Dephasing in coherently split quasicondensates

Abstract

We numerically model the evolution of a pair of coherently split quasicondensates. A truly one-dimensional case is assumed, so that the loss of the (initially high) coherence between the two quasicondensates is due to dephasing only, but not due to the violation of integrability and subsequent thermalization (which are excluded from the present model). We confirm the subexponential time evolution of the coherence between two quasicondensates ∝ exp[−(t/t 0 ) 2/3 ], experimentally observed by Hofferberth et al. [Nature 449, 324 (2007)]. The characteristic time t 0 is found to scale as the square of the ratio of the linear density of a quasicondensate to its temperature, and we analyze the full distribution function of the interference contrast and the decay of the phase correlation.

Thermalization in a one-dimensional integrable system

“…Note that the obtained thermalization time τ eq is always shorter than the time needed for a sound wave to traverse the distance L. Therefore the thermalization observed in our simulations is a local physical effect, which is not related to specific boundary conditions. The thermalization time τ eq should not be confused with the time τ d ∼ mλ 2 T /h [7], where λ T = 2h 2n /(mk B T ), of dephasing between two 1D quasicondensates initially prepared in thermallike states with strongly mutually correlated fluctuations. Fig.…”

Pinning quantum phase transition in a Tonks-Girardeau gas: Diagnostics by ground-state fidelity and the Loschmidt echo

“…The LE of the TG gas is formally equivalent to the corresponding echo for a gas of noninteracting fermions [21]. The Loschmidt echo of one-dimensional interacting Bose gases was recently related [19] to a series of experiments [23][24][25] and theoretical studies [26][27][28][29][30][31] on interference between split parallel 1D Bose systems. …”

Coherence and Josephson oscillations between two tunnel-coupled one-dimensional atomic quasicondensates at finite temperature

“…Note that anharmonic Hamiltonian terms, which depend on the density fluctuations neglected in our present theory, do not affect much the static properties of the quasicondensate [11]. One needs to take them into account in the analysis [20] of a slow process of the system's relaxation towards equilibrium starting from a nonequilibrium, prethermalized initial state [21], characterized by two different temperatures T + and T − T + for the symmetric and antisymmetric modes, respectively.…”