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1.
We study the nonlocal properties of states resulting from the mixture of an arbitrary entangled state rho of two d-dimensional systems and completely depolarized noise, with respective weights p and 1-p. We first construct a local model for the case in which rho is maximally entangled and p at or below a certain bound. We then extend the model to arbitrary rho. Our results provide bounds on the resistance to noise of the nonlocal correlations of entangled states. For projective measurements, the critical value of the noise parameter p for which the state becomes local is at least asymptotically log(d) larger than the critical value for separability. 相似文献
2.
采用高斯分解法,分析并讨论了非局域非线性介质的Z扫描特性.基于介质的非线性响应函数为高斯型,给出了用于确定非局域非线性介质的非线性折射率系数的透过率表达式,分析了非局域非线性介质的非局域程度对透过率曲线的影响,得到了计算非局域非线性介质的非线性折射率系数以及非局域程度的方法,讨论了由于非局域性条件所带来的对实验上的一些参数的调整,提出了测量介质非局域程度的可行的实验方法并说明了其他注意事项.同时还数值模拟了在介质的响应函数为双曲正割型情况下通过薄样品的远场Z扫描曲线,并与高斯响应情况下的结果进行了比较.
关键词:
非局域程度
薄介质
远场条件
Z扫描曲线')" href="#">Z扫描曲线 相似文献
3.
Gregori G Glenzer SH Knight J Niemann C Price D Froula DH Edwards MJ Town RP Brantov A Rozmus W Bychenkov VY 《Physical review letters》2004,92(20):205006
We present the first direct measurements of spatially and temporally resolved temperature and density profiles produced by nonlocal transport in a laser plasma. Absolutely calibrated measurements have been performed by Rayleigh scattering and by resolving the ion-acoustic wave spectra across the plasma volume with Thomson scattering. We find that the electron temperature and density profiles disagree with flux-limited models, but are consistent with nonlocal transport modeling. 相似文献
4.
Two nonlocal and unknown pure qubit states can, with a certain probability of success, be discriminated unambiguously with
the aid of local operations, classical communication, and shared entanglements (LOCCSE). We present a scheme for such kind
of nonlocal unambiguous quantum state discrimination. This scheme consists of a nonlocal positive operator valued measurement
(POVM). This nonlocal POVM can be realized by performing nonlocal unitary operations on initial system and ancillary qubits,
and local von Neumann projective measurements on the ancilla plus initial system. By utilizing the degrees of freedom of the
original system Hilbert space, we need far more simpler operations than those required by the original Neumark approach. We
construct a quantum logic network to implement the required nonlocal POVM. 相似文献
5.
We study a generalization of irreversible thermodynamics with nonlocal closing relation. Thus parabolic and hyperbolic models can be described within one single theory. In the 1-d case, Guyer–Krumhansl equation and classical Fourier heat conduction may be obtained, depending on the constitutive assumptions. The thermodynamical restrictions in form of the Clausius–Duhem inequality are studied taking into account an extra flux of entropy corresponding to nonlocal irreversible effects. Numerical solutions to the resulting initial-boundary value problem are calculated and compared with available experimental results. 相似文献
6.
We investigate the local implementation of a nonlocal quantum Toffoli gate via partially entangled states. Firstly, we show
how the nonlocal Toffoli gate can be implemented with unit fidelity and a certain probability by employing two partially entangled
qubit pairs as quantum channels. The quantum circuit that does this proposed implementation is built entirely of local single-level
and two-level gates if the target node harness a three-level qudit as a catalyser. This enables the construction of this key
nonlocal quantum gate with existing technology. Then, we put forward a scheme to realize deterministic and exact implementation
of this nonlocal gate via more partially entangled pairs. In this scheme, the control nodes’ local positive operator valued
measurements (POVMs) lies at the heart. We construct the required POVMs. The fact that the deterministic and exact implementation
of a nonlocal multi-qubit gate could be realized by using partially entangled qubit pairs and comparatively fewer resources
cost is notable. 相似文献
7.
It is known that all causal correlations between two parties which output each 1 bit, a and b, when receiving each 1 bit, x and y, can be expressed as convex combinations of local correlations (i.e., correlations that can be simulated with local random variables) and nonlocal correlations of the form a+b=xy mod 2. We show that a single instance of the latter elementary nonlocal correlation suffices to simulate exactly all possible projective measurements that can be performed on a maximally entangled state of two qubits, with no communication needed at all. This elementary nonlocal correlation thus defines some unit of nonlocality, which we call a nl bit. 相似文献
8.
Hu SX Smalyuk VA Goncharov VN Skupsky S Sangster TC Meyerhofer DD Shvarts D 《Physical review letters》2008,101(5):055002
We present for the first time the experimental validation of the nonlocal thermal-transport model for a National Ignition Facility relevant laser intensity of approximately 10(15) W/cm(2) on OMEGA. The measured thin target trajectories are in good agreement with predictions based on the nonlocal model over the full range of laser intensities from 2 x 10(14) to 10(15) W/cm(2}) The standard local thermal-transport model with a constant flux limiter of 0.06 disagrees with experimental measurements at a high intensity of approximately 10(15) W/cm(2) but agrees at lower intensities. These results show the significance of nonlocal effects for direct-drive ignition designs. 相似文献
9.
《Physics letters. A》2020,384(23):126573
We construct an expression for the Green function of a differential operator satisfying nonlocal, homogeneous boundary conditions starting from the fundamental solution of the differential operator. This also provides the solution to the boundary value problem of an inhomogeneous partial differential equation with inhomogeneous, nonlocal boundary conditions. The construction applies for a broad class of linear partial differential equations and linear boundary conditions. 相似文献
10.
A. V. Belinsky 《Optics and Spectroscopy》2017,123(3):419-424
We analyze the scheme of an experiment in which, by examining suppression effects of the cross correlation of photons in a beamsplitter and by preparing squeezed states, it is proven that the phase difference of photons in Fock states cannot acquire a certain value, since, otherwise, the simultaneous existence of these two effects would be impossible. We show that this reveals an intrinsic inconsistency of the nonlocal classical interpretation of quantum mechanics on the basis of nonlocal classical “realism.” 相似文献
11.
Local measurements on bipartite maximally entangled states can yield correlations that are maximally nonlocal, monogamous, and with fully random outcomes. This makes these states ideal for bipartite cryptographic tasks. Genuine-multipartite nonlocality constitutes a stronger notion of nonlocality in the multipartite case. Maximal genuine-multipartite nonlocality, monogamy, and random outcomes are thus highly desired properties for genuine-multipartite cryptographic scenarios. We prove that local measurements on any Greenberger-Horne-Zeilinger state can produce correlations that are fully genuine-multipartite nonlocal, monogamous, and with fully random outcomes. A key ingredient in our proof is a multipartite chained Bell inequality detecting genuine-multipartite nonlocality, which we introduce. Finally, we discuss applications to device-independent secret sharing. 相似文献
12.
13.
We investigate the nonlocal dynamics of a single particle placed in an infinite well with moving walls. It is shown that in this situation, the Schrödinger equation (SE) violates local causality by causing instantaneous changes in the probability current everywhere inside the well. This violation is formalized by designing a gedanken faster-than-light communication device which uses an ensemble of long narrow cavities and weak measurements to resolve the weak value of the momentum far away from the movable wall. Our system is free from the usual features causing nonphysical violations of local causality when using the (nonrelativistic) SE, such as instantaneous changes in potentials or states involving arbitrarily high energies or velocities. We explore in detail several possible artifacts that could account for the failure of the SE to respect local causality for systems involving time-dependent boundary conditions. 相似文献
14.
Sergey G. Bochkarev Andrei V. Brantov Valery Yu. Bychenkov Wojciech Rozmus 《Journal of Russian Laser Research》2011,32(2):163-176
We study ultrashort-laser-pulse absorption and plasma heating at a sharp plasma–vacuum interface using advanced models for
all-range plasma permittivity and nonlocal heat transport. The electron response includes both collisional and collisionless
dissipative effects in the plasma of an arbitrary ion charge. We show that nonlocal electron heat transport is important for
correct determination of the value of electron temperature and spatial temperature profile. Nonlocal electron heat flux comes
into play after electrons heat up to temperatures of the order of 1 keV and to temperatures several times less for low-density
targets. 相似文献
15.
Understanding the nonlinear optical effect of novel materials plays a crucial role in the fields of photonics and optoelectronics. Herein, we theoretically and experimentally investigate the simultaneous presence of third-order locally refractive nonlinearity and thermally induced nonlocal nonlinearity saturation. We present analytical expressions for the closed-aperture Z-scan trace and the number of spatial self-phase modulation(SSPM) rings,which allows one to unambiguously and conveniently separate the contributions of local and nonlocal nonlinear refraction in the case that both effects occur simultaneously. As a test, we study both the local and thermally induced nonlocal nonlinear refraction in fullerene/toluene solution by performing continuous-wave Z-scan and SSPM measurements at two different wavelengths. This work enriches the understanding of the physical mechanism of the optical nonlinear refraction effect in solution dispersions of nanomaterials, which can be exploited for nonlinear photonic devices. 相似文献
16.
Wei HanK.M. McCreary K. PiW.H. Wang Yan LiH. Wen J.R. ChenR.K. Kawakami 《Journal of magnetism and magnetic materials》2012,324(4):369-381
We review our recent work on spin injection, transport and relaxation in graphene. The spin injection and transport in single layer graphene (SLG) were investigated using nonlocal magnetoresistance (MR) measurements. Spin injection was performed using either transparent contacts (Co/SLG) or tunneling contacts (Co/MgO/SLG). With tunneling contacts, the nonlocal MR was increased by a factor of ∼1000 and the spin injection/detection efficiency was greatly enhanced from ∼1% (transparent contacts) to ∼30%. Spin relaxation was investigated on graphene spin valves using nonlocal Hanle measurements. For transparent contacts, the spin lifetime was in the range of 50-100 ps. The effects of surface chemical doping showed that for spin lifetimes in the order of 100 ps, charged impurity scattering (Au) was not the dominant mechanism for spin relaxation. While using tunneling contacts to suppress the contact-induced spin relaxation, we observed the spin lifetimes as long as 771 ps at room temperature, 1.2 ns at 4 K in SLG, and 6.2 ns at 20 K in bilayer graphene (BLG). Furthermore, contrasting spin relaxation behaviors were observed in SLG and BLG. We found that Elliot-Yafet spin relaxation dominated in SLG at low temperatures whereas Dyakonov-Perel spin relaxation dominated in BLG at low temperatures. Gate tunable spin transport was studied using the SLG property of gate tunable conductivity and incorporating different types of contacts (transparent and tunneling contacts). Consistent with theoretical predictions, the nonlocal MR was proportional to the SLG conductivity for transparent contacts and varied inversely with the SLG conductivity for tunneling contacts. Finally, bipolar spin transport in SLG was studied and an electron-hole asymmetry was observed for SLG spin valves with transparent contacts, in which nonlocal MR was roughly independent of DC bias current for electrons, but varied significantly with DC bias current for holes. These results are very important for the use of graphene for spin-based logic and information storage applications. 相似文献
17.
18.
GianCarlo Ghirardi 《Foundations of Physics》2000,30(9):1337-1385
In this paper we reconsider the constraints which are imposed by relativistic requirements to any model of dynamical reduction. We review the debate on the subject and we call attention on the fundamental contributions by Aharonov and Albert. Having done this we present a new formulation, which is much simpler and more apt for our analysis, of the proposal put forward by these authors to perform measurements of nonlocal observables by means of local interactions and detections. We take into account recently proposed relativistic models of dynamical reduction and we show that, in spite of some mathematical difficulties related to the appearence of divergences, they represent a perfectly appropriate conceptual framework which meets all necessary requirements for a relativistic account of wave packet reduction. Subtle questions like the appropriate way to deal with counterfactual reasoning in a relativistic and nonlocal context are also analyzed in detail. 相似文献
19.
Zhiping Dai Shiqing Tang Zhenjun Yang Zhenfeng Yang Shumin Zhang Xingliang Li 《Journal of Russian Laser Research》2017,38(3):241-248
The nonlocal nonlinear Schrödinger equation (NNLSE) describes the propagation dynamics of optical beams in nonlinear media with a spatial nonlocal response. Based on NNLSE, we obtain the generalized sine hollow solitons and breathers and show that the transverse intensity evolutions of them are always periodical. However, if the incident power takes a critical value, the beam width can remain invariant during the propagation, just like the solitons. Otherwise, the beam width varies periodically, just like the breathers. We investigate the evolution characteristics for both cases analytically and numerically in detail. 相似文献
20.
Froula DH Ross JS Pollock BB Davis P James AN Divol L Edwards MJ Offenberger AA Price D Town RP Tynan GR Glenzer SH 《Physical review letters》2007,98(13):135001
We present a direct measurement of the quenching of nonlocal heat transport in a laser-produced plasma by applying large external magnetic fields (>10 T). The temporally resolved Thomson-scattering measurements of the electron temperature profile show that the heat front propagation transverse to a high-power laser beam is slowed resulting in extremely strong local heating. We find agreement with hydrodynamic modeling when including a magnetic field model that self-consistently evolves the fields in the plasma. 相似文献