Quantum Logic Networks for Probabilistic and Controlled Teleportation of Unknown Quantum States

We present simplification schemes for probabilistic and controlled teleportation of the unknown quantum states of both one particle and two particles and construct efficient quantum logic networks for implementing the new schemes by means of the primitive operations consisting of single-qubit gates, two-qubit controlled-not gates, Von Neumann measurement, and classically controlled operations. In these schemes the teleportation are not always successful but with certain probability.     

Quantum Logic Networks for Probabilistic and Controlled Teleportation of Unknown Quantum States

We present simplification schemes for probabilistic and controlled teleportation of the unknown quantum states of both one particle and two particles and construct efficient quantum logic networks for implementing the new schemes by means of the primitive operations consisting of single-qubit gates, two-qubit controlled-not gates, Von Neumann measurement, and classically controlled operations. In these schemes the teleportation are not always successful but with certain probability.     

Hyperentanglement-assisted hyperdistillation for hyper-encoding photon system

In quantum information processing, the quality of photon system is decreased by the inevitable interaction with environment, which will greatly reduce the efficiency and security of quantum information processing. In this paper, we propose hyperentanglement-assisted hyperdistillation schemes to guarantee the quality of hyper-encoding photon system based on the method of quantum hyper-teleportation, which can increase the success probability of hyperdistillation and reduce the resource consumption. First, we propose a hyperentanglement-assisted single-photon hyperdistillation (HASPHD) scheme for polarization and spatial qubits to get rid of the vacuum state component caused by transmission loss, whose success probability can achieve the optimal one by increasing the efficiency of quantum hyper-teleportation. Subsequently, we present two hyperentanglement-assisted hyperentanglement distillation (HAHED) schemes for photon system to protect hyperentanglement from both transmission loss and quantum channel noise, which can recover the less-entangled mixed state to maximally hyperentangled state for known-parameter and unknown-parameter cases with high success probability and low resource consumption. In these hyperdistillation schemes, the influence of imperfect effects of optical elements can be largely decreased by the quantum hyper-teleportation method. These characters make the hyperentanglement-assisted hyperdistillation schemes have potential application prospects in practical quantum information processing.     

High‐Fidelity Hybrid Quantum Gates between a Flying Photon and Diamond Nitrogen‐Vacancy Centers Assisted by Low‐Q Single‐Sided Cavities

High‐fidelity universal quantum gates are crucial in quantum computing. Three high‐fidelity universal quantum gates, namely the hybrid controlled NOT gate, the hybrid Toffoli gate, and the hybrid Fredkin gate, on a flying photon qubit and diamond nitrogen‐vacancy (NV) centers, assisted by low‐Q single‐sided cavities, are presented. Errors due to the imperfection of the practical input–output process are detected to improve the fidelity of these quantum gates, which therefore relaxes the requirement on their implementation, since strong coupling is no longer mandatory. In addition, quantum gates have the advantage that they can work faithfully even when the resonant condition among the NV center, the photon, and the cavity is not strictly satisfied, or the NV centers are not identical. The performance and success probability of these quantum gates are analyzed, finding that these schemes are feasible with current technology.     

Fault-tolerant topological one-way quantum computation with probabilistic two-qubit gates

We propose a scalable way to construct a 3D cluster state for fault-tolerant topological one-way computation (TOWC) even if the entangling two-qubit gates succeed with a small probability. It is shown that fault-tolerant TOWC can be performed with the success probability of the two-qubit gate such as 0.5 (0.1) provided that the unheralded error probability of the two-qubit gate is less than 0.040% (0.016%). Furthermore, the resource usage is considerably suppressed compared to the conventional fault-tolerant schemes with probabilistic two-qubit gates.     

基于光量子态避错及容错传输的量子通信

量子通信以量子态为信息载体在远距离的通信各方之间传递信息,因此量子态的传输和远距离共享是量子通信的首要步骤.信道噪声不仅会影响通信效率还可能被窃听者利用从而威胁通信安全,对抗信道噪声是实现安全高效量子通信亟需解决的问题.本文介绍基于光量子态的两类对抗信道噪声的实用方法——量子态的避错传输和容错的量子通信,包括对抗噪声的基本原理和两种方法的代表性方案,并从资源消耗和可操作性的角度分析了方案的实用价值.     

用一个纠缠态实现多粒子纠缠态的量子隐形传送

提出分别在二维和高维系统中利用一个纠缠态作量子通道实现M粒子纠缠态的量子隐形传送方案. 该方案有多个接收者,通过控制引进辅助粒子数,可以任意调节传送后的纠缠态在各接收者之间的粒子数分布, 且成功传送的概率为1. 关键词： 量子隐形传态 纠缠态 量子通道     

量子过程神经网络模型算法及应用

为提高过程神经网络的逼近和泛化能力, 从研究过程神经元信息处理的量子计算实现机理入手, 提出基于量子旋转门及多位受控非门的物理意义构造量子过程神经元的新思想. 将离散化后的过程式输入信息作为受控非门的控制位, 经过量子旋转门作用后控制目标量子位的状态, 以目标量子位处于状态|1>概率幅作为量子过程神经元的输出. 以量子过程神经元为隐层, 普通神经元为输出层, 可构成量子过程神经网络. 基于量子计算机理推导了该模型的学习算法. 将该模型用于太阳黑子数年均值预测, 应用结果表明, 所提方法与普通过程神经网络相比, 预测精度有所提高, 对于复杂预测问题具有一定理论意义和实用价值.     

实现D-J量子算法的物理方案

利用腔QED技术,我们在本文提出了两个物理方案用来实现最简单版本的Deutsch-Jozsa(D-J)量子算法.第一个方案是比较理想的方案,这个方案可以推广到多个量子比特输入的Deutsch-Jozsa量子算法.我们只需要通过实现控制-非门和一系列单个量子比特操作,就可以简单的实现该方案.我们在这个方案中详细地讨论了基于腔QED技术最简单版本的Deutsch-Jozsa量子算法的实现过程.另一个方案是不需要控制-非门的更简单的方案,但是这个方案仅仅适用于实现这种最简单版本的Deutsch-Jozsa量子算法,这个方案只需要实现单个量子比特操作即可.显然,该方案比第一个方案更简化.我们的这两个方案可能是实现量子计算机的一个重要环节.     

Implementation of Quantum Controlled-Not Gates via Singly Charged Quantum Dots in Cavity QED

The CNOT gates for photon-photon and photon-electron are constructed in quantum dot-cavity system based on the properties of singly charged dots in strong and weak-coupling cavities. The fidelities of these gates can reach relatively high values even if the cavity decay and leakage are considered. These types of gate plays an important role in hybrid quantum information systems. By using the wavelength division multiplexer (WDM) and polarization maintaining fiber circulator (PMFC) in the setup the success probabilities of the schemes are improved.     

飞秒激光直写光量子逻辑门

量子比特在同一时刻可处于所有可能状态上的叠加特性使得量子计算机具有天然的并行计算能力,在处理某些特定问题时具有超越经典计算机的明显优势.飞秒激光直写技术因其具有单步骤高效加工真三维光波导回路的能力,在制备通用型集成光量子计算机的基本单元—量子逻辑门中发挥着越来越重要的作用.本文综述了飞秒激光直写由定向耦合器构成的光量子比特逻辑门的进展.主要包括定向耦合器的功能、构成、直写和性能表征,集成波片、哈达玛门和泡利交换门等单量子比特逻辑门、受控非门和受控相位门等两量子比特逻辑门的直写加工,并对飞秒激光加工三量子比特逻辑门进行了展望.     

用两粒子纠缠对进行{\bf\large{N}}粒子纠缠态的隐形传送

本文提出了一个方案:将三粒子纠缠态从一个发送者传给两个接收者之一,并将其推广到N粒子纠缠态的传送。这里，我们仅用两粒子纠缠对作通道就实现了N粒子纠缠态的传送。此方案相比以往的方案节省了大量纠缠资源，且成功传送的几率达到了1。     

Communication Complexity as a Principle of Quantum Mechanics

We introduce a two-party communication complexity problem in which the probability of success by using a particular strategy allows the parties to detect with certainty whether or not some forbidden communication has taken place. We show that theprobability of success is bounded by nature; any conceivable method which gives a probability of success outside these bounds is impossible. Moreover, any conceivable method to solve the problem which gives a probability success within these bounds is possible in nature. This example suggests that a suitaby chosen set of communication complexity problems could be the basis of an information-theoretic axiomatization of quantum mechanics.     

Bidirectional transfer of quantum information for unknown photons via cross-Kerr nonlinearity and photon-number-resolving measurement

We propose an arbitrary controlled-unitary(CU) gate and a bidirectional transfer scheme of quantum information(BTQI) for unknown photons.The proposed CU gate utilizes quantum non-demolition photon-number-resolving measurement based on the weak cross-Kerr nonlinearities(XKNLs) and two quantum bus beams;the proposed CU gate consists of consecutive operations of a controlled-path gate and a gathering-path gate.It is almost deterministic and is feasible with current technology when a strong amplitude of the coherent state and weak XKNLs are employed.Compared with the existing optical multi-qubit or controlled gates,which utilize XKNLs and homodyne detectors,the proposed CU gate can increase experimental realization feasibility and enhance robustness against decoherence.According to the CU gate,we present a BTQI scheme in which the two unknown states of photons between two parties(Alice and Bob) are mutually swapped by transferring only a single photon.Consequently,by using the proposed CU gate,it is possible to experimentally implement the BTQI scheme with a certain probability of success.     

Several teleportation schemes of an arbitrary unknown multi-particle state via different quantum channels

We first provide four new schemes for two-party quantum teleportation of an arbitrary unknown multi-particle state by using three-, four-, and five-particle states as the quantum channel, respectively. The successful probability and fidelity of the four schemes reach 1. In the first two schemes, the receiver can only apply one of the unitary transformations to reconstruct the original state, making it easier for these two schemes to be directly realized. In the third and fourth schemes, the sender can preform Bell-state measurements instead of multipartite entanglement measurements of the existing similar schemes, which makes real experiments more suitable. It is found that the last three schemes may become tripartite controlled teleportation schemes of teleporting an arbitrary multi-particle state after a simple modification. Finally, we present a new scheme for three-party sharing an arbitrary unknown multi-particle state. In this scheme, the sender first shares three three-particle GHZ states with two agents. After setting up the secure quantum channel, an arbitrary unknown multi-particle state can be perfectly teleported if the sender performs three Bell-state measurements, and either of two receivers operates an appropriate unitary transformation to obtain the original state with the help of other receiver's three single-particle measurements. The successful probability and fidelity of this scheme also reach 1. It is demonstrated that this scheme can be generalized easily to the case of sharing an arbitrary unknown multi-particle state among several agents.     

概率远程制备多粒子GHZ纠缠态

利用一个(N 1)粒子部分纠缠Greenberger-Home-Zeilinger(GHZ)态作为量子通道,提出了概率远程制备N粒子GHZ态的两个方案.我们考虑了怎样远程制备一个任意的GHZ态,即两个参数α和β都是复数的情况.此外,计算了远程制备总的成功概率和需要的经典信息量.     

A Spatial Domain Quantum Watermarking Scheme

This paper presents a spatial domain quantum watermarking scheme. For a quantum watermarking scheme, a feasible quantum circuit is a key to achieve it. This paper gives a feasible quantum circuit for the presented scheme. In order to give the quantum circuit, a new quantum multi-control rotation gate, which can be achieved with quantum basic gates, is designed. With this quantum circuit, our scheme can arbitrarily control the embedding position of watermark images on carrier images with the aid of auxiliary qubits. Besides reversely acting the given quantum circuit, the paper gives another watermark extracting algorithm based on quantum measurements. Moreover, this paper also gives a new quantum image scrambling method and its quantum circuit. Differ from other quantum watermarking schemes, all given quantum circuits can be implemented with basic quantum gates. Moreover, the scheme is a spatial domain watermarking scheme, and is not based on any transform algorithm on quantum images. Meanwhile, it can make sure the watermark be secure even though the watermark has been found. With the given quantum circuit, this paper implements simulation experiments for the presented scheme. The experimental result shows that the scheme does well in the visual quality and the embedding capacity.     

加权量子搜索算法及其相位匹配条件研究

目前的Grover算法在无序数据库中搜索多个目标时,得到不同目标的几率是相等的,不考虑各个目标重要程度的差异;并且当目标数超过数据库记录总数的四分之一时,搜索到目标的几率迅速下降,当目标数超过记录总数的一半时,算法失效.针对这两个问题,首先提出一种基于加权目标的搜索算法.根据各子目标的重要程度,为每个子目标赋予一个权系数,应用这些权系数将多个子目标表示成一个量子叠加态,这样可使得到每个子目标的几率等于其自身的权系数;其次,提出自适应相位匹配条件,该条件中两次相位旋转的方向相反,大小根据目标量子叠加态和系统初始状态的内积决定.当该内积大于等于((3-√5)/8)^1/2时,至多只需两步搜索,即可以恒等于1的几率得到搜索目标.实验表明,算法及其相位匹配条件是有效的.     

Effective schemes for preparation of Greenberger–Horne–Zeilinger and W maximally entangled states with cross-Kerr nonlinearity and parity-check measurement

Schemes to generate Greenberger–Horne–Zeilinger and W maximally entangled states of distant photons with the help of cross-Kerr nonlinearity and parity-check measurement are proposed in this paper. The schemes are based on optical elements, single polarization photons, cross-Kerr nonlinearity, and the conventional photon detectors, which are feasible with existing experimental technology. The schemes are quite different a higher success probability, without the resorting to collective unitary evolution. All these advantages make present schemes more efficient and more convenient than others in the applications in quantum communication.