Non-equilibrium dynamics of a driven Bose-Einstein condensate at finite temperature

Lei Feng, Logan W. Clark, Li-Chung Ha +1 more

Kalai Kumar Rajagopal, Gafurjan Ismailovich Ibragimov

T. P. Billam

In this thesis we investigate the static properties and non-equilibrium dynamics of bright solitary waves in atomic Bose-Einstein condensates in the zero-temperature limit, and we investigate the non-equilibrium dynamics of a driven atomic Bose-Einstein condensate at finite temperature. Bright solitary waves in atomic Bose-Einstein condensates are non-dispersive and soliton-like matter-waves which could be used in future atom-interferometry exper-iments. Using the mean-field, Gross-Pitaevskii description, we propose an exper-imental scheme to generate pairs of bright solitary waves with controlled velocity and relative phase; this scheme could form an important part of a future atom in-terferometer, and we demonstrate that it can also be used to test the validity of the mean-field model of bright solitary waves. We also develop a method to quanti-tatively assess how soliton-like static, three-dimensional bright solitary waves are; this assessment is particularly relevant for the design of future experiments. In reality, the non-zero temperatures and highly non-equilibrium dynamics occur-ring in a bright solitary wave interferometer are likely to necessitate a theoretical description which explicitly accounts for the non-condensate fraction. We show that a second-order, number-conserving description offers a minimal self-consistent treatment of the relevant condensate – non-condensate interactions at low temper-atures and for moderate non-condensate fractions. We develop a method to obtain a fully-dynamical numerical solution to the integro-differential equations of motion of this description, and solve these equations for a driven, quasi-one-dimensional test system. We show that rapid non-condensate growth predicted by lower-order descriptions, and associated with linear dynamical instabilities, can be damped by the self-consistent treatment of interactions included in the second-order descrip-tion. 1 Bright solitary waves and non-equilibrium dynamics in atomic Bose-Einstein condensates

Matthew J. Davis, Tod M. Wright, Tapio Simula +2 more

Dilute gas Bose-Einstein condensates (BECs) are an example of a superfluid, and exhibit many of the same phenomena as the strongly interacting superfluid helium. However, their isolation from the environment combined with their inhomogeneous density profiles make it difficult to observe some phenomena, such as the thermo-mechanical effect, in experiments. Here we perform dynamical simulations of a finite temperature Bose-Einstein condensate coupled to spatially separated heat and particle reservoirs to observe such non-equilibrium superfluid phenomena. We analyse the resulting steady-state non-equilibrium flows in the BEC, and consider the prospect of observing sustained superfluid turbulence.

Jonas Rønning, Audun Skaugen, Emilio Hernández-Garcı́a +2 more

Matthew J. Davis, Tod M. Wright, Tapio Simula +2 more

Dilute gas Bose-Einstein condensates (BECs) are an example of a superfluid, and exhibit many of the same phenomena as the strongly interacting superfluid helium. However, their isolation from the environment combined with their inhomogeneous density profiles make it difficult to observe some phenomena, such as the thermo-mechanical effect, in experiments. Here we perform dynamical simulations of a finite temperature Bose-Einstein condensate coupled to spatially separated heat and particle reservoirs to observe such non-equilibrium superfluid phenomena. We analyse the resulting steady-state non-equilibrium flows in the BEC, and consider the prospect of observing sustained superfluid turbulence.