Intrinsic dephasing in one-dimensional ultracold atom interferometers.
Quantum-phase fluctuations prevent true long-range phase order from forming in interacting 1D condensates, even at zero temperature. Nevertheless, by dynamically splitting the condensate into two parallel decoupled tubes the system can be prepared with a macroscopic relative phase, facilitating interferometric measurement. Here, we describe a dephasing mechanism whereby the quantum-phase fluctuations, which are so effective in equilibrium, act to destroy the macroscopic relative phase that was imposed as a nonequilibrium initial condition. We show that the phase coherence between the condensates decays exponentially with a dephasing time that depends on intrinsic parameters: the interaction strength, sound velocity, and density. Interestingly, significant temperature dependence appears only above a cross-over scale T*. In contrast to the usual phase diffusion, which is essentially an effect of confinement and leads to Gaussian decay, the exponential dephasing caused by fluctuations is a bulk effect that survives the thermodynamic limit.
Bistritzer
R
R
Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel. rafi.bistritzer@weizmann.ac.il
Altman
E
E
D005615:Freezing; D005740:Gases / Q000737:chemistry*; D007368:Interferometry; D008433:Mathematics; D008962:Models, Theoretical; D011789:Quantum Theory; D013816:Thermodynamics; D013997:Time Factors
D005740:Gases