Experimental simulation of the Unruh effect on an NMR quantum simulator

A triad mode resonance, or three-wave resonance, is typical of dynamical systems with quadratic nonlinearities. Suspended cables are found to be rich in triad mode resonant dynamics. In this paper, modulation equations for cable’s triad resonance are formulated by the multiple scale method. Dynamic conservative quantities, i.e., mode energy and Manley-Rowe relations, are then constructed. Equilibrium/dynamic solutions of the modulation equations are obtained, and full investigations into their stability and bifurcation characteristics are presented. Various bifurcation behaviors are detected in cable’s triad resonant responses, such as saddle-node, Hopf, pitchfork and period-doubling bifurcations. Nonlinear behaviors, like jump and saturation phenomena, are also found in cable’s responses. Based upon the bifurcation analysis, two interesting properties associated with activation of cable’s triad resonance are also proposed, i.e., energy barrier and directional dependence. The first gives the critical amplitude of high-frequency mode to activate cable’s triad resonance, and the second characterizes the degree of difficulty for activating cable’s triad resonance in two opposite directions, i.e., with positive or negative internal detuning parameter.     

Quantum state and process tomography via adaptive measurements

We investigate quantum state tomography(QST) for pure states and quantum process tomography(QPT) for unitary channels via adaptive measurements. For a quantum system with a d-dimensional Hilbert space, we first propose an adaptive protocol where only 2d. 1 measurement outcomes are used to accomplish the QST for all pure states. This idea is then extended to study QPT for unitary channels, where an adaptive unitary process tomography(AUPT) protocol of d2+d.1measurement outcomes is constructed for any unitary channel. We experimentally implement the AUPT protocol in a 2-qubit nuclear magnetic resonance system. We examine the performance of the AUPT protocol when applied to Hadamard gate, T gate(/8 phase gate), and controlled-NOT gate,respectively, as these gates form the universal gate set for quantum information processing purpose. As a comparison, standard QPT is also implemented for each gate. Our experimental results show that the AUPT protocol that reconstructing unitary channels via adaptive measurements significantly reduce the number of experiments required by standard QPT without considerable loss of fidelity.     

Experimental study on generation of high energy few cycle pulses with hollow fiber filled with neon

25 fs pulses with energy up to 0.8 mJ from a multi-pass amplifier system have been spectrally broadened from 460 nm to 950 nm due to strong self-phase modulation (SPM) effect in a gas filled hollow fiber. Using a set of chirped mirrors, the ultra-broadband dispersion compensation was achieved, and the compressed pulses reached their transform limit. Under optimized conditions we achieved pulses with duration of 5.1 fs and with energy of 400 μJ, corresponding to the peak power up to 80 GW. Supported by the National Natural Science Foundation of China (Grant Nos. 60608003, 60490280, 60225005 and 60621063)     

聚合物纳米杂化材料的控制合成、自组装及功能化

聚合物纳米杂化材料的制备及功能化是当前国际前沿研究课题之一.特殊结构的聚合物可以通过分子间特殊相互作用,在纳米尺度上自发地组装成具有特殊结构和形态的集合体,这类材料在新材料、电子以及生物医学等领域具有广泛的应用前景.本文介绍国内外,特别是厦门大学在双亲性分子及嵌段共聚物的模板自组装、基于POSS单体纳米构筑单元以及POSS嵌段聚合物自组装的有机/无机纳米杂化材料、模板控制导电高分子材料纳米形态构筑等领域材料的可控合成和组装,与此同时对相关材料的性能及功能化应用进行了简要的讨论.     

Generic preparation and entanglement detection of equal superposition states

Quantum superposition is a fundamental principle of quantum mechanics, so it is not surprising that equal superposition states (ESS) serve as powerful resources for quantum information processing. In this work, we propose a quantum circuit that creates an arbitrary dimensional ESS. The circuit construction is efficient as the number of required elementary gates scales polynomially with the number of required qubits. For experimental realization of the method, we use techniques of nuclear magnetic resonance (NMR).We have succeeded in preparing a 9-dimensional ESS on a 4-qubit NMR quantum register. The full tomography indicates that the fidelity of our prepared state with respect to the ideal 9-dimensional ESS is over 96%. We also prove the prepared state is pseudo-entangled by directly measuring an entanglement witness operator. Our result can be useful for the implementation of those quantum algorithms that require an ESS as an input state.     

左截断相依数据下非参数回归的局部M 估计

本文对左截断模型, 利用局部多项式的方法构造了非参数回归函数的局部M 估计. 在观察样本为平稳α-混合序列下, 建立了该估计量的强弱相合性以及渐近正态性. 模拟研究显示回归函数的局部M 估计比Nadaraya-Watson 型估计和局部多项式估计更稳健.     

Stochastic programming based capacity planning for semiconductor wafer fab with uncertain demand and capacity

Capacity planning is a challenging problem in semiconductor manufacturing industry due to high uncertainties both in market and manufacturing systems, short product life cycle, and expensive capital invest. To tackle this problem, this paper proposes a scenario-based stochastic programming model which considers demand and capacity uncertainties via scenarios, where the overall equipment efficiency is employed to describe the uncertain capacity for the first time. Based on the decentralized structure of tool procurement, production, stockout, and inventory decision-making processes, recourse approximation strategies are presented with varying degree of information share. The computational experiments show that the resulting tool set is robust enough to cope with the changes in capacity with the expected profits being maximized for different scenarios, and the scheme can generate pretty good solutions in reasonable computational time.     

Synchronously pumped femtosecond optical parametric oscillator at 1053 nm

A femtosecond optical parametric oscillator synchronously pumped by a Ti:Sapphire oscillator is reported. By the cavity length tuning, the signal wavelength is continuously tuned from 1000 to 1200 nm. The average output power of 32 mW is obtained at 1053 nm. The pulse width is measured to be 342 fs by intensity autocorrelation method. In addition, we observed bichromatic emission during the cavity length tuning process. Supported by the National High Technology Program Research and Development Program of China, the National Natural Science Foundation of China (Grant Nos. 60490280 and 10804128), and the National Basic Research Program of China (Grant No. 2007CB815104)     

Experimental preparation of topologically ordered states via adiabatic evolution

Topological orders are a class of exotic states of matter characterized by patterns of long-range entanglement. Certain topologically ordered systems are proposed as potential realization of fault-tolerant quantum computation. Topological orders can arise in two-dimensional spin-lattice models. In this paper, we engineer a time-dependent Hamiltonian to prepare a topologically ordered state through adiabatic evolution. The other sectors in the degenerate ground-state space of the model are obtained by applying nontrivial operations corresponding to closed string operators. Each sector is highly entangled, as shown from the completely reconstructed density matrices. This paves the way towards exploring the properties of topological orders and the application of topological orders in topological quantum memory.     

血脑屏障药物筛选模型的建立及丹参活性成分筛选分析

ECV304细胞在C6细胞的诱导下生长,通过细胞培养时间优化、渗透系数测定和细胞形态学观察等,建立ECV304/C6共培养血脑屏障(BBB)药物筛选模型.将该模型应用于从丹参提取液中筛选可能作用于中枢神经系统(CNS)的活性成分,结合液相色谱-质谱联用技术(LC-MS)分析,发现丹参提取液中至少有16种成分能够穿越BBB模型,其中4种成分被确认为隐丹参酮、丹参酮Ⅰ、丹参素和原儿茶酸.通过定量构效关系(QASR)分析,进一步从理论上证明所确认的4种化合物均符合CNS靶向药物的特征.研究结果表明,ECV304/C6共培养BBB模型能够在模拟生理状态下从中药复杂体系中筛选分离跨越BBB的活性成分组,可用于CNS药物开发的早期快速筛选,服务于中药现代化研究.