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

TL;DR

This paper studies the universal dynamics of phase separation in two-component Bose-Einstein condensates, revealing critical exponents and scaling laws that connect superfluidity breakdown with defect formation.

Contribution

It analytically and numerically characterizes the critical exponents and universal scaling laws in phase separation dynamics driven by interaction quenching.

Findings

Critical velocity vanishes at the phase transition point.

Universal scaling laws for domain number and bifurcation delay.

Static and dynamical critical exponents are determined as v=1/2 and z=2.

Abstract

We investigate the non-equilibrium dynamics across the miscible-immiscible phase separation in a binary mixture of Bose-Einstein condensates. The excitation spectra reveal that the Landau critical velocity vanishes at the critical point, where the superfluidity spontaneously breaks down. We analytically extract the dynamical critical exponent $z=2$ from the Landau critical velocity. Moreover, by simulating the real-time dynamics across the critical point, we find the average domain number and the average bifurcation delay show universal scaling laws with respect to the quench time. We then numerically extract the static correlation length critical exponent $v=1/2$ and the dynamical critical exponent $z=2$ according to Kibble-Zurek mechanism. The scaling exponents $(v=1/2, z=2)$ in the phase separation driven by quenching the atom-atom interaction are different from the ones $(v=1/2, z=1)$ in the phase separation driven by quenching the Rabi coupling strength [PRL \textbf{102}, 070401 (2009); PRL \textbf{107}, 230402 (2011)]. Our study explores the connections between the spontaneous superfluidity breakdown and the spontaneous defect formation in the phase separation dynamics.