High-fidelity entangling gate for double-quantum-dot spin qubits
High-fidelity entangling gate for double-quantum-dot spin qubits
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DOI：
10.1038/s41534-016-0003-1
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发表时间：
2017-01-19
影响因子：
7.6
通讯作者：
Yacoby, Amir
中科院分区：
文献类型：
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作者：
Nichol, John M.;Orona, Lucas A.;Yacoby, Amir
半导体中的电子自旋是有前途的量子位，因为它们的相干时间较长，可实现近 109 种相干量子门操作。然而，开发可扩展的高保真双量子位门仍然具有挑战性。在这里，我们通过使用每个量子位中两个点之间的磁场梯度来抑制电荷噪声导致的退相干，展示了砷化镓中两个双量子点自旋量子位之间的纠缠门。当磁梯度主导电子之间的压控交换相互作用时，量子位相干时间会增加一个数量级。使用随机基准测试，我们测量出接近 99% 的单量子位门保真度，并通过自洽量子测量、状态和过程断层扫描，我们测量出 90% 的纠缠门保真度。未来，在硅等无核自旋材料中以大梯度运行双量子点自旋量子位，应该能够使双量子位门的保真度超过容错量子信息处理的阈值。
Electron spins in semiconductors are promising qubits because their long coherence times enable nearly 109 coherent quantum gate operations. However, developing a scalable high-fidelity two-qubit gate remains challenging. Here, we demonstrate an entangling gate between two double-quantum-dot spin qubits in GaAs by using a magnetic field gradient between the two dots in each qubit to suppress decoherence due to charge noise. When the magnetic gradient dominates the voltage-controlled exchange interaction between electrons, qubit coherence times increase by an order of magnitude. Using randomized benchmarking, we measure single-qubit gate fidelities of similar to 99%, and through self-consistent quantum measurement, state, and process tomography, we measure an entangling gate fidelity of 90%. In the future, operating double quantum dot spin qubits with large gradients in nuclear-spin-free materials, such as Si, should enable a two-qubit gate fidelity surpassing the threshold for fault-tolerant quantum information processing.