scholarly journals Boosting engine performance with Bose-Einstein condensation

2022 ◽  
Author(s):  
Nathan Myers ◽  
Francisco José Peña ◽  
Oscar Andrés Negrete ◽  
Patricio Vargas ◽  
Gabriele De Chiara ◽  
...  
Keyword(s):  
Gas Phase ◽  
Large Fraction ◽  
Engine Performance ◽  
Einstein Condensate ◽  
Einstein Condensation ◽  
Engine Operation ◽  
Bose Einstein Condensate ◽  
Working Medium ◽  
State Of Matter ◽  
Bose Einstein

Abstract At low-temperatures a gas of bosons will undergo a phase transition into a quantum state of matter known as a Bose-Einstein condensate (BEC), in which a large fraction of the particles will occupy the ground state simultaneously. Here we explore the performance of an endoreversible Otto cycle operating with a harmonically confined Bose gas as the working medium. We analyze the engine operation in three regimes, with the working medium in the BEC phase, in the gas phase, and driven across the BEC transition during each cycle. We find that the unique properties of the BEC phase allow for enhanced engine performance, including increased power output and higher efficiency at maximum power.

scholarly journals Do we need a non-perturbative theory of Bose-Einstein condensation?

2021 ◽  
Vol 2103 (1) ◽  
pp. 012200
Author(s):  
K G Zloshchastiev
Keyword(s):  
Phase Contrast ◽  
Einstein Condensate ◽  
Einstein Condensation ◽  
One Dimensional ◽  
Quantum Fluid ◽  
Bose Einstein Condensate ◽  
Dipole Force ◽  
Theoretical Assumptions ◽  
Bose Einstein ◽  
Best Fit

Abstract We recall the experimental data of one-dimensional axial propagation of sound near the center of the Bose-Einstein condensate cloud, which used the optical dipole force method of a focused laser beam and rapid sequencing of nondestructive phase-contrast images. We reanalyze these data within the general quantum fluid framework but without model-specific theoretical assumptions; using the standard best fit techniques. We demonstrate that some of their features cannot be explained by means of the perturbative two-body approximation and Gross-Pitaevskii model, and conjecture possible solutions.

λ-Transition to the Bose-Einstein Condensate

1995 ◽  
Vol 50 (10) ◽  
pp. 921-930 ◽  
Author(s):  
Siegfried Grossmann ◽  
Martin Holthaus
Keyword(s):  
Heat Capacity ◽  
Three Dimensional ◽  
Einstein Condensate ◽  
Einstein Condensation ◽  
Condensation Temperature ◽  
Harmonic Oscillator Potential ◽  
Bose Einstein Condensate ◽  
Bose Einstein ◽  
Analytical Expressions ◽  
Grand Canonical

Abstract We study Bose-Einstein condensation of comparatively small numbers of atoms trapped by a three-dimensional harmonic oscillator potential. Under the assumption that grand canonical statis­tics applies, we derive analytical expressions for the condensation temperature, the ground state occupation, and the specific heat capacity. For a gas of TV atoms the condensation temperature is proportional to N1/3, apart from a downward shift of order N-1/3. A signature of the condensation is a pronounced peak of the heat capacity. For not too small N the heat capacity is nearly discon­tinuous at the onset of condensation; the magnitude of the jump is about 6.6 N k. Our continuum approximations are derived with the help of the proper density of states which allows us to calculate finite-AT-corrections, and checked against numerical computations.

MODULATION OF ORDER PARAMETER OF EXCITON BOSE-EINSTEIN CONDENSATE IN A RING

2004 ◽  
Vol 18 (27n29) ◽  
pp. 3797-3802 ◽  
Author(s):  
S.-R. ERIC YANG ◽  
Q-HAN PARK ◽  
J. YEO
Keyword(s):  
Ground State ◽  
Order Parameter ◽  
Weak Magnetic Field ◽  
Random Potential ◽  
Einstein Condensate ◽  
Einstein Condensation ◽  
Random Potentials ◽  
Bose Einstein Condensate ◽  
The Mean ◽  
Bose Einstein

We have studied theoretically the Bose-Einstein condensation (BEC) of two-dimensional excitons in a ring with a random variation of the effective exciton potential along the circumference. We derive a nonlinear Gross-Pitaevkii equation (GPE) for such a condensate, which is valid even in the presence of a weak magnetic field. For several types of the random potentials our numerical solution of the ground state of the GPE displays a necklace-like structure. This is a consequence of the interplay between the random potential and a strong nonlinear repulsive term of the GPE. We have investigated how the mean distance between modulation peaks depends on properties of the random potentials.

NEW INSIGHT ON THE CHAIN STATES AND BOSE-EINSTEIN CONDENSATE IN LIGHT NUCLEI

2008 ◽  
Vol 17 (10) ◽  
pp. 2150-2154 ◽  
Author(s):  
S. YU. TORILOV ◽  
K. A. GRIDNEV ◽  
W. GREINER
Keyword(s):  
Cluster Model ◽  
Einstein Condensate ◽  
Light Nuclei ◽  
Einstein Condensation ◽  
Pitaevskii Equation ◽  
Deformed Nuclei ◽  
Bose Einstein Condensation ◽  
Bose Einstein Condensate ◽  
Alpha Cluster ◽  
Bose Einstein

The simple alpha-cluster model was used for the consideration of the chain states and Bose-Einstein condensation in the light self-conjugated nuclei. Obtained results were compared with predictions of the shell-model for the deformed nuclei, with calculations based on Gross-Pitaevskii equation and with recent experimental results.

scholarly journals Phase Structure of Bose - Einstein Condensate in Ultra - Cold Bose Gases

2015 ◽  
Vol 24 (4) ◽  
pp. 343
Author(s):  
Tran Huu Phat ◽  
Le Viet Hoa ◽  
Dang Thi Minh Hue
Keyword(s):  
Phase Structure ◽  
Einstein Condensate ◽  
Einstein Condensation ◽  
Double Bubble ◽  
Bose Gases ◽  
Goldstone Theorem ◽  
Bose Einstein Condensate ◽  
Different Types ◽  
Higher Temperature ◽  
Bose Einstein

The Bose - Einstein condensation of ultra - cold Bose gases is studied by means of the Cornwall - Jackiw - Tomboulis effective potential approach in the improved double - bubble approximation which preserves the Goldstone theorem. The phase structure of Bose - Einstein condensate associating with two different types of phase transition is systematically investigated. Its main feature is that the symmetry which was broken at zero temperature gets restore at higher temperature.

EXCITON-PHONON PACKETS WITH BOSE–EINSTEIN CONDENSATE

2003 ◽  
Vol 17 (28) ◽  
pp. 5289-5293
Author(s):  
D. ROUBTSOV ◽  
Y. LÉPINE
Keyword(s):  
Wave Function ◽  
Coherent State ◽  
Einstein Condensate ◽  
Einstein Condensation ◽  
Inhomogeneous State ◽  
Bose Einstein Condensation ◽  
Bose Einstein Condensate ◽  
Bose Einstein

We discuss the possibility for a moving droplet of excitons and phonons to form a coherent state inside the packet. We describe such an inhomogeneous state in terms of Bose–Einstein condensation and prescribe it a macroscopic wave function. Existence and, thus, coherency of such a Bose-core inside the droplet can be checked experimentally if two moving packets are allowed to interact.

scholarly journals Bose-Einstein Condensation from the QCD Boltzmann Equation

Particles ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 231-241 ◽  
Author(s):  
Brent Harrison ◽  
Andre Peshier
Keyword(s):  
Boltzmann Equation ◽  
Initial Conditions ◽  
Einstein Condensate ◽  
Einstein Condensation ◽  
Relaxation Time Approximation ◽  
Cylindrically Symmetric ◽  
Bose Einstein Condensate ◽  
Scattering Approximation ◽  
Momentum Distributions ◽  
Bose Einstein

We present a novel numerical scheme to solve the QCD Boltzmann equation in the soft scattering approximation, for the quenched limit of QCD. Using this we can readily investigate the evolution of spatially homogeneous systems of gluons distributed isotropically in momentum space. We numerically confirm that for so-called “overpopulated” initial conditions, a (transient) Bose-Einstein condensate could emerge in a finite time. Going beyond existing results, we analyze the formation dynamics of this condensate. The scheme is extended to systems with cylindrically symmetric momentum distributions, in order to investigate the effects of anisotropy. In particular, we compare the rates at which isotropization and equilibration occur. We also compare our results from the soft scattering scheme to the relaxation time approximation.

FRACTIONAL MATHEMATICAL INVESTIGATION OF BOSE–EINSTEIN CONDENSATION IN DILUTE 87Rb, 23Na AND 7Li ATOMIC GASES

2012 ◽  
Vol 26 (17) ◽  
pp. 1250096 ◽  
Author(s):  
HÜSEYİN ERTİK ◽  
HÜSEYİN ŞİRİN ◽  
DOǦAN DEMİRHAN ◽  
FEVZİ BÜYÜKKİLİÇ
Keyword(s):  
Three Dimensional ◽  
Einstein Condensate ◽  
Einstein Condensation ◽  
Atomic Gases ◽  
Transition Temperatures ◽  
Interparticle Interactions ◽  
Bose Einstein Condensation ◽  
Bose Einstein Condensate ◽  
Einstein Distribution ◽  
Bose Einstein

Although atomic Bose gases are experimentally investigated in the dilute regime, interparticle interactions play an important role on the transition temperatures of Bose–Einstein condensation. In this study, Bose–Einstein condensation is handled using fractional calculus for a Bose gas consisting of interacting bosons which are trapped in a three-dimensional harmonic oscillator. In this frame, in order to introduce the nonextensive effect, fractionally generalized Bose–Einstein distribution function which features Mittag–Leffler function is adopted. The dependence of the transition temperature of Bose–Einstein condensation on α (a measure of fractality of space) has been established. The transition temperatures for the dilute 87 Rb , 23 Na and 7 Li atomic gases have been obtained in consistent with experimental data and the nature of the interactions in the Bose–Einstein condensate has been enlightened. In the course of our investigations, we have arrived to the conclusion that for α < 1 attractive interactions and for α > 1 repulsive interactions are predominant.

The weakly interacting Bose gas at the critical temperature

2019 ◽  
pp. 361-372
Author(s):  
Jean Zinn-Justin
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Transition Temperature ◽  
Einstein Condensate ◽  
Einstein Condensation ◽  
Superfluid Phase ◽  
Bose Einstein Condensate ◽  
Repulsive Interactions ◽  
Euclidean Field Theory ◽  
Bose Einstein

Chapter 20 examines effects of weak repulsive interactions in a Bose–Einstein condensate and the transition from Bose–Einstein condensate to superfluid phase transition. Renormalization group methods are used and a universal amplitude is calculated by non–perturbative methods. After the discovery of the predicted Bose–Einstein condensation, which is a property of free bosons, an interesting issue was the effects of weak repulsive interactions. In this chapter, it is shown that, near the transition temperature, the initial non–relativistic field theory can be replaced by a relativistic effective Euclidean field theory known to describe a superfluid phase transition (a dimensional reduction). These theoretical considerations are illustrated by an evaluation of the universal variation of the transition temperature at weak coupling. For this purpose, the O(2) symmetry of the model is generalized to O(N) symmetry, and large N techniques are used.

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