Quantum bath refrigeration towards absolute zero: unattainability principle challenged

摘要

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