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1.
Entangled two-photon generalized binomial states of the electromagnetic field in two separate cavities are considered. The
nonlocal properties of this entangled field state are analyzed by studying the electric field correlations between the two
cavities. A Bell’s inequality violation is obtained using an appropriate dichotomic cavity operator that is, in principle,
measurable.
The text was submitted by the authors in English. 相似文献
2.
The Wigner function and the symplectic tomogram of an entangled quantum state, which is a superposition of the photon’s coherent
states (even and odd coherent states), is studied. Photon statistics and violation of Bell’s inequality for the photon state
are discussed. 相似文献
3.
We present a discrete model theory similar in structure to ordinary quantum mechanics, but based on a finite field instead of complex amplitudes. The interpretation of this theory involves only the “modal” concepts of possibility and necessity rather than quantitative probability measures. Despite its simplicity, our model theory includes entangled states and has versions of both Bell’s theorem and the no cloning theorem. 相似文献
4.
C. S. Unnikrishnan 《Optics and Spectroscopy》2001,91(3):393-398
The Einstein-Podolsky-Rosen (EPR) nonlocality puzzle has been recognized as one of the most important unresolved issues in the foundational aspects of quantum mechanics. We show that the problem is more or less entirely resolved, if the quantum correlations are calculated directly from local quantities, which preserve the phase information in the quantum system. We assume strict locality for the probability amplitudes instead of local realism for the outcomes and calculate an amplitude correlation function. Then the experimentally observed correlation of outcomes is calculated from the square of the amplitude correlation function. Locality of amplitudes implies that measurement on one particle does not collapse the companion particle to a definite state. Apart from resolving the EPR puzzle, this approach shows that the physical interpretation of apparently “nonlocal” effects, such as quantum teleportation and entanglement swapping, are different from what is usually assumed. Bell-type measurements do not change distant states. Yet the correlations are correctly reproduced, when measured, if complex probability amplitudes are treated as the basic local quantities. As examples, we derive the quantum correlations of two-particle maximally entangled states and the three-particle Greenberger-Horne-Zeilinger entangled state. 相似文献
5.
We consider the irreversible dynamics of two two-level atoms that interact with a bipartite broad-band electromagnetic field
in an entangled state that forms a heat bath with a quantum correlation. Using Ito’s stochastic integration technique, we
have derived a kinetic equation for atoms and found their steady state, which turns out to be inseparable and leads to a violation
of Bell’s inequalities. The application of the atomic state found as a quantum channel for teleportation is considered. We
have calculated the channel quality or fidelity that determines the possibilities for using the channel, in particular, characterizes
its security. The process of teleportation by means of a quantum channel formed by an entangled heat bath is considered. Comparison
of two (atomic and light) channels has shown that they have different properties with regard to separability and identical
properties with regard to nonlocality. This means that nonlocality can be completely transferred from light to atoms. 相似文献
6.
C. S. Unnikrishnan 《Pramana》2005,65(3):359-379
I discuss in detail the result that the Bell’s inequalities derived in the context of local hidden variable theories for discrete
quantized observables can be satisfied only if a fundamental conservation law is violated on the average. This result shows
that such theories are physically nonviable, and makes the demarcating criteria of the Bell’s inequalities redundant. I show
that a unique correlation function can be derived from the validity of the conservation law alone and this coincides with
the quantum mechanical correlation function. Thus, any theory with a different correlation function, like any local hidden
variable theory, is incompatible with the fundamental conservation laws and space-time symmetries. The results are discussed
in the context of two-particle singlet and triplet states, GHZ states, and two-particle double slit interferometry. Some observations
on quantum entropy, entanglement, and nonlocality are also discussed. 相似文献
7.
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
8.
M. Revzen 《Foundations of Physics》2006,36(4):546-562
Some entangled states have nonnegative Wigner representative function. The latter allow being viewed as a distribution function of local hidden variables. It is argued herewith that the interpretation of expectation values using such distribution functions as local hidden variable theory requires restrictions pertaining to the observables under study. The reasoning lead to support the view that violation of Bell’s inequalities that is always possible for entangled states hinges not only on the states involved but also whether the dynamical variables have their values defined even when they cannot be measured. 相似文献
9.
Several quantum-mechanical correlations, notably, quantum entanglement, measurement-induced nonlocality and Bell nonlocality are studied for a two qubit-system having no mutual interaction. Analytical expressions for the measures of these quantum-mechanical correlations of different bipartite partitions of the system are obtained, for initially two entangled qubits and the two photons are in their vacuum states. It is found that the qubits-fields interaction leads to the loss and gain of the initial quantum correlations. The lost initial quantum correlations transfer from the qubits to the cavity fields. It is found that the maximal violation of Bell’s inequality is occurring when the quantum correlations of both the logarithmic negativity and measurement-induced nonlocality reach particular values. The maximal violation of Bell’s inequality occurs only for certain bipartite partitions of the system. The frequency detuning leads to quick oscillations of the quantum correlations and inhibits their transfer from the qubits to the cavity modes. It is also found that the dynamical behavior of the quantum correlation clearly depends on the qubit distribution angle. 相似文献
10.
Francesco De Martini 《Foundations of Physics》2011,41(3):363-370
Two quantum Macro-states and their Macroscopic Quantum Superpositions (MQS) localized in two far apart, space-like separated
sites can be non-locally correlated by any entangled couple of single-particles having interacted in the past. This novel
“Macro-Macro” paradigm is investigated on the basis of a recent study on an entangled Micro-Macro system involving N≈105 particles. Crucial experimental issues as the violation of Bell’s inequalities by the Macro-Macro system are considered. 相似文献
11.
Luiz Carlos Ryff 《Foundations of Physics Letters》1997,10(3):207-220
An experiment is discussed in which a conflict between the wave like and nonlocal properties of photons leads to an apparent
paradox. Possible ways of circumventing this contradiction are suggested. The experiment allows us to prove a Bell’s theorem
for two particles without using an inequality and to test local realism against quantum mechanics introducing additional assumptions
weaker than nonenhancement. 相似文献
12.
The structure of maximal violators of Bell’s inequalities for Jordan algebras is investigated. It is proved that the spin
factor V
2 is responsible for maximal values of Bell’s correlations in a faithful state. In this situation maximally correlated subsystems
must overlap in a nonassociative subalgebra. For operator commuting subalgebras it is shown that maximal violators have the
structure of the spin systems and that the global state (faithful on local subalgebras) acts as the trace on local subalgebras. 相似文献
13.
Andrei Khrennikov 《International Journal of Theoretical Physics》2012,51(8):2488-2502
This paper discusses a possible resolution of the nonobjectivity-nonlocality dilemma in quantum mechanics in the light of experimental tests of the Bell inequality for two entangled photons and a Bell-like inequality for a single neutron. My conclusion is that these experiments show that quantum mechanics is nonobjective: that is, the values of physical observables cannot be assigned to a system before measurement. Bell’s assumption of nonlocality has to be rejected as having no direct experimental confirmation, at least thus far. I also consider the relationships between nonobjectivity and contextuality. Specifically, I analyze the impact of the Kochen-Specker theorem on the problem of contextuality of quantum observables. I argue that, just as von Neumann’s “no-go” theorem, the Kochen-Specker theorem is based on assumptions that do not correspond to the real physical situation. Finally, I present a theory of measurement based on a classical, purely wave model (pre-quantum classical statistical field theory), a model that reproduces quantum probabilities. In this model continuous fields are transformed into discrete clicks of detectors. While this model is classical, it is nonobjective. In this case, nonobjectivity is the result of the dependence of experimental outcomes on the context of measurement, in accordance with Bohr’s view. 相似文献
14.
Louis Sica 《Foundations of Physics Letters》2002,15(5):473-486
Proofs of Bell’s theorem and the data analysis used to show its violation have commonly assumed a spatially stationary underlying
process. However, it has been shown recently that the appropriate Bell’s inequality holds identically for cross correlations
of three or four lists of ±l’s, independently of statistical assumptions. When data consistent with its derivation are analyzed
without imposition of the stationarity assumption, the resulting correlations satisfy the Bell inequality. 相似文献
15.
Thomas Filk 《International Journal of Theoretical Physics》2006,45(6):1166-1180
The famous “spooky action at a distance” in the EPR-scenario is shown to be a local interaction, once entanglement is interpreted as a kind of “nearest neighbor” relation among quantum systems. Furthermore, the wave function itself is interpreted as encoding the “nearest neighbor” relations between a quantum system and spatial points. This interpretation becomes natural, if we view space and distance in terms of relations among spatial points. Therefore, “position” becomes a purely relational concept. This relational picture leads to a new perspective onto the quantum mechanical formalism, where many of the “weird” aspects, like the particle-wave duality, the non-locality of entanglement, or the “mystery” of the double-slit experiment, disappear. Furthermore, this picture circumvents the restrictions set by Bell’s inequalities, i.e., a possible (realistic) hidden variable theory based on these concepts can be local and at the same time reproduce the results of quantum mechanics.
PACS: 03.65.Ud, 04.60.Nc 相似文献
16.
Travis Norsen 《Foundations of Physics》2009,39(3):273-294
J.S. Bell believed that his famous theorem entailed a deep and troubling conflict between the empirically verified predictions
of quantum theory and the notion of local causality that is motivated by relativity theory. Yet many physicists continue to
accept, usually on the reports of textbook writers and other commentators, that Bell’s own view was wrong, and that, in fact,
the theorem only brings out a conflict with determinism or the hidden-variables program or realism or some other such principle
that (unlike local causality), allegedly, nobody should have believed anyway. Moreover, typically such beliefs arise without
the person in question even being aware that the view they are accepting differs so radically from Bell’s own. Here we try
to shed some light on the situation by focusing on the concept of local causality that is the heart of Bell’s theorem, and,
in particular, by contrasting Bell’s own understanding with the analysis of Jon Jarrett which has been the most influential
source, in recent decades, for the kinds of claims mentioned previously. We point out a crucial difference between Jarrett’s
and Bell’s own understanding of Bell’s formulation of local causality, which turns out to be the basis for the erroneous claim,
made by Jarrett and many others, that Bell misunderstood the implications of his own theorem. 相似文献
17.
H. Hafermann S. Brener A. N. Rubtsov M. I. Katsnelson A. I. Lichtenstein 《JETP Letters》2008,86(10):677-682
A general cluster dual fermion approach to nonlocal correlations in crystals is formulated. The scheme allows the treatment
of long-range correlations beyond the cluster dynamical mean field theory and nonlocal effects in realistic calculations of
multiorbital systems. The simplest approximation is shown to exactly correspond to the free-cluster dynamical mean field theory.
This approach is applied to the one-dimensional Hubbard model. Already the first dual-fermion correction to the free cluster
leads to a drastic improvement of the calculated Green’s function. 相似文献
18.
A. F. Kracklauer 《Optics and Spectroscopy》2007,103(3):451-460
19.
H. Hafermann S. Brener A. N. Rubtsov M. I. Katsnelson A. I. Lichtenstein 《JETP Letters》2007,86(10):677-682
A general cluster dual fermion approach to nonlocal correlations in crystals is formulated. The scheme allows the treatment
of long-range correlations beyond the cluster dynamical mean field theory and nonlocal effects in realistic calculations of
multiorbital systems. The simplest approximation is shown to exactly correspond to the free-cluster dynamical mean field theory.
This approach is applied to the one-dimensional Hubbard model. Already the first dual-fermion correction to the free cluster
leads to a drastic improvement of the calculated Green’s function.
The text was submitted by the authors in English. 相似文献
20.