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Colloquium: High-Efficiency, Low-Noise, Broadband Quantum Memory in Atomic Vapor

ABSTRACT

Quantum memory stands as a pivotal component in long-distance quantum communication and quantum computation. The capacity to efficiently and accurately write optical quantum information into a memory and retrieve it on demand is indispensable for advancing the practical realization of these technologies. Our researches are centered on the experimental development of high-performance quantum memory, utilizing atomic vapor cells as the medium.

Firstly, we improved the memory efficiency of broadband optical quantum information by optimizing the temporal mode of driving optical field pulses in real-time. This optimization yielded a bandwidth of 160 MHz, a memory efficiency of 82%, and a fidelity of 98%. Subsequently, to further increase memory efficiency while addressing the concurrent issue of four-wave mixing nonlinear noise, we integrated optical quantum interference techniques into the quantum memory process. This approach resulted in a 7% increase in memory efficiency and suppressed 80% of the four-wave mixing noise through interference cancellation.  Lastly, we developed artificial intelligence control to optimize the spatial distribution of atomic spin waves. This optimization led to a further reduction of the four-wave mixing noise to below 1%, enabling us to achieve a memory efficiency of 92% and a fidelity of 99% for a 10ns-long signal optical pulse at single-photon level.

 

BIOGRAPHY

Prof. Liqing Chen is a Professor of the School of Physics and Electronic Science at East China Normal University, Shanghai. She received her Ph.D. in atomic and molecular physics from the University of Science and Technology of China in 2005. Her research focuses on experimental research on quantum control, broadband quantum memory and quantum measurements of magnetic field, phase and angular velocity based on atom-light hybrid system. She has published more than 40 papers in physics journals, including Science Advances, Nature Communications, Physical Review Letter, won "Shanghai's Outstanding Innovative Young Woman" as well as the First Prize in Shanghai Natural Science Awards

Event Details
Speaker
Prof. Liqing Chen
Professor, East China Normal University

Date & Time
20 November 2024 3 pm

Venue
LT-15, Yeung Kin Man Academic Building, City University of Hong Kong

Chair
Prof. Jeff Ou (34422825)
jeffou@cityu.edu.hk