首页/论文/quant-ph/0106014

arXiv quant-ph/01060142001-06-04quant-ph

Aligning Reference Frames Using Quantum States

E. Bagan, M. Baig, R. Munoz-Tapia

备注：: 4 pages
发表信息：: Phys. Rev. Lett. 87, 257903 (2001)
DOI：: 10.1103/PhysRevLett.87.257903

英文摘要：

We analyze the problem of sending, in a single transmission, the information required to specify an orthogonal trihedron or reference frame through a quantum channel made out of N elementary spins. We analytically obtain the optimal strategy, i.e., the best encoding state and the best measurement. For large N, we show that the average error goes to zero linearly in 1/N. Finally, we discus the construction of finite optimal measurements.

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。

阅读原文

阅读 PDF ↗

arXiv 页面 ↗HTML 原文 ↗

本文内容

英文摘要相关论文

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。

继续探索

相关论文

On the communication complexity of establishing a shared reference frame

We discuss the communication complexity of establishing a shared reference frame, in particular examining the case of aligning spatial axes via the exchange of spin-1/2 particles. Unlike previous work we allow for multiple rounds of communication, and we give several simple examples demonstrating that nontrivial tradeoffs between the number of rounds and the type of communication required exist. We then give an explicit protocol for aligning spatial axes via the exchange of spin-1/2 particles which makes no use of either exchanged entangled states or of joint measurements. Rather it works by p…

2003-06-02quant-ph

Optimal state for keeping reference frames aligned and the Platonic solids

The optimal N qubit states featuring highest sensitivity to small misalignment of cartesian reference frames are found using the Quantum Cramer-Rao bound. It is shown that the optimal states are supported on the symmetric subspace and hence are mathematically equivalent to a single spin J=N/2. Majorana representation of spin states is used to reveal a beautiful connection between the states optimal for aligning reference frames and the platonic solids.

2008-12-01quant-ph

Aligning Spatial Frames Through Quantum Channels

We review the optimal protocols for aligning spatial frames using quantum systems. The communication problem addressed here concerns a type of information that cannot be digitalized. Asher Peres referred to it as "unspeakable information". We comment on his contribution to this subject and give a brief account of his scientific interaction with the authors.

2005-05-19quant-ph

Entanglement assisted alignment of reference frames using a dense covariant coding

We present a procedure inspired by dense coding, which enables a highly efficient transmission of information of a continuous nature. The procedure requires the sender and the recipient to share a maximally entangled state. We deal with the concrete problem of aligning reference frames or trihedra by means of a quantum system. We find the optimal covariant measurement and compute the corresponding average error, which has a remarkably simple close form. The connection of this procedure with that of estimating unitary transformations on qubits is briefly discussed.

2004-04-28quant-ph

Generating nonclassical correlations without fully aligning measurements

We investigate the scenario where spatially separated parties perform measurements in randomly chosen bases on an N-partite Greenberger-Horne-Zeilinger state. We show that without any alignment of the measurements, the observers will obtain correlations that violate a Bell inequality with a probability that rapidly approaches 1 as N increases and that this probability is robust against noise. We also prove that restricting these randomly chosen measurements to a plane perpendicular to a common direction will always generate correlations that violate some Bell inequality. Specifically, if each …

2011-03-02quant-ph

Biased decoy-state reference-frame-independent quantum key distribution

Without actively aligning the reference frames, the reference-frame-independent quantum key distribution (RFI-QKD) can generate secure keys even when the reference frames drift slowly. Here, we propose a new scheme on the decoy-state RFI-QKD, where the basis assignments of two legitimate parties are biased, reducing the fraction of mismatched-basis data. When accounting for statistical fluctuations under different misalignments of reference frames, we investigate the performance of biased decoy-state RFI-QKD with full parameter optimization. We also make a clear comparison between the new sche…

2017-03-11quant-ph

更多相关论文收起更多论文

Observers can always generate nonlocal correlations without aligning measurements by covering all their bases

Quantum theory allows for correlations between the outcomes of distant measurements that are inconsistent with any locally causal theory, as demonstrated by the violation of a Bell inequality. Typical demonstrations of these correlations require careful alignment between the measurements, which requires distant parties to share a reference frame. Here, we prove, following a numerical observation by Shadbolt et al., that if two parties share a Bell state and each party randomly chooses three orthogonal measurements, then the parties will always violate a Bell inequality. Furthermore, we prove t…

2012-02-06quant-ph

多方参考系无关量子保密通信

Multipartite reference-frame-independent quantum cryptographic communication

Korea Institute of Science and Technology (KIST)（韩国科学技术院）；Hyundai Motor Company（现代汽车公司）；Korea University of Science and Technology（韩国科学技术大学）；Korea University（高丽大学）

提出基于GHZ态的多方参考系无关量子密码协议，推广安全参数至N方，推导渐近密钥率，实验验证四光子GHZ态下参数与密钥率的参考系不变性。

2026-06-11quant-ph

Measuring concurrence in qubit Werner states without aligned reference frame

The genuine concurrence is a standard quantifier of multipartite entanglement, detection and quantification of which still remains a difficult problem from both theoretical and experimental point of view. Although many efforts have been devoted toward the detection of multipartite entanglement (e.g., using entanglement witnesses), measuring the degree of multipartite entanglement, in general, requires some knowledge about an exact shape of a density matrix of the quantum state. An experimental reconstruction of such density matrix can be done by full state tomography which amounts to having th…

2021-05-13quant-ph

Reference frames, superselection rules, and quantum information

Recently, there has been much interest in a new kind of ``unspeakable'' quantum information that stands to regular quantum information in the same way that a direction in space or a moment in time stands to a classical bit string: the former can only be encoded using particular degrees of freedom while the latter are indifferent to the physical nature of the information carriers. The problem of correlating distant reference frames, of which aligning Cartesian axes and synchronizing clocks are important instances, is an example of a task that requires the exchange of unspeakable information and…

2007-04-10quant-ph

Robustness of reference-frame-independent quantum key distribution against the relative motion of the reference frames

Reference-Frame-Independent quantum key distribution (RFI-QKD) is known to be robust against slowly varying reference frames. However, other QKD protocols such as BB84 can also provide secrete keys if the speed of the relative motion of the reference frames is slow enough. While there has been a few studies to quantify the speed of the relative motion of the reference frames in RFI- QKD, it is not yet clear if RFI-QKD provides better performance than other QKD protocols under this condition. Here, we analyze and compare the security of RFI-QKD and BB84 protocol in the presence of the relative …

2017-01-26quant-ph

The reference-frame independence of quantum probabilities

We investigate the transformation rule of a single particle wave-function under a change of reference frame. A postulate is raised, and some fundamental aspects regarding the reference-frame independence of quantum probabilities are explored.

2022-12-30quant-ph