Quantum sensors operated in real time

From gravitational-wave detectors to cryogenically cooled nanoresonators, quantum effects have been shown to enhance capabilities of various devices in sensing external perturbations. Although this fact has led to important breakthroughs in the field of quantum metrology, one often forgets that the vast majority of real-life applications require quantum sensors to track signals that vary over time—e.g., gravitational waves generated by black holes merging, or fluctuating magnetic fields generated by the human brain. In my talk, I will summarise recent results obtained with my group, in which we combine the description of continuously monitored quantum sensors with methods of statistical inference, so that quantum effects can still be used to boost their sensitivity in “real time”. Firstly, I will focus on an optomechanical sensor operated in the non-linear regime, in order to show how the non-classical correlations of photons being emitted may then enhance the sensitivity after resorting to Bayesian inference. Secondly, I will consider the setting of optically pumped atomic magnetometers, in which case I will demonstrate that it is enough to use less demanding methods of (Extended) Kalman Filtering and measurement-based feedback in order to maintain the quantum-enhanced sensitivity or, in other words, drive the atomic ensemble into a highly entangled (spin-squeezed) state tailored to efficiently track a fluctuating magnetic field.

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Hybrid event:

Onsite: Room D, the Institute of Physics PAS, Al. Lotników 32/46,

Zoom: https://zoom.us/j/82380380442?pwd=Z3IyeEhlZmFHU1B2M2VUVVJhODkrUT09 (Passcode: 134595, Meeting ID: 823 8038 0442)