近日，浙江大学的宋超及其研究小组与美国得克萨斯农工大学的Girish S. Agarwal等人合作并取得一项新进展。经过不懈努力，他们成功测试量子速度极限的统一界限。相关研究成果已于2024年10月21日在国际知名学术期刊《物理评论A》上发表。

在本研究中，研究人员通过引入适用于所有演化时间的统一界限，利用超导电路在各种场景下对量子速度极限（QSLs）进行了实验验证。研究人员通过精心设计超导谐振子的初始态布居，探索了每个参数区间以及临界点的动力学演化。研究人员在有限能级态以及无限能级的经典和非经典高斯态上测试了统一界限，从而验证了QSLs的判据。这项研究工作极大地深化了对幺正量子演化的理解。

据悉，量子速度极限（QSLs）对量子系统演化速度施加了基本限制。对于哈密顿量不随时间变化的系统，QSLs与初始状态的能量谱紧密相关，这体现了时间-能量不确定性关系的推广。基于哈密顿量的任意阶范数、倒谱的双能量以及能量的标准差，已经提出了不同类型的QSLs，揭示了量子态演化的三个动力学参数区间。尽管理论上取得了进展，但全面的实验验证仍然难以实现。

附：英文原文

Title: Testing the unified bounds of the quantum speed limit

Author: Yaozu Wu, Jiale Yuan, Chuanyu Zhang, Zitian Zhu, Jinfeng Deng, Xu Zhang, Pengfei Zhang, Qiujiang Guo, Zhen Wang, Jiehui Huang, Chao Song, Hekang Li, Da-Wei Wang, H. Wang, Girish S. Agarwal

Issue&Volume: 2024/10/21

Abstract: Quantum speed limits (QSLs) impose fundamental constraints on the evolution speed of quantum systems. For systems with time-independent Hamiltonians, the QSLs are intricately linked to the energy spectra of the initial state, which signify the generalization of the time-energy uncertainty relation. Based on arbitrary-order norms of the Hamiltonian, dual energies from inverted spectra, and the standard deviation of energy, different types of QSLs have been proposed, revealing three dynamical parameter regimes of quantum state evolution. Despite the theoretical advancements, a comprehensive experimental examination remains elusive. In this research, by introducing unified bounds suitable for all evolution times, we present the experimental verification to the QSLs in various scenarios with a superconducting circuit. We explore the dynamical evolution with regard to each parameter regime as well as the critical point by carefully engineering the initial-state population of the superconducting resonator. We test our unified bounds over finite-level states and infinite-level classical and nonclassical Gaussian states, which validates the criteria for the QSLs. Our work substantially deepens our comprehension of unitary quantum evolution.

DOI: 10.1103/PhysRevA.110.042215

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.042215