title: Quantum bath refrigeration towards absolute zero: challenging the unattainability principle.
abstract: A minimal model of a quantum refrigerator, 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 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.
authors.affiliation: Department of Optics, Palacký University, Olomouc, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Kolář
authors.forename: D
authors.initials: D
authors.lastname: Gelbwaser-Klimovsky
authors.forename: R
authors.initials: R
authors.lastname: Alicki
authors.forename: G
authors.initials: G
authors.lastname: Kurizki