Derivation of optimal quantum sequential measurement using convex programming

2018 Fiscal Year Final Research Report

• Project/Area Number: 17H07115
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Single-year Grants
• Research Field: Communication/Network engineering
• Research Institution: Tamagawa University
• Principal Investigator: NAKAHIRA Kenji 玉川大学, 量子情報科学研究所, 教授 (90804005)
• Project Period (FY): 2017-08-25 – 2019-03-31
• Keywords: 量子測定 / 量子情報 / 量子光学 / 最適逐次測定

Outline of Final Research Achievements

Optimization of quantum sequential measurements is required for practical optical communications with quantum measurements. We have developed a widely applicable method to optimize sequential measurements.　Specifically, we have first formulated the problem of obtaining a minimum-error sequential measurement as a convex programming problem, which enables an effective analysis. Next, we have derived a necessary and sufficient condition for optimality and have devised a numerical technique to compute an optimal solution. Moreover, these techniques have been extended to a large class of optimality criteria. We have obtained optimal sequential measurements for several sets of signals that had not been revealed by conventional methods.

Free Research Field

量子情報理論

Academic Significance and Societal Importance of the Research Achievements

光通信において従来の古典的な測定を用いて光信号を受信する代わりに量子測定と呼ばれる量子雑音にロバストな測定を用いると，原理的にはより高い通信性能が得られることが知られている。ただし，現在のテクノロジーで実用的な量子測定を実現するためには逐次測定と呼ばれる種類の測定に限定して設計を行う必要がある。本研究では，最適な逐次測定を求めるための問題を定式化して性能評価を行うための汎用的な手法を開発した。本成果は，現在のテクノロジーで実現可能な量子測定の設計に活用できる。