We present an experimental investigation of coherent crosstalk cancellation methods for light delivered to a linear ion chain cryogenic quantum register. The ions are individually addressed using focused laser beams oriented perpendicular to the crystal axis, which are created by imaging each output of a multi-core photonic-crystal fibre waveguide array onto a single ion. The measured nearest-neighbor native crosstalk intensity of this device for ions spaced by 5 µm is found to be . We show that we can suppress this intensity crosstalk from waveguide channel coupling and optical diffraction effects by a factor using cancellation light supplied to neighboring channels which destructively interferes with the crosstalk. We measure a rotation error per gate on the order of on spectator qubits, demonstrating a suppression of crosstalk error by a factor of . We compare the performance to composite pulse methods for crosstalk cancellation, and describe the appropriate calibration methods and procedures to mitigate phase drifts between these different optical paths, including accounting for problems arising due to pulsing of optical modulators.

中文翻译：

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在阱离子实验中物理相干消除光寻址串扰


我们提出了对传送到线性离子链低温量子寄存器的光的相干串扰消除方法的实验研究。离子使用垂直于晶轴的聚焦激光束单独寻址，该激光束是通过将多核光子晶体光纤波导阵列的每个输出成像到单个离子上而创建的。对于以 5 μm 为间距的离子，该器件测得的最近邻天然串扰强度为 。我们表明，我们可以通过使用提供给相邻通道的抵消光来抑制波导通道耦合和光学衍射效应的这种强度串扰，该抵消光会对串扰产生破坏性干扰。我们按照旁观者量子比特的数量级测量每个门的旋转误差，证明串扰误差的抑制系数为 。我们将串扰消除性能与复合脉冲方法进行了比较，并描述了适当的校准方法和程序，以减轻这些不同光路之间的相位漂移，包括考虑由于光调制器脉冲而出现的问题。