Zengke Zhang

A centralized quantum switch network based on probabilistic channels

We present a practical scheme for deterministically teleporting quantum information via probabilistic communication channels in a centralized quantum switch network. In the network, a central quantum switch agent is assigned for regulating probabilistic channels so as to construct a direct deterministic channel between the sender and the receiver. This scheme is further extended to a hierarchical network and a tree network involving multiple agents. The advantage of the scheme is that all required multi qubit gates from distributed terminal agents are uniformly performed by a central agent, with which the physical design of terminal nodes is greatly simplified and more reliable deterministic teleportation can be realized in a centralized quantum probabilistic network.

Improved scheme for probabilistic transformation and teleportation of multi-particle quantum states

Abstract In most probabilistic teleportation schemes, if the teleportation fails, the unknown quantum state will be completely ruined. In addition, the frequently proposed high-dimensional unitary operations are very difficult to realize experimentally. To maintain the integrity of the unknown quantum state to be teleported, this analysis does not focus attention on the original multi-particle state but seeks to construct a faithful channel with an ancillary particle and a unified high-dimensional unitary operation. The result shows that if the construction of the multi-group Einstein-Podolsky-Rosen pair succeeds, the original multi-particle state can be used to deterministically teleport the unknown quantum state of the entangled multiple particles which avoids undermining the integrity of the unknown state brought about by failure. This unified high-dimensional operation is appealing due to the obvious experimental convenience.

Computing nonlinear lts estimator based on a random differential evolution strategy

Abstract Nonlinear least trimmed squares (NLTS) estimator is a very important kind of nonlinear robust estimator, which is widely used for recovering an ideal high-quality signal from contaminated data. However, the NLTS estimator has not been widely used because it is hard to compute. This paper develops an algorithm to compute the NLTS estimator based on a random differential evolution (DE) strategy. The strategy which uses random DE schemes and control variables improves the DE performance. The simulation results demonstrate that the algorithm gives better performance and is more convenient than existing computing algorithms for the NLTS estimator. The algorithm makes the NLTS estimator easy to apply in practice, even for large data sets, e.g. in a data mining context.

Efficient Scheme for Optimizing Quantum Fourier Circuits

Abstract In quantum circuits, importing of additional qubits can reduce the operation time and prevent decoherence induced by the environment. However, excessive qubits may make the quantum system vulnerable. This paper describes how to relax existing qubits without additional qubits to significantly reduce the operation time of the quantum Fourier circuit compared to a circuit without optimization. The results indicate that this scheme makes full use of the qubits relaxation. The concepts can be applied to improve similar quantum circuits and guide the physical implementations of quantum algorithms or devices.

Quantum network optimization based on the use of relaxing qubits

Any quantum algorithm has to be implemented by quantum circuit. However, due to the existence of decoherence time and the difficulty of importing ancillae qubits, we introduce a new method which can greatly reduce the operating time steps by making good use of relaxing qubits without new ancillae qubits. This concept presented in this paper can be generalized to the other quantum networks.

Synchronizing Chaotic Systems Based on Tridiagonal Structure

Abstract The design approach based on tridiagonal structure combines the structure analysis with the design of stabilizing controller. During the design procedure, the original nonlinear affine systems is transformed into a stable system with special tridiagonal structure. In this study, the method is proposed for synchronizing chaotic systems. There are several advantages in this method for synchronizing chaotic systems: (a) it presents a systematic procedure for construct a proper controller in chaos synchronization; (b) it can be applied to a variety of chaotic systems with lower triangular structure. Examples of Lorenz system, Chuas circuit and Duffing system are presented.

A quantum switching architecture on the basis of limited nonlocal operation

Abstract Quantum information system is fragile to be disturbed by the external environment. Quantum switching architecture is one of the promising schemes for transferring input quantum data to its destination port substituted for fully connected quantum networks. Since at present, interactions between the qubits are limited to a small number of neighboring qubits, one novel approach was extended, and the improved architecture was further demonstrated under limited nonlocal operation. The performance evaluation shows that the whole architecture with improved control module can achieve a time complexity of O(n2) and will be more feasible for physical realization.