2025-08-28 東京大学
(a) 本研究で用いた実験系の模式図。シリコン空孔中心の電子スピン量子ビットに対して、光学的な測定を繰り返し行い、その結果を高速で処理してフィードバックする。(b) 直近の測定結果のみに基づくマルコフ的なフィードバックプロトコル。(c) 過去の測定結果の履歴も活用した非マルコフ的なフィードバックプロトコル。
＜関連情報＞
- https://www.t.u-tokyo.ac.jp/press/pr2025-08-28-002
- https://www.t.u-tokyo.ac.jp/hubfs/press-release/2025/0828/002/text.pdf
- https://journals.aps.org/prx/abstract/10.1103/5lp2-9sps
反復的量子情報伝達によるエントロピー減少の実験的検証 Experimentally Probing Entropy Reduction via Iterative Quantum Information Transfer
Toshihiro Yada, Pieter-Jan Stas, Aziza Suleymanzade, Erik N. Knall, Nobuyuki Yoshioka, Takahiro Sagawa, and Mikhail D. Lukin
Physical Review X Published: 26 August, 2025
DOI: https://doi.org/10.1103/5lp2-9sps
Abstract
Thermodynamic principles governing energy and information are important tools for a deeper understanding and better control of quantum systems. In this work, we experimentally investigate the interplay of the thermodynamic costs and information flow in a quantum system undergoing iterative quantum measurement and feedback. Our study employs a state stabilization protocol involving repeated measurement and feedback on an electronic spin qubit associated with a silicon-vacancy center in diamond, which is strongly coupled to a diamond nanocavity. This setup allows us to verify the fundamental laws of nonequilibrium quantum thermodynamics, including the second law and the fluctuation theorem, both of which incorporate measures of quantum information flow induced by iterative measurement and feedback. We further assess the reducible entropy based on the feedback’s causal structure and quantitatively demonstrate the thermodynamic advantages of non-Markovian feedback over Markovian feedback. For that purpose, we extend the theoretical framework of quantum thermodynamics to include the causal structure of the applied feedback protocol. Our work lays the foundation for investigating the entropic and energetic costs of real-time quantum control in various quantum systems.
