Entangled phase states via quantum beam splitter

We study the entanglement effect of beam splitter on the temporally stable phase states. Specifically, we consider the eigenstates (phase states) of a unitary phase operator resulting from the polar decomposition of ladder operators of generalized Weyl-Heisenberg algebras possessing finite dimensional representation space. The linear entropy that measures the degree of entanglement at the output of the beam splitter is analytically obtained. We find that the entanglement is not only strongly dependent on the Hilbert space dimension but also quite related to strength the parameter ensuring the temporal stability of the phase states. Finally, we discuss the evolution of the entangled phase states.     

高效双螺旋点扩展函数相位片的设计与实验研究

双螺旋点扩展函数具有随离焦连续旋转变化的特性, 结合单分子定位方法可用于厚样品三维超分辨成像及分子定位追踪研究. 但双螺旋点扩展函数不足之处是光能利用率低, 对于光子数受限的荧光显微成像而言其应用受限. 本文通过对双螺旋点扩展函数在空域、频域和拉盖尔-高斯模式面等三个不同域中进行约束优化. 模拟结果表明, 优化后的双螺旋点扩展函数的光能效率提高了30多倍. 同时, 基于最优设计方案制备了相位片, 并实验验证了该设计的正确性. 与文献报道相比较, 本文结果在成像深度和光能利用率方面都有所改善. 关键词： 双螺旋点扩展函数 超分辨成像 轴向定位 优化算法     

相空间中对称的纠缠相干态及其非经典特性

研究相空间中对称的纠缠相干态, 通过引入正交基矢, 利用concurrence方法计算了纠缠度, 研究了它们的单、双模压缩以及反聚束效应. 数值计算表明, 相空间中对称的纠缠相干态与非经典效应之间存在着密切的联系. 关键词： 纠缠相干态 concurrence 非经典效应     

On Fermionic Entangled State Representation and Fermionic Entangled Wigner Operator

By analogy with the bosonic bipartite entangled state we construct fermionic entangled state with the Grassmann numbers. The Wigner operator in the fermionic entangled state representation is introduced, whose marginal distributions are understood in an entangled way. The technique of integration within an ordered product (IWOP) of Fermi operators is used in our discussion.     

Nanofiber-based double-helix dipole trap for cold neutral atoms

A double-helix optical trapping potential for cold atoms can be straightforwardly created inside the evanescent field of an optical nanofiber. It suffices to send three circularly polarized light fields through the nanofiber; two counterpropagating and far red-detuned with respect to the atomic transition and the third far blue-detuned. Assuming realistic experimental parameters, the transverse confinement of the resulting potential allows one to reach the one-dimensional regime with cesium atoms for temperatures of several μK. Moreover, by locally varying the nanofiber diameter, the radius and pitch of the double-helix can be modulated, thereby opening a realm of applications in cold-atom physics.     

Entangled chimeras in nonlocally coupled bicomponent phase oscillators: From synchronous to asynchronous chimeras

Chimera states, a symmetry-breaking spatiotemporal pattern in nonlocally coupled identical dynamical units, have been identified in various systems and generalized to coupled nonidentical oscillators. It has been shown that strong heterogeneity in the frequencies of nonidentical oscillators might be harmful to chimera states. In this work, we consider a ring of nonlocally coupled bicomponent phase oscillators in which two types of oscillators are randomly distributed along the ring: some oscillators with natural frequency ω₁ and others with ω₂ . In this model, the heterogeneity in frequency is measured by frequency mismatch |ω₁−ω₂| between the oscillators in these two subpopulations. We report that the nonlocally coupled bicomponent phase oscillators allow for chimera states no matter how large the frequency mismatch is. The bicomponent oscillators are composed of two chimera states, one supported by oscillators with natural frequency ω₁ and the other by oscillators with natural frequency ω₂. The two chimera states in two subpopulations are synchronized at weak frequency mismatch, in which the coherent oscillators in them share similar mean phase velocity, and are desynchronized at large frequency mismatch, in which the coherent oscillators in different subpopulations have distinct mean phase velocities. The synchronization–desynchronization transition between chimera states in these two subpopulations is observed with the increase in the frequency mismatch. The observed phenomena are theoretically analyzed by passing to the continuum limit and using the Ott-Antonsen approach.     

Entangled Quantum States

Entangled quantum states are an important component of quantum computingtechniques such as quantum error correction, dense coding, and quantumteleportation. We determine the requirements for a state in the Hilbert space C ⁹to be entangled and a solution to the corresponding factorization problem if thisis not the case.     

Entangled photon holes

Most experimental demonstrations of entanglement require nonclassical states and correlated measurements of single-photon detection events. It is shown here that entanglement can produce a large decrease in the rate of two-photon absorption for a classical input state that can be observed using classical detectors. These effects can be interpreted as being due to the creation of entangled photon holes that are somewhat analogous to the holes of semiconductor theory.     

Entangled Fractional Fourier Transform for the Multipartite Entangled State Representation

We deduce entangled fractional Fourier transformation (EFFT) for the multipartite entangled state representation, which was newly constructed with two mutually conjugate n-mode entangled states of continuum variables in n-mode Fock space. We establish a formalism of EFFT for quantum mechanical wave functions, which provides us a convenient way to derive some wave functions. We find that the eigenmode of EFFT is different from the usual Hermite Polynomials. We also derive the EFFT of the n-mode squeezed state.     

On Fermionic Entangled State Representation and Fermionic Entangled Wigner Operator

By analogy with the bosonic bipartite entangled state we construct fermionic entangled state with the Grassmann numbers. The Wigner operator in the fermionic entangled state representation is introduced, whose marginal distributions are understood in an entangled way. The technique of integration within an ordered product （IWOP） of Fermi operators is used in our discussion.     

Remote Preparation of a Two-Particle Entangled State by a Bipartite Entangled State and a Tripartite Entangled W State

We propose a scheme to remotely prepare a general two-particle entangled state by using a bipartite entangled state and a tripartite entangled W state as the quantum channel.Our scheme consists of one sender and two remote receivers.The sender can help either one of the receivers to remotely reconstruct the original state with the assistance of the other receiver's single-particle orthogonal measurement.We obtain the total success probability and discuss the classical communication cost in our remote state preparation scheme.     

On the Entangled Fractional Fourier Transform in Tripartite Entangled State Representation

Based on the newly constructed two mutually conjugate 3-mode entangled states of continuum variablesin three-mode Fock space we introduce entangled fractional Fourier transform (EFFT) for the tripartite entangled staterepresentations, which are not a direct product of three 1-dimensional FFTs. The eigenmodes of EFFT are obtained,which is different from the usual Hermite polynomials. The EFFT of the three-mode squeezed state is derived.     

Squeezing for Entangled States of Two Entangled Particles with Different Masses

Using the technique of integration within an ordered product of operators we present a convenient approach for introducing the squeezing operator for the entangled states of two entangled particles with different masses. We also introduce one-sided squeezing operators.     

On the Entangled Fractional Fourier Transform in Tripartite Entangled State Representation

Based on the newly constructed two mutually conjugate 3-mode entangled states of continuum variables in three-mode Fock space we introduce entangled fractional Fourier transform (EFFT) for the tripartite entangled state representations, which are not a direct product of three 1-dimensional FFTs. The eigenmodes of EFFT are obtained,which is different from the usual Hermite polynomials. The EFFT of the three-mode squeezed state is derived.     

Nonlinear Einstein-Podolsky-Rosen Entangled States

Using the properties of the inverses of annihilation and creation operators of f-oscillator we introduce the notion of nonlinear Einstein Podolsky-Rosen entangled state and study its properties.     

Multipartite Fully Entangled Fraction

Fully entangled fraction is a definition for bipartite states, which is tightly related to bipartite maximally entangled states, and has clear experimental and theoretical significance. In this work, we generalize it to multipartite case, we call the generalized version multipartite fully entangled fraction (MFEF). MFEF measures the closeness of a state to GHZ states. The analytical expressions of MFEF are very difficult to obtain except for very special states, however, we show that, the MFEF of any state is determined by a system of finite-order polynomial equations. Therefore, the MFEF can be efficiently numerically computed.     

利用部分纠缠的特殊二粒子W态和部分纠缠的二粒子态传送二粒子纠缠态

提出了利用部分纠缠的特殊二粒子W态和部分纠缠的二粒子态组成量子信道,隐形传送一个二粒子纠缠态的方案。发送者进行两次Bell基测量,接受者先在{|0〉,|1〉}基下进行一次测量,然后实施一次控制—非操作,最后引进一个辅助粒子并进行一组适当的幺正变换操作,便可以一定的概率实现二粒子纠缠态的隐形传送。分析表明:当量子信道处于最大纠缠,即信道由一个特殊二粒子W态和一个Bell态组成时,本方案的传输概率达到2/3,传输效果介于完全由W态组成量子信道与完全由Bell态组成量子信道的方案之间。