Critical phase induced by Berry phase and dissipation in a spin chain

TL;DR

This paper investigates how dissipation and Berry phase effects induce complex phase transitions and stable gapless phases in SU(N) spin chains, revealing new fixed points and critical behaviors relevant to quantum systems with long-range interactions.

Contribution

It introduces a novel analysis of dissipation and Berry phase interplay in SU(N) spin chains, uncovering new fixed points and phases not previously characterized.

Findings

Identified a second-order phase transition between critical and ordered phases.

Discovered a stable, gapless, nonrelativistic phase induced by dissipation.

Found a new critical point in the relativistic version of the model.

Abstract

Motivated by experiments on spin chains embedded in a metallic bath, as well as closed quantum systems described by long-range interacting Hamiltonians, we study a critical SU(N) spin chain perturbed by dissipation, or equivalently, after space-time rotation, long-range spatial interactions. The interplay of dissipation and the Wess-Zumino (Berry phase) term results in a rich phase diagram with multiple renormalization-group fixed points. For a range of the exponent that characterizes the dissipative bath, we find a second-order phase transition between the fixed point that describes an isolated critical spin chain and a dissipation-induced-ordered phase. More interestingly, for a different range of the exponent, we find a stable, gapless, nonrelativistic phase of matter whose existence necessarily requires coupling to the dissipative bath. Upon tuning the exponent, we find that the fixed point corresponding to this gapless, stable phase "annihilates" the fixed point that describes the transition out of this phase to the ordered phase. We also study a relativistic version of our model, and we identify a new critical point. We discuss the implications of our work for Kondo lattice systems and engineered long-range interacting quantum systems.