Coherent quantum oscillations and echo measurements of a Si charge qubit
Coherent quantum oscillations and echo measurements of a Si charge qubit
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DOI：
10.1103/physrevb.88.075416
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发表时间：
2013-08-13
影响因子：
3.7
通讯作者：
Eriksson, M. A.
中科院分区：
文献类型：
--
作者：
Shi, Zhan;Simmons, C. B.;Eriksson, M. A.
通过实验证明和表征了在 Si/SiGe 异质结构中制造的双量子点中电荷量子位的快速量子振荡。测得的非均匀移相时间T-2*范围为127 ps至2.1 ns；它很大程度上取决于两个量子位状态的能量差如何随外部电压变化，这与由失谐噪声（改变量子位双阱电势的不对称性的电荷噪声）主导的退相干过程一致。在最短 T-2* 的情况下，应用电荷回波脉冲序列将测量的不均匀退相干时间从 127 ps 增加到 760 ps，这表明低频噪声过程是一种重要的移相机制。
Fast quantum oscillations of a charge qubit in a double quantum dot fabricated in a Si/SiGe heterostructure are demonstrated and characterized experimentally. The measured inhomogeneous dephasing time T-2* ranges from 127 ps to 2.1 ns; it depends substantially on how the energy difference of the two qubit states varies with external voltages, consistent with a decoherence process that is dominated by detuning noise (charge noise that changes the asymmetry of the qubit's double-well potential). In the regime with the shortest T-2*, applying a charge-echo pulse sequence increases the measured inhomogeneous decoherence time from 127 to 760 ps, demonstrating that low-frequency noise processes are an important dephasing mechanism.