标题： 声子计数的交叉-克尔非线性 显示英文标题

标题： Cross-Kerr nonlinearity for phonon counting

摘要： 量子谐振子的状态测量在量子光学和量子信息处理中至关重要。在囚禁离子系统中，我们通过有效交叉Kerr耦合到另一个运动模式，实验证明了对离子运动模式状态的投影测量。这种耦合是由离子之间库仑相互作用的固有非线性引起的。我们通过光谱解析第一个模式的运动边带由于第二个模式存在单声子而产生的频率位移，并利用它来重构第二个模式的声子数分布。 显示英文摘要

摘要： State measurement of a quantum harmonic oscillator is essential in quantum optics and quantum information processing. In a system of trapped ions, we experimentally demonstrate the projective measurement of the state of the ions' motional mode via an effective cross-Kerr coupling to another motional mode. This coupling is induced by the intrinsic nonlinearity of the Coulomb interaction between the ions. We spectroscopically resolve the frequency shift of the motional sideband of the first mode due to presence of single phonons in the second mode and use it to reconstruct the phonon number distribution of the second mode.