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1.
The theoretical resource state for the implementation of the Deutsch-Jozsa algorithm is a multiqubit pure uncorrelated state. We show that N-qubit pure uncorrelated quantum states cannot admit rotationally invariant nonlocal realistic theories with a violation factor of 3N. We find the violation factor 3Nwhen the measurement setup is entire range of settings for each of the observers, that is, considering rotationally invariant nonlocal realistic theories along with the property of a correlation function in the quantum theory. The implementation of the Deutsch-Jozsa algorithm theoretically relying on N-qubit pure uncorrelated states rules out rotationally invariant nonlocal realism with a violation factor of 3Nin an ideal case. Our analysis relies on the property of theoretical resource states for the algorithm. We cannot simulate the Deutsch-Jozsa algorithm by using rotationally invariant nonlocal realistic theories due to the property of theoretical resource states for the algorithm.  相似文献   

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We assume that time invariance of physical laws is true. We assume that one source of 2N uncorrelated spin-carrying particles emits them in a state, which can be described as a multipartite pure uncorrelated state (+∞>N≥1). We assume that each of them is a spin-1/2 pure state lying in the \(\frac{z+x}{\sqrt{2}}\) direction. We assume that the measurement setup is two-orthogonal-settings for each of the observers. We show that 2N-particle pure uncorrelated quantum state violates a time invariant nonlocal realistic theory. 2N implies that we consider Bose-Einstein statistics.  相似文献   

4.
《Physics letters. A》1998,245(5):335-338
We have transposed Peres' argument [Phys. Rev. Lett. 74 (1995) 4571] about the single-particle nonlocality from the Fock space into an experimentally feasible scheme in cavity QED. The present scheme consists of a new proposal to demonstrate the single-particle nonlocality, where the single-particle state is constructed with a coherent factor which is crucial to reveal its nonlocal character.  相似文献   

5.
We study experimentally and theoretically the nonlocal response of a medium with thermal nonlinearity and show that despite its inherently infinite range it can be accurately characterized by a well-defined nonlocal response function. We retrieve the shape of this function and analyze its transformation with the change of boundaries.  相似文献   

6.
It is shown that the before-before (or Suarez-Scarani) experiment refutes hidden variable models with a deterministic (“realistic”) nonlocal part, whereas experiments violating Leggett-type inequalities refute models with biased random local part. Therefore the claim that Gröblacher et al. (Nature 446:871–875, 2007) present “an experimental test of nonlocal realism” is misleading, and Marek ?ukowski’s (Found. Phys. 38:1070, 2008) comment misses the point. A new experiment is suggested.  相似文献   

7.
It was shown by Bell that no local hidden variable model is compatible with quantum mechanics. If, instead, one permits the hidden variables to be entirely nonlocal, then any quantum mechanical predictions can be recovered. In this Letter, we consider general hidden variable models which can have both local and nonlocal parts. We show the existence of (experimentally verifiable) quantum correlations that are incompatible with any hidden variable model having a nontrivial local part, such as the model proposed by Leggett.  相似文献   

8.
Efficient local implementation of a nonlocal M-control and N-target controlled unitary gate is considered. We first show that with the assistance of two non-symmetric qubit(1)-qutrit(N) Greenberger-Horne-Zeilinger (GHZ) states, a nonlocal 2-control and N-target controlled unitary gate can be constructed from 2 local two-qubit CNOT gates, 2N local two-qutrit conditional SWAP gates, N local qutrit-qubit controlled unitary gates, and 2N single-qutrit gates. At each target node, the two third levels of the two GHZ target qutrits are used to expose one and only one initial computational state to the local qutrit-qubit controlled unitary gate, instead of being used to hide certain states from the conditional dynamics. This scheme can be generalized straightforwardly to implement a higher-order nonlocal M-control and N-target controlled unitary gate by using M non-symmetric qubit(1)-qutrit(N) GHZ states as quantum channels. Neither the number of the additional levels of each GHZ target particle nor that of single-qutrit gates needs to increase with M. For certain realistic physical systems, the total gate time may be reduced compared with that required in previous schemes.  相似文献   

9.
We consider the steady state of an open system in which there is a flux of matter between two reservoirs at different chemical potentials. For a large system of size N, the probability of any macroscopic density profile rho(x) is exp[-NF([rho])]; F thus generalizes to nonequilibrium systems the notion of free energy density for equilibrium systems. Our exact expression for F is a nonlocal functional of rho, which yields the macroscopically long range correlations in the nonequilibrium steady state previously predicted by fluctuating hydrodynamics and observed experimentally.  相似文献   

10.
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   

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We discuss an experimentally amenable class of two-particle states of motion giving rise to nonlocal spatial interference under position measurements. Using the concept of modular variables, we derive a separability criterion which is violated by these non-Gaussian states. While we focus on the free motion of material particles, the presented results are valid for any pair of canonically conjugate continuous variable observables and should apply to a variety of bipartite interference phenomena.  相似文献   

13.
We consider Bell tests involving bipartite states shared between three parties. We show that the simple inclusion of a third part may greatly simplify the measurement scenario (in terms of the number of measurement settings per part) and allows the identification of previously unknown nonlocal resources.  相似文献   

14.
We present a formalism to derive entanglement criteria beyond the Gaussian regime that can be readily tested by only homodyne detection. The measured observable is the Einstein-Podolsky-Rosen (EPR) correlation. Its arbitrary functional form enables us to detect non-Gaussian entanglement even when an entanglement test based on second-order moments fails. We illustrate the power of our experimentally friendly criteria for a broad class of non-Gaussian states under realistic conditions. We also show rigorously that quantum teleportation for continuous variables employs a specific functional form of EPR correlation.  相似文献   

15.
We experimentally demonstrate the superior discrimination of separated, unentangled two-qubit correlated states using nonlocal measurements, when compared with measurements based on local operations and classical communications. When predicted theoretically, this phenomenon was dubbed "quantum nonlocality without entanglement." We characterize the performance of the nonlocal, or joint, measurement with a payoff function, for which we measure 0.72 +/- 0.02, compared with the maximum locally achievable value of 2/3 and the overall optimal value of 0.75.  相似文献   

16.
A brief and critical survey of wave-particle duality and nonlocality aspects of light is presented. A recent attempt to establish a reasonable framework for nonlocal realistic theories based on physically sound arguments and a proposed experiment to decide between such theories and the usual interpretation of quantum mechanical formalism are reviewed. It is shown that a nonlocal realistic approach may raise some new questions which could be answered by means of a program based on a sequence of experiments.  相似文献   

17.
First it is proved that, in a deterministic theory, Malus' law requires that, if a photon is successively transmitted by two polarizers with appropriately chosen settings, the first transmission influences a hidden variable (co-) determining the second one. We derive from this that in an ideal EPR experiment (giving the result predicted by quantum mechanics for two correlated photons transmitted by two polarizers with suitably chosen settings) there has to be a nonlocal influence from the first transmission interaction to the second. Subsequently we argue that we can abandon determinism as an assumption so that the locality hypothesis is in any case untenable if the predictions of quantum mechanics are all correct.  相似文献   

18.
We show that a study of the processes
can provide information on the pion structure functions. Using a realistic parton distribution for the pion we calculate cross sections and relevant distributions for these processes. The results show that such measurements are experimentally accessible.  相似文献   

19.
We reveal that lattice interfaces imprinted in nonlocal nonlinear media support surface solitons that do not exist in other similar settings, including interfaces of local and nonlocal uniform materials. We show the impact of nonlocality on the domains of existence and stability of the surface solitons, focusing on new types of dipole solitons residing partially inside the optical lattice. We find that such solitons feature strongly asymmetric shapes and that they are stable in large parts of their existence domain.  相似文献   

20.
It is shown analytically that, in a trap filled by a Bose-Einstein condensate of atoms with a negative S-scattering length, there exists an instability caused by the nonlocal interaction of atoms. For this effect to be efficiently discovered experimentally, it is necessary to considerably decrease the absolute value of the scattering length using the Feshbach effect.  相似文献   

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