| 研究実績の概要 |
During the second year of this project, FY2021, we extended the theoretical insights gained in FY2020 to areas closer to applied technologies, such as quantum devices benchmarking and learning. In this regard, we obtained the first closed-form expression for the guesswork in the presence of quantum side-information. The guesswork is defined as the expected number of attempts needed before guessing a password or breaking a code. As such, the guesswork seems more relevant than other information-theoretic measures in many practical applications. Our work constitutes the first non-trivial, exact, closed-form calculation of the guesswork in the presence of quantum side-information, that is, in the case in which the eavesdropper possess some "quantum bits" correlated with the password to be guessed.
Also, we achieved a new understanding for the sender‐receiver correlations that can be established by means of a quantum communication device. We formulated the problem in a game-theoretic scenario called "communication game". In this way, we were able to characterize the input-output correlations for a large class of quantum communication channels of practical relevance.
Finally, we explored the theory of quantum thermodynamics from the viewpoint of statistical inference, discovering that many results of nonequilibrium quantum thermodynamics can be clarified by invoking the concept of Bayesian retrodiction.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
3: やや遅れている
理由
The theoretical research activities and the corresponding publication rate is proceeding as expected, but the travel restrictions caused by the COVID pandemic have seriously affected the dissemination of our results in international meetings and conferences, and scientific exchanges with the international community. We hope that the coming fiscal year FY2022 will see an improvement from this viewpoint.
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| 今後の研究の推進方策 |
As anticipated in the research proposal, the third year will be devoted not only to the consolidation of the results obtained so far in quantum information theory and quantum resource theories, but also to the exploration of new avenues concerning the role of statistical inference in quantum resource theories and more generally in physics and science. In this direction, we already obtained some foundational work in statistical mechanics (see the two papers published on PRE and AVS Quantum Science) and we are planning to move on from there.
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