Title: Optimized quantum measurement: from cooling to shaping

Speaker: Jun Jing (景俊), School of Physics, Zhejiang University

Date and Time: 2023年12月14日 2:00pm

Location: 培黎职业学院综合楼2层

Abstract：A quantum resonator in a thermal-equilibrium state with a high temperature has a large average population and is featured with a significant occupation over Fock states with a high excitation number. In this work, we use the “free-evolution and measurement” cycles to optimize the measurement-based cooling in terms of the average-population reduction rate, the success probability, the target-state fidelity, and the numbers of running cycles. The scheme of projective measurement is generalized to POVM, based on which a quantum charging architecture is established to transform the thermal state to a population-inverted state. We then can modify an energetic yet unusable system to be a battery with a near-unit ratio of ergotropy (usable energy by unitary transformation) to energy. Through our schemes, quantum measurement becomes an interesting tool to shape quantum systems.

References:

[1] J. Yan and J. Jing*, External-level assisted cooling by measurement, Physical Review A 104, 063105 (2021).

[2] J. Yan and J. Jing*, Simultaneous cooling by measuring one ancillary system, Physical Review A 105, 052607 (2022).

[3] J. Yan and J. Jing*, Optimizing measurement-based cooling by reinforcement learning, Physical Review A 106, 033124 (2022).

[4] J. Yan and J. Jing*, Charging by quantum measurement, Physical Review Applied 19, 064069 (2023).

About the speaker: Dr. Jun Jing is a full professor at the institute of optics and quantum information, School of Physics, Zhejiang University. He got his bachelor and PhD degree from Department of Physics, Shanghai Jiaotong University. He was a postdoctoral research associate at Stevens Institute of Technology, New Jersey, USA, a research scientist at University at Buffalo, The State University of New York, USA, and a visiting scholar at Basque Country University, Bilbao, Spain. He is devoted to theoretical physics covering open quantum system dynamics, quantum measurement and control, and quantum information. He is the first author and/or the corresponding author of over 80 peer-reviewed papers, over 50% of which are published at APS journals.