Scientific Results

Optimal Control for One-Qubit Quantum Sensing

Year: 2018

Authors: Poggiali F., Cappellaro P., Fabbri N.

Autors Affiliation: LENS European Laboratory for Non-Linear Spectroscopy, Università di Firenze, I-50019 Sesto Fiorentino, Italy; INO-CNR Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche, I-50019 Sesto Fiorentino, Italy; Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

Abstract: Quantum systems can be exquisite sensors thanks to their sensitivity to external perturbations. This same characteristic also makes them fragile to external noise. Quantum control can tackle the challenge of protecting a quantum sensor from environmental noise, while strongly coupling the sensor with the field to be measured. As the compromise between these two conflicting requirements does not always have an intuitive solution, optimal control based on a numerical search could prove very effective. Here, we adapt optimal control theory to the quantum-sensing scenario by introducing a cost function that, unlike the usual fidelity of operation, correctly takes into account both the field to be measured and the environmental noise. We experimentally implement this novel control paradigm using a nitrogen vacancy center in diamond, finding improved sensitivity to a broad set of time-varying fields. The demonstrated robustness and efficiency of the numerical optimization, as well as the sensitivity advantage it bestows, will prove beneficial to many quantum-sensing applications.

Journal/Review: PHYSICAL REVIEW X

Volume: 8 (2)      Pages from: 021059-1  to: 021059-13

KeyWords: Cost functions; Optimization; Quantum optics, Environmental noise; External perturbations; Nitrogen-vacancy center; Numerical optimizations; Numerical search; Optimal control theory; Optimal controls; Sensing applications, Control theory; Diamond
DOI: 10.1103/PhysRevX.8.021059

Citations: 13
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