A research group led by Professor Mio Murao has successfully demonstrated that quantum memory holds an advantage over classical memory in the tasks of quantum information processing known as storage and retrieval. There were two approaches: a classical strategy, in which the contents of quantum operations are temporarily recorded in classical memory, and a quantum strategy, in which they are stored as quantum states in quantum memory. The research group focused on a quantum operation called an “isometric operation,” which represents information encoding, and by analytically solving the problem of determining the optimal estimation accuracy for this operation, they demonstrated that the estimation of isometric operations is subject to a limit known as the standard quantum limit. By comparing this classical limit with existing quantum strategies, they successfully demonstrated the superiority of quantum strategies. The paper detailing these findings was published online in the May 13 issue of “Physical Review Letters”.
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