The physical implementation of logical qubits using trapped ions

容错是构建大规模量子计算机的关键一步。如果没有容错，量子门中的小不确定性会在算法过程中累积，从而限制了可以执行的计算的大小。虽然不可克隆定理排除了经典校正方案的天真实现，但新的校正方案如Steane码被开发出来。与量子纠错码相关的一个重要概念是逻辑量子比特。通过使用多个物理量子比特来形成更少数量的鲁棒逻辑量子比特来实现检测和纠正错误。一个逻辑量子位的物理实现需要多个量子位和对它们执行高保真门的能力。该项目的目标是实现一个基于离子限制在微加工表面陷阱上的逻辑量子位，并使用该量子位来纠正多个错误。该项目将利用已经证明的概念，目前正在苏塞克斯的离子量子技术集团开发中。每个物理量子位将是一个基于镱离子的微波修饰态量子位，被捕获在一个微加工的表面陷阱上。曲面陷波器将由X结几何体组成。门将通过射频和微波辐射结合磁场梯度来实现[1]。逻辑量子位的实现是该集团长期努力构建2017年初发布的蓝图中所述的大规模量子计算机的一个组成部分

Fault tolerance is a key step toward the construction of a large-scale quantum computer. Without fault tolerance,small infidelities in quantum gates accumulate over the course of an algorithm, limiting the size of computationsthat could be performed. While the no-cloning Theorem ruled out the naive implementation of classical correctionschemes, new ones such as the Steane code were developed. An important notion associated with quantum error correctioncodes is the logical qubit. Detecting and correcting errors is achieved by using multiple physical qubits to forma smaller number of robust logical qubits. The physical implementation of a logical qubit requires multiple qubit andthe ability to perform high fidelity gates on them.The project aims to realize a logical qubit based on ions confined on a microfabricated surface trap and use thesystem to correct for multiple errors. This project will make use of concepts that have already been demonstratedand currently are under development at the Ion Quantum Technology Group at Sussex. Each physical qubit will bea microwave dressed state qubit based on ytterbium ions, trapped on a microfabricated surface trap. The surface trapwill consist of an X-junction geometry. Gates will be realized through RF and microwave radiation in combinationwith magnetic field gradients [1]. The implementation of a logical qubit forms an integral part of the group's long termeffort to construct a large scale quantum computer as laid out in the blueprint published early 2017