Critical Quantum Metrology with a Finite-Component Quantum Phase Transition

• Published in: Physical review letters Vol. 124; no. 12; p. 120504
• Main Authors: Garbe, Louis, Bina, Matteo, Keller, Arne, Paris, Matteo G A, Felicetti, Simone
• Format: Journal Article
• Language: English
• Published: United States 27.03.2020
• ISSN: 1079-7114
• DOI: 10.1103/PhysRevLett.124.120504

Physical systems close to a quantum phase transition exhibit a divergent susceptibility, suggesting that an arbitrarily high precision may be achieved by exploiting quantum critical systems as probes to estimate a physical parameter. However, such an improvement in sensitivity is counterbalanced by the closing of the energy gap, which implies a critical slowing down and an inevitable growth of the protocol duration. Here, we design different metrological protocols that exploit the superradiant phase transition of the quantum Rabi model, a finite-component system composed of a single two-level atom interacting with a single bosonic mode. We show that, in spite of the critical slowing down, critical quantum optical probes can achieve a quantum-enhanced time scaling of the sensitivity in frequency-estimation protocols.