Entangling gates with performance close to fundamental limits

牛津大学和NIST博尔德离子阱小组都展示了双量子位纠缠门，保真度达到了世界纪录的99.9%，明显高于任何其他量子位平台[balance等人]。Phys.Rev.Lett。2016, Gaebler et al.，《物理学报》。2016]。然而，误差仍然比拉曼光子散射设定的准基本极限高出约一个数量级。牛津大学最近还实现了离子阱中最快的纠缠门（480ns） [Schäfer等人，Nature 2018]，其速度与最近在硅器件中展示的双量子比特门相似。这个项目将有一个雄心勃勃的目标，即尽量减少剩余的技术误差，使光子散射的最佳保真度接近99.99%的极限。学生还将研究通过控制驱动栅极的激光场的光学相位和/或减小Lamb-Dicke参数来进一步加速栅极速度的新想法的实用性。该项目属于EPSRC量子器件组件和系统主题

The Oxford and NIST Boulder ion trap groups have both demonstrated two-qubit entangling gates with world-record 99.9% fidelity, significantly higher than in any other qubit platform [Ballance et al. Phys.Rev.Lett. 2016, Gaebler et al., Phys.Rev.Lett. 2016]. However, the error is still about one order of magnitude above the quasi-fundamental limit set by Raman photon scattering. Oxford have also recently achieved the fastest (480ns) entangling gate in ion traps [Schäfer et al., Nature 2018] which is similar in speed to the recently-demonstrated two-qubit gates in silicon devices. This project will have the ambitious goal of minimizing the remaining technical errors, to push the best fidelity closer to the photon scattering limit of 99.99%. The student will also investigate the practicality of demonstrating new ideas for accelerating the gate speed further by control of the optical phase of the laser field that drives the gate, and/or reduction of the Lamb-Dicke parameter. This project falls under the EPSRC Quantum devices components and systems theme