Universal space-time scaling symmetry in the dynamics of bosons across a quantum phase transition

TL;DR

This paper demonstrates that the dynamics of bosons crossing a quantum phase transition exhibit universal space-time scaling symmetry, confirmed through experiments with Bose condensates in a shaken optical lattice.

Contribution

It provides experimental evidence for universal space-time scaling symmetry in quantum critical dynamics of bosons, aligning with theoretical predictions.

Findings

Temporal scaling exponent approximately 0.50

Spatial scaling exponent approximately 0.26

Scaling symmetry confirmed in experimental data

Abstract

The dynamics of many-body systems spanning condensed matter, cosmology, and beyond is hypothesized to be universal when the systems cross continuous phase transitions. The universal dynamics is expected to satisfy a scaling symmetry of space and time with the crossing rate, inspired by the Kibble-Zurek mechanism. We test this symmetry based on Bose condensates in a shaken optical lattice. Shaking the lattice drives condensates across an effectively ferromagnetic quantum phase transition. After crossing the critical point, the condensates manifest delayed growth of spin fluctuations and develop anti-ferromagnetic spatial correlations resulting from sub-Poisson generation of topological defects. The characteristic times and lengths scale as power-laws of the crossing rate, yielding the temporal exponent 0.50(2) and the spatial exponent 0.26(2), consistent with theory. Furthermore, the fluctuations and correlations are invariant in scaled space-time coordinates, in support of the scaling symmetry of quantum critical dynamics.