title: Quantum gases. Critical dynamics of spontaneous symmetry breaking in a homogeneous Bose gas.
abstract: Kibble-Zurek theory models the dynamics of spontaneous symmetry breaking, which plays an important role in a wide variety of physical contexts, ranging from cosmology to superconductors. We explored these dynamics 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 verified 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 confirmed its underlying hypothesis, the freezing of the correlation length near the transition. Our measurements agree with a beyond-mean-field theory and support the expectation that the dynamical critical exponent for this universality class is z = 3/2.
authors.affiliation: Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK. nn270@cam.ac.uk.
authors.forename: Nir
authors.initials: N
authors.lastname: Navon
authors.affiliation: Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Alexander L
authors.initials: AL
authors.lastname: Gaunt
authors.affiliation: Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Smith
authors.affiliation: Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Zoran
authors.initials: Z
authors.lastname: Hadzibabic