Title: Observing and Verifying the Quantum Trajectory of a Mechanical Resonator Show Chinese title

Title: 观察和验证机械谐振器的量子轨迹

Abstract: Continuous weak measurement allows localizing open quantum systems in state space, and tracing out their quantum trajectory as they evolve in time. Efficient quantum measurement schemes have previously enabled recording quantum trajectories of microwave photon and qubit states. We apply these concepts to a macroscopic mechanical resonator, and follow the quantum trajectory of its motional state conditioned on a continuous optical measurement record. Starting with a thermal mixture, we eventually obtain coherent states of 78% purity--comparable to a displaced thermal state of occupation 0.14. We introduce a retrodictive measurement protocol to directly verify state purity along the trajectory, and furthermore observe state collapse and decoherence. This opens the door to measurement-based creation of advanced quantum states, and potential tests of gravitational decoherence models. Show Chinese abstract

Abstract: 连续弱测量允许在状态空间中定位开放量子系统，并跟踪它们随时间演化的量子轨迹。 高效的量子测量方案以前已实现了对微波光子和量子比特状态的量子轨迹记录。 我们将这些概念应用于宏观机械谐振器，并根据连续光学测量记录跟踪其运动状态的量子轨迹。 从热混合态开始，我们最终获得了纯度为78%的相干态——与占据数为0.14的位移热态相当。 我们引入了一种回溯性测量协议，以直接验证轨迹上的态纯度，并进一步观察到态坍缩和退相干。 这为基于测量的先进量子态创建打开了大门，并可能对引力退相干模型进行测试。