Remote preparation of an arbitrary multi-qubit state via two-qubit entangled states

We propose a novel scheme for remote preparation of an arbitrary n-qubit state with the aid of an appropriate local \(2^n\times 2^n\) unitary operation and n maximally entangled two-qubit states. The analytical expression of local unitary operation, which is constructed in the form of iterative process, is presented for the preparation of n-qubit state in detail. We obtain the total successful probabilities of the scheme in the general and special cases, respectively. The feasibility of our scheme in preparing remotely multi-qubit states is explicitly demonstrated by theoretical studies and concrete examples, and our results show that the novel proposal could enlarge the applied range of remote state preparation.     

Multi-party quantum state sharing of an arbitrary multi-qubit state via \chi -type entangled states

By using the \(\chi \) -type entangled states, a novel scheme for multi-party quantum state sharing (MQSTS) of an arbitrary multi-qubit state is investigated. It is shown that the MQSTS scheme can be faithfully realized by performing appropriate Bell state measurements, Z basis measurements and local unitary operations, rather than multi-qubit entanglement or multi-particle joint measurements. Thus, our MQSTS scheme is more convenient in a practical application than some previous schemes. Furthermore, its intrinsic efficiency for qubits approaches 100 %, and the total efficiency really approaches the maximal value, which is higher than those of the previous MQSTS schemes. Finally, we analyze the security from the views of participant attack and outside attack in detail.     

Generation of a genuine four-particle entangled state of trap ions

We present a scheme for the generation of a genuine four-qubit entangled state in an ion trap. This state has many interesting entanglement properties and possible applications in quantum information processing and fundamental tests of quantum physics. In our scheme, the ion is driven by a standing-wave field, whose frequency is resonant with the ion carrier transition. By adjusting the phase of the field, both the vibration mode population and the ionic carrier excitation can be avoided. So our scheme is insensitive to the vibration states, which is important in view of decoherence.     

Optimal remote preparation of arbitrary multi-qubit real-parameter states via two-qubit entangled states

In this paper, we present an efficient scheme for remote state preparation of arbitrary n-qubit states with real coefficients. Quantum channel is composed of n maximally two-qubit entangled states, and several appropriate mutually orthogonal bases including the real parameters of prepared states are delicately constructed without the introduction of auxiliary particles. It is noted that the successful probability is 100% by using our proposal under the condition that the parameters of prepared states are all real. Compared to general states, the probability of our protocol is improved at the cost of the information reduction in the transmitted state.     

Deterministic remote preparation of arbitrary multi-qubit equatorial states via two-qubit entangled states

We propose an efficient scheme for remotely preparing an arbitrary n-qubit equatorial state via n two-qubit maximally entangled states. Compared to the former scheme (Wei et al. in Quantum Inf Process 16:260, 2017) that has the 50% successful probability when the amplitude factors of prepared states are \(2^{-n{/}2}\), the probability would be increased to 100% by using of our modified proposal. The feasibility of our scheme for remote preparation arbitrary multi-qubit equatorial states is explicitly demonstrated by theoretical studies and concrete examples.     

Efficient quantum dialogue using entangled states and entanglement swapping without information leakage

We propose a novel quantum dialogue protocol by using the generalized Bell states and entanglement swapping. In the protocol, a sequence of ordered two-qutrit entangled states acts as quantum information channel for exchanging secret messages directly and simultaneously. Besides, a secret key string is shared between the communicants to overcome information leakage. Different from those previous information leakage-resistant quantum dialogue protocols, the particles, composed of one of each pair of entangled states, are transmitted only one time in the proposed protocol. Security analysis shows that our protocol can overcome information leakage and resist several well-known attacks. Moreover, the efficiency of our scheme is acceptable.     

Deterministic controlled bidirectional remote state preparation via a six-qubit entangled state

In this paper, we presented a controlled bidirectional remote state preparation scheme which used the six-qubit entangled state as quantum channel. In our scheme, Alice and Bob can prepare simultaneously an arbitrary single-qubit state in each other’s place with the control of the supervisor Charlie. The success probability for our scheme reaches unit. Furthermore, we analyze the expression of quantum channel for controlled bidirectional remote state preparation. Finally, we discuss the security of our scheme, the detailed security analysis shows that the supervisor Charlie’s control can greatly improve the security of our scheme.

     

Cryptanalysis and improvement of efficient quantum dialogue using entangled states and entanglement swapping without information leakage

The novel quantum dialogue (QD) protocol by using the three-dimensional Bell states and entanglement swapping (Wang et al. in Quantum Inf Process 15(6):2593–2603, 2016) is analyzed. It is shown that there is the information leakage problem in this QD protocol. To be specific, one quarter information of the secret messages exchanged is leaked out unconsciously. Afterward, it is improved to a truly secure one without information leakage. Besides, the security of the improved QD protocol is analyzed in detail. It is shown that the improved QD protocol has some obvious features compared with the original one.     

Isolation enhanced circularly polarized patch antenna array using modified electric‐field‐coupled resonator

A modified electric‐field‐coupled (MELC) resonator featuring negative permittivity is proposed to enhance the inter‐element isolation of a circularly polarized (CP) patch antenna array operated at Chinese compass navigation satellite system (CNSS) downlink band. The resonator comprises two capacitive gaps and a common inductive strip connected to the ground plane by two metal vias. A suspended microstrip line excitation is employed to efficiently design and investigate the MELC resonator whose constitutive parameters are subsequently extracted. A dual‐element CNSS antenna array has been prototyped and measured. The experimental results demonstrate that under the assistance of the proposed MELC resonator, a mutual coupling reduction of 15 dB has been achieved while maintaining good impedance matching and CP radiation performance. Details of the design considerations along with simulation and measurement results are presented and discussed.     

Quantum information splitting of an arbitrary three-qubit state by using a genuinely entangled five-qubit state and a Bell-state

A new application of the genuinely entangled five-qubit state introduced by Brown et al. (J Phys A 38(5), 1119–1131, 2005) is investigated for quantum information splitting (QIS) of an arbitrary three-qubit state. We demonstrate that such a genuine five-qubit entangled state and a Bell-state can be used to realize the deterministic QIS of an arbitrary three-qubit state by performing the Bell-state measurements and single qubit measurement. The presented protocol is showed to be secure against certain eavesdropping attacks.     

Engineering information in states of a nanomechanical resonator coupled to a Cooper pair box

We take advantage of a system composed by a nanoresonator coupled to a Cooper pair box, plus the binary code associated with a field spectrum, to engineer informations in the nanoresonator quantum states. The subject constitutes an illustration of a previous “hole burning protocol” of ours and the feasibility of the scheme is considered.     

An efficient scheme for multi-party quantum state sharing of an arbitrary multi-qubit state with one GHZ channel

We present an innovative and extremely efficient scheme to share an arbitrary multi-qubit state between n agents with only 1 GHZ channel under control of m agents in a network. Compared with existing ones in this literature, our scheme requires less communication resources, least qubits and only three physical favorable simple operations (single-qubit measurement, Bell-basis measurement and CNOT gate operations) are included, leading to a higher overall efficiency.     

Quantum information processing through a genuine five-qubit entangled state in cavity QED

The utility of a five-qubit entangled state for quantum teleportation, quantum state sharing and superdense coding is investigated. The state can be utilized for perfect teleportation and quantum state sharing of an arbitrary single- and two-qubit state. The capacity of superdense coding of the state reaches the “Holevo bound”, which means that five classical bits can be transmitted by sending three qubits. The preparation of the five-qubit state and detection of the multipartite states in cavity QED are discussed. The distinct advantage of the feasible cavity QED technology that we use is insensitive to the thermal field and the cavity decay.     

Deterministic remote preparation of an arbitrary qubit state using a partially entangled state and finite classical communication

Quantum Information Processing - We propose a deterministic remote state preparation (RSP) scheme for preparing an arbitrary (including pure and mixed) qubit, where a partially entangled state and...     

岩石饱和度阵列耦合谐振器的研究

大多岩石饱和度检测设备存在精度低、结构单一的问题,依据岩石含水量与介电常数之间线性关系,设计一种以耦合微带环阵列结构的饱和度谐振检测系统.根据岩石介电常数变化,微带环产生不同谐振频率和Q值求,通过谐振参数反演岩石介电常数求得饱和度.研究工作包括微带环结构设计仿真,阵列结构设计,系统硬件设计.岩石样本测试显示阵列结构具有更高精度,误差＜0.95％.这种新型阵列传感器系统精度高、体积小适合岩石饱和度检测.     

Generation of steady three- and four-dimensional entangled states via quantum-jump-based feedback

A scheme is presented for generating steady three- (four-) dimensional entangled states for two atoms trapped in a strongly dissipative single-mode (double-mode) cavity via quantum-jump-based feedback. The cavity decay is no longer undesirable, but plays an integral part in the schemes. Numerical results show that the target states could be obtained from any initial states via quantum-jump-based feedback. Moreover, our scheme is insensitive to moderate fluctuations of experimental parameters and detection inefficiencies without atomic decay since the system can always reach the target state. Nevertheless, the atomic decay still plays a negative role in the current scheme. The scheme can be generalized to realize $N$ -dimensional entanglement for two atoms.     

Schemes generating entangled states and entanglement swapping between photons and three-level atoms inside optical cavities for quantum communication

We propose quantum information processing schemes based on cavity quantum electrodynamics (QED) for quantum communication. First, to generate entangled states (Bell and Greenberger–Horne–Zeilinger [GHZ] states) between flying photons and three-level atoms inside optical cavities, we utilize a controlled phase flip (CPF) gate that can be implemented via cavity QED). Subsequently, we present an entanglement swapping scheme that can be realized using single-qubit measurements and CPF gates via optical cavities. These schemes can be directly applied to construct an entanglement channel for a communication system between two users. Consequently, it is possible for the trust center, having quantum nodes, to accomplish the linked channel (entanglement channel) between the two separate long-distance users via the distribution of Bell states and entanglement swapping. Furthermore, in our schemes, the main physical component is the CPF gate between the photons and the three-level atoms in cavity QED, which is feasible in practice. Thus, our schemes can be experimentally realized with current technology.     

Generation of entangled coherent-squeezed states: their entanglement and nonclassical properties

In this paper, after a brief review on the coherent states and squeezed states, we introduce two classes of entangled coherent-squeezed states. Next, in order to generate the introduced entangled states, we present a theoretical scheme based on the resonant atom-field interaction. In the proposed model, a \(\varLambda \)-type three-level atom interacts with a two-mode quantized field in the presence of two strong classical fields. Then, we study the amount of entanglement of the generated entangled states using the concurrence and linear entropy. Moreover, we evaluate a few of their nonclassical properties such as photon statistics, second-order correlation function, and quadrature squeezing and establish their nonclassicality features.     

Quantum state manipulation of dipole emitters with a plasmonic double-bar resonator

We demonstrate efficient processes of entanglement generation and quantum state transfer (QST) with dipole emitters coupled to a plasmonic double-bar resonator. The bipartite and multipartite maximal entanglement and complete QST can be deterministically achieved by selecting appropriate coupling strength between individual emitters and the resonator mode. Moreover, the entanglement dynamics show that high fidelities of entanglement generation and QST can be realized even under imprecise coupling strength and the system decay. The feasibility analysis and practical implementation are discussed, which manifest that our schemes may be meaningful for exploring solid-state quantum information processing with the metal plasmonic mode.