210

Coupez, Bernard; Wipff, Georges

2003-06-01

318

BCS-BEC crossover and quantum phase transition in an ultracold Fermi gas under spin-orbit coupling  

NASA Astrophysics Data System (ADS)

In this work, we study the BCS-BEC crossover and quantum phase transition in a Fermi gas under Rashba spin-orbit coupling close to a Feshbach resonance. By adopting a two-channel model, we take into account the closed-channel molecules, and show that combined with spin-orbit coupling, a finite background scattering in the open channel can lead to two branches of solution for both the two-body and the many-body ground states. The branching of the two-body bound-state solution originates from the avoided crossing between bound states in the open and the closed channels, respectively. For the many-body states, we identify a quantum phase transition in the upper branch regardless of the sign of the background scattering length, which is in clear contrast to the case without spin-orbit coupling. For systems with negative background scattering length in particular, we show that the bound state in the open channel, and hence the quantum phase transition in the upper branch, are induced by spin-orbit coupling. We then characterize the critical detuning of the quantum phase transition for both positive and negative background scattering lengths, and demonstrate the optimal parameters for the critical point to be probed experimentally.

Wu, Fan; Zhang, Ren; Deng, Tian-Shu; Zhang, Wei; Yi, Wei; Guo, Guang-Can

2014-06-01

319

High-power quantum cascade lasers (QCLs) grown by GasMBE  

Microsoft Academic Search

This paper is a brief summary of the technological development and state-of-the-art performance of quantum cascade lasers produced at the Centre for Quantum Devices. Laser design will be discussed, as well as experimental details of device fabrication. Recent work has focused on the development of high peak and average power QCLs emitting at room temperature and above. Scaling of the

Manijeh Razeghi; Steven Slivken

2003-01-01

320

Nice Initial Complexes of Some Classical Ideals  

Microsoft Academic Search

This is a survey article on Gorenstein initial complexes of extensively studied ideals in commutative algebra and algebraic geometry. These include defining ideals of Segre and Veronese varieties, toric deformations of flag varieties known as Hibi ideals, determinantal ideals of generic matrices of indeterminates, and ideals generated by Pfaffians of generic skew symmetric matrices. We give a summary of recent

Aldo Conca; Serkan Hosten; Rekha R. Thomas

2005-01-01

321

Quantum de Laval nozzle: Stability and quantum dynamics of sonic horizons in a toroidally trapped Bose gas containing a superflow  

SciTech Connect

We study an experimentally realizable system containing stable black hole-white hole acoustic horizons in toroidally trapped Bose-Einstein condensates--the quantum de Laval nozzle. We numerically obtain stationary flow configurations and assess their stability using Bogoliubov theory, finding both in hydrodynamic and nonhydrodynamic regimes there exist dynamically unstable regions associated with the creation of positive and negative energy quasiparticle pairs in analogy with the gravitational Hawking effect. The dynamical instability takes the form of a two mode squeezing interaction between resonant pairs of Bogoliubov modes. We study the evolution of dynamically unstable flows using the truncated Wigner method, which confirms the two mode squeezed state picture of the analogue Hawking effect for low winding number.

Jain, P. [School of Chemical and Physical Sciences, Victoria University of Wellington (New Zealand); Jack Dodd and Dan Walls Centre for Photonics and Ultra Cold Atoms, University of Otago (New Zealand); Bradley, A. S. [ARC Centre of Excellence for Quantum-Atom Optics, Department of Physics, University of Queensland, Brisbane, QLD 4072 (Australia); Gardiner, C. W. [Jack Dodd and Dan Walls Centre for Photonics and Ultra Cold Atoms, University of Otago (New Zealand)

2007-08-15

322

Quantum de Laval nozzle: Stability and quantum dynamics of sonic horizons in a toroidally trapped Bose gas containing a superflow  

NASA Astrophysics Data System (ADS)

We study an experimentally realizable system containing stable black hole white hole acoustic horizons in toroidally trapped Bose-Einstein condensates—the quantum de Laval nozzle. We numerically obtain stationary flow configurations and assess their stability using Bogoliubov theory, finding both in hydrodynamic and nonhydrodynamic regimes there exist dynamically unstable regions associated with the creation of positive and negative energy quasiparticle pairs in analogy with the gravitational Hawking effect. The dynamical instability takes the form of a two mode squeezing interaction between resonant pairs of Bogoliubov modes. We study the evolution of dynamically unstable flows using the truncated Wigner method, which confirms the two mode squeezed state picture of the analogue Hawking effect for low winding number.

Jain, P.; Bradley, A. S.; Gardiner, C. W.

2007-08-01

323

The Quantum Field Theory of the Ensemble Operator  

SciTech Connect

Quantum field theory (QFT) provides a systematic investigative tool for ensembles of molecules. The grand-canonical ensemble operator (GCEO) for an ideal gas is presented in terms of the Fock creation and annihilation operators. The ideal GCEO can be shown to obey a simple equation which facilitates calculation of quantum-statistical properties of bosonic and fermionic molecules. Examples are linked-cluster QFT derivations of the grand-canonical partition function and the Poisson distribution for non-interacting molecules. The Boltzmann limit is achieved by omitting exchange diagrams. Summations of Feynman diagrams for long- and short-range interactions to infinite order lead to a useful model of the pair-correlation function and a new avenue for the study of dynamics near the critical point for gas-liquid phase transitions.

Porter, Richard N. [Department of Chemistry, State University of New York, Stony Brook, New York, 11794-3400 (United States)

2009-03-09

324

Toric ideals of phylogenetic invariants.  

PubMed

Statistical models of evolution are algebraic varieties in the space of joint probability distributions on the leaf colorations of a phylogenetic tree. The phylogenetic invariants of a model are the polynomials which vanish on the variety. Several widely used models for biological sequences have transition matrices that can be diagonalized by means of the Fourier transform of an Abelian group. Their phylogenetic invariants form a toric ideal in the Fourier coordinates. We determine generators and Gröbner bases for these toric ideals. For the Jukes-Cantor and Kimura models on a binary tree, our Gröbner bases consist of certain explicitly constructed polynomials of degree at most four. PMID:15882142

Sturmfels, Bernd; Sullivant, Seth

2005-05-01

325

Toric ideals of phylogenetic invariants.  

PubMed

Statistical models of evolution are algebraic varieties in the space of joint probability distributions on the leaf colorations of a phylogenetic tree. The phylogenetic invariants of a model are the polynomials which vanish on the variety. Several widely used models for biological sequences have transition matrices that can be diagonalized by means of the Fourier transform of an abelian group. Their phylogenetic invariants form a toric ideal in the Fourier coordinates. We determine generators and Gröbner bases for these toric ideals. For the Jukes-Cantor and Kimura models on a binary tree, our Gröbner bases consist of certain explicitly constructed polynomials of degree at most four. PMID:15767777

Sturmfels, Bernd; Sullivant, Seth

2005-03-01

326

Fuzzy ideals in BCI-algebras  

Microsoft Academic Search

The aim of this paper is to introduce the notions of fuzzy BCI-positive implicative ideals and fuzzy BCI-implicative ideals of BCI-algebras and to investigate their properties. We give several characterizations of fuzzy BCI-positive implicative ideals and fuzzy BCI-implicative ideals. The extension theorems of fuzzy BCI-positive implicative ideals and fuzzy BCI-implicative ideals are obtained. We discuss the relations among various fuzzy

Yong Lin Liu; Jie Meng

2001-01-01

327

Controllable manipulation and detection of local densities and bipartite entanglement in a quantum gas by a dissipative defect  

SciTech Connect

We study the complex dynamics of a one-dimensional Bose gas subjected to a dissipative local defect which induces one-body atom losses. In experiments these atom losses occur, for example, when a focused electron or light beam or a single trapped ion is brought into contact with a quantum gas. We discuss how within such setups one can measure or manipulate densities locally and specify the excitations that are induced by the defect. In certain situations the defect can be used to generate entanglement in a controlled way despite its dissipative nature. The careful examination of the interplay between hole excitations and the collapse of the wave function due to nondetection of loss is crucial for the understanding of the dynamics we observe.

Barmettler, Peter; Kollath, Corinna [Departement de Physique Theorique, Universite de Geneve, CH-1211 Geneve (Switzerland) and Centre de Physique Theorique, Ecole Polytechnique, CNRS, F-91128 Palaiseau (France)

2011-10-15

328

Stimulated Scattering of Indirect Excitons in Coupled Quantum Wells: Signature of a Degenerate Bose-Gas of Excitons  

SciTech Connect

We observe and analyze strongly nonlinear photoluminescence kinetics of indirect excitons in GaAs/AlGaAs coupled quantum wells at low bath temperatures, {ge}50 mK . The long recombination lifetime of indirect excitons promotes accumulation of these Bose particles in the lowest energy states and allows the photoexcited excitons to cool down to temperatures where the dilute 2D gas of indirect excitons becomes statistically degenerate. Our main result{emdash}a strong enhancement of the exciton scattering rate to the low-energy states with increasing concentration of the indirect excitons{emdash}reveals bosonic stimulation of exciton scattering, which is a signature of a degenerate Bose-gas of excitons.

Butov, L. V.; Ivanov, A. L.; Imamoglu, A.; Littlewood, P. B.; Shashkin, A. A.; Dolgopolov, V. T.; Campman, K. L.; Gossard, A. C.

2001-06-11

329

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

330

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

331

Computation of ideal MHD equilibria  

Microsoft Academic Search

This paper reviews two- and three-dimensional ideal MHD equilibrium codes, with particular emphasis on axisymmetric toroidal calculations. In this case (Tokamak geometry), the equilibrium problem can be formulated in three essentially different ways, depending on whether (I) mirror currents in a copper shell or (II) given, applied external currents provide for balancing of the hoop force and shaping of the

K. Lackner

1976-01-01

332

Quantum-well structures of InAlP\\/InGaP grown by gas-source molecular-beam epitaxy  

Microsoft Academic Search

Both single quantum-well (SQW) and multiple quantum-well (MQW) structures have been produced using the technique of gas-source molecular-beam epitaxy to grow the two wide band-gap ternary alloys, InAlP and InGaP. SQWs as narrow as two monolayers observed by bright field Transmission Electron Microscopy were found to be laterally uniform with abrupt InAlP\\/InGaP interfaces. Photoluminescence of SQWs of differing thickness produced

M. J. Hafich; H. Y. Lee; G. Y. Robinson; D. Li; N. Otsuka

1991-01-01

333

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

334

The vertex ideal of a lattice  

Microsoft Academic Search

We introduce a monomial ideal whose standard monomials encode the vertices of all fibers of a lattice. We study the minimal generators, the radical, the associated primes and the primary decomposition of this ideal, as well as its relation to initial ideals of lattice ideals.

Serkan Hosten; Diane Maclagan

2000-01-01

335

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

336

Quantum Number Dependence of Lineshift Coefficients Induced by Collisions with Noble Gas Perturbers in the nu(3) Band of NO(2).  

PubMed

To complete our study concerning lineshift in the rovibrational spectrum of (14)N(16)O(2), a pulse-driven three-channel lead salt diode laser spectrometer was applied to record high-resolution spectra at room temperature in the 6.2-µm region corresponding to the nu(3) band at low NO(2) concentrations. The shift was studied for collisions with the noble gases He, Ne, Ar, Kr, and Xe. This paper extends our recently published data in order to analyze the quantum number dependence of the shift effect more precisely. Therefore, in this paper, additionally eight unresolved NO(2) doublets covering an enlarged quantum number range (10 gas) and additionally broadening coefficients gamma(NO(2)-noble gas) were determined. Hereby, the experimental data confirm general trends published recently. In this study, in the case of broadening for the lighter rare gases helium, neon, and argon, only a slight decrease of gamma(NO(2)-noble gas) was observed, whereas for the rare gases with a higher atomic weight, i.e., krypton and xenon, a pronounced decrease of gamma(NO(2)-noble gas) with increasing rotational quantum number N(") occurred. All measured lineshift coefficients were negative. The absolute value of the determined lineshift coefficient ||delta(NO(2)-noble gas) || increases with the mass of the noble gas perturber, i.e., ||delta(NO(2)-He) || < ||delta(NO(2)-Ne) || < ||delta(NO(2)-Ar) || < ||delta(NO(2)-Kr) || < ||delta(NO(2)-Xe) ||. Within the studied quantum number range, an increase ||delta(NO(2)-noble gas) || with increase of N(") was observed. A typical trend of the shift and broadening data on the quantum number K(")(a) was not observed. Copyright 2000 Academic Press. PMID:10637106

Sumpf; Bouazza; Kissel; Kronfeldt

2000-02-01

337

Representation of Ideal Magnetohydrodynamic Modes  

SciTech Connect

One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through ? ? = ? X (xi X B) ensures that ? B • ? ? = 0 at a resonance, with ? labelling an equilibrium flux surface. Also useful for the analysis of guiding center orbits in a perturbed field is the representation ? ? = ? X ?B. These two representations are equivalent, but the vanishing of ? B • ?? at a resonance is necessary but not sufficient for the preservation of field line topology, and a indiscriminate use of either perturbation in fact destroys the original equilibrium flux topology. It is necessary to find the perturbed field to all orders in xi to conserve the original topology. The effect of using linearized perturbations on stability and growth rate calculations is discussed

Roscoe B. White

2013-01-15

338

Cylindrical magnets and ideal solenoids  

NASA Astrophysics Data System (ADS)

Both wire-wound solenoids and cylindrical magnets can be approximated as ideal azimuthally symmetric solenoids. We present an exact solution for the magnetic field of an ideal solenoid in an easy to use form. The field is expressed in terms of a single function that can be rapidly computed by means of a compact efficient algorithm, which can be coded as an add-in function to a spreadsheet, making field calculations accessible to introductory students. These expressions are not only accurate but are also as fast as most approximate expressions. We demonstrate their utility by simulating the dropping of a cylindrical magnet through a nonmagnetic conducting tube and comparing the calculation with data obtained from experiments suitable for an undergraduate laboratory.

Derby, Norman; Olbert, Stanislaw

2010-03-01

339

Statistical mechanics based on fractional classical and quantum mechanics  

NASA Astrophysics Data System (ADS)

The purpose of this work is to study some problems in statistical mechanics based on the fractional classical and quantum mechanics. At first stage we have presented the thermodynamical properties of the classical ideal gas and the system of N classical oscillators. In both cases, the Hamiltonian contains fractional exponents of the phase space (position and momentum). At the second stage, in the context of the fractional quantum mechanics, we have calculated the thermodynamical properties for the black body radiation, studied the Bose-Einstein statistics with the related problem of the condensation and the Fermi-Dirac statistics.

Korichi, Z.; Meftah, M. T.

2014-03-01

340

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

341

Circulant Digraphs and Monomial Ideals  

Microsoft Academic Search

\\u000a It is known that there exists a Minimum Distance Diagram (MDD) for circulant digraphs of degree two (or double-loop computer\\u000a networks) which is an L-shape. Its description provides the graph’s diameter and average distance on constant time. In this\\u000a paper we clarify, justify and extend these diagrams to circulant digraphs of arbitrary degree by presenting monomial ideals\\u000a as a natural

Domingo Gomez-perez; Jaime Gutierrez; Álvar Ibeas

2005-01-01

342

Ideal Resistivity in One Dimension  

Microsoft Academic Search

We analyze the ideal resistivity, rho, of a one-dimensional metal at high temperatures. We have adapted a diagrammatic technique introduced by Berezinskii in the context of static disorder. Retaining the dominant vertices in the limit of vanishing electron-phonon coupling constant, g, and phonon frequency, Omega0, with g2Omega0 finite, we obtain a dc resistivity rho~T2 instead of T. The result may

Anupam Madhukar; Morrel H. Cohen

1977-01-01

343

Norm inequalities in operator ideals  

Microsoft Academic Search

In this paper we introduce a new technique for proving norm inequalities in operator ideals with a unitarily invariant norm. Among the well-known inequalities which can be proved with this technique are the Löwner–Heinz inequality, inequalities relating various operator means and the Corach–Porta–Recht inequality. We prove two general inequalities and from them we derive several inequalities by specialization, many of

Gabriel Larotonda

2008-01-01

344

Electric field effects on the quantum efficiency of Cesium-iodide photocathodes in gas media.  

National Technical Information Service (NTIS)

We have measured the quantum efficiency (QE) of Cesium iodide photocathodes as a function of the electric field strength in a parallel-plate geometry, in CH(sub 4), C(sub 2)H(sub 6) AND i-C(sub 4)H(sub 10) both in charge collection and multiplication mode...

A. Breskin R. Chechik A. Buzulutskov D. Vartsky G. Malamud

1993-01-01

345

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. [1] Eyring, H., Powell, R.E., Duffy, G.H., and Parlin, R.B., ``The stability of detonation,'' Chem. Rev. 45, 69-181 (1949). [2] Haskins, P.J., Cook, M.D., and Wood, A.D., ``On the dependence of critical diameter and velocity decrement at failure on the burn law,'' in proceedings of the 33rd International Pyrotechnics Seminar, Fort Collins, Co, USA, 385-391 (2006).

Haskins, P. J.; Cook, M. D.

2007-06-01

346

Thermodynamic properties and ideal-gas enthalpies of formation for butyl vinyl ether, 1,2-dimethoxyethane, methyl glycolate, bicyclo[2.2.1]hept-2-ene, 5-vinylbicyclo[2.2.1]hept-2-ene, trans-azobenzene, butyl acrylate, di-tert-butyl ether, and hexane-1,6-diol  

Microsoft Academic Search

Ideal-gas enthalpies of formation of butyl vinyl ether, 1,2-dimethoxyethane, methyl glycolate, bicyclo-[2.2.1]hept-2-ene, 5-vinylbicyclo[2.2.1]hept-2-ene, trans-azobenzene, butyl acrylate, di-tert-butyl ether, and hexane-1,6-diol are reported. Enthalpies of fusion were determined for bicyclo[2.2.1]hept-2-ene and trans-azobenzene. 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

W. V. Steele; R. D. Chirico; S. E. Knipmeyer; A. Nguyen; N. K. Smith

1996-01-01

347

Electric field effects on the quantum efficiency of Cesium-iodide photocathodes in gas media  

Microsoft Academic Search

We have measured the quantum efficiency (QE) of Cesium iodide photocathodes as a function of the electric field strength in a parallel-plate geometry, in CH4, C2H6, and i-C4H10 both in charge collection and multiplication modes. It was found that in the collection mode the QE value in gases is lower compared to that of vacuum and is independent on the

A. Breskin; A. Buzulutskov; R. Chechik; D. Vartsky; G. Malamud; P. Mine

1993-01-01

348

Observation of dipole-dipole interaction in a degenerate quantum gas.  

PubMed

We have investigated the expansion of a Bose-Einstein condensate of strongly magnetic chromium atoms. The long-range and anisotropic magnetic dipole-dipole interaction leads to an anisotropic deformation of the expanding chromium condensate which depends on the orientation of the atomic dipole moments. Our measurements are consistent with the theory of dipolar quantum gases and show that a chromium condensate is an excellent model system to study dipolar interactions in such gases. PMID:16241705

Stuhler, J; Griesmaier, A; Koch, T; Fattori, M; Pfau, T; Giovanazzi, S; Pedri, P; Santos, L

2005-10-01

349

Observation of Dipole-Dipole Interaction in a Degenerate Quantum Gas  

SciTech Connect

We have investigated the expansion of a Bose-Einstein condensate of strongly magnetic chromium atoms. The long-range and anisotropic magnetic dipole-dipole interaction leads to an anisotropic deformation of the expanding chromium condensate which depends on the orientation of the atomic dipole moments. Our measurements are consistent with the theory of dipolar quantum gases and show that a chromium condensate is an excellent model system to study dipolar interactions in such gases.

Stuhler, J.; Griesmaier, A.; Koch, T.; Fattori, M.; Pfau, T. [5. Physikalisches Institut, Universitaet Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart (Germany); Giovanazzi, S. [Physikalisches Institut, Universitaet Tuebingen, Auf der Morgenstelle 14, 72076 Tuebingen (Germany); Pedri, P.; Santos, L. [Institut fuer Theoretische Physik III, Universitaet Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart (Germany)

2005-10-07

350

The Gas Sensing Mechanism of the Low-Dimension Carbon Composites with Metal Oxide Quantum Dots  

NASA Astrophysics Data System (ADS)

In this paper, we obtained three kinds of composite materials which were composed of metal oxides (ZnO, SnO2 and TiO2) and CNTs through catalytic pyrolysis method. Then we carried out the surface morphology, field emission and gas sensitivity properties test for them, and summarized the composite ways of metal oxides/CNTs by comparing three composite properties such as the changes in field emission and gas sensing properties, so that we might explore a set of preparation methods and processes of high performance gas sensors. At the same time, the study of field emission can also provide some improved methods to the traditional display technology.

Ma, Hui; Zhou, Weiman; Yuan, Wu; Jie, Zheng; Liu, Hongzhong; Li, Xin.

351

Logarithmic oscillators: ideal Hamiltonian thermostats.  

PubMed

A logarithmic oscillator (in short, log-oscillator) behaves like an ideal thermostat because of its infinite heat capacity: When it weakly couples to another system, time averages of the system observables agree with ensemble averages from a Gibbs distribution with a temperature T that is given by the strength of the logarithmic potential. The resulting equations of motion are Hamiltonian and may be implemented not only in a computer but also with real-world experiments, e.g., with cold atoms. PMID:23004579

Campisi, Michele; Zhan, Fei; Talkner, Peter; Hänggi, Peter

2012-06-22

352

Nearly ideal lens optimization procedure  

SciTech Connect

The Brixner lens optimization procedure, in which a lens design moves steadily toward diffraction-limited performance, samples lens performance with bundles of precisely traced skew rays, analyzes performance by calculating the image-spot sizes and positions, and optimizes performance in a least squares system that minimizes the lateral ray deviations from their ideal image points. Minimizing the rms image-spot size minimizes the rms optical path differences (OPDs). Minimizing the rms OPDs also optimizes the diffraction modulation transfer function (DMTF). Minimizing the image-spot size and position errors also minimizes and balances the Seidel and higher-order aberrations. 23 refs., 2 figs.

Brixner, B.

1985-01-01

353

Fractional topological excitations and quantum phase transition in a bilayer two-dimensional electron gas adjacent to a superconductor film  

NASA Astrophysics Data System (ADS)

We study a bilayer two-dimension-electron-gas (2DEG) adjacent to a type-II superconductor thin film with a pinned vortex lattice. We find that with increasing interlayer tunneling, the system of half-filling presents three phases: gapped phase-I (topological insulator), gapless critical phase-II (metal), and gapped phase-III (band insulator). The total Hall conductance for phase-I/III is 2/0 e2/h , and has nonquantized values in phase-II. The excitation (response to topological defect, a local vortex defect) in these three phases shows different behaviors due to the topological property of the system, including fractional charge e/2 for each layer in phase-I. While in the case of quarter-filling, the system undergoes a quantum phase transition from metallic phase to topological insulator phase.

Hao, Ningning; Zhang, Wei; Wang, Zhigang; Wang, Yupeng; Zhang, Ping

2010-03-01

354

QUALITAS: A mid-infrared spectrometer for sensitive trace gas measurements based on quantum cascade lasers in CW operation  

NASA Astrophysics Data System (ADS)

We describe QUALITAS, a mid-infrared spectrometer with multipass absorption cell, suitable to apply lead chalcogenide and quantum cascade lasers as light sources in CW operation at cryogenic temperatures. The instrument has been designed for the measurement of trace gases such as carbon monoxide, nitrous oxide or methane in the clean atmosphere from space-restricted and experimentally challenging mobile platforms. The design involves compact optics, which fit into the space limitations of a standard aircraft borne 19 in. rack (W×H×D~48×45×40 cm3). The instrument allows high sensitivity (~5×10-7 m-1 Hz-1/2 during flight; ~1×10-7 m-1 Hz-1/2 in the laboratory) in combination with a low sample gas volume (0.3 L) for high time resolution (<1 s, using a moderately sized pump). We employ a combination of elements already applied in former spectrometers in our laboratory and a novel arrangement of spherical mirrors. The design criteria, the optical, electronic and mechanical set-up are described in detail. The application of the instrument to measure atmospheric concentrations of carbon monoxide is discussed, using both, a lead chalcogenide as well as a DFB-structured quantum cascade laser (R3 line at 2158.3 cm-1).

Kormann, R.; Königstedt, R.; Parchatka, U.; Lelieveld, J.; Fischer, H.

2005-07-01

355

Growth initiation for buried-heterostructure quantum-cascade laser regrowth by gas-source molecular-beam epitaxy  

NASA Astrophysics Data System (ADS)

We describe an optimized growth sequence for the overgrowth of quantum cascade laser ridge sidewalls with semi-insulating InP:Fe. A thin In0.52Al0.48As spacer layer grown on the laser ridge sidewalls before InP:Fe prevents the formation of void defects at this interface, which appear otherwise. Elimination of these voids at the sidewalls has led to more than a two-fold improvement of the thermal conductivity in a 7 ?m wide buried-heterostructure quantum-cascade laser overgrown with InP:Fe by gas-source molecular-beam epitaxy, and has allowed the continuous-wave operation of the laser up to 210 K. The measured thermal conductance is Gth=500 W/K cm2 at 210 K and Gth=1020 W/K cm2 at 127 K, comparable to the state of the art literature values obtained with regrowth by metal-organic vapor-phase epitaxy.

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

2014-07-01

356

ENVIRONMENTAL ANALYSIS BY AB INITIO QUANTUM MECHANICAL COMPUTATION AND GAS CHROMATOGRAPHY/FOURIER TRANSFORM INFRARED SPECTROMETRY.  

EPA Science Inventory

Computational chemistry, in conjunction with gas chromatography/mass spectrometry/Fourier transform infrared spectrometry (GC/MS/FT-IR), was used to tentatively identify seven tetrachlorobutadiene (TCBD) isomers detected in an environmental sample. Computation of the TCBD infrare...

357

Fast Quantum Computing with Buckyballs  

Microsoft Academic Search

We have found that encapsulated atoms in fullerene molecules, which carry a spin, can be used for fast quantum computing. We describe the scheme for performing quantum computations, going through the preparation of the qubit state and the realization of a two-qubit quantum gate. When we apply a static magnetic field to each encased spin, we find out the ideal

Maria Silvia Garelli; Feodor V Kusmartsev

2005-01-01

358

A magnetohydrodynamic model for quantum plasmas  

SciTech Connect

The quantum hydrodynamic model for charged particle systems is extended to the cases of nonzero magnetic fields. In this way, quantum corrections to magnetohydrodynamics are obtained starting from the quantum hydrodynamical model with magnetic fields. The importance of the quantum corrections is described by a parameter H which can be significant in dense astrophysical plasmas. The quantum magnetohydrodynamic model is analyzed in the infinite conductivity limit. The conditions for equilibrium in ideal quantum magnetohydrodynamics are established. Translationally invariant exact equilibrium solutions are obtained in the case of the ideal quantum magnetohydrodynamic model.

Haas, F. [Universidade do Vale do Rio dos Sinos-UNISINOS, Avenue Unisinos, 950 93022-000 Sao Leopoldo, Rio Grande do Sul (Brazil)

2005-06-15

359

Rokhsar-Kivelson model of quantum dimers as a gas of free fermionic strings  

SciTech Connect

The (2+1)-dimensional quantum dimer model on a square lattice, proposed by Rokhsar and Kivelson as a theory of layered superconductivity, is shown to be equivalent to a many-body theory of free, transversely oscillating strings obeying Fermi statistics. A Jordan-Wigner construction for string field operators is presented. Topological defects are shown to be linearly confined in pairs by dynamical strings. Exact upper and lower bounds are placed on the ground-state energy and the string tension. It is argued that the system is in a spin-fluid phase and that there is no gap in the excitation spectrum.

Orland, P. (The Niels Bohr Institute, Blegdamsvej 17, Dk-2100, Copenhagen O (Denmark) The City University of New York, Baruch College, 17 Lexington Ave., New York, New York 10010 (United States))

1994-02-01

360

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

361

Finite-temperature quantum Monte Carlo study of the one-dimensional polarized Fermi gas  

SciTech Connect

Quantum Monte Carlo (QMC) techniques are used to provide an approximation-free investigation of the phases of the one-dimensional attractive Hubbard Hamiltonian in the presence of population imbalance. The temperature at which the ''Fulde-Ferrell-Larkin-Ovchinnikov'' (FFLO) phase is destroyed by thermal fluctuations is determined as a function of the polarization. It is shown that the presence of a confining potential does not dramatically alter the FFLO regime and that recent experiments on trapped atomic gases likely lie just within the stable temperature range.

Wolak, M. J. [Centre for Quantum Technologies, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Rousseau, V. G. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Miniatura, C. [Centre for Quantum Technologies, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); INLN, Universite de Nice-Sophia Antipolis, CNRS, 1361 route des Lucioles, F-06560 Valbonne (France); Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Gremaud, B. [Centre for Quantum Technologies, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Laboratoire Kastler Brossel, UPMC-Paris 6, ENS, CNRS, 4 Place Jussieu, F-75005 Paris (France); Scalettar, R. T. [Physics Department, University of California, Davis, California 95616 (United States); Batrouni, G. G. [Centre for Quantum Technologies, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); INLN, Universite de Nice-Sophia Antipolis, CNRS, 1361 route des Lucioles, F-06560 Valbonne (France)

2010-07-15

362

Adiabatic Quantum Motors  

NASA Astrophysics Data System (ADS)

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.

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

2013-08-01

363

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

364

Perpetual motion of a mobile impurity in a one-dimensional quantum gas  

NASA Astrophysics Data System (ADS)

Consider an impurity particle injected in a degenerate one-dimensional gas of noninteracting fermions (or, equivalently, Tonks-Girardeau bosons) with some initial momentum p0. We examine the infinite-time value of the momentum of the impurity, p?, as a function of p0. A lower bound on |p?(p0)| is derived under fairly general conditions. The derivation, based on the existence of the lower edge of the spectrum of the host gas, does not resort to any approximations. The existence of such bound implies the perpetual motion of the impurity in a one-dimensional gas of noninteracting fermions or Tonks-Girardeau bosons at zero temperature. The bound admits an especially simple and useful form when the interaction between the impurity and host particles is everywhere repulsive.

Lychkovskiy, O.

2014-03-01

365

Molecular structure of chloro-dodecafluorosubphthalocyanato boron(III) by gas-phase electron diffraction and quantum chemical calculations.  

PubMed

The molecular structure of the chloro-dodecafluorosubphthalocyaninato boron(III) (F-SubPc) was determined with use of Gas Electron Diffraction (GED) and high-level quantum chemical calculations. The present results show that the F-SubPc molecule has a cone-shaped configuration, isoindole units are not planar, and the pyrrole ring has an envelope conformation. The structure parameters in the gas phase are determined. Some structural details can be observed such as the dihedral angle about the bond connecting the pyrrole ring and the benzene ring being ca. 174 degrees . High-level theoretical calculations with several extended basis sets for this molecule have been carried out. The calculations are in very good agreement with experimental methods: X-ray and GED. Nevertheless, some disagreements particularly related to the B-Cl bond distance found in GED are discussed. Vibrational frequencies were computed obtaining eight values below 100 cm-1 and three bending potentials were examined. They suggest that this molecule is very flexible. PMID:17447746

Samdal, S; Volden, H V; Ferro, V R; García de la Vega, J M; Gonzalez-Rodríguez, D; Torres, T

2007-05-24

366

Quantum Monte Carlo study of the dynamic structure factor in the gas and crystal phase of hard-sphere bosons  

NASA Astrophysics Data System (ADS)

We investigate the dynamic structure factor of a system of Bose particles at zero temperature using quantum Monte Carlo methods. Interactions are modeled using a hard-sphere potential of size a and simulations are performed for values of the gas parameter na3 ranging from the dilute regime up to densities n where the thermodynamically stable phase is a solid. With increasing density, we observe a crossover of the dispersion of elementary excitations from a Bogoliubov-type spectrum to a phonon-maxon-roton curve and the emergence of a broad multiphonon contribution accompanying the single-quasiparticle peak. In particular, for na3=0.2138, which corresponds to superfluid 4He at equilibrium density, the extracted spectrum turns out to be in good agreement with the experimental energy-momentum dispersion relation in the roton region and for higher momenta. The behavior of the spectral function at the same density in the stable solid and metastable gas phase above the freezing point is also discussed.

Rota, R.; Tramonto, F.; Galli, D. E.; Giorgini, S.

2013-12-01

367

Manifestation of quantum resonances and antiresonances in a finite-temperature dilute atomic gas  

SciTech Connect

We investigate the effect of temperature on resonant and antiresonant dynamics in a dilute atomic gas kicked periodically by a standing-wave laser field. Our numerical calculations are based on a Monte Carlo method for an incoherent mixture of noninteracting plane waves, and show that the atomic dynamics are highly sensitive to the initial momentum width of the gas. We explain this sensitivity by examining the time evolution of individual atomic center-of-mass momentum eigenstates with varying quasimomentum, and we determine analytic expressions for the evolution of the second-order momentum moment to illustrate the range of behaviors.

Saunders, M.; Halkyard, P. L.; Challis, K. J.; Gardiner, S. A. [Department of Physics, Durham University, Rochester Building, South Road, Durham DH1 3LE (United Kingdom)

2007-10-15

368

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

369

Manifestation of quantum resonances and antiresonances in a finite-temperature dilute atomic gas  

NASA Astrophysics Data System (ADS)

We investigate the effect of temperature on resonant and antiresonant dynamics in a dilute atomic gas kicked periodically by a standing-wave laser field. Our numerical calculations are based on a Monte Carlo method for an incoherent mixture of noninteracting plane waves, and show that the atomic dynamics are highly sensitive to the initial momentum width of the gas. We explain this sensitivity by examining the time evolution of individual atomic center-of-mass momentum eigenstates with varying quasimomentum, and we determine analytic expressions for the evolution of the second-order momentum moment to illustrate the range of behaviors.

Saunders, M.; Halkyard, P. L.; Challis, K. J.; Gardiner, S. A.

2007-10-01

370

Quantum oscillations of the two-dimensional hole gas at atomically flat diamond surfaces  

NASA Astrophysics Data System (ADS)

Shubnikov-de Haas oscillations are observed in atomically flat hydrogen-terminated diamond surfaces with high-density hole carriers introduced by the electric field effect using an ionic liquid. The Shubnikov-de Haas oscillations depend only on the magnetic field component perpendicular to the diamond surface, thus providing evidence of two-dimensional Fermi surfaces. The effective masses estimated from the temperature dependence of the oscillations are close to the cyclotron effective masses of the valence band maxima in diamond. The estimated quantum scattering time is one order of magnitude longer than the transport scattering time and indicates that the carrier mobility is locally as high as several thousand cm2/V s at low temperature.

Takahide, Yamaguchi; Okazaki, Hiroyuki; Deguchi, Keita; Uji, Shinya; Takeya, Hiroyuki; Takano, Yoshihiko; Tsuboi, Hidetoshi; Kawarada, Hiroshi

2014-06-01

371

Relaxation explosion of a quantum degenerate exciton gas in Cu2O  

NASA Astrophysics Data System (ADS)

We present our recent experimental studies on anomalous luminescence and its connection to Bose-Einstein condensation (BEC) transition of dark excitons in a bulk semiconductor. Our sensitive and quantitative detection of this nonluminous quasi-particle using hydrogen-like internal transitions allows obtaining continuous spectra of dark excitons using a quantum cascade laser. According to quantitative measurements on the two-body inelastic collision cross section of excitons, the system needs to be cooled to sub-Kelvin temperatures. We discuss in detail our recent observation of an explosive phenomenon when the BEC criterion is satisfied (Yoshioka et al 2011 Nature Commun. 2 328) for trapped excitons using a helium-3 refrigerator, and outline a plausible scenario when the BEC transition occurs in an inelastic environment. We also discuss how to increase the condensate fraction in order to study the unique ground state of many-body electric excitations in solids.

Yoshioka, Kosuke; Kuwata-Gonokami, Makoto

2012-05-01

372

Variational mixed quantum/semiclassical simulation of dihalogen guest and rare-gas solid host dynamics.  

PubMed

A variational mixed quantum-semiclassical theory for the internal nuclear dynamics of a small molecule and the induced small-amplitude coherent motion of a low-temperature host medium is developed, tested, and used to simulate the temporal evolution of nonstationary states of the internal molecular and surrounding medium degrees of freedom. In this theory, termed the Fixed Vibrational Basis/Gaussian Bath (FVB/GB) method, the system is treated fully quantum mechanically while Gaussian wave packets are used for the bath degrees of freedom. An approximate time-dependent wave function of the entire model is obtained instead of just a reduced system density matrix, so the theory enables the analysis of the entangled system and bath dynamics that ensues following initial displacement of the internal-molecular (system) coordinate from its equilibrium position. The norm- and energy-conserving properties of the propagation of our trial wave function are natural consequences of the Dirac-Frenkel-McLachlan variational principle. The variational approach also stabilizes the time evolution in comparison to the same ansatz propagated under a previously employed locally quadratic approximation to the bath potential and system-bath interaction terms in the bath-parameter equations of motion. Dynamics calculations are carried out for molecular iodine in a 2D krypton lattice that reveal both the time-course of vibrational decoherence and the details of host-atom motion accompanying energy dissipation and dephasing. This work sets the stage for the comprehensive simulation of ultrafast time-resolved optical experiments on small molecules in low-temperature solids. PMID:25053307

Cheng, Xiaolu; Cina, Jeffrey A

2014-07-21

373

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

374

An ideal ocular nutritional supplement?  

PubMed

The role of nutritional supplementation in prevention of onset or progression of ocular disease is of interest to health care professionals and patients. The aim of this review is to identify those antioxidants most appropriate for inclusion in an ideal ocular nutritional supplement, suitable for those with a family history of glaucoma, cataract, or age-related macular disease, or lifestyle factors predisposing onset of these conditions, such as smoking, poor nutritional status, or high levels of sunlight exposure. It would also be suitable for those with early stages of age-related ocular disease. Literature searches were carried out on Web of Science and PubMed for articles relating to the use of nutrients in ocular disease. Those highlighted for possible inclusion were vitamins A, B, C and E, carotenoids beta-carotene, lutein, and zeaxanthin, minerals selenium and zinc, and the herb, Ginkgo biloba. Conflicting evidence is presented for vitamins A and E in prevention of ocular disease; these vitamins have roles in the production of rhodopsin and prevention of lipid peroxidation respectively. B vitamins have been linked with a reduced risk of cataract and studies have provided evidence supporting a protective role of vitamin C in cataract prevention. Beta-carotene is active in the prevention of free radical formation, but has been linked with an increased risk of lung cancer in smokers. Improvements in visual function in patients with age-related macular disease have been noted with lutein and zeaxanthin supplementation. Selenium has been linked with a reduced risk of cataract and activates the antioxidant enzyme glutathione peroxidase, protecting cell membranes from oxidative damage while zinc, although an essential component of antioxidant enzymes, has been highlighted for risk of adverse effects. As well as reducing platelet aggregation and increasing vasodilation, Gingko biloba has been linked with improvements in pre-existing field damage in some patients with normal tension glaucoma. We advocate that vitamins C and E, and lutein/zeaxanthin should be included in our theoretically ideal ocular nutritional supplement. PMID:15228513

Bartlett, Hannah; Eperjesi, Frank

2004-07-01

375

Open path trace gas measurements using a pulse quantum cascade laser  

NASA Astrophysics Data System (ADS)

We report the application of a pulsed distributed feedback (DFB) quantum cascade laser (QCL) for a 6 km long open path spectroscopic monitoring of ozone, ammonia, water vapor and carbon dioxide. The thermal chirp during a 200 ns long excitation pulse is used for fast wavelength scanning of about 1 cm-1 in the spectral range 1043-1049 cm-1. This tuning method has the advantage of not being affected by the atmospheric turbulence, which is essential for long open path measurements. The intrinsic haze immunity of mid IR laser sources is an additional important advantage of mid-IR open path spectroscopy, compared with standard UV-visible DOAS. The third major advantage of the method reported is the possibility to measure many more organic and inorganic atmospheric species compared to the UV-visible DOAS. The obtained sensitivity for ozone and ammonia of the order of 10 ppm.m retrieved from the absorption spectra for averaging times less than 1 min are comparable with teh UV DOAS values. The open path of 6 km is covered using average laser power of less than 0.2 mW, which shows much higher efficiency of spectroscopy using narrowband laser source, compared to broadband light as Xe lamp.

Taslakov, Marian; Simeonov, Valentin; van den Bergh, Hubert

2005-04-01

376

Excitonic Energy Shifts in CdMnTe/CdMgTe Quantum Wells under Resonant Excitation in Presence of 2D Carrier Gas  

NASA Astrophysics Data System (ADS)

Systematic studies of amplitude and energy changes of excitonic lines in a strong excitation regime were carried out by a pump-probe method. The series of samples containing quantum wells with well width from 80 Å to 140 Å was investigated. One 80 Å sample was n-doped with iodine, the rest of the quantum wells were intentionally undoped but contained a 2D gas of free holes. Its density could be varied by changing an intensity of additional illumination. The resonant creation of high population of e1hh1 excitons causes the energetic blue shift of the same due to interactions between excitons. The blue shift did not depend on the concentration of 2D gas of carriers whereas it did depend on the power of excitation beam. Model calculations of absorption show qualitative agreement with the experimental data.

Trajnerowicz, A.; Golnik, A.; Kossacki, P.; Bardyszewski, W.; Wiater, M.; Karczewski, G.; Wojtowicz, T.

2008-11-01

377

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

2008-10-01

378

Practicing Identity: A Crafty Ideal?  

NASA Astrophysics Data System (ADS)

This paper focuses on the materialization of technological practices as a form of identity expression. Contextual analyses of a Mycenaean workshop area in the Late Bronze Age citadel of Tiryns (Argolis, Greece) are presented to investigate the interaction of different artisans under changing socio-political and economic circumstances. The case study indicates that although certain technological practices are often linked to specific crafts, they do not necessarily imply the separation of job tasks related to the working of one specific material versus another. Shared technological practices and activities, therefore, may be a factor in shaping cohesive group identities of specialized artisans. Since tracing artisans' identities is easier said than done on the basis of excavated materials alone, we employ the concepts of multiple chaînes opératoires combined with cross-craft interactions as a methodology in order to retrieve distinctive sets of both social and technological practices from the archaeological remains. These methodological concepts are not restricted to a specific set of steps in the production cycle, but ideally encompass reconstructing contexts of extraction, manufacture, distribution and discard/reuse for a range of artefacts. Therefore, these concepts reveal both technological practices, and, by contextualising these technological practices in their spatial layout, equally focus on social contacts that would have taken place during any of these actions. Our detailed contextual study demonstrates that the material remains when analysed in their entirety are complementary to textual evidence. In this case study they even form a source of information on palatial spheres of life about which the fragmentary Linear B texts, so far, remain silent.

Brysbaert, A.; Vetters, M.

379

The facet ideal of a simplicial complex  

Microsoft Academic Search

.  ?To a simplicial complex, we associate a square-free monomial ideal in the polynomial ring generated by its vertex set over\\u000a a field. We study algebraic properties of this ideal via combinatorial properties of the simplicial complex. By generalizing\\u000a the notion of a tree from graphs to simplicial complexes, we show that ideals associated to trees satisfy sliding depth condition,\\u000a and

Sara Faridi

2002-01-01

380

Gorenstein rings and irreducible parameter ideals  

Microsoft Academic Search

Given a Noetherian local ring (R,m) it is shown that there exists an integer\\u000al such that R is Gorenstein if and only if some system of parameters contained\\u000ain m^l generates an irreducible ideal. We obtain as a corollary that R is\\u000aGorenstein if and only if every power of the maximal ideal contains an\\u000airreducible parameter ideal.

Thomas Marley; Mark W. Rogers; Hideto Sakurai

2008-01-01

381

On the ideals of equivariant tree models  

Microsoft Academic Search

We introduce equivariant tree models in algebraic statistics, which unify and generalise existing tree models such as the\\u000a general Markov model, the strand symmetric model, and group-based models such as the Jukes–Cantor and Kimura models. We focus\\u000a on the ideals of such models. We show how the ideals for general trees can be determined from the ideals for stars. A

Jan Draisma; Jochen Kuttler

2009-01-01

382

A quartz enhanced photo-acoustic gas sensor based on a custom tuning fork and a terahertz quantum cascade laser.  

PubMed

An innovative quartz enhanced photoacoustic (QEPAS) gas sensing system operating in the THz spectral range and employing a custom quartz tuning fork (QTF) is described. The QTF dimensions are 3.3 cm × 0.4 cm × 0.8 cm, with the two prongs spaced by ?800 ?m. To test our sensor we used a quantum cascade laser as the light source and selected a methanol rotational absorption line at 131.054 cm(-1) (?3.93 THz), with line-strength S = 4.28 × 10(-21) cm mol(-1). The sensor was operated at 10 Torr pressure on the first flexion QTF resonance frequency of 4245 Hz. The corresponding Q-factor was 74?760. Stepwise concentration measurements were performed to verify the linearity of the QEPAS signal as a function of the methanol concentration. The achieved sensitivity of the system is 7 parts per million in 4 seconds, corresponding to a QEPAS normalized noise-equivalent absorption of 2 × 10(-10) W cm(-1) Hz(-1/2), comparable with the best result of mid-IR QEPAS systems. PMID:24167816

Patimisco, Pietro; Borri, Simone; Sampaolo, Angelo; Beere, Harvey E; Ritchie, David A; Vitiello, Miriam S; Scamarcio, Gaetano; Spagnolo, Vincenzo

2014-05-01

383

Gas Phase Photoacoustic Sensor at 8.41 mu m Using Quartz Tuning Forks and Amplitude Modulated Quantum Cascade Lasers  

SciTech Connect

We demonstrate the performance of a novel long-wave infrared photoacoustic laser absorbance spectrometer for gas-phase species using an amplitude modulated (AM) quantum cascade (QC) laser and a quartz tuning fork microphone. Photoacoustic signal was generated by focusing the output of a Fabry-Perot QC laser operating at 8.41 ?m between the legs of a quartz tuning fork which served as a transducer for the transient acoustic pressure wave. The QC laser was modulated at the resonant frequency of the tuning fork (32.8 kHz) and delivered a modest 5.3 mW at the tuning fork. This spectrometer was calibrated using the infrared absorber Freon-134a by performing a simultaneous absorption measurement using a 35 cm absorption cell. The NEAS of this instrument was determined to be 2 x 10{sup -8} W cm-1 Hz{sup -1/2}. A corresponding theoretical analysis of the instrument sensitivity is presented and is capable of quantitatively reproducing the experimental NEAS, indicating that the fundamental sensitivity of this technique is limited by the noise floor of the tuning fork itself.

Wojcik, Michael D.; Phillips, Mark C.; Cannon, Bret D.; Taubman, Matthew S.

2006-10-01

384

Equilibrium structure of maleic anhydride from gas-phase electron diffraction (GED) and quantum-chemical studies  

NASA Astrophysics Data System (ADS)

The molecular structure of maleic anhydride was reinvestigated by the gas-phase electron diffraction (GED) method because it was determined with large uncertainties in a previous study. To take into account vibrational effects, the corrections to the experimental bond lengths ( r a) were calculated using quadratic and cubic force constants from high-level ab initio calculations (MP2/aug-cc-pVTZ). The determined equilibrium structural parameters ( re(C-C) = 1.485(1) Å, re(C dbnd C) = 1.332(1) Å, re(C-O) = 1.386(1) Å, re(C dbnd O) = 1.192(1) Å, ? e(C-C dbnd C) = 107.8(1)°, ? e(O dbnd C-C) = 129.2(2)°) are very close to the parameters of the r s structure from a previous microwave spectroscopic (MW) study. Some aspects of the combined analysis of GED and MW data are discussed. The agreement of the experimental rotational constants, B0(i) (MW), corrected for anharmonic effects, Be(i) (MW), with the rotational constants derived from the determined equilibrium geometry, is better than with Be(i) values from quantum-chemical calculations.

Vogt, Natalja; Altova, Ekaterina P.; Karasev, Nikolai M.

2010-08-01

385

[A trace methane gas sensor using mid-infrared quantum cascaded laser at 7.5 microm].  

PubMed

Presented is a compact instrument developed for in situ high-stable and sensitive continuous measurement of trace gases in air, with results shown for ambient methane (CH4) concentration accurate, real-time and in-situ. This instrument takes advantage of recent technology in thermoelectrically cooling (TEC) pulsed Fabry-Perot (FP) quantum cascaded laser (QCL) driving in a pulse mode operating at 7.5 microm ambient temperature to cover a fundamental spectral absorption band near v4 of CH4. A high quality Liquid Nitrogen (LN) cooled Mercury Cadmium Telluride (HgCdTe) mid-infrared (MIR) detector is used along with a total reflection coated gold ellipsoid mirror offering 20 cm single pass optical absorption in an open-path cell to achieve stability of 5.2 x 10(-3) under experimental condition of 200 micromol x mol(-1) measured ambient CH4. The instrument integrated software via time discriminating electronics technology to control QCL provides continuous quantitative trace gas measurements without calibration. The results show that the instrument can be applied to field measurements of gases of environmental concern. Additional, operator could substitute a QCL operating at a different wavelength to measure other gases. PMID:23387197

Chen, Chen; Dang, Jing-Min; Huang, Jian-Qiang; Yang, Yue; Wang, Yi-Ding

2012-11-01

386

Quantum Lattice-Gas Algorithm for Quantum Turbulence - CAP Simulations on 12,288 Cores of Cray XT-5 Einstein at NAVO  

Microsoft Academic Search

A novel unitary quantum lattice algorithm is developed to explore quantum turbulence. Because of its low memory requirements and its near perfect parallelization to the full 12,288 cores on the Cray XT5, simulations were run up to spatial grids of 5,7603. The Gross-Pitaevskii equation, which describes the ground state of a Bose Einstein condensate (BEC), is solved and it is

George Vahala; Jeffrey Yepez; Min Soe; Linda Vahala; Sean Ziegeler

2009-01-01

387

Momentum relaxation of a mobile impurity in a one-dimensional quantum gas  

NASA Astrophysics Data System (ADS)

We investigate the time evolution of the momentum of an impurity atom injected into a degenerate Tonks-Girardeau gas. We establish that given an initial momentum p0 the impurity relaxes to a steady state with a nonvanishing momentum p?. The nature of the steady state is found to depend drastically on whether the masses of the impurity and the host are equal. This is due to multiple coherent scattering processes leading to a resonant interaction between the impurity and the host in the case of equal masses. The dependence of p? on p0 remains nontrivial even in the limit of vanishing interaction between the impurity and host particles. In this limit p?(p0) is found explicitly.

Burovski, E.; Cheianov, V.; Gamayun, O.; Lychkovskiy, O.

2014-04-01

388

Quantum networking with photons and trapped atoms (Invited)  

NASA Astrophysics Data System (ADS)

Distributed quantum information processing requires a reliable quantum memory and a faithful carrier of quantum information. Atomic qubits have very long coherence times and are thus excellent candidates for quantum information storage, whereas photons are ideal for the transport of quantum information as they can travel long distances with a minimum of decoherence. We discuss the theoretical and experimental combination of these two systems and their use for not only quantum information transfer but also scalable quantum computation architectures.

Moehring, D. L.; Madsen, M. J.; Younge, K. C.; Kohn, R. N., Jr.; Maunz, P.; Duan, L.-M.; Monroe, C.; Blinov, B. B.

2007-02-01

389

Quantum networking with photons and trapped atoms (Invited)  

SciTech Connect

Distributed quantum information processing requires a reliable quantum memory and a faithful carrier of quantum information. Atomic qubits have very long coherence times and are thus excellent candidates for quantum information storage, whereas photons are ideal for the transport of quantum information as they can travel long distances with a minimum of decoherence. We discuss the theoretical and experimental combination of these two systems and their use for not only quantum information transfer but also scalable quantum computation architectures.

Moehring, D. L.; Madsen, M. J.; Younge, K. C.; Kohn, R. N. Jr.; Maunz, P.; Duan, L.-M.; Monroe, C.; Blinov, B. B. [FOCUS Center and Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States); Department of Physics, University of Washington, Seattle, Washington 98195 (United States)

2007-02-15

390

Quantum Computation of Fluid Dynamics  

Microsoft Academic Search

Presented is a quantum lattice gas for Navier-Stokes fluid dynamicssimulation. The quantum lattice-gas transport equation at the microscopicscale is presented as a generalization of the classical lattice-gastransport equation. A special type of quantum computer network is proposedthat is suitable for implementing the quantum lattice gas. Thequantum computer network undergoes a partial collapse of the wavefunctionat every time step of the

Jeffrey Yepez

1998-01-01

391

Ring graphs and complete intersection toric ideals  

Microsoft Academic Search

We study the family of graphs whose number of primitive cycles equals its cycle rank. It is shown that this family is precisely the family of ring graphs. Then we study the complete intersection property of toric ideals of bipartite graphs and oriented graphs. An interesting application is that complete intersection toric ideals of bipartite graphs correspond to ring graphs

Isidoro Gitler; Enrique Reyes; Rafael H. Villarreal

2010-01-01

392

Maintaining ideal body weight counseling sessions  

SciTech Connect

The purpose of this program is to provide employees with the motivation, knowledge and skills necessary to maintain ideal body weight throughout life. The target audience for this program, which is conducted in an industrial setting, is the employee 40 years of age or younger who is at or near his/her ideal body weight.

Brammer, S.H.

1980-10-09

393

Interplay of spin dynamics of trions and two-dimensional electron gas in a n-doped CdTe single quantum well  

NASA Astrophysics Data System (ADS)

We used the photoinduced Faraday rotation technique to study the low-temperature spin relaxation of excitons, trions, and two-dimensional electron gas in n-doped single CdTe/CdMgTe quantum wells with different concentrations of electrons. A pulsed (ps) optical excitation tuned to an exciton line allows the simple observation of the exciton spin relaxation (18 36 ps), whereas an excitation resonant with a trion state demonstrates a biexponential spin relaxation. The shorter characteristic time (40±10 ps) then belongs to the photocreated hole spin relaxation, and the longer one (180±20 ps) is attributed to the spin relaxation of the electron gas, initially polarized through the creation of trions by using circularly polarized light. This interpretation is confirmed by the oscillations shown by the photoinduced Faraday rotation in a transverse magnetic field, which provide the Landé factor of the free electron in a CdTe quantum well (|ge?|=1.342±0.001). Finally, the observed interplay of trions and electron gas polarization is quantitatively explained with a system of four rate equations involving the spin populations of trions and those of the electron gas.

Tribollet, J.; Bernardot, F.; Menant, M.; Karczewski, G.; Testelin, C.; Chamarro, M.

2003-12-01

394

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

NASA Astrophysics Data System (ADS)

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 (C3 sbnd C4 sbnd C5) and (C2 sbnd C3 sbnd C5) is 154.1°. The direction of the deviation is the same as that of the side acetamide group. The piracetam molecule is stabilized in the gas phase by an intramolecular hydrogen bond between the N9H 2 group and the oxygen O6, bonded to C2. The principal structural parameters ( re, Å and ?e, degrees; uncertainties are 3 ?LS values) were found to be: r(?3 sbnd ?4) = 1.533(1), r(C4 sbnd C5) = 1.540(1), r(N1 sbnd C5) = 1.456(1), r(C2 sbnd C3) = 1.520(1), r(N1 sbnd C7) = 1.452(1), r(C7 sbnd C8) = 1.537(1), r(N1 sbnd C2) = 1.365(2), r(C8 sbnd N9) = 1.360(2), r(C2 dbnd O6) = 1.229(1), r(C8 dbnd O10) = 1.221(1), ?C2 sbnd N1 sbnd C5 = 113.4(6), ?N1 sbnd C2 sbnd C3 = 106.9(6), ?N1 sbnd C7 sbnd C8 = 111.9(6), ?C7 sbnd C8 sbnd N9 = 112.5(6), ?N1 sbnd C2 sbnd O6 = 123.0(4), ?C3 sbnd N1 sbnd C7 = 120.4(4), ?C7 sbnd C8 sbnd O10 = 120.2(4), ?C5 sbnd N1 sbnd C2 sbnd O6 = 170(6), ?C3 sbnd C2 sbnd N1 sbnd C7 = 178(6), ?C2 sbnd N1 sbnd C7 sbnd C8 = 84.2, ?N1 sbnd C7 sbnd C8 sbnd O10 = 111.9.

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

2010-12-01

395

Uniform electron gas at warm, dense matter conditions  

NASA Astrophysics Data System (ADS)

A simple, practical model for computing the equilibrium thermodynamics and structure of the uniform electron gas (jellium) by classical strong-coupling methods is proposed. Conditions addressed are those of interest for recent studies of warm dense matter: solid densities and temperatures from zero to plasma states. An effective pair potential and coupling constant are introduced, incorporating the ideal gas, low density, and weak-coupling quantum limits. The resulting parameter-free, analytic model is illustrated by the calculation of the pair correlation function via strong-coupling classical liquid state theory. The results compare favorably with the first finite-temperature restricted path integral Monte Carlo simulations reported recently.

Dutta, Sandipan; Dufty, James

2013-06-01

396

Expansion of the Gibbs potential for quantum many-body systems: general formalism with applications to the spin glass and the weakly nonideal Bose gas.  

PubMed

For general quantum systems the power expansion of the Gibbs potential and consequently the power expansion of the self-energy is derived in terms of the interaction strength. Employing a generalization of the projector technique, a compact representation of the general terms of the expansion results. The general aspects of the approach are discussed with special emphasis on the effects characteristic for quantum systems. The expansion is systematic and leads directly to contributions beyond the mean field of all thermodynamic quantities. These features are explicitly demonstrated and illustrated for two nontrivial systems, the infinite-range quantum spin glass and the weakly interacting Bose gas. The Onsager terms of both systems are calculated, which represent the first beyond-mean-field contributions. For the spin glass Thouless-Anderson-Palmer-like equations are presented and discussed in the paramagnetic region. The investigation of the Bose gas leads to a beyond-mean-field thermodynamic description. At the Bose-Einstein condensation temperature complete agreement is found with the results presented recently by alternative techniques. PMID:16486238

Plefka, T

2006-01-01

397

Ideal regularization for learning kernels from labels.  

PubMed

In this paper, we propose a new form of regularization that is able to utilize the label information of a data set for learning kernels. The proposed regularization, referred to as ideal regularization, is a linear function of the kernel matrix to be learned. The ideal regularization allows us to develop efficient algorithms to exploit labels. Three applications of the ideal regularization are considered. Firstly, we use the ideal regularization to incorporate the labels into a standard kernel, making the resulting kernel more appropriate for learning tasks. Next, we employ the ideal regularization to learn a data-dependent kernel matrix from an initial kernel matrix (which contains prior similarity information, geometric structures, and labels of the data). Finally, we incorporate the ideal regularization to some state-of-the-art kernel learning problems. With this regularization, these learning problems can be formulated as simpler ones which permit more efficient solvers. Empirical results show that the ideal regularization exploits the labels effectively and efficiently. PMID:24824969

Pan, Binbin; Lai, Jianhuang; Shen, Lixin

2014-08-01

398

On ideal AFROC and FROC observers  

NASA Astrophysics Data System (ADS)

Detection of multiple lesions (signals) in images is a medically important task and Free-response Receiver Operating Characteristic (FROC) analyses and its variants, such as Alternative FROC (AFROC) analyses, are commonly used to quantify performance in such tasks. However, ideal observers that optimize FROC or AFROC performance metrics have not yet been formulated in the general case. If available, such ideal observers may turn out to be valuable for imaging system optimization and in the design of computer aided diagnosis (CAD) techniques for lesion detection in medical images. In this paper we derive ideal AFROC and FROC observers. They are ideal in that they maximize, amongst all decision strategies, the area under the associated AFROC or FROC curve. In addition these ideal observers minimize Bayes risk for particular choices of cost constraints. Calculation of observer performance for these ideal observers is computationally quite complex. We can reduce this complexity by considering forms of these observers that use false positive reports derived from signal-absent images only. We present a performance comparison of our ideal AFROC observer versus that of a more conventional scan-statistic observer.

Khurd, Parmeshwar; Liu, Bin; Gindi, Gene

2009-02-01

399

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

400

AlGaN/AlN multiple quantum wells grown by MOVPE on AlN templates using nitrogen as a carrier gas  

NASA Astrophysics Data System (ADS)

Al xGa 1-xN/AlN multiple quantum wells (MQWs) structures were grown by metalorganic vapour phase epitaxy (MOVPE) on pseudo AlN substrates using nitrogen as a carrier gas. Results of X-ray diffraction (XRD) and reciprocal space mapping (RSM) indicated no sign of strain relaxation in the quantum wells with respect to the AlN substrate. The MQW parameters such as thicknesses, growth rates and material compositions were extracted from XRD measurements and demonstrated an agreement with our growth conditions. No indication of parasitic reactions between ammonia and trimethyl-aluminium (TMAl) was detected in our growth process. Optical measurements revealed well-defined photoluminescence peaks at 288 and 280 nm, which are in a good agreement with the transmission experimental data. The piezo-electric field value in the studied structures was estimated to be 900 kV/cm.

Gautier, S.; Aggerstam, T.; Pinos, A.; Marcinkevi?ius, S.; Liu, K.; Shur, M.; O'Malley, S. M.; Sirenko, A. A.; Djebbour, Z.; Migan-Dubois, A.; Moudakir, T.; Ougazzaden, A.

2008-11-01

401

Alloy-disorder scattering of the interacting electron gas in quantum wells and heterostructures of Al x Ga1 - x As  

NASA Astrophysics Data System (ADS)

The question whether alloy disorder is screened or unscreened is of fundamental importance. Therefore, we calculate the mobility of the interacting two-dimensional electron gas as realized in Al x Ga1 - x As quantum wells and heterostructures in the presence of alloy-disorder scattering. For the screening we use the randomphase approximation and we include many-body effects due to exchange and correlation. We propose to determine the alloy disorder potential V AD from mobility measurements. If we use V AD = 1.04 eV we can explain recent experimental results obtained for quantum wells and heterostructures with ultrahigh mobility. From the anomalous linear temperature dependence of the mobility measured in heterostructures, we conclude that the alloy disorder is screened. More experiments are needed to confirm the screening of the alloy disorder and we propose some measurements.

Gold, A.

2013-12-01

402

Spin Fluctuations, Susceptibility, and the Dipole Oscillation of a Nearly Ferromagnetic Fermi Gas  

SciTech Connect

We discuss the spin fluctuations and the role played by the magnetic susceptibility in an atomic Fermi gas interacting with a positive scattering length. Both thermal and zero-temperature quantum fluctuations are considered. Using a sum rule approach and recent ab initio Monte Carlo results for the magnetic susceptibility of uniform matter, we provide explicit predictions for the frequency of the spin dipole oscillation of a gas trapped by a harmonic potential and discuss the deviations from the ideal gas behavior when the system approaches the ferromagnetic transition. The role of the Landau's parameters in the characterization of the magnetic properties is also discussed.

Recati, Alessio; Stringari, Sandro [Dipartimento di Fisica, Universita di Trento and INO-CNR BEC Center, I-38123 Povo (Italy)

2011-02-25

403

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

404

Idealized Modeling of Circulation Under Landfast Ice.  

National Technical Information Service (NTIS)

Idealized analytical and numerical models are used to elucidate the effects of a spatially variable landfast ice cover on under ice circulation. Three separate forcing mechanisms are investigated; lateral inflow onto an ice covered shelf (an elevated sea ...

J. L. Kasper T. Weingartner

2011-01-01

405

Toric ideals of homogeneous phylogenetic models  

Microsoft Academic Search

We consider the model of phylogenetic trees in which every node of the tree is an observed, binary random variable and the transition probabilities are given by the same matrix on each edge of the tree. The ideal of invariants of this model is a toric ideal in ℂ[p;i1;…i;n;]. We are able to compute the Göbner basis and minimal generating

Nicholas Eriksson

2004-01-01

406

Sahaja: an Indian ideal of mental health.  

PubMed

Sahaja is an Indian ideal of mental and spiritual health that has received special emphasis in the Sikh scriptures--especially, the Adi Granth. Since the concept of sahaja has long been associated with mystical thought and practice, its description has become shrouded in peculiar esoteric terminologies. It is the purpose of this communication to divest sahaja of its esoteric, mystic connotations and to redefine it as a mental health ideal in the context of contemporary conditions. PMID:1114187

Neki, J S

1975-02-01

407

Ideal shrinking and expansion of discrete sequences  

NASA Technical Reports Server (NTRS)

Ideal methods are described for shrinking or expanding a discrete sequence, image, or image sequence. The methods are ideal in the sense that they preserve the frequency spectrum of the input up to the Nyquist limit of the input or output, whichever is smaller. Fast implementations that make use of the discrete Fourier transform or the discrete Hartley transform are described. The techniques lead to a new multiresolution image pyramid.

Watson, Andrew B.

1986-01-01

408

Ideal classes of three dimensional Sklyanin algebras  

Microsoft Academic Search

In this paper we classify graded reflexive ideals, up to isomorphism and\\u000ashift, in certain three dimensional Artin-Schelter regular algebras. This\\u000aclassification is similar to the classification of right ideals in the first\\u000aWeyl algebra, a problem that was completely settled recently. The situation we\\u000aconsider is substantially more complicated however.

KOEN DE NAEGHEL; MICHEL VAN DEN BERGH

2005-01-01

409

Guiding center equations for ideal magnetohydrodynamic modes  

SciTech Connect

Guiding center simulations are routinely used for the discovery of mode-particle resonances in tokamaks, for both resistive and ideal instabilities and to find modifications of particle distributions caused by a given spectrum of modes, including large scale avalanches during events with a number of large amplitude modes. One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through {delta}B-vector={nabla} Multiplication-Sign ({xi}-vector Multiplication-Sign B-vector), however, perturbs the magnetic topology, introducing extraneous magnetic islands in the field. A proper treatment of an ideal perturbation involves a full Lagrangian displacement of the field due to the perturbation and conserves magnetic topology as it should. In order to examine the effect of ideal magnetohydrodynamic modes on particle trajectories, the guiding center equations should include a correct Lagrangian treatment. Guiding center equations for an ideal displacement {xi}-vector are derived which preserve the magnetic topology and are used to examine mode particle resonances in toroidal confinement devices. These simulations are compared to others which are identical in all respects except that they use the linear representation for the field. Unlike the case for the magnetic field, the use of the linear field perturbation in the guiding center equations does not result in extraneous mode particle resonances.

White, R. B. [Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543 (United States)

2013-04-15

410

Guiding Center Equations for Ideal Magnetohydrodynamic Modes  

SciTech Connect

Guiding center simulations are routinely used for the discovery of mode-particle resonances in tokamaks, for both resistive and ideal instabilities and to find modifications of particle distributions caused by a given spectrum of modes, including large scale avalanches during events with a number of large amplitude modes. One of the most fundamental properties of ideal magnetohydrodynamics is the condition that plasma motion cannot change magnetic topology. The conventional representation of ideal magnetohydrodynamic modes by perturbing a toroidal equilibrium field through ?~B = ? X (? X B) however perturbs the magnetic topology, introducing extraneous magnetic islands in the field. A proper treatment of an ideal perturbation involves a full Lagrangian displacement of the field due to the perturbation and conserves magnetic topology as it should. In order to examine the effect of ideal magnetohydrodynamic modes on particle trajectories the guiding center equations should include a correct Lagrangian treatment. Guiding center equations for an ideal displacement ? are derived which perserve the magnetic topology and are used to examine mode particle resonances in toroidal confinement devices. These simulations are compared to others which are identical in all respects except that they use the linear representation for the field. Unlike the case for the magnetic field, the use of the linear field perturbation in the guiding center equations does not result in extraneous mode particle resonances.

Roscoe B. White

2013-02-21

411

The Statistical Mechanics of Ideal MHD Turbulence  

NASA Technical Reports Server (NTRS)

Turbulence is a universal, nonlinear phenomenon found in all energetic fluid and plasma motion. In particular. understanding magneto hydrodynamic (MHD) turbulence and incorporating its effects in the computation and prediction of the flow of ionized gases in space, for example, are great challenges that must be met if such computations and predictions are to be meaningful. Although a general solution to the "problem of turbulence" does not exist in closed form, numerical integrations allow us to explore the phase space of solutions for both ideal and dissipative flows. For homogeneous, incompressible turbulence, Fourier methods are appropriate, and phase space is defined by the Fourier coefficients of the physical fields. In the case of ideal MHD flows, a fairly robust statistical mechanics has been developed, in which the symmetry and ergodic properties of phase space is understood. A discussion of these properties will illuminate our principal discovery: Coherent structure and randomness co-exist in ideal MHD turbulence. For dissipative flows, as opposed to ideal flows, progress beyond the dimensional analysis of Kolmogorov has been difficult. Here, some possible future directions that draw on the ideal results will also be discussed. Our conclusion will be that while ideal turbulence is now well understood, real turbulence still presents great challenges.

Shebalin, John V.

2003-01-01

412

Low-energy electron scattering by cubane: Resonant states and Ramsauer-Townsend features from quantum calculations in the gas phase  

NASA Astrophysics Data System (ADS)

Calculations are carried out, using a nonempirical modeling of the interaction potential and solving the quantum scattering coupled channel equations, for low energy electron scattering from cubane (C8H8) molecules in the gas phase. Total integral cross sections are obtained and partial contributions are analyzed for the most important irreducible representations that describe the continuum electron in the Oh molecular symmetry. Several trapping resonances are found and analyzed in terms of the molecular-type features of the resonant electron states associated with them. A Ramsauer-Townsend minimum is also found and its possible behavior related to features of the scattering length as k-->0.

Gianturco, F. A.; Lucchese, R. R.; Grandi, A.; Sanna, N.

2004-03-01

413

Short Introduction to Quantum Computation.  

National Technical Information Service (NTIS)

This paper presents a quantum lattice gas method useful for nano- scale computing and quantum computing. There are several important issues that arise when one considers fabricating nano-scale computing devices, and these issues are different depending on...

J. Yepez

1996-01-01

414

Development of an external cavity quantum cascade laser spectrometer at 7.5 ?m for gas detection  

NASA Astrophysics Data System (ADS)

We report the development of an external cavity quantum cascade laser spectrometer at 7.5 ?m. The quantum cascade laser and its anti-reflection coating were specially developed for this application. We provide details of the external cavity design and data processing. A continuous wave emission is demonstrated from 1,293 up to 1,350 cm-1. A preliminary test of the spectrometer was realized by measurements on acetone and phosphoryl chloride.

Mammez, D.; Vallon, R.; Parvitte, B.; Mammez, M.-H.; Carras, M.; Zéninari, V.

2014-02-01

415

The influence of electron degeneracy on the contribution of bound states to the non-ideal hydrogen plasma EOS  

Microsoft Academic Search

An equation of state for a weakly non-ideal hydrogen plasma was developed to account for the influence of degenerate electrons on the contribution of bound states. Asymptotic expressions for the contribution were derived and compared. In this work, the reduced model EOS includes the ideal gas contribution with degenerate electrons and relativistic corrections, bound states contribution and the Coulomb interaction

Andrey N Starostin; Vitali C Roerich; Victor K Gryaznov; Vladimir E Fortov; Igor L Iosilevskiy

2009-01-01

416

Symmetries and currents of the ideal and unitary Fermi gases  

NASA Astrophysics Data System (ADS)

The maximal algebra of symmetries of the free single-particle Schrödinger equation is determined and its relevance for the holographic duality in non-relativistic Fermi systems is investigated. This algebra of symmetries is an infinite dimensional extension of the Schrödinger algebra, it is isomorphic to the Weyl algebra of quantum observables, and it may be interpreted as a non-relativistic higher-spin algebra. The associated infinite collection of Noether currents bilinear in the fermions are derived from their relativistic counterparts via a light-like dimensional reduction. The minimal coupling of these currents to background sources is rewritten in a compact way by making use of Weyl quantisation. Pushing forward the similarities with the holographic correspondence between the minimal higher-spin gravity and the critical O( N ) model, a putative bulk dual of the unitary and the ideal Fermi gases is briefly discussed.

Bekaert, Xavier; Meunier, Elisa; Moroz, Sergej

2012-02-01

417

Stability of detonations for an idealized condensed-phase model  

NASA Astrophysics Data System (ADS)

The stability of travelling wave Chapmanvon Neumannring type is formulated for a general system that incorporates the idealized gas and condensed-phase (liquid or solid) detonation models. The general model consists of a two-component mixture with a one-step irreversible reaction between reactant and product. The reaction rate has both temperature and pressure sensitivities and has a variable reaction order. The idealized condensed-phase model assumes a pressure-sensitive reaction rate, a constant-=3, and invokes the strong shock limit. A linear stability analysis of the steady, planar, ZND detonation wave for the general model is conducted using a normal-mode approach. An asymptotic analysis of the eigenmode structure at the end of the reaction zone is conducted, and spatial boundedness (closure) conditions formally derived, whose precise form depends on the magnitude of the detonation overdrive and reaction order. A scaling analysis of the transonic flow region for ChapmanJouguet detonations. Neutral stability boundaries are calculated for the idealized condensed-phase model for one- and two-dimensional perturbations. Comparisons of the growth rates and frequencies predicted by the normal-mode analysis for an unstable detonation are made with a numerical solution of the reactive Euler equations. The numerical calculations are conducted using a new, high-order algorithm that employs a shock-fitting strategy, an approach that has significant advantages over standard shock-capturing methods for calculating unstable detonations. For the idealized condensed-phase model, nonlinear numerical solutions are also obtained to study the long-time behaviour of one- and two-dimensional unstable Chapman-Jouguet ZND waves.

Short, M.; Anguelova, I. I.; Aslam, T. D.; Bdzil, J. B.; Henrick, A. K.; Sharpe, G. J.

418

Variation of the emission characteristics of an atom located near an ideally conducting conical surface  

SciTech Connect

The line width and the emission frequency of an atom located near the vertex of an ideally conducting cone or inside a conical cavity in an ideal conductor are analysed. It is shown that the influence of the vertex diminishes with decrease in the vertex angle. On the other hand, the line width and the emission frequency of an atom located in a conical cavity may both increase and decrease greatly, depending on the position of the atom and on the vertex angle of the cavity. The results obtained may prove useful in the development of both monatomic microlasers and spectrally selective near-field nanoscopes. (physical basis of quantum electronics)

Klimov, Vasilii V; Perventsev, Ya A [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

1999-10-31

419

Thermodynamic properties and ideal-gas enthalpies of formation for butyl vinyl ether, 1,2-dimethoxyethane, methyl glycolate, bicyclo[2.2.1]hept-2-ene, 5-vinylbicyclo[2.2.1]hept-2-ene, trans-azobenzene, butyl acrylate, di-tert-butyl ether, and hexane-1,6-diol  

SciTech Connect

Ideal-gas enthalpies of formation of butyl vinyl ether, 1,2-dimethoxyethane, methyl glycolate, bicyclo-[2.2.1]hept-2-ene, 5-vinylbicyclo[2.2.1]hept-2-ene, trans-azobenzene, butyl acrylate, di-tert-butyl ether, and hexane-1,6-diol are reported. Enthalpies of fusion were determined for bicyclo[2.2.1]hept-2-ene and trans-azobenzene. 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 bicyclo[2.2.1]hept-2-ene. For butyl vinyl ether and 1,2-dimethoxyethane, 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 bicyclo[2.2.1]hept-2-ene, 5-vinylbicyclo[2.2.1]hept-2-ene, trans-azobenzene, butyl acrylate, and di-tert-butyl ether. Group-additivity parameters or ring-correction terms useful in the application of the Benson 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). IIT Research Inst.] [National Inst. for Petroleum and Energy Research, Bartlesville, OK (United States). IIT Research Inst.

1996-11-01

420

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

NASA Astrophysics Data System (ADS)

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.

Bhaskaran, Renjith; Sarma, Manabendra

2013-07-01

421

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

422

LATTICE GAS SUPERFLUID  

Microsoft Academic Search

A quantum computer, with controlled decoherence, constructed out of a lattice based array of qubits undergoing a particular local and unitary evolution is eectively a bose condensate. Presented is a coupled lattice gas system, a quantum lattice gas and a classical lattice gas in mutual contact through \\\\external\\

JEFFREY YEPEZ

423

Quantum computation: algorithms and implementation in quantum dot devices  

NASA Astrophysics Data System (ADS)

In this thesis, we explore several aspects of both the software and hardware of quantum computation. First, we examine the computational power of multi-particle quantum random walks in terms of distinguishing mathematical graphs. We study both interacting and non-interacting multi-particle walks on strongly regular graphs, proving some limitations on distinguishing powers and presenting extensive numerical evidence indicative of interactions providing more distinguishing power. We then study the recently proposed adiabatic quantum algorithm for Google PageRank, and show that it exhibits power-law scaling for realistic WWW-like graphs. Turning to hardware, we next analyze the thermal physics of two nearby 2D electron gas (2DEG), and show that an analogue of the Coulomb drag effect exists for heat transfer. In some distance and temperature, this heat transfer is more significant than phonon dissipation channels. After that, we study the dephasing of two-electron states in a single silicon quantum dot. Specifically, we consider dephasing due to the electron-phonon coupling and charge noise, separately treating orbital and valley excitations. In an ideal system, dephasing due to charge noise is strongly suppressed due to a vanishing dipole moment. However, introduction of disorder or anharmonicity leads to large effective dipole moments, and hence possibly strong dephasing. Building on this work, we next consider more realistic systems, including structural disorder systems. We present experiment and theory, which demonstrate energy levels that vary with quantum dot translation, implying a structurally disordered system. Finally, we turn to the issues of valley mixing and valley-orbit hybridization, which occurs due to atomic-scale disorder at quantum well interfaces. We develop a new theoretical approach to study these effects, which we name the disorder-expansion technique. We demonstrate that this method successfully reproduces atomistic tight-binding techniques, while using a fraction of the computational resources and providing considerably more physical insight. Using this technique, we demonstrate that large dipole moments can exist between valley states in disordered systems, and calculate corrections to intervalley tunnel rates..

Gamble, John King

424

Rabindranath Tagore's Ideals of Aesthetic Education.  

ERIC Educational Resources Information Center

Rabindranath Tagore (1861-1941) was an Indian educator who established the Santiniketan schools, which replicated to a large extent the ashram or forest school of ancient India, where gurus and their pupils lived in a residential hermitage. Tagore's aesthetic ideals of education as manifested in the school at Santiniketan are discussed. (RM)

Lal, Swati

1984-01-01

425

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

426

Ideal Spatial Adaptation by Wavelet Shrinkage  

Microsoft Academic Search

With ideal spatial adaptation, an oracle furnishes information about how best toadapt a spatially variable estimator, whether piecewise constant, piecewise polynomial,variable knot spline, or variable bandwidth kernel, to the unknown function. Estimationwith the aid of an oracle offers dramatic advantages over traditional linear estimationby nonadaptive kernels; however, it is a priori unclear whether such performance canbe obtained by a procedure

1994-01-01

427

Developing Ideal Student and Residency Programs.  

ERIC Educational Resources Information Center

The Veterans Administration (VA) is a primary educator of optometry students, with each college of optometry being affiliated with at least one VA hospital. Ideally, fourth-year optometry students rotate through a specific VA facility for about 12 weeks. Guidelines are designed to provide optimum care in a rich learning environment. (MSE)

Selvin, Gerald J.

1993-01-01

428

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

429

The bodhisattva ideal and organ transplantation  

Microsoft Academic Search

Mahayana Buddhism has as its ideal thebodhisattva (Sanskrit: enlightenment being). The bodhisattva practices are based on the Six Perfections, the first of which is the perfection of giving. This perfection of giving involves not only one's possessions but also includes one's body. Numerous scriptural quotations relate to bodhisattvas offering their bodies and organs to those in need. Therefore, Mahayana Buddhism

Phillip A. Lecso

1991-01-01

430

Ideal light concentrators with reflector gaps  

DOEpatents

A cylindrical or trough-like radiant energy concentration and collection device is provided. The device includes an energy absorber, a glazing enveloping the absorber and a reflective wall. The ideal contour of the reflective wall is determined with reference to a virtual absorber and not the actual absorber cross section.

Winston, Roland (Chicago, IL)

1980-01-01

431

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

432

Using Galois Ideals for Computing Relative Resolvents  

Microsoft Academic Search

In this paper we show that some ideals which occur in Galois theory are generated by triangular sets of polynomials. This geometric property seems important for the development of symbolic methods in Galois theory. It may and should be exploited in order to obtain more efficient algorithms, and it enables us to present a new algebraic method for computing relative

Philippe Aubry; Annick Valibouze

2000-01-01

433

Ideal orifice pulse tube refrigerator performance  

NASA Technical Reports Server (NTRS)

The recent development of orifice pulse tube refrigerators has raised questions as to what limits their ultimate performance. Using an analogy to the Stirling cycle refrigerator, the efficiency (cooling power per unit input power) of an ideal orifice pulse tube refrigerator is shown to be T1/T0, the ratio of the cold temperature to the hot temperature.

Kittel, P.

1992-01-01

434

HLLC solver for ideal relativistic MHD  

NASA Astrophysics Data System (ADS)

An approximate Riemann solver of Godunov type for ideal relativistic magnetohydrodynamic equations (RMHD) named as HLLC ("C" denotes contact) is developed. In HLLC the Riemann fan is approximated by two intermediate states, which are separated by the entropy wave. Numerical tests show that HLLC resolves contact discontinuity more accurately than the Harten-Lax-van Leer (HLL) method and an isolated contact discontinuity exactly.

Honkkila, V.; Janhunen, P.

2007-05-01

435

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

436

Career Education as an Educational Ideal  

ERIC Educational Resources Information Center

Supporters of career education infer that it can meet ideal standards better than any other alternative. It is questionable whether this claim should be made for concepts evolved for dealing with the limited concerns of career development. Education is not simply a means for turning individuals into contributing economic producers. (SA)

Smith, Philip L.

1973-01-01

437

Axisymmetric ideal MHD stellar wind flow  

NASA Technical Reports Server (NTRS)

The ideal MHD equations are reduced to a single equation under the assumption of axisymmetric flow. A variational principle from which the equation is derivable is given. The characteristics of the equation are briefly discussed. The equation is used to rederive the theorem of Gussenhoven and Carovillano.

Heinemann, M.; Olbert, S.

1978-01-01

438

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

Microsoft Academic Search

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

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

2004-01-01

439

Creating, maintaining, and breaking of quantum entanglement in quantum operations  

NASA Astrophysics Data System (ADS)

We study the evolution of entanglement in quantum gates in terms of Choi-Jamiolkowski relative states negativity. SQiSW (generated by XY-interaction), CNOT and CZ gates are considered in ideal case and under amplitude and phase relaxation. In addition, we consider an important task of analyzing entanglement of "pure" noise, which is obtained by deducting an ideal gate from a noisy one.

Bogdanov, Yu. I.; Chernyavskiy, A. Yu.; Holevo, A. S.; Lukichev, V. F.; Orlikovsky, Alexander A.; Bantysh, B. I.

2013-01-01

440

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

441

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  

NASA Astrophysics Data System (ADS)

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 shot-noise limited sensitivity and high resolution, capable of resolving rovibrational states and Doppler lineshapes. Both reactions yield inverted vibrational populations. For the HCl reaction, strongly bimodal rotational distributions are observed, suggesting microscopic branching of the reaction mechanism. Alternatively, such structure may result from a quantum-resonance mediated reaction similar to those found in the well-characterized F + HD system. For the H2O reaction, a small, but significant, branching into v = 2 is particularly remarkable because this manifold is accessible only via the additional center of mass collision energy in the crossed jets. Rotationally hyperthermal HF is also observed. Ab initio calculations of the transition state geometry suggest mechanisms for both rotational and vibrational excitation. Exothermic chemical reaction dynamics at the gas-liquid interface have been investigated by colliding a supersonic jet of F atoms with liquid squalane (C30H62), a low vapor pressure hydrocarbon compatible with the high vacuum environment. IR spectroscopy provides absolute HF( v,J) product densities and Doppler resolved velocity component distributions perpendicular to the surface normal. Compared to analogous gas-phase F + hydrocarbon reactions, the liquid surface is a more effective "heat sink," yet vibrationally excited populations reveal incomplete thermal accommodation with the surface. Non-Boltzmann J-state populations and hot Doppler lineshapes that broaden with HF excitation indicate two competing scattering mechanisms: (i) a direct reactive scattering channel, whereby newly formed molecules leave the surface without equilibrating, and (ii) a partially accommodated fraction that shares vibrational, rotational, and translational energy with the liquid surface before returning to the gas phase. Finally, a velocity map ion imaging apparatus has been implemented to investigate reaction dynamics in crossed molecular beams. Resonantly enhanced multiphoton ionization (REMPI) results in rotational, vibrational, and electronic state selectivity. Velocity map imaging measurements provide differential cross sections and information about the internal energy distribution of the undetected collision partner.

Zolot, Alexander M.

442

Roton-Type Mode Softening in a Quantum Gas with Cavity-Mediated Long-Range Interactions  

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

443

Ultra-shallow quantum dots in an undoped GaAs/AlGaAs two-dimensional electron gas  

SciTech Connect

We report quantum dots fabricated on very shallow 2-dimensional electron gases, only 30 nm below the surface, in undoped GaAs/AlGaAs heterostructures grown by molecular beam epitaxy. Due to the absence of dopants, an improvement of more than one order of magnitude in mobility (at 2 Multiplication-Sign 10{sup 11} cm{sup -2}) with respect to doped heterostructures with similar depths is observed. These undoped wafers can easily be gated with surface metallic gates patterned by e-beam lithography, as demonstrated here from single-level transport through a quantum dot showing large charging energies (up to 1.75 meV) and excited state energies (up to 0.5 meV).

Mak, W. Y.; Sfigakis, F.; Beere, H. E.; Farrer, I.; Griffiths, J. P.; Jones, G. A. C.; Ritchie, D. A. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom)] [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Das Gupta, K. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom) [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Klochan, O.; Hamilton, A. R. [School of Physics, University of New South Wales, Sydney (Australia)] [School of Physics, University of New South Wales, Sydney (Australia)

2013-03-11

444

High-power room-temperature continuous-wave operation of quantum cascade lasers grown by GasMBE  

Microsoft Academic Search

Very high power continuous-wave quantum cascade lasers are demonstrated in the mid-infrared (3 - 6 mum) wavelength range. lambda~6 mum high-reflectivity coated QCLs are demonstrated producing over 370 mW continuous-wave power at room temperature with continuous-wave operation up to 333 K. Advanced heterostructure geometries, including the use of a thick electroplated gold, epilayer-side heat sink and a buried-ridge heterostructure are

Allan J. Evans; John E. David; Lisa C. Doris; Jae S. Yu; Steven Slivken; Manijeh Razeghi

2004-01-01

445

Ideal photon number amplifier and duplicator  

NASA Technical Reports Server (NTRS)

The photon number-amplification and number-duplication mechanism are analyzed in the ideal case. The search for unitary evolutions leads to consider also a number-deamplification mechanism, the symmetry between amplification and deamplification being broken by the integer-value nature of the number operator. Both transformations, amplification and duplication, need an auxiliary field which, in the case of amplification, turns out to be amplified in the inverse way. Input-output energy conservation is accounted for using a classical pump or through frequency-conversion of the fields. Ignoring one of the fields is equivalent to considering the amplifier as an open system involving entropy production. The Hamiltonians of the ideal devices are given and compared with those of realistic systems.

Dariano, G. M.

1992-01-01

446

Ideal efficiency of propellers - Theodorsen revisited  

NASA Technical Reports Server (NTRS)

Theodorsen's 1948 analog evaluation of the parameters governing the ideal (friction-free) efficiency of propellers is updated and extended by computer. The results are presented both in his format and in a much more convenient one by Kramer that avoids iteration: curves of power coefficient at constant ideal efficiency are plotted vs propeller advance coefficient. The curves for a wide range of blade numbers are collapsed into just three sets (with some approximation) by use of multiple, shifted (and distorted) abscissae scales. Along with an overview of Theodorsen's theory, analytic asymptotic results at low and high advance coefficients are given. At the low end, the disagreement with actuator disk theory is given support and physical interpretation. At the high end, exact agreement is found with the thrust of a slender twisted delta propeller.

Ribner, H. S.; Foster, S. P.

1990-01-01

447

Cubic structures and ideal class groups  

Microsoft Academic Search

We establish a generalization of Breen's theory of cubic structures on line bundles over group schemes. We study such “n-cubic structures” inductively using multiextensions. As a result we obtain information on the set of isomorphism classes of line bundles with n-cubic structures over finite multiplicative group schemes over Spec(Z) by relating this set to certain corresponding eigenspaces of ideal class

Georgios Pappas

2005-01-01

448

Bose Einstein Condensation of Ideal Bose Gases  

NASA Astrophysics Data System (ADS)

Bose Einstein condensation (BEC) is studied for ideal boson gases with a wide class of the dispersion relations. A criterion of the BEC, the transition temperature and a fraction of the condensate are calculated under the appropriate thermodynamic limits. The correspondence between the dispersion relation (spectrum) and the trap potential is shown. This gives the criterion for the trap shape and the dimensionality of the system.

Ieda, Jun'ichi; Tsurumi, Takeya; Wadati, Miki

2001-05-01

449

The nonstationary ideal in the Rmax extension  

Microsoft Academic Search

The forcing construction ?max<\\/sub>, invented by W. Hugh Woodin, produces a\\u000amodel whose collection of subsets of ?? is in some sense maximal.\\u000aIn this paper we study the Boolean algebra induced by the nonstationary ideal\\u000aon ?? in this model. Among other things we show that the induced\\u000aquotient does not have a simply definable form. We also prove

Paul B. Larson

2007-01-01

450

CMHOG: Code for Ideal Compressible Hydrodynamics  

NASA Astrophysics Data System (ADS)

CMHOG (Connection Machine Higher Order Godunov) is a code for ideal compressible hydrodynamics based on the Lagrange-plus-remap version of the piecewise parabolic method (PPM) of Colella & Woodward (1984, J. Comp. Phys., 74, 1). It works in one-, two- or three-dimensional Cartesian coordinates with either an adiabatic or isothermal equation of state. A limited amount of extra physics has been added using operator splitting, including optically-thin radiative cooling, and chemistry for combustion simulations.

Piner, B. Glenn; Stone, James M.; Teuben, Peter J.

2011-01-01

451

Digital Quantum Simulation of Spin Systems in Superconducting Circuits  

NASA Astrophysics Data System (ADS)

We propose the implementation of a digital quantum simulator for prototypical spin models in a circuit quantum electrodynamics architecture. We consider the feasibility of the quantum simulation of Heisenberg and frustrated Ising models in transmon qubits coupled to coplanar waveguide microwave resonators. Furthermore, we analyze the time evolution of these models and compare the ideal spin dynamics with a realistic version of the proposed quantum simulator. Finally, we discuss the key steps for developing a toolbox of digital quantum simulators in superconducting circuits.

Heras, U. Las; Mezzacapo, A.; Lamata, L.; Filipp, S.; Wallraff, A.; Solano, E.

2014-05-01

452

Benchmark quantum Monte Carlo calculations of the ground-state kinetic, interaction and total energy of the three-dimensional electron gas.  

PubMed

We report variational and diffusion quantum Monte Carlo ground-state energies of the three-dimensional electron gas using a model periodic Coulomb interaction and backflow corrections for N = 54, 102, 178, and 226 electrons. We remove finite-size effects by extrapolation and we find lower energies than previously reported. Using the Hellman-Feynman operator sampling method introduced in Gaudoin and Pitarke (2007 Phys. Rev. Lett. 99 126406), we compute accurately, within the fixed-node approximation, the separate kinetic and interaction contributions to the total ground-state energy. The difference between the interaction energies obtained from the original Slater-determinant nodes and the backflow-displaced nodes is found to be considerably larger than the difference between the corresponding kinetic energies. PMID:21389370

Gurtubay, I G; Gaudoin, R; Pitarke, J M

2010-02-17

453

Interaction effects in a two-dimensional electron gas in a random magnetic field: Implications for composite fermions and the quantum critical point  

NASA Astrophysics Data System (ADS)

We consider a clean two-dimensional interacting electron gas subject to a random perpendicular magnetic field h(r) . The field is nonquantizing in the sense that Nh , a typical flux into the area ?F2 in the units of the flux quantum ( ?F is the de Broglie wavelength), is small, Nh?1 . If the spatial scale ? of change of h(r) is much larger than ?F , the electrons move along semiclassical trajectories. We demonstrate that a weak-field-induced curving of the trajectories affects the interaction-induced electron lifetime in a singular fashion: it gives rise to the correction to the lifetime with a very sharp energy dependence. The correction persists within the interval ?˜?0=EFNh2/3 much smaller than the Fermi energy EF . It emerges in the third order in the interaction strength; the underlying physics is that a small phase volume ˜(?/EF)1/2 for scattering processes involving two electron-hole pairs is suppressed by curving. An even more surprising effect that we find is that disorder-averaged interaction correction to the density of states ??(?) exhibits oscillatory behavior periodic in (?/?0)3/2 . In our calculations of interaction corrections, a random field is incorporated via the phases of the Green functions in the coordinate space. We discuss the relevance of the new low-energy scale for realizations of a smooth random field in composite fermions and in disordered phase of spin-fermion model of ferromagnetic quantum criticality.

Sedrakyan, T. A.; Raikh, M. E.

2008-03-01

454

Toward three-dimensional quantum state-resolved collision dynamics at the gas-liquid interface: theoretical investigation of incident angle.  

PubMed

Quantum state-resolved energy transfer dynamics at the gas-liquid interface are explored through a comparison of classical molecular dynamics (MD) simulations and previously reported experimental studies (Perkins, B. G.; et al. J. Phys. Chem. A 2008, 112, 9234). Theoretically, large scale MD trajectory calculations have been performed for collisions of CO(2) with a model fluorinated self-assembled monolayer surface (F-SAMs), based on an explicit atom-atom interaction potential obtained from earlier theoretical studies (Martinez-Nunez, E.; et al. J. Phys. Chem. C 2007, 111, 354). Initial conditions for the simulations match those in the experimental studies where high-energy jet-cooled CO(2) molecules (E(inc) = 10.6(8) kcal/mol, approximately 10 cm(-1)) are scattered from a 300 K perfluorinated liquid surface (PFPE) from a range of incident angles (theta(inc) = 0-60 degrees ). Nascent CO(2) rotational distributions prove to be remarkably well characterized by a simple two-temperature trapping-desorption (TD) and impulsive scattering (IS) model with nearly quantitative agreement between experimental and theoretical column integrated densities. Furthermore, three-dimensional (3D) quantum state resolved flux maps for glancing incident angles (theta(inc) approximately 60 degrees ) reveal broad, lobular distributions peaking strongly in the forward subspecular direction as cos(n)(theta(scat) - theta') with n approximately 5.6(1.2) and theta' approximately 49(2) degrees . PMID:19334697

Perkins, Bradford G; Nesbitt, David J

2009-04-23

455

Model carbyne knots vs ideal knots.  

PubMed

The structure and stability of model carbyne knots built from 60 to 120 carbon atoms with 0, 3, 4,., 7 crossings have been estimated by semiempirical AM1 calculations. The calculations have shown an increase of the knot-cycle energy difference (deltaE) with an increasing number of knot crossings and a decrease of deltaE with an increasing number of atoms constituting the molecule. The deltaE changes nonlinearly with the characteristics of the corresponding ideal knots such as the average crossing number (ACN) and the length-to-diameter ratio (L/D). The molecular mechanic strain energy of carbyne knots correlates similarly with ACN and L/D of ideal knots. The calculated energy of the model carbyne knots correlates also with the electrophoretic mobility or sedimentation coefficient of DNA knots. Thus, similarly to characteristics of ideal knots, the energy of carbyne knots is a rather easily available parameter which can be used for further correlations with some characteristics of DNA knots. PMID:12767144

Dobrowolski, Jan Cz; Mazurek, Aleksander P

2003-01-01

456

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

457

Elastin: a representative ideal protein elastomer.  

PubMed Central

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.

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

2002-01-01

458

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

459

On fuzzy ideals in BCK\\/BCI-algebras  

Microsoft Academic Search

In the present paper we give a procedure by which we generate a fuzzy ideal (resp. closed fuzzy ideal) by a fuzzy set in a BCI-algebra. As applications we prove: The set of all the fuzzy ideals in a BCI-algebra forms a complete lattice (called fuzzy ideal lattice). The set of all the closed fuzzy ideals in a BCI-algebra is

Jie Meng; Xiu-é Guo

2005-01-01

460

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

461

Planetesimal and Protoplanet Dynamics in a Turbulent Protoplanetary Disk: Ideal Stratified Disks  

Microsoft Academic Search

Due to the gravitational influence of density fluctuations driven by magneto-rotational instability in the gas disk, planetesimals and protoplanets undergo diffusive radial migration as well as changes in other orbital properties. The magnitude of the effect on particle orbits can have important consequences for planet formation scenarios. We use the local-shearing-box approximation to simulate an ideal, isothermal, magnetized gas disk

Chao-Chin Yang; Mordecai-Mark Mac Low; Kristen Menou

2011-01-01

462

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

463

Demonstrating the Gas Laws.  

ERIC Educational Resources Information Center

Presents a complete computer program demonstrating the relationship between volume/pressure for Boyle's Law, volume/temperature for Charles' Law, and volume/moles of gas for Avagadro's Law. The programing reinforces students' application of gas laws and equates a simulated moving piston to theoretical values derived using the ideal gas law.…

Holko, David A.

1982-01-01

464

Low-threshold 7.3 mum quantum cascade lasers grown by gas-source molecular beam epitaxy  

Microsoft Academic Search

We report low-threshold 7.3 mum superlattice-based quantum cascade lasers. The threshold current density is 3.4 kA\\/cm2 at 300 K and 1.25 kA\\/cm2 at 79 K in pulsed mode for narrow (~20 mum), 2-mm-long laser diodes. The characteristic temperature (T0) is 210 K. The slope efficiencies are 153 and 650 mW\\/A at 300 and 100 K, respectively. Power output is in

S. Slivken; A. Matlis; A. Rybaltowski; Z. Wu; M. Razeghi

1999-01-01

465

Quantum light in coupled interferometers for quantum gravity tests.  

PubMed

In recent years quantum correlations have received a lot of attention as a key ingredient in advanced quantum metrology protocols. In this Letter we show that they provide even larger advantages when considering multiple-interferometer setups. In particular, we demonstrate that the use of quantum correlated light beams in coupled interferometers leads to substantial advantages with respect to classical light, up to a noise-free scenario for the ideal lossless case. On the one hand, our results prompt the possibility of testing quantum gravity in experimental configurations affordable in current quantum optics laboratories and strongly improve the precision in "larger size experiments" such as the Fermilab holometer; on the other hand, they pave the way for future applications to high precision measurements and quantum metrology. PMID:23745871

Ruo Berchera, I; Degiovanni, I P; Olivares, S; Genovese, M

2013-05-24

466

Initialization and readout of spin chains for quantum information transport  

Microsoft Academic Search

Linear chains of spins acting as quantum wires are a promising approach for achieving scalable quantum information processors. Nuclear spins in apatite crystals provide an ideal test bed for the experimental study of quantum information transport, as they closely emulate a one-dimensional spin chain, while magnetic resonance techniques can be used to drive the spin chain dynamics and probe the

Gurneet Kaur; Paola Cappellaro

2012-01-01

467

Statistical Theory of the Ideal MHD Geodynamo  

NASA Technical Reports Server (NTRS)

A statistical theory of geodynamo action is developed, using a mathematical model of the geodynamo as a rotating outer core containing an ideal (i.e., no dissipation), incompressible, turbulent, convecting magnetofluid. On the concentric inner and outer spherical bounding surfaces the normal components of the velocity, magnetic field, vorticity and electric current are zero, as is the temperature fluctuation. This allows the use of a set of Galerkin expansion functions that are common to both velocity and magnetic field, as well as vorticity, current and the temperature fluctuation. The resulting dynamical system, based on the Boussinesq form of the magnetohydrodynamic (MHD) equations, represents MHD turbulence in a spherical domain. These basic equations (minus the temperature equation) and boundary conditions have been used previously in numerical simulations of forced, decaying MHD turbulence inside a sphere [1,2]. Here, the ideal case is studied through statistical analysis and leads to a prediction that an ideal coherent structure will be found in the form of a large-scale quasistationary magnetic field that results from broken ergodicity, an effect that has been previously studied both analytically and numerically for homogeneous MHD turbulence [3,4]. The axial dipole component becomes prominent when there is a relatively large magnetic helicity (proportional to the global correlation of magnetic vector potential and magnetic field) and a stationary, nonzero cross helicity (proportional to the global correlation of velocity and magnetic field). The expected angle of the dipole moment vector with respect to the rotation axis is found to decrease to a minimum as the average cross helicity increases for a fixed value of magnetic helicity and then to increase again when average cross helicity approaches its maximum possible value. Only a relatively small value of cross helicity is needed to produce a dipole moment vector that is aligned at approx.10deg with the rotation axis.

Shebalin, J. V.

2012-01-01

468

The ideal science student and problem solving  

NASA Astrophysics Data System (ADS)

The purpose of this dissertation was to examine the relationship between students' social mental models of the ideal science student, science epistemological beliefs, problem solving strategies used, and problem solving ability in a robotics environment. Participants were twenty-six academically advanced eleven and twelve year old students attending the Center for Talented Youth summer camp. Survey data was collected from the students including demographic background, views of the ideal science student, and science epistemological beliefs. Students also solved a robotics challenge. This problem solving session was videotaped and students were asked to think aloud as they solved the problem. Two social mental models were identified, a traits-based social mental model and a robust social mental model. A significant association was found between social mental model group and strategy usage. The robust social mental model group is more likely to use domain specific strategies than the traits-based group. Additionally, the robust social mental model group achieved significantly higher scores on their final solution than the traits-based social mental model group. Science epistemological beliefs do not appear to be associated with students' social mental model of the ideal science student. While students with a puzzle-solver view of science were more likely to use domain specific strategies in the planning phase of the problem solving session, there was no significant difference in problem solving ability between this group and students who have a dynamic view of the nature of science knowledge. This difference in strategy usage and problem solving performance may be due to a difference in the students' views of learning and cognition. The robust social mental model group evidenced a situative view of learning and cognition. These students made excellent use of the tools available in the task environment. The traits-based social mental model group displayed an information processing view of learning and cognition. These students were more likely to attempt to solve the problem based only on their mental representations of the problems.

Sullivan, Florence R.

469

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

470

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

471

"The Scientific Method" as Myth and Ideal  

NASA Astrophysics Data System (ADS)

"The Scientific Method" as it has been portrayed in popular and introductory contexts has been declared a myth. The variation that one finds in introductory presentations of "The Scientific Method" is explained by the fact that there is no canonical account among historians and philosophers of science. What, in particular, is wrong with "The Scientific Method"? This essay provides a fairly comprehensive survey of shortcomings of "The Scientific Method". Included are corrections to several misconceptions that often accompany such presentations. Rather than treating "The Scientific Method" as a useful approximation or an ideal, the myth should be discarded. Lessons can be learned for introductory pedagogical contexts from considering the shortcomings of the myth.

Woodcock, Brian A.

2014-05-01

472

Broken symmetry in ideal magnetohydrodynamic turbulence  

NASA Technical Reports Server (NTRS)

A numerical study of the long-time evolution of a number of cases of inviscid, isotropic, incompressible, three-dimensional fluid, and magneto-fluid turbulence has been completed. The results confirm that ideal magnetohydrodynamic turbulence is non-ergodic if there is no external magnetic field present. This is due essentially to a canonical symmetry being broken in an arbitrary dynamical representation. The broken symmetry manifests itself as a coherent structure, i.e., a non-zero time-averaged part of the turbulent magnetic field. The coherent structure is observed, in one case, to contain about eighteen percent of the total energy.

Shebalin, John V.

1993-01-01

473

Quantum rotor in nanostructured superconductors  

NASA Astrophysics Data System (ADS)

Despite its apparent simplicity, the idealized model of a particle constrained to move on a circle has intriguing dynamic properties and immediate experimental relevance. While a rotor is rather easy to set up classically, the quantum regime is harder to realize and investigate. Here we demonstrate that the quantum dynamics of quasiparticles in certain classes of nanostructured superconductors can be mapped onto a quantum rotor. Furthermore, we provide a straightforward experimental procedure to convert this nanoscale superconducting rotor into a regular or inverted quantum pendulum with tunable gravitational field, inertia, and drive. We detail how these novel states can be detected via scanning tunneling spectroscopy. The proposed experiments will provide insights into quantum dynamics and quantum chaos.

Lin, Shi-Hsin; Miloševi?, M. V.; Covaci, L.; Jankó, B.; Peeters, F. M.

2014-04-01

474

Quantum rotor in nanostructured superconductors.  

PubMed

Despite its apparent simplicity, the idealized model of a particle constrained to move on a circle has intriguing dynamic properties and immediate experimental relevance. While a rotor is rather easy to set up classically, the quantum regime is harder to realize and investigate. Here we demonstrate that the quantum dynamics of quasiparticles in certain classes of nanostructured superconductors can be mapped onto a quantum rotor. Furthermore, we provide a straightforward experimental procedure to convert this nanoscale superconducting rotor into a regular or inverted quantum pendulum with tunable gravitational field, inertia, and drive. We detail how these novel states can be detected via scanning tunneling spectroscopy. The proposed experiments will provide insights into quantum dynamics and quantum chaos. PMID:24686241

Lin, Shi-Hsin; Miloševi?, M V; Covaci, L; Jankó, B; Peeters, F M

2014-01-01

475

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.