Experimental demonstration of adaptive quantum state estimation
Experimental demonstration of adaptive quantum state estimation
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DOI：
10.1103/physrevlett.109.130404
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发表时间：
2012-09
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影响因子：
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通讯作者：
R. Okamoto;Minako Iefuji;S. Oyama;Koichi Yamagata;H. Imai;A. Fujiwara;S. Takeuchi
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文献类型：
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作者：
R. Okamoto;Minako Iefuji;S. Oyama;Koichi Yamagata;H. Imai;A. Fujiwara;S. Takeuchi
仅提供摘要形式。量子理论本质上是统计的。这需要在许多相同制备的量子对象上重复实验，例如，量子态，如果想要知道指定量子态的参数的“真态”或“真值”。这样的估计过程对于量子通信和量子计算特别重要，并且对于量子计量学也是必不可少的[1，2]。在应用中，需要设计估计过程，使得参数的估计值应该接近真值（一致性），并且对于给定的有限数量的样本，估计值的不确定性应该尽可能小（效率）。为了实现这些要求，Nagaoka提出了一种自适应量子态估计（AQSE）方法[3]，最近Fujiwara证明了AQSE的强一致性和渐近有效性[4]。在本文中，我们报告了使用光子的AQSE的第一个实验演示[5]。使用AQSE（图1）估计了半波片（HWP）的角度，该半波片（HWP）将输入光子的线性偏振化。用300个输入光子执行AQSE序列，并且对于HWP的四种不同设置，该序列重复500次。对这些结果的统计分析验证了AQSE的强一致性和渐近有效性。最近，已经在数学上证明了AQSE的精度优于传统的状态层析成像[6]。因此，预计AQSE将在量子信息处理，通信和计量学的广泛领域提供有用的方法。这项工作得到了JSPS量子控制论，JSPS-Kakenhi，JST-CREST，FIRST计划，促进科学和技术特别协调基金，光科学和技术研究基金会的部分支持。
Summary form only given. Quantum theory is inherently statistical. This entails repetition of experiments over a number of identically prepared quantum objects, for example, quantum states, if one wants to know the “true state” or the “true value” of the parameter that specifies the quantum state. Such an estimation procedure is particularly important for quantum communication and quantum computation, and is also indispensable to quantum metrology [1,2]. In applications, one needs to design the estimation procedure in such a way that the estimated value of the parameter should be close to the true value (consistency), and that the uncertainty of the estimated value should be as small as possible (efficiency) for a given limited number of samples. In order to realize these requirements, Nagaoka advocated an adaptive quantum state estimation (AQSE) procedure [3], and recently Fujiwara proved the strong consistency and asymptotic efficiency for AQSE [4]. In this paper, we report the first experimental demonstration of AQSE using photons[5]. The angle of a half wave plate (HWP) that initializes the linear polarization of input photons is estimated using AQSE (Fig. 1). sequence of AQSE is carried out with 300 input photons, and the sequence is repeated 500 times for four different settings of HWP. The statistical analysis of these results verifies the strong consistency and asymptotic efficiency of AQSE. Recently, it has been mathematically proven that the precision of AQSE outperforms the conventional state tomography [6]. It is thus expected that AQSE will provide a useful methodology in the broad area of quantum information processing, communication, and metrology. This work was supported in part by JSPS Quantum Cybernetics, JSPS-Kakenhi, JST-CREST, FIRST Program, Special Coordination Funds for Promoting Science and Technology, Research Foundation for Opto-Science and Technology.