We present a systematic simple method for constructing deterministic remote operations on single and multiple systems of arbitrary discrete dimensionality. These operations include remote rotations, remote interactions and measurements. The resources needed for an operation on a two-level system are one ebit and a bidirectional communication of two cbits, and for an n-level system, a pair of entangled n-level particles and two classical ``nits''. In the latter case, there are $n-1$ possible distinct operations per one n-level entangled pair. Similar results apply for generating interaction between a pair of remote systems and for remote measurements. We further consider remote operations on $N$ spatially distributed systems, and show that the number of possible distinct operations increases here exponentially, with the available number of entangled pairs that are initial distributed between the systems. Our results follow from the properties of a hybrid state-operator object (``stator''), which describes quantum correlations between states and operations.
Controlled and combined remote implementations of partially unknown quantum operations of multiqubits using GHZ states
我们提出并证明了利用GHZ态的部分未知量子操作的受控和组合远程实现协议[An Min Wang：PRA，\textbf{74}，032317（2006）].详细描述了单量子比特、单控制器和双控制器情况下的协议。然后，我们将协议扩展到多个控制器和两个控制器的多量子比特的情况。由于我们的协议必须要求控制器的启动和授权或两个控制器一起工作和合作，量子操作的受控和组合的远程实现肯定可以提高远程量子信息处理的安全性，并有可能有更多的应用。此外，我们的协议与两个代理是有助于最大限度地达到量子操作的远程实现的功率在理论上，因为不同的代理可能有不同的操作资源和不同的操作权限在实践中。
Shared entanglement between spatially separated systems is an essential resource for quantum information processing including long-distance quantum cryptography and teleportation. While purification protocols for mixed distributed entangled quantum states exist, it is not clear how to optimally distribute entanglement to remote locations. Here, we describe a deterministic protocol for generating a maximally entangled state between remote locations that only uses local operations on qubits, and requires no classical communication between the separated parties. The procedure may provide protecti…
Fidelity of remote state preparation can be enhanced by local operation
远程态制备（Remote State Preparation，RSP）是一种量子信息协议，它允许在一个预先共享的非经典资源态和一个经典信道的帮助下，在一个遥远的位置制备一个量子态。成功完成此任务的效率可以通过资源状态的RSP-fidelity来表示。在本文中，我们研究的影响，通过施加一定的本地操作的资源状态上的RSP-fidelity。我们证明了对任何单位局部操作，RSP保真度都不会增加。然而，对于非单位的本地操作，如本地振幅阻尼信道，我们发现，一些资源状态可以被增强，以增加的RSP保真度。给出了对称局部幅度阻尼信道增强贝尔对角资源状态的最佳参数。此外，我们还证明了在局域退相干的情况下，响应面保真度会突然变化甚至瞬间消失。
Client-server models enable computations to be hosted remotely on quantum servers. We present a novel protocol for realizing this task, with practical advantages when using technology feasible in the near term. Client tasks are realized as linear combinations of operations implemented by the server, where the linear coefficients are hidden from the server. We report on an experimental demonstration of our protocol using linear optics, which realizes linear combination of two single-qubit operations by a remote single-qubit control. In addition, we explain when our protocol can remain efficient…
We study remote creation of coherence (RCC) for a quantum system, A, with the help of quantum operations on another system, B, and one-way classical communication.We show that all the nonincoherent quantum states are useful for RCC and all the incoherent-quantum states are not. The necessary and sufficient conditions of RCC for the quantum operations on system B are presented for pure states. The upper bound of average RCC is derived, giving a relation among the entanglement (concurrence), the RCC of the given quantum state, and the RCC of the corresponding maximally entangled state. Moreover,…
Quamtum remote rotation allows implement local quantum operation on remote systems with shared entanglement. Here we report an experimental demonstration of remote rotation on single photons using linear optical element. And the local dephase is also teleported during the process. The scheme can be generalized to any controlled rotation commutes with $σ_{z}$.
A scheme for the deterministic joint remote preparation of a four- qubit cluster-type state using only two Greenberger-Horne-Zeilinger (GHZ) states as quantum channels is presented. In this scheme, the first sender per- forms a two-qubit projective measurement according to the real coefficient of the desired state. Then, the other sender utilizes the measurement result and the complex coefficient to perform another projective measurement. To obtain the desired state, the receiver applies appropriate unitary operations to his/her own two qubits and two CNOT operations to the two ancillary ones.…
Future quantum networks will enable the distribution of entanglement between distant locations and allow applications in quantum communication, quantum sensing and distributed quantum computation. At the core of this network lies the ability of generating and storing entanglement at remote, interconnected quantum nodes. While remote physical systems of various nature have been successfully entangled, none of these realisations encompassed all of the requirements for network operation, such as telecom-compatibility and multimode operation. Here we report the demonstration of heralded entangleme…
Storage and retrieval of single photons transmitted between remote quantum memories
基本量子网络操作涉及将量子比特状态存储在原子量子存储器节点中，然后通过单光子激发将信息检索并传输到远程量子存储器节点以进行进一步存储或分析。因此，量子网络操作的实现以实现这种物质到光和/或光到物质量子态映射的能力为条件。在这里，我们报告了使用两个远程原子系综生成、传输、存储和检索单个量子的情况。通过Duan、Lukin、Cirac和Zoller（DLCZ）的协议[Nature v.414，413（2001）]，从A点的冷原子系综产生单个光子，并通过100米长的光纤将其导向B点。光子经由Fleischhauer和Lukin的暗态极化激元方法转换成单个集体激发[Phys. Rev. Lett. 84，5094（2000）]。在可编程的存储时间之后，原子激发被转换回单个光子。对于500纳秒的存储时间，通过测量λ关系参数α，实验证明了这一点。通过强度互相关测量观察到超过十微秒的存储时间。存储周期的长度比实现光子和原子量子之间的转换的时间长两个数量级。远程量子存储器之间的单量子受控传输是迈向分布式量子网络的重要一步。
Non-Gaussian states with Wigner negativity are of particular interest in quantum technology due to their potential applications in quantum computing and quantum metrology. However, how to create such states at a remote location remains a challenge, which is important for efficiently distributing quantum resource between distant nodes in a network. Here, we experimentally prepare optical non-Gaussian state with negative Wigner function at a remote node via local non-Gaussian operation and shared Gaussian entangled state existing quantum steering. By performing photon subtraction on one mode, Wi…
We present two schemes for joint remote preparation of an arbitrary four-qubit j\c{hi}i -type entangled state via three three- and (N+1)-qubit GHZ states as the quantum channel, respectively. In these schemes, two senders (or N senders) share the original state which they wish to help the receiver to remotely prepare. To complete the JRSP schemes, several novel sets of mutually orthogonal basis vectors are introduced. It is shown that, only if two senders (or N senders) collaborate with each other, and perform projective measurements under suitable measuring basis on their own qubits respectiv…
Magnon cat state represents a macroscopic quantum superposition of collective magnetic excitations of large number spins that not only provides fundamental tests of macroscopic quantum effects but also finds applications in quantum metrology and quantum computation. In particular, remote generation and manipulation of Schrödinger cat states are particularly interesting for the development of long-distance and large-scale quantum information processing. Here, we propose an approach to remotely prepare magnon even/odd cat states by performing local non-Gaussian operations on the optical mode tha…
A critical element towards the realization of scalable quantum processors is non-local coupling between nodes. Scaling connectivity beyond nearest-neighbor interactions requires the implementation of a mediating interaction often termed a 'quantum bus'. Cavity photons have long been used as a bus by the superconducting qubit community, but it has only recently been demonstrated that spin-based qubits in double quantum dot architectures can reach the strong coupling regime and exhibit spin-spin interactions via the exchange of real or virtual photons. Two-qubit gate operations are predicted in …
Iterates of quantum operations and their convergence are investigated in the context of mean ergodic theory. We discuss in detail the convergence of the iterates and show that the uniform ergodic theorem plays an essential role. Our results will follow from some general theorems concerning completely positive maps, mean ergodic operators, and operator algebras on Hilbert spaces. A few examples of both finite and infinite dimensional Hilbert spaces are presented as well.
Local Operations and Field Mediated Entanglement without a Local Tensor Product Structure
University of Vienna（维也纳大学）；Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences（奥地利科学院量子光学和量子信息研究所）；ETH Zurich（苏黎世联邦理工学院）；Università di Roma Tor Vergata（罗马第二大学）；Sezione INFN Roma2（INFN罗马第二分部）
