Institute for Theoretical Physics and Institute for Gravitational Physics (Albert-Einstein-Institute), Leibniz University Hannover, Callinstrasse 38, 30167 Hannover, Germany.
Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland.
Phys Rev Lett. 2016 Jan 8;116(1):013002. doi: 10.1103/PhysRevLett.116.013002.
Optical clocks based on ensembles of trapped ions promise record frequency accuracy with good short-term stability. Most suitable ion species lack closed transitions, so the clock signal must be read out indirectly by transferring the quantum state of the clock ions to cotrapped logic ions of a different species. Existing methods of quantum logic readout require a linear overhead in either time or the number of logic ions. Here we describe a quantum algorithmic readout whose overhead scales logarithmically with the number of clock ions in both of these respects. The scheme allows a quantum nondemolition readout of the number of excited clock ions using a single multispecies gate operation which can also be used in other areas of ion trap technology such as quantum information processing, quantum simulations, metrology, and precision spectroscopy.
基于囚禁离子的光学钟具有创纪录的频率精度和良好的短期稳定性。大多数合适的离子种类缺乏闭合跃迁，因此时钟信号必须通过将时钟离子的量子态转移到不同种类的共囚禁逻辑离子来间接读出。现有的量子逻辑读出方法在时间或逻辑离子数量上都需要线性开销。在这里，我们描述了一种量子算法读出方法，它在这两个方面的时钟离子数量的开销都呈对数级增长。该方案允许使用单个多物种门操作对激发态时钟离子的数量进行量子无损读出，该操作也可用于离子阱技术的其他领域，如量子信息处理、量子模拟、计量学和精密光谱学。
