Cech Marcel, Lesanovsky Igor, Carollo Federico
Institut für Theoretische Physik, Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen, Germany.
School of Physics and Astronomy and Centre for the Mathematics and Theoretical Physics of Quantum Non-Equilibrium Systems, The University of Nottingham, Nottingham NG7 2RD, United Kingdom.
Phys Rev Lett. 2023 Sep 22;131(12):120401. doi: 10.1103/PhysRevLett.131.120401.
Quantum computers have recently become available as noisy intermediate-scale quantum devices. Already these machines yield a useful environment for research on quantum systems and dynamics. Building on this opportunity, we investigate open-system dynamics that are simulated on a quantum computer by coupling a system of interest to an ancilla. After each interaction the ancilla is measured, and the sequence of measurements defines a quantum trajectory. Using a thermodynamic analogy, which identifies trajectories as microstates, we show how to bias the dynamics of the open system in order to enhance the probability of quantum trajectories with desired properties, e.g., particular measurement patterns or temporal correlations. We discuss how such a biased-generally non-Markovian-dynamics can be implemented on a unitary, gate-based quantum computer and show proof-of-principle results on the publicly accessible ibmq_jakarta machine. While our analysis is solely conducted on small systems, it highlights the challenges in controlling complex aspects of open-system dynamics on digital quantum computers.
量子计算机最近已作为有噪声的中等规模量子设备投入使用。这些机器已经为量子系统和动力学的研究提供了一个有用的环境。基于这一契机，我们研究了通过将感兴趣的系统与辅助系统耦合在量子计算机上模拟的开放系统动力学。每次相互作用后对辅助系统进行测量，测量序列定义了一条量子轨迹。利用一种将轨迹识别为微观状态的热力学类比，我们展示了如何使开放系统的动力学产生偏差，以提高具有所需特性（例如特定测量模式或时间相关性）的量子轨迹的概率。我们讨论了如何在基于门的酉量子计算机上实现这种有偏差的——通常是非马尔可夫的——动力学，并在公开可用的ibmq_jakarta机器上展示了原理验证结果。虽然我们的分析仅在小系统上进行，但它突出了在数字量子计算机上控制开放系统动力学复杂方面的挑战。
