Variational-state quantum metrology

Journal article

Quantum technologies exploit entanglement to enhance various tasks beyond their classical limits including computation, communication and measurements. Quantum metrology aims to increase the precision of a measured quantity that is estimated in the presence of statistical errors using entangled quantum states. We present a novel approach for finding (near) optimal states for metrology in the presence of noise, using variational techniques as a tool for efficiently searching the high-dimensional space of quantum states, which would be classically intractable. We comprehensively explore systems consisting of up to 9 qubits and find new highly entangled states that are not symmetric under permutations and non-trivially outperform previously known states up to a constant factor 2. We consider a range of environmental noise models; while passive quantum states cannot achieve a fundamentally superior scaling (as established by prior asymptotic results) we do observe a significant absolute quantum advantage. We finally outline a possible experimental setup for variational quantum metrology which can be implemented in near-term hardware.

Authors: Koczor, B; Endo, S; Jones, T; Matsuzaki, Y; Benjamin, SC

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: IOP Publishing
• Journal: New Journal of Physics
• Volume: 22
• Issue: 8
• Article number: 83038
• Publication date: 2020-08-14
• Acceptance date: 2020-05-26
• DOI: 10.1088/1367-2630/ab965e
• EISSN: 1367-2630
• Language: English
• Keywords: quantum simulation; quantum algorithms; quantum information processing; quantum sensing; FFR; quantum metrology