2026-08-24 東京大学
量子状態から仕事を取り出す際に可能な操作の概念図：青い矢印が電子やスピンなどの量子系を表し、緑色の影がそれに対する操作者を表す。従来は、（a）多体系全体を自由に操作できる場合と、（c）各粒子を独立にしか操作できない場合という両極端の状況が主に議論されてきたが、本研究ではその中間に位置する（b）局所操作と古典通信の下での、量子状態の熱的な性質を明らかにした。
＜関連情報＞
- https://www.t.u-tokyo.ac.jp/press/pr2026-08-24-001
- https://journals.aps.org/prl/abstract/10.1103/zsb1-gx7f
局所操作と古典通信における抽出可能な仕事による熱状態との等価性の検証 Testing the Equivalence to Thermal States via Extractable Work under Local Operations and Classical Communication
Toshihiro Yada, Nobuyuki Yoshioka, and Takahiro Sagawa
Physical Review Letters Published: 21 August, 2026
DOI: https://doi.org/10.1103/zsb1-gx7f
Abstract
Understanding the thermal behavior of quantum many-body pure states is one of the most fundamental issues in quantum thermodynamics. It is widely known that typical pure states yield vanishing work, just as thermal states do, when one restricts to local operations that cannot access correlations among subsystems. However, it remains unclear whether this equivalence to thermal states persists under local operations and classical communication (LOCC), where classically accessible correlations can be exploited for work extraction. In this Letter, we establish criteria for determining whether many-body pure states remain equivalent to thermal states even under LOCC, and show that this thermal equivalence is governed by their multipartite quantum correlation structure. We show that states with asymptotically maximal multipartite entanglement, such as Haar-random states, cannot yield extensive work under LOCC, whereas some states with limited multipartite entanglement, such as constant-degree graph states, allow extensive work extraction despite being locally indistinguishable from thermal states. Thus, our Letter provides a refined operational notion of thermal equivalence beyond the traditional local regime, which is becoming increasingly important due to the recent expansion of experimentally accessible operations.
