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Full-Text Articles in Physics
Dipolar Oscillations In A Quantum Degenerate Fermi–Bose Atomic Mixture, Francesca Ferlaino, Robert Brecha, Peter Hannaford, Francesco Riboli, Giacomo Roati, Giovanni Modugno, Massimo Inguscio
Dipolar Oscillations In A Quantum Degenerate Fermi–Bose Atomic Mixture, Francesca Ferlaino, Robert Brecha, Peter Hannaford, Francesco Riboli, Giacomo Roati, Giovanni Modugno, Massimo Inguscio
Robert J. Brecha
We study the dynamics of coupled dipolar oscillations in a Fermi–Bose mixture of 40K and 87Rb atoms. This low-energy collective mode is strongly affected by the interspecies interactions. Measurements are performed in the classical and quantum degenerate regimes and reveal the crucial role of the statistical properties of the mixture. At the onset of quantum degeneracy, we investigate the role of Pauli blocking and superfluidity for K and Rb atoms, respectively, resulting in a change in the collisional interactions.
Permutation Cycles In The Bose-Einstein Condensation Of A Trapped Ideal Gas, Wj Mullin
Permutation Cycles In The Bose-Einstein Condensation Of A Trapped Ideal Gas, Wj Mullin
William J. Mullin
We consider Bose–Einstein condensation for non-interacting particles trapped in a harmonic potential by considering the length of permutation cycles arising from wave function symmetry. This approach had been considered previously by Matsubara and Feynman for a homogeneous gas in a box with periodic boundary conditions. For the ideal gas in a harmonic potential, one can treat the problem nearly exactly by analytical means. One clearly sees that the noncondensate is made up of permutation loops that are of length less-than-or-equals, slantN1/3, and that the phase transition consists of the sudden growth of longer permutation cycles. The condensate is seen to …
Path-Integral Monte Carlo And The Squeezed Trapped Bose-Einstein Gas, Jp Fernandez, Wj Mullin
Path-Integral Monte Carlo And The Squeezed Trapped Bose-Einstein Gas, Jp Fernandez, Wj Mullin
William J. Mullin
Bose-Einstein condensation has been experimentally found to take place in finite trapped systems when one of the confining frequencies is increased until the gas becomes effectively two-dimensional (2D). We confirm the plausibility of this result by performing path-integral Monte Carlo (PIMC) simulations of trapped Bose gases of increasing anisotropy and comparing them to the predictions of finite-temperature many-body theory. PIMC simulations provide an essentially exact description of these systems; they yield the density profile directly and provide two different estimates for the condensate fraction. For the ideal gas, we find that the PIMC column density of the squeezed gas corresponds …
The Condensate Number In Pimc Treatments Of Trapped Bosons, Wj Mullin, Sd Heinrichs, Jp Fernandez
The Condensate Number In Pimc Treatments Of Trapped Bosons, Wj Mullin, Sd Heinrichs, Jp Fernandez
William J. Mullin
In path integral Monte Carlo (PIMC) treatments of harmonically trapped bosons, one cannot use the usual long-range constant limit of the one-body reduced density matrix ρ1 to determine the condensate number n0 because ρ1 always approaches zero in a trap. W. Krauth found that the longest permutation cycle arising in the simulation gives a consistent value of n0. Our analytical studies of the ideal gas suggest other ways of using permutation cycles to determine n0. We test these approaches on simulations involving finite-size ideal and interacting gases and find that the methods are consistent.
Interference Of Bose-Einstein Condensates: Quantum Nonlocal Effects, Wj Mullin, F Laloe
Interference Of Bose-Einstein Condensates: Quantum Nonlocal Effects, Wj Mullin, F Laloe
William J. Mullin
Quantum systems in Fock states do not have a phase. When two or more Bose-Einstein condensates are sent into interferometers, they nevertheless acquire a relative phase under the effect of quantum measurements. The usual explanation relies on spontaneous symmetry breaking, where phases are ascribed to all condensates and treated as unknown classical quantities. However, this image is not always sufficient: when all particles are measured, quantum mechanics predicts probabilities that are sometimes in contradiction with it, as illustrated by quantum violations of local realism. In this Rapid communication, we show that interferometers can be used to demonstrate a large variety …