超导量子计算中的量子纠错

项目名称： 超导量子计算中的量子纠错

项目编号： No.11474177

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 孙麓岩

作者单位： 清华大学

项目金额： 110万元

中文摘要： 基于超导的量子计算实验在过去的十多年已经有了长足的发展,但是到目前为止还没有实现一个通过纠错使寿命得到延长的量子存储。实现这样一个由量子纠错保护的量子存储是目前整个量子计算领域最急需解决的关键问题之一。能够克服量子退相干影响的量子纠错也是实现大规模量子计算必不可少的要求。最近一个基于微波谐振腔中薛定谔猫态的量子纠错方案引起了人们的关注。该方案利用了谐振子本身即具有无限维Hilbert空间的特点来对冗余量子信息进行编码而不会增加错误症状的个数，同时又利用了微波谐振腔优异的相干性能，因此极大简化了对硬件的要求。电路腔量子电动力学的快速发展大大提高了该量子纠错方案的可行性。根据已发表的理论工作，我们计划在实验上实现一个由该量子纠错方案保护的量子存储，并在此量子存储基础上实现一组通用量子逻辑门操作。我们实验的实现将会为逻辑比特层面上的量子计算打下一个坚实的基础，进而大大推进超导量子计算的进展。

中文关键词： 量子计算；超导量子比特；电路量子电动力学；固态量子计算；量子退相干

英文摘要： Quantum information processing based on superconducting qubits has made tremendous progress toward realizing a practical quantum computer in the past decade. However, no quantum memory with an extended lifetime has ever been demonstrated. To realize such a quantum memory protected by quantum error correction (QEC) is considered to be one of the most urgent goals for the whole field of quantum computation. Because of the fragile nature of quantum information, QEC is required for fault-tolerant quantum computation. In a recent proposal, quantum information is encoded in Schrodinger cat states in a microwave cavity which can be QEC protected. This scheme benefits from the infinite dimensional Hilbert space of a harmonic oscillator for redundant information encoding, only one single error syndrome to track, and long coherence times of the microwave cavity, thus greatly reducing the requirements on hardware. The fast development of circuit quantum electrodynamics has put a realization of this QEC scheme within the reach of current technology. In this proposal, we plan to first realize such a QEC protected quantum memory experimentally, and then extend this quantum memory further to achieve logical operations on the quantum memories. Our experimental efforts will be based on published theoretical work. To achieve these goals, we need to solve problems related to the imperfections during the QEC process such as the ancillary qubit decoherence and the deterministic decay of the Schrodinger cat states. The achievement of the proposed experiment will pave the way towards operations and algorithms on logical qubits and thus greatly move quantum computation based on superconducting qubits forward.

英文关键词： Quantum computation;superconducting qubits;circuit QED;solid state quantum computation;quantum decoherence