Fast Gates

阱离子装置在少量量子位上展示了构建量子计算机所需的所有构件，其精度优于任何竞争对手的技术。然而，由于缠结门的限制，这些装置的速度并没有相应提高。该项目的目的是通过利用光学相位控制来显著加快捕获离子纠缠门的速度，同时消除目前限制误差的几个基本来源，从而改变这种情况。在初步工作中，我们最近展示了捕获离子量子位的第一个高速纠缠逻辑门[Schafer等人，Nature 555,75(2018)]。我们在1.6微秒门时间内实现了99.8%的保真度，接近报道的最高双量子位门保真度99.9%，但速度快了一个数量级。在这个项目的过程中，我们将扩展这种概念验证技术，以演示多量子位寄存器的第一个高速控制。该项目将涉及实验和理论工作，包括：-开发和数值模拟相位控制的快速纠缠门动力学-建立一个新的设备优化高速多量子位纠缠门-复杂的经典控制技术，以精确控制多量子位寄存器的光相互作用相位

Trapped-ion devices have demonstrated, on a small number of qubits, all the building-blocks required to build a quantum computer with precision better than any competing technology. However the speed of these devices, limited by the entangling gates, has not increased commensurately. The aim of this project is to change this by exploiting optical phase control to significantly speed up trapped-ion entangling gates whilst also removing several currently limiting fundamental sources of error.In preliminary work, we have recently demonstrated the first high-speed entangling logic gates for trapped-ion qubits [Schafer et al., Nature 555, 75 (2018)]. We achieved a fidelity of 99.8% for a 1.6 microsecond gate time, close to the highest reported two-qubit gate fidelities of 99.9%, but more than an order of magnitude faster. Over the course of this project we will extend this proof-of-concept technique to demonstrate the first high-speed control of multi-qubit registers.The project will involve both experimental and theoretical work, including:- developing and numerically modelling phase-controlled fast entangling gate dynamics- building a new apparatus optimised for high-speed multi-qubit entangling gates- sophisticated classical control techniques to precisely control the optical interaction phase of multi-qubit register