Critical dynamics of spontaneous symmetry breaking in a homogeneous Bose gas

Abstract

We explore the dynamics of spontaneous symmetry breaking in a homogeneous system by thermally quenching an atomic gas with short-range interactions through the Bose-Einstein phase transition. Using homodyne matter-wave interferometry to measure first-order correlation functions, we verify the central quantitative prediction of the Kibble-Zurek theory, namely the homogeneous-system power-law scaling of the coherence length with the quench rate. Moreover, we directly confirm its underlying hypothesis, the freezing of the correlation length near the transition due to critical slowing down. Our measurements agree with beyond mean-field theory, and support the previously unverified expectation that the dynamical critical exponent for this universality class, which includes the λ-transition of liquid 4 He, is z = 3/2.Continuous symmetry-breaking phase transitions are ubiquitous, from the cooling of the early universe to the λ-transition of superfluid helium. Near a second-order transition, critical long-range fluctuations are characterized by a diverging correlation length ξ and details of the short-range physics are largely unimportant. Consequently, all systems can be classified into a small number of universality classes, according to their generic features such as symmetries, dimensionality and range of interactions (1). Close to the critical point, many physical quantities exhibit power-law behavior governed 1 arXiv:1410.8487v1 [cond-mat.quant-gas]

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“…As a result, BoseEinstein condensation occurs, enabling the study of quantum hydrodynamics in ultracold atomic gases [99,100]. In fact, nucleation of a quantized vortex [101,102], quantized vortex lattice formation [103,104], superfluidity and phase slip [105,106,107], and the Kibble-Zureck mechanism [108,109,110] have been experimentally and theoretically studied.…”

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