Causality and defect formation in the dynamics of an engineered quantum phase transition in a coupled binary Bose–Einstein condensate

Abstract

Continuous phase transitions occur in a wide range of physical systems, and provide a context for the study of non-equilibrium dynamics and the formation of topological defects. The Kibble-Zurek (KZ) mechanism predicts the scaling of the resulting density of defects as a function of the quench rate through a critical point, and this can provide an estimate of the critical exponents of a phase transition. In this work, we extend our previous study of the miscible-immiscible phase transition of a binary Bose-Einstein condensate (BEC) composed of two hyperfine states in which the spin dynamics are confined to one dimension (Sabbatini et al 2011 Phys. Rev. Lett. 107 230402). The transition is engineered by controlling a Hamiltonian quench of the coupling amplitude of the two hyperfine states and results in the formation of a random pattern of spatial domains. Using the numerical truncated Wigner phase-space method, we show that in a ring BEC the number of domains formed in the phase transitions scales as predicted by the KZ theory. We also consider the same experiment performed with a harmonically trapped BEC, and investigate 4

Nonadiabatic quantum phase transition in a trapped spinor condensate

“…Otherwise the choice of the order parameter in the broken symmetry phase is done homogeneously along the system. The effect of the moving front changes the qualitative result of the KZ theory and scaling exponents as well [14][15][16][17][18][19].…”

Universality of miscible–immiscible phase separation dynamics in two-component Bose–Einstein condensates

“…From the non-equilibrium dynamics far from the critical point, we numerically extract two universal scalings for the average domain number and the average bifurcation delay with respect to the quench rate, and we find the critical exponents derived from the numerical results consist well with the analytical exponents. These scaling exponents in the phase separation induced by tuning the atom-atom interaction are different from the ones [5][6][7][8], in which the phase separation is induced by tuning the Rabi coupling strength.…”

“…Although all this work and the previous ones [5][6][7][8] study miscible-immiscible transitions, there are significant differences between their KZ scalings. Firstly, the miscible-immiscible transitions are induced by different sources.…”

“…The non-equilibrium dynamics of quantum phase transitions have attracted great interest in many branches of physics, including cosmology, particle physics and condensed matter physics [1][2][3]. When a system is driven across a phase transition and enters a symmetry broken phase, one of the most nontrivial results is the creation of topological defects, such as domains [4][5][6][7][8][9][10][11][12][13], vortices [14][15][16] and solitons [17][18][19]. The possibility to engineer a quantum phase transition and recover its universality from topological defects is of great significance in non-equilibrium physics [20].…”

“…Up to now, great efforts have been made to create multi-component BECs with different atomic species [38,39], isotopes [40] or spin states [41][42][43]. Multi-component BECs exhibit rich physics not accessible in a single-component BEC, including phase separation with symmetry breaking [5,[44][45][46][47][48][49], Josephon oscillation [51] and domain walls [6][7][8][9][10][11]. Remarkably, the phase separation in multicomponent BECs has been observed in several experiments [38][39][40][41]43].…”