标题： 超快相干激发钙$^+$离子 显示英文标题

标题： Ultrafast coherent excitation of a Ca$^+$ ion

摘要： 被俘获的离子是实现可扩展量子计算机的一个研究充分且有前景的系统。更快的量子门将大大提升此类系统的适用性，并允许在计算步骤数量上更具灵活性。在本文中，我们提出了一种脉冲激光系统，该系统以5 GHz的重复率提供皮秒脉冲，并与Ca$^+$中S$_{1/2}$到P$_{3/2}$转换共振，用于实现快速相位门操作的相干态转移。光脉冲序列来源于锁模稳定光学频率梳，并继承了其频率稳定性。使用单个被捕获的离子，我们实现了三种不同的技术来测量离子-激光耦合强度并表征激光发出的脉冲序列，并展示了如何满足实现快速相位门操作的所有要求。 显示英文摘要

摘要： Trapped ions are a well-studied and promising system for the realization of a scalable quantum computer. Faster quantum gates would greatly improve the applicability of such a system and allow for greater flexibility in the number of calculation steps. In this paper we present a pulsed laser system, delivering picosecond pulses at a repetition rate of 5 GHz and resonant to the S$_{1/2}$ to P$_{3/2}$ transition in Ca$^+$ for coherent population transfer to implement fast phase gate operations. The optical pulse train is derived from a mode-locked, stabilized optical frequency comb and inherits its frequency stability. Using a single trapped ion, we implement three different techniques for measuring the ion-laser coupling strength and characterizing the pulse train emitted by the laser, and show how all requirements can be met for an implementation of a fast phase gate operation.