A singlet state prepared with resonant interaction via trapped ions

A simple scheme for the generation of the three-qutrit Λ-type singlet state with resonant interaction via trapped ions is proposed. In the present proposal, the required interaction time is very short due to resonant interaction. The present proposal may be realized based on the current technologies. We also note that the three-ion three-level maximally entangled state can be generated via resonant interaction in one step.     

通过幺正操作传送未知两个三能级粒子纠缠态

我们提出一个把未知的两个三能级粒子纠缠态传送给两个接收者的方案,该方案使用一个未知的五个三能级粒子纠缠态作为量子通道。必须指出该方案能够推广到传送未知的N个三能级粒子纠缠态给M个接收者的情况,使用的是未知(N.M 1)个三能级粒子纠缠态作为量子通道。在传送过程中,需要执行适当的幺正操作和(N.M 1)次独立测量,而且该方案不涉及Bell态测量。     

传送两原子直积态的腔QED方案(英文)

本文提出一个基于原子和腔场共振相互作用传送未知原子直积态的腔QED方案,原子和腔场通过J-C哈密顿量发生共振相互作用.在这个方案里,我们只需要用两个原子接受被传送的原子态以及两个单模腔作为量子通道.该方案既不需要贝尔态测量,也不需要任何操作重构纠缠初态,并且传送成功的概率为100%.这个方案也可以推广到传送n个原子的直积态.     

双模最小关联混合态作为量子信道实现量子隐形传态的保真度

基于Braunstein和Kimble提出的B-K方案以双模最小关联混合态作为量子信道实施对未知量子态的隐形传送，并以传送相干态为例进行了研究.结果表明：双模最小关联混合态作为一种广义的Einstein-Podolsky-Rosen型纠缠态在实现量子隐形传态中能很好地担当量子信道的角色，在纠缠度和压缩度选择适当的条件下被传送未知量子态的保真度可以达到1.这是比双模压缩真空态更优越的量子信道. 关键词： 量子隐形传态 双模最小关联混合态 保真度     

腔QED制备三原子W态的一般方案

本文提出了一个基于腔QED技术的制备三原子最大W态的一般方案.通过讨论表明三个原子不论是被同时注入腔中还是在不同的时刻被注入腔中我们都能得到三原子最大W态.该方案可以在当前的技术范围内实现并且可以推广到制备n个原子的W态.     

Multi-parties Controlled Dense Coding via Maximal Slice States and the Physical Realization Using the Optical Elements

An efficient scheme for controlled dense coding is presented with the aid of the introduction of auxiliary particles, appropriate local unitary operations and measurement basis. In this proposal, the four-qubits maximal slice state, which belongs to partially entangled states, is used as quantum channel. The concrete implementation procedures for our scheme with one sender, one receiver and two controllers are given in detail, and the average transmitted classical information from the sender to the receiver is calculated. Additionally, the physical realization of this proposal is discussed based on the optical elements.     

Phase unwrapping by accumulation of residual maps

We present a path independent (global) algorithm for phase unwrapping based on the minimisation of a robust cost function. The algorithm incorporates an outlier rejection mechanism making it robust to large inconsistencies and discontinuities. The proposal consists on an iterative incremental scheme that unwraps a sub-estimation of the residual phase at each iteration. The sub-estimation degree is controlled by an algorithm׳s parameter. We present an efficiently computational multigrid implementation based on a nested strategy: the process is iterated by using multiple resolutions. The proposal׳s performance is demonstrated by experiments with synthetic and real data, and successfully compared with algorithms of the state of the art.     

Quantum Zeno subspace and entangled Bose-Einstein condensates

We discuss a proposal for the efficient generation of the maximally entangled atomic N-GHZ state in a spinor-1 condensate by driving internal state atomic Raman transitions using (classical) laser fields. We illustrate the dynamics in terms of a quantum Zeno subspace and identify the resultant atomic elastic collision in facilitating the deterministic entanglement creation. Our proposal can be readily implemented in several laboratories where ferromagnetic spinor condensates (of 87Rb atoms) are investigated.     

Test of cold denaturation mechanism for proteins as a function of water's structure

At low temperatures and high pressures (ranging from approximately 200 up to 700 MPa), some proteins become thermodynamically unstable by means of a phenomenon know as cold denaturation. A microscopic understanding of the mechanisms leading to cold denaturation is very difficult to develop, due in part to the complexity of the protein–solvent interactions. A possible proposal to explain the cold denaturation of proteins based on a relation between hydrophobicity and the loss of the local low-density water structure at high pressures is explained in detail. In the present paper, this mechanism is tested for the first time by means of full atom numerical simulations. In good agreement with the proposal, cold denaturation resulting in the unfolded state has been found at the high-density liquid (HDL) state of water, at which the amount of open tetragonal hydrogen bonds decreases at cooling.     

Spin-charge separation in the quantum spin Hall state

The quantum spin Hall state is a topologically nontrivial insulator state protected by the time-reversal symmetry. We show that such a state always leads to spin-charge separation in the presence of a pi flux. Our result is generally valid for any interacting system. We present a proposal to experimentally observe the phenomenon of spin-charge separation in the recently discovered quantum spin Hall system.