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arXiv 1306.0642quant-ph
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动态解耦条件下的去相辅助参数估计

Dephasing-assisted parameter estimation in the presence of dynamical decoupling

Qing-Shou Tan, Yixiao Huang, Le-Man Kuang, Xiaoguang Wang

摘要:

研究了在动态退耦(DD)脉冲作用下,原子干涉仪中的退相辅助参数估计(PPE)精度的提高。通过对自旋压缩和量子费舍尔信息的计算,发现退相噪声通过诱导自旋压缩可以改善PPE,而DD脉冲可以使这种改善最大化。结果表明,在DD脉冲作用下,退相诱导的SS可以达到\textquotedblleft单轴扭转\textquotedblright模型的极限,即$ξ^2\simeq N^{-2/3}$,其中$ξ^2$为SS参数,N为原子数.特别地,我们发现DD脉冲可以将退相引起的QFI放大$\simeq N/2$倍,这意味着在DD脉冲的控制下,退相噪声可以将PPE增强到$\sqrt{2}/N$的量级,与海森堡极限(1/N)相同.

英文摘要:

We study the dephasing-assisted precision of parameter estimation (PPE) enhancement in atom interferometer under dynamical decoupling (DD) pulses. Through calculating spin squeezing (SS) and quantum Fisher information (QFI), we find that dephasing noise can improve PPE by inducing SS, and the DD pulses can maximize the improvement. It is indicated that in the presence of DD pulses, the dephasing-induced SS can reach the limit of \textquotedblleft one-axis twisting\textquotedblright\ model, $ξ^2\simeq N^{-2/3}$ with $ξ^2$ being the SS parameter and N the number of atoms. In particular, we find that the DD pulses can amplify the dephasing-induced QFI by a factor of $\simeq N/2$ compared with the noise-free case, which means that under the control of DD pulses, the dephasing noise can enhance the PPE to the scale of $\sqrt{2}/N$, the same order of magnitude of Heisenberg limit (1/N).

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