Fluctuation and Dissipation at a Quantum Critical Point

TL;DR

This paper investigates how quantum fluctuations induce dissipation at zero temperature in quantum critical theories using holography, revealing a qualitative change in particle dynamics as the dynamical exponent crosses z=2.

Contribution

It provides analytic correlation and response functions for particles in quantum critical theories and uncovers a mass-independent long-time behavior for z > 2.

Findings

Dissipative behavior arises from quantum fluctuations at zero temperature.

Behavior qualitatively changes at dynamical exponent z=2.

Long-time particle dynamics become mass-independent for z > 2.

Abstract

In non-relativistic field theories, quantum fluctuations give rise to dissipative behaviour even at zero temperature. Here we use holographic methods to explore the dissipative dynamics of massive particles coupled to quantum critical theories. We present analytic expressions for correlation functions and response functions. The behaviour changes qualitatively as the dynamical exponent passes through z = 2. In particular, for z > 2, the long time dynamics of the particle is independent of its inertial mass.