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arXiv 1306.5423quant-phphysics.atom-ph
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用CPMG序列抑制单原子量子比特的相位退相干

Suppressing phase decoherence of a single atom qubit with CPMG sequence

Shi Yu, Peng Xu, Xiaodong He, Min Liu, Jin Wang, Mingsheng Zhan

摘要:

实验证明了在光偶极阱中,利用Carr-Purcell-Meiboom-Gill(CPMG)脉冲序列对存储在单个\textsuperscript{87} Rb原子中的量子比特的退相具有很强的抑制作用.作为自旋回波的重复,CPMG序列是抑制非均匀和均匀相位退相干机制的最佳选择。在波长为830 nm、势深为0.7 mK的陷阱中,单原子自旋弛豫时间为830.8 ms,$T_{2}^{\ast}$的可逆非均匀退相时间为1.4 ms,自旋回波过程中的均匀退相时间为$T_{2}^{\prime}$ =102.7 ms,通过采用脉冲数n = 6的CPMG序列,均匀退相被进一步抑制了3倍,其相应的相干时间延长到$T_{2}^{\prime}$ =304.5 ms。

英文摘要:

We experimentally demonstrate the strong suppression of dephasing of a qubit stored in a single \textsuperscript{87}Rb atom in an optical dipole trap by using Carr-Purcell-Meiboom-Gill(CPMG) pulse sequences. Regarded as a repetition of spin echo, CPMG sequence is an optimal choice for suppressing both inhomogeneous and homogeneous phase decoherence mechanisms. In the trap with 830 nm wavelength and 0.7 mK potential depth, the spin relaxation time of single atoms is showed to be 830.8 ms. We obtain the reversible inhomogeneous dephasing time of $T_{2}^{\ast}$=1.4 ms. The homogeneous dephasing time is $T_{2}^{\prime}$ =102.7 ms in the spin echo process, by employing CPMG sequence with pulse number n = 6 the homogeneous dephasing is further suppressed by a factor of 3, and its corresponding coherence time is extended to $T_{2}^{\prime}$=304.5 ms.

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