Quantum bath refrigeration towards absolute zero: unattainability principle challenged

TL;DR

This study presents a quantum refrigerator model that challenges the unattainability principle by showing that cooling to absolute zero may be theoretically achievable with certain quantum baths, contrary to traditional thermodynamic limits.

Contribution

The paper introduces a minimal quantum refrigerator model demonstrating that cooling rates do not vanish at zero temperature for specific realistic quantum baths, questioning established thermodynamic principles.

Findings

Cooling rate remains finite as T approaches 0 for certain baths.

Challenges the traditional unattainability principle of absolute zero.

Quantum effects can alter thermodynamic limits.

Abstract

A minimal model of a quantum refrigerator (QR), i.e. a periodically phase-flipped two-level system permanently coupled to a finite-capacity bath (cold bath) and an infinite heat dump (hot bath), is introduced and used to investigate the cooling of the cold bath towards the absolute zero (T=0). Remarkably, the temperature scaling of the cold-bath cooling rate reveals that it does not vanish as T->0 for certain realistic quantized baths, e.g. phonons in strongly disordered media (fractons) or quantized spin-waves in ferromagnets (magnons). This result challenges Nernst's third-law formulation known as the unattainability principle.