scholarly journals Bose-Einstein Condensation and Supersolids

2021 ◽  
pp. 29-36
Author(s):  
Moorad Alexanian ◽  
Vanik E. Mkrtchian
Keyword(s):  
Wave Function ◽  
Einstein Condensate ◽  
External Potential ◽  
Three Dimensions ◽  
Einstein Condensation ◽  
Correct Trial ◽  
Self Organized ◽  
Bose Einstein Condensate ◽  
Wide Range ◽  
Bose Einstein

We consider interacting Bose particles in an external potential. It is shown that a Bose-Einstein condensate is possible at finite temperatures that describes a super solid in three dimensions (3D) for a wide range of potentials in the absence of an external potential. However, for 2D, a self-organized super solid exists for finite temperatures provided the interaction between bosons is nonlocal and of infinitely long-range. It is interesting that in the absence of the latter type of potential and in the presence of a lattice potential, there is no Bose-Einstein condensate and so in such a case, a 2D super solid is not possible at finite temperatures. We also propose the correct Bloch form of the condensate wave function valid for finite temperatures, which may be used as the correct trial wave function.

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 Polaron Problems in Ultracold Atoms: Role of a Fermi Sea across Different Spatial Dimensions and Quantum Fluctuations of a Bose Medium

Atoms ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 18
Author(s):  
Hiroyuki Tajima ◽  
Junichi Takahashi ◽  
Simeon Mistakidis ◽  
Eiji Nakano ◽  
Kei Iida
Keyword(s):  
Spectral Function ◽  
Einstein Condensate ◽  
Three Dimensions ◽  
Quantum Gas ◽  
Many Body ◽  
Bose Einstein Condensate ◽  
Spatial Dimensions ◽  
Three Body ◽  
Bose Einstein ◽  
The Impact

The notion of a polaron, originally introduced in the context of electrons in ionic lattices, helps us to understand how a quantum impurity behaves when being immersed in and interacting with a many-body background. We discuss the impact of the impurities on the medium particles by considering feedback effects from polarons that can be realized in ultracold quantum gas experiments. In particular, we exemplify the modifications of the medium in the presence of either Fermi or Bose polarons. Regarding Fermi polarons we present a corresponding many-body diagrammatic approach operating at finite temperatures and discuss how mediated two- and three-body interactions are implemented within this framework. Utilizing this approach, we analyze the behavior of the spectral function of Fermi polarons at finite temperature by varying impurity-medium interactions as well as spatial dimensions from three to one. Interestingly, we reveal that the spectral function of the medium atoms could be a useful quantity for analyzing the transition/crossover from attractive polarons to molecules in three-dimensions. As for the Bose polaron, we showcase the depletion of the background Bose-Einstein condensate in the vicinity of the impurity atom. Such spatial modulations would be important for future investigations regarding the quantification of interpolaron correlations in Bose polaron problems.

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.

scholarly journals Two distinguishable impurities in BEC: squeezing and entanglement of two Bose polarons

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Christos Charalambous ◽  
Miguel A. Garcia-March ◽  
Aniello Lampo ◽  
Mohammad Mehboud ◽  
Maciej Lewenstein
Keyword(s):  
Sudden Death ◽  
Stochastic Equations ◽  
Einstein Condensate ◽  
Time Limit ◽  
External Potential ◽  
Harmonic Potential ◽  
Bose Einstein Condensate ◽  
Brownian Particles ◽  
Bose Einstein ◽  
Asymptotic Time

We study entanglement and squeezing of two uncoupled impurities immersed in a Bose-Einstein condensate. We treat them as two quantum Brownian particles interacting with a bath composed of the Bogoliubov modes of the condensate. The Langevin-like quantum stochastic equations derived exhibit memory effects. We study two scenarios: (i) In the absence of an external potential, we observe sudden death of entanglement; (ii) In the presence of an external harmonic potential, entanglement survives even at the asymptotic time limit. Our study considers experimentally tunable parameters.

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.

Phase separation in spin-orbit-angular-momentum coupling Bose–Einstein condensate systems

2020 ◽  
Vol 34 (23) ◽  
pp. 2050241
Author(s):  
Jin Xu ◽  
Jinbin Li
Keyword(s):  
Angular Momentum ◽  
Phase Separation ◽  
Coupling Strength ◽  
Interaction Strength ◽  
Einstein Condensate ◽  
Three Dimensions ◽  
Pitaevskii Equation ◽  
Spin Orbit ◽  
Bose Einstein Condensate ◽  
Bose Einstein

We study the phase separation in three-component spin-orbit-angular-momentum coupled Bose–Einstein condensate with spin-1 in three dimensions. Different types of phase-separation are acquired upon an increase of the coupling strength, magnetic gradient strength, spin-dependent interaction strength and particle number above a critical value. Increasing the value of coupling strength and other related parameters shows distinct behaviors which are produced by repulsion for large strengths of spin-orbit angular-momentum (SOAM) coupling. The present investigation is carried out through a numerical Crank–Nicolson method of the underlying mean-field Gross–Pitaevskii equation.

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 A degenerate Fermi gas of polar molecules

Science ◽  
2019 ◽  
Vol 363 (6429) ◽  
pp. 853-856 ◽  
Author(s):  
Luigi De Marco ◽  
Giacomo Valtolina ◽  
Kyle Matsuda ◽  
William G. Tobias ◽  
Jacob P. Covey ◽  
...  
Keyword(s):  
Fermi Gas ◽  
Einstein Condensate ◽  
Polar Molecules ◽  
Ultracold Molecules ◽  
Experimental Realization ◽  
Bose Einstein Condensate ◽  
Degenerate Fermi Gas ◽  
Fermi Temperature ◽  
Wide Range ◽  
Bose Einstein

Experimental realization of a quantum degenerate gas of molecules would provide access to a wide range of phenomena in molecular and quantum sciences. However, the very complexity that makes ultracold molecules so enticing has made reaching degeneracy an outstanding experimental challenge over the past decade. We now report the production of a degenerate Fermi gas of ultracold polar molecules of potassium-rubidium. Through coherent adiabatic association in a deeply degenerate mixture of a rubidium Bose-Einstein condensate and a potassium Fermi gas, we produce molecules at temperatures below 0.3 times the Fermi temperature. We explore the properties of this reactive gas and demonstrate how degeneracy suppresses chemical reactions, making a long-lived degenerate gas of polar molecules a reality.

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