Robust operating point for capacitively coupled singlet-triplet qubits
Robust operating point for capacitively coupled singlet-triplet qubits
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DOI：
10.1103/physrevb.96.201307
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发表时间：
2017-03
影响因子：
3.7
通讯作者：
M. Wolfe;Fernando A. Calderon-Vargas;J. Kestner
中科院分区：
文献类型：
--
作者：
M. Wolfe;Fernando A. Calderon-Vargas;J. Kestner
半导体异质结中横向量子点中的单、三重态量子比特通过交换作用和磁场梯度表现出高保真的单量子比特门。高保真的两量子比特纠缠门的产生具有挑战性，因为弱的量子比特之间的相互作用会导致慢门在存在噪声的情况下积累误差。然而，量子比特间的静电相互作用也产生了局域双势垒失谐的位移，有效地改变了交换对栅极电压的依赖关系。我们考虑一个工作点，其中有效交换是一阶对电荷涨落不敏感的，同时保持非零相互作用。这个“甜蜜点”只存在于互动中。我们证明了在相互作用的甜蜜点工作可以直接产生最大纠缠态的门，并模拟了在真实1/f噪声下的门的演化。我们报道了在GaAs和Si系统中双量子位栅保真度高于99%的理论结果。
Singlet-triplet qubits in lateral quantum dots in semiconductor heterostructures exhibit high-fidelity single-qubit gates via exchange interactions and magnetic field gradients. High-fidelity two-qubit entangling gates are challenging to generate since weak interqubit interactions result in slow gates that accumulate error in the presence of noise. However, the interqubit electrostatic interaction also produces a shift in the local double well detunings, effectively changing the dependence of exchange on the gate voltages. We consider an operating point where the effective exchange is first order insensitive to charge fluctuations while maintaining nonzero interactions. This "sweet spot" exists only in the presence of interactions. We show that working at the interacting sweet spot can directly produce maximally entangling gates and we simulate the gate evolution under realistic 1/f noise. We report theoretical two-qubit gate fidelities above 99% in GaAs and Si systems.