Observer-based feedback control of two-level open stochastic quantum system

The observer-based feedback control for the two-level bilinear open stochastic quantum system is proposed in this paper. The state of open stochastic quantum system (OSQS) is described in the Cartesian coordinate system. The proposed state observer is designed by using state-dependent differential Riccati equation (SDDRE) and constructed for optimally estimating the state of OSQS from measurement output of the system. The state of observer is continuously updated by the output data of continuous weak measurement (CWM). A Lyapunov Feedback control is designed based on estimated state of the observer for the state transfer of OSQS. An exponential Lyapunov function is chosen to ensure the stability of the system. The observer-based Lyapunov feedback control (OLFC) strategy is developed according to the stochastic Lyapunov stability theorem. The numerical simulation results verify the achievability of the proposed OLFC strategy in terms of state estimation and state transfer of OSQS. Numerical simulations demonstrate that the observer tracks the state of system asymptotically with minimum error of ± 3%. The proposed OLFC has the ability to move the state of OSQS from arbitrary initial state to the final target eigenstate with high fidelity ≥ 90%.     

单个控制场下开放量子系统的状态转移(英文)

研究了开放量子系统的状态转移问题.利用刘维尔超算符将其矩阵动力学模型转换为向量形式.给定一个耗散的量子系统的动力学模型,在一个随时变化的外部控制场中,以系统状态和目标状态的密度矩阵的误差平方作为性能指标,推导出改进的状态转移最优控制律.在数值仿真实验中,我们研究了一个热浴中的自旋1/2粒子系统在单个外部控制场作用下的动力学特性.在所提出的最优控制作用下,分别选择本征态、纯态和混合态作为系统的初始状态和目标状态.对此系统中状态转移的实验结果进行了性能对比分析.     

Orbit consensus of quantum networks based on interaction design

For a general quantum network system with a non-zero Hamiltonian H composed of n identical m-level quantum subsystems, any symmetric consensus state in the interaction picture exactly corresponds to an orbit in the Schrödinger picture, which is called the H-orbit of the symmetric consensus state. By using the interaction picture transformation and the tool of the LaSalle invariance principle, this paper analyzes the orbit consensus of this quantum network and designs the corresponding swapping operators such that the system converges to the H-orbit of the target symmetric consensus state that exists in the interaction picture. In particular, we prove the convergence of the quantum network to the H-orbit when the quantum interaction graph is connected and the system Hamiltonian is permutation invariant. The orbit consensuses of a four-qubit network system and a quantum network of three identical three-level subsystems are achieved numerically, which verifies the correctness of our theoretical results and the effectiveness of the designed swapping operators.     

Rapid Lyapunov control for decoherence-free subspaces of Markovian open quantum systems

A Lyapunov-based rapid control scheme is proposed to drive a Markovian open quantum system to a decoherence-free subspace by constructing the control Hamiltonians of the system. Based on Lyapunov theory, we design a general form of control laws, which includes the standard Lyapunov control law. The convergence of the control system to the decoherence-free subspace is strictly proved. By analyzing the relationship between the LaSalle invariant set and the decoherence-free subspace, we propose a construction method for the control Hamiltonians to further speed up the control process. Simulation experiments on a three-level quantum system demonstrate that the rapid Lyapunov control scheme proposed in this paper has a good control performance.     

Experimental quantum teleportation of a two-qubit composite system

Quantum teleportation, a way to transfer the state of a quantum system from one location to another, is central to quantum communication and plays an important role in a number of quantum computation protocols. Although significant experimental advances h…     

科技期刊开放获取对科学建制的影响

【目的】 探讨基于数字技术的开放获取期刊出版模式对现代科学建制的影响,及其可能的应对方式。【方法】 根据默顿科学社会学理论,分析开放获取期刊出现后的代表性事件及其后续的影响。【结果】 开放获取期刊代表了数字技术与知识共享理念的结合,对现代科学建制产生深刻影响。开放获取期刊不但把新的角色引入科学建制,带来科学建制中行动者的重新定位和分工,而且使传统科技期刊的同行评议制度和质量控制机制受到冲击和挑战。【结论】 科技期刊开放获取运动要在继承科学知识公有性的理念之余,维护同行评议机制,保障科技期刊对科学知识生产的质量控制功能。     

Bifurcation with regard to combined interaction parameter in a life energy system dynamic model of two components with multiple delays

Bifurcation theory is commonly used to study the dynamical behavior of ecosystems. It involves the analysis of points in the parameter space where the stability of the system changes qualitatively. The type of bifurcation that associates equilibria with periodic solution is called Hopf bifurcation. In this paper, a life energy system dynamic model of two components with multiple delays is presented. It is shown that the interaction parameters of the delayed ecosystem play a fundamental role in classifying the rich dynamics and bifurcation phenomena. Regarding the combined interaction parameter as a bifurcation parameter, the bifurcation values in the parameter plane are displayed. The direction of the Hopf bifurcation and the stability of the bifurcating periodic solutions are determined by applying the normal form theory and the center manifold theorem. Moreover, the amplitudes of oscillations always increase as the interaction parameters increase, while the robustness of periods occurs as the interaction parameters vary. From an ecological point of view, the existence of Hopf bifurcation expresses periodic oscillatory behavior of the life energy system.     

The integration of open access journals in the scholarly communication system: Three science fields

The greatest number of open access journals (OAJs) is found in the sciences and their influence is growing. However, there are only a few studies on the acceptance and thereby integration of these OAJs in the scholarly communication system. Even fewer studies provide insight into the differences across disciplines. This study is an analysis of the citing behaviour in journals within three science fields: biology, mathematics, and pharmacy and pharmacology. It is a statistical analysis of OAJs as well as non-OAJs including both the citing and cited side of the journal to journal citations. The multivariate linear regression reveals many similarities in citing behaviour across fields and media. But it also points to great differences in the integration of OAJs. The integration of OAJs in the scholarly communication system varies considerably across fields. The implications for bibliometric research are discussed.     

Managing open innovation projects with science-based and market-based partners

This paper examines the relationship between (outside-in) open innovation and the financial performance of R&D projects, drawing on a unique dataset that contains information on the open innovation practices, management and performance of 489 R&D projects of a large European multinational firm. We introduce two types of open innovation partnerships – science-based and market-based partnerships – and examine their relationships with project financial performance. In addition, we investigate whether the open innovation—project performance relationships are influenced by the way how R&D projects are managed. Our results show that R&D projects with open innovation partnerships are associated with a better financial performance providing that they are managed in the most suitable way. Market-based partnerships are positively correlated with project performance if a formal project management process is used; however these partnerships are associated with a lower performance for loosely managed projects. In contrast, science-based partnerships are associated with higher project revenues for loosely managed projects only.     

Experimental exploration of five-qubit quantum error-correcting code with superconducting qubits

Quantum error correction is an essential ingredient for universal quantum computing.Despite tremendous experimental efforts in the study of quantum error correc...