Critical Sensing with a Single Bosonic Mode Without Boson-Boson Interactions

Critical phenomena of quantum systems are useful for enhancement of quantum sensing. However, experimental realizations of criticality enhancement are confined to very few systems, owing to the stringent requirements, including the thermodynamical or scaling limit, and fine control of interacting quantum subsystems or particles. Here, a simple critical quantum sensing scheme is proposed that requires neither of these conditions. The critical system is realized with a single parametrically-driven bosonic mode involving many non-interacting bosons. The quantum Fisher information is calculated, which confirms the criticality-enabled enhancement. The response of one of the quadratures to the variation of the control parameter is further detailed. The numerical results reveal that its inverted variance exhibits a diverging behavior at the critical point. Based on the presently available control techniques of parametric driving, it is expected that scheme can be realized in different systems, e.g., ion traps and superconducting circuits. A protocol is proposed for the critical sensing with a single parametrically-driven bosonic mode. Below the critical point, the system has a ladder-type eigenspectrum, underlain by squeezed Fock eigenstates. The results reveal that both the quantum Fisher information and the inverted variance exhibit a diverging behavior approaching the critical point, which confirms the criticality-enhanced quantum sensing. image