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arXiv 2407.06006quant-ph
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利用低深度数字量子电路实现海森堡极限的贝叶斯相位估计

Heisenberg-limited Bayesian phase estimation with low-depth digital quantum circuits

California Institute of Technology(加州理工学院);School of Physics and Astronomy, Tel Aviv University(特拉维夫大学物理与天文学学院);Racah Institute of Physics, The Hebrew University of Jerusalem(耶路撒冷希伯来大学拉卡物理研究所)

Su Direkci, Ran Finkelstein, Manuel Endres, Tuvia Gefen

AI总结:

本研究提出了一种利用低深度数字量子电路实现海森堡极限的贝叶斯相位估计方案,通过优化测量策略和初始态选择,提升了相位估计的精度和效率。

摘要:

最优的相位估计协议需要复杂的状态准备和读出方案,通常在许多量子平台中不可用或无法扩展。我们开发并分析了一种方案,该方案利用简单的数字量子电路,其深度与量子比特数量呈对数关系,以在常数开销内实现接近最优的精度。我们发现,对于具有任意宽度的高斯先验相位分布,最优的初始状态可以近似用不同数量的格林伯格-霍恩-泽尔inger态的乘积来实现。利用本地、自适应的测量,优化于先验分布和初始状态,我们证明了海森堡标度是可行的,并且所提出的方案在利用相似初始状态的已知方案中表现更优。对于一个示例先验宽度,我们进行了详细的比较,发现也可以通过使用非自适应测量的方案实现海森堡标度,只要正确分配每个GHZ态和单量子比特旋转的副本数量。我们还提出了一种高效的相位解缠协议,以扩展所提出方案的动态范围,并证明该协议在使用更少额外原子的情况下实现了更高的精度。最后,我们讨论了噪声和不完美门的影响。

英文摘要:

Optimal phase estimation protocols require complex state preparation and readout schemes, generally unavailable or unscalable in many quantum platforms. We develop and analyze a scheme that achieves near-optimal precision up to a constant overhead for Bayesian phase estimation, using simple digital quantum circuits with depths scaling logarithmically with the number of qubits. We find that for Gaussian prior phase distributions with arbitrary widths, the optimal initial state can be approximated with products of Greenberger-Horne-Zeilinger states with varying number of qubits. Using local, adaptive measurements optimized for the prior distribution and the initial state, we show that Heisenberg scaling is achievable and that the proposed scheme outperforms known schemes in the literature that utilize a similar set of initial states. For an example prior width, we present a detailed comparison and find that is also possible to achieve Heisenberg scaling with a scheme that employs non-adaptive measurements, with the right allocation of copies per GHZ state and single-qubit rotations. We also propose an efficient phase unwinding protocol to extend the dynamic range of the proposed scheme, and show that it outperforms existing protocols by achieving an enhanced precision with a smaller number of additional atoms. Lastly, we discuss the impact of noise and imperfect gates.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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