近日，俄罗斯量子中心的Aleksey K. Fedorov及其研究小组与美国芝加哥大学的Alexey Galda等人合作并取得一项新进展。经过不懈努力，他们利用超导和俘获量子三比特成功证实宇称-时间对称性破缺相变现象。相关研究成果已于2024年3月25日在国际知名学术期刊《物理评论A》上发表。

在这项工作中，研究人员专注于模拟非幺正宇称-时间对称系统，这种系统表现出独特的对称性破缺相变以及其他在封闭系统中没有对应的独特特征。研究人员证明了一个量子三比特系统，一个三能级的量子系统，能够实现这种非平衡相变。为了验证这一点，研究人员利用了两个不同的物理平台：俘获离子阵列和超导传输子。

通过数字方式精确控制这两个系统的三个能级，他们成功地实验模拟了宇称-时间对称性破缺的相变过程。 这项研究不仅揭示了多能级（高维量子态）处理器在模拟复杂物理效应方面的巨大潜力，而且展示了额外可访问能级在模拟受控环境中所发挥的关键作用。

据悉，可扩展量子计算机有望解决复杂的计算问题，如质因数分解、组合优化、多体物理模拟和量子化学。非保守量子动力学的模拟虽然是理解许多现实世界现象的关键，但对幺正量子计算提出了挑战。

附：英文原文

Title: Demonstration of a parity-time-symmetry-breaking phase transition using superconducting and trapped-ion qutrits

Author: Alena S. Kazmina, Ilia V. Zalivako, Alexander S. Borisenko, Nikita A. Nemkov, Anastasiia S. Nikolaeva, Ilya A. Simakov, Arina V. Kuznetsova, Elena Yu. Egorova, Kristina P. Galstyan, Nikita V. Semenin, Andrey E. Korolkov, Ilya N. Moskalenko, Nikolay N. Abramov, Ilya S. Besedin, Daria A. Kalacheva, Viktor B. Lubsanov, Aleksey N. Bolgar, Evgeniy O. Kiktenko, Ksenia Yu. Khabarova, Alexey Galda, Ilya A. Semerikov, Nikolay N. Kolachevsky, Nataliya Maleeva, Aleksey K. Fedorov

Issue&Volume: 2024/03/25

Abstract: Scalable quantum computers hold the promise to solve hard computational problems, such as prime factorization, combinatorial optimization, simulation of many-body physics, and quantum chemistry. While being key to understanding many real-world phenomena, simulation of nonconservative quantum dynamics presents a challenge for unitary quantum computation. In this work, we focus on simulating nonunitary parity-time-symmetric systems, which exhibit a distinctive symmetry-breaking phase transition as well as other unique features that have no counterpart in closed systems. We show that a qutrit, a three-level quantum system, is capable of realizing this nonequilibrium phase transition. By using two physical platforms, an array of trapped ions and a superconducting transmon, and by controlling their three energy levels in a digital manner, we experimentally simulate the parity-time-symmetry-breaking phase transition. Our results indicate the potential advantage of multilevel (qudit) processors in simulating physical effects, where additional accessible levels can play the role of a controlled environment.

DOI: 10.1103/PhysRevA.109.032619

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.032619