Critical Quantum Metrology in the Non-Linear Quantum Rabi Model.

The quantum Rabi model (QRM) with linear coupling between light mode and qubit exhibits the analog of a second-order phase transition for vanishing mode frequency which allows for criticality-enhanced quantum metrology in a few-body system. We show that the QRM including a nonlinear coupling term exhibits much higher measurement precisions due to its first-order-like phase transition at finite frequency, avoiding the detrimental slowing-down effect close to the critical point of the linear QRM. When a bias term is added to the Hamiltonian, the system can be used as a fluxmeter or magnetometer if implemented in circuit QED platforms.

Citation

Zu-Jian Ying, Simone Felicetti, Gang Liu, Daniel Braak. Critical Quantum Metrology in the Non-Linear Quantum Rabi Model. Entropy (Basel, Switzerland). 2022 Jul 22;24(8)

PMID: 35892995

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