| 21. |
- Khrennikov, Andrei, 1958-, et al.
(författare)
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Classical signal model reproducing quantum probabilities for single and coincidence detections
- 2012
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 361
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Tidskriftsartikel (refereegranskat)abstract
- We present a simple classical (random) signal model reproducing Born's rule. The crucial point of our approach is that the presence of detector's threshold and calibration procedure have to be treated not as simply experimental technicalities, but as the basic counterparts of the theoretical model. We call this approach threshold signal detection model (TSD). The experiment on coincidence detection which was done by Grangier in 1986 [22] played a crucial role in rejection of (semi-)classical field models in favour of quantum mechanics (QM): impossibility to resolve the wave-particle duality in favour of a purely wavemodel. QM predicts that the relative probability of coincidence detection, the coefficient g((2)) (0); is zero (for one photon states), but in (semi-) classicalmodels g((2)) (0) >= 1 : In TSD the coefficient g((2)) (0) decreases as 1/epsilon(2)(d); where epsilon(d) > 0 is the detection threshold. Hence, by increasing this threshold an experimenter can make the coefficient g((2)) (0) essentially less than 1. The TSD-prediction can be tested experimentally in new Grangier type experiments presenting a detailed monitoring of dependence of the coefficient g((2)) (0) on the detection threshold. Structurally our model has some similarity with the prequantum model of Grossing et al. Subquantum stochasticity is composed of the two counterparts: a stationary process in the space of internal degrees of freedom and the random walk type motion describing the temporal dynamics.
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| 22. |
- Khrennikov, Andrei, 1958-, et al.
(författare)
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Distance Dependence of Entangled Photons in Waveguides
- 2012
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Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X .- 1551-7616. - 9780735410046 ; 1424, s. 262-269
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Tidskriftsartikel (refereegranskat)abstract
- The distance dependence of the probability of observing two photons in a waveguide is investigated and the Glauber correlation functions of the entangled photons are considered. First the case of a hollow waveguide with modal dispersion is treated in detail: the spatial and temporal dependence of the correlation functions is evaluated and the distance dependence of the probability of observing two photons upper bounds and asymptotic expressions valid for large distances are derived. Second the generalization to a real fibre with both material and modal dispersion, allowing dispersion shift, is discussed.
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| 23. |
- Khrennikov, Andrei, et al.
(författare)
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On an experimental test of prequantum theory of classical random fields : an estimate from above of the coefficient of second-order coherence
- 2012
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Ingår i: International Journal of Quantum Information. - 0219-7499. ; 10:8, s. Article ID: 1241014-
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Tidskriftsartikel (refereegranskat)abstract
- We show that quantum probabilities for photon detection can be reproduced by a model in which classical random fields interact with detectors of the threshold type. This approach is applied to the old problem of distinguishing classical and quantum light sources with the aid of the coefficient of second-order coherence g(2) (0) ( the problem of "existence of photon"). In our classical random field model, we obtain an estimate of this coefficient implying that it becomes strictly less than one for sufficiently small value of parameter is an element of = (epsilon) over bar/epsilon(d), where (epsilon) over bar (pulse) is the average energy of pulses (photons) emitted by a source and epsilon(d) is the detection threshold. This prediction can in principle be tested experimentally. Thus in the presented model experimental technicalities (such as e. g. the detection thresholds) are lifted to the level of the fundamental entities of theory.
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| 24. |
- Khrennikov, Andrei, et al.
(författare)
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On the quantization of the electromagnetic field of a layered dielectric waveguide
- 2012
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Ingår i: QUANTUM THEORY. - : AIP. - 9780735411265 ; , s. 285-299
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Konferensbidrag (refereegranskat)abstract
- This paper gives a detailed derivation of the classical electromagnetic modes of a layered circularly symmetrical dielectric waveguide. The corresponding Hamilton function is derived by using suitable canonical observables and the standard analogy to the classical harmonic oscillator. The derivation is generic in the sense that it can be used as an "algorithm" to compute the electromagnetic field of the waveguide. The associated Hamilton operator can then be obtained by using the standard quantization procedure where the canonical observables are replaced by the corresponding operators i.e., the creation and the annihilation operators of the photon (or equivalently, the position and the momentum operators of the harmonic oscillator) and by taking the appropriate commutation relations into account.
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| 25. |
- Khrennikov, Andrei, et al.
(författare)
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Photon Flux and Distance from the Source : Consequences for Quantum Communication
- 2014
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Ingår i: Foundations of physics. - : Springer Science and Business Media LLC. - 0015-9018 .- 1572-9516. ; 44:4, s. 389-405
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Tidskriftsartikel (refereegranskat)abstract
- The paper explores the fundamental physical principles of quantum mechanics (in fact, quantum field theory) that limit the bit rate for long distances and examines the assumption used in this exploration that losses can be ignored. Propagation of photons in optical fibers is modelled using methods of quantum electrodynamics. We define the "photon duration" as the standard deviation of the photon arrival time; we find its asymptotics for long distances and then obtain the main result of the paper: the linear dependence of photon duration on the distance when losses can be ignored. This effect puts the limit to joint increasing of the photon flux and the distance from the source and it has consequences for quantum communication. Once quantum communication develops into a real technology (including essential decrease of losses in optical fibres), it would be appealing to engineers to increase both the photon flux and the distance. And here our "photon flux/distance effect" has to be taken into account. This effect also may set an additional constraint to the performance of a loophole free test of Bell's type-to close jointly the detection and locality loopholes.
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| 26. |
- Khrennikov, Andrei, 1958-, et al.
(författare)
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Quantization of propagating modes in optical fibres
- 2012
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 85
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Tidskriftsartikel (refereegranskat)abstract
- The electromagnetic fields of a single optic fibre mode are quantized based on the observationthat these fields can be derived from a scalar harmonic oscillator function depending on onlytime and the axial wavenumber. Asymptotic results for both the one-photon probabilitydensity and two-photon correlation density functions within the forward light cone arepresented, showing an algebraic decay for large times or distances. This algebraic decay,increasing the uncertainty in the arrival time of the photons, also remains in the presence ofdispersion shift, in qualitative agreement with experimental results. Also presented are explicitformulae to be used in parameter studies to optimize quantum optic fibre communications.
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| 27. |
- Khrennikov, Andrei, et al.
(författare)
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Quantum rule for detection probability from Brownian motion in the space of classical fields
- 2013
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Ingår i: Theoretical and mathematical physics. - : Springer Science and Business Media LLC. - 0040-5779 .- 1573-9333. ; 174:2, s. 298-306
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Tidskriftsartikel (refereegranskat)abstract
- We obtain Born's rule from the classical theory of random waves in combination with the use of thresholdtype detectors. We consider a model of classical random waves interacting with classical detectors and reproducing Born's rule. We do not discuss complicated interpretational problems of quantum foundations. The reader can select between the "weak interpretation," the classical mathematical simulation of the quantum measurement process, and the "strong interpretation," the classical wave model of the real quantum (in fact, subquantum) phenomena.
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| 28. |
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| 29. |
- Nilsson, Börje, et al.
(författare)
-
Estimation of initial one photon temporal modes in waveguides using the asymptotic radiation zone
- 2014
-
Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T163
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Tidskriftsartikel (refereegranskat)abstract
- There are two optic fibre properties in particular that obstruct the transfer over long distances in quantum communications. One of them is dispersion, which reduces the maximum bit rate. In classical communication with modern highly purified fibres, dispersion is the major limiting factor. The other property is the material loss that causes fluctuations in addition to a general annihilation with distance of photons. It is believed that losses are the major limiting factor in quantum communication over long distances if the bit rate is not an issue. Of major interest in quantum communication is the photon source. It is therefore a high priority to develop methods for the determination of properties like initial temporal modes, repeatability, independence of sequentially emitted photons, etc., for a source emitting single photons in a given spatial mode. In the current paper we suggest that the source properties can be estimated using statistics of the run times of the photons. This requires that the fibre is modelled with sufficient accuracy. To simplify the analysis, it is assumed that the fibre losses can be neglected and that the photons are independent and identically generated. Energy detection in one spin state is employed, making the modelling scalar. The one photon initial temporal mode is found by maximizing a maximum-likelihood function based on running time statistics. Unfortunately, this optimization problem is, in general, not convex. However, for photon detection in the so-called asymptotic radiation zone, where the probability density can be determined to a sufficient degree with asymptotic methods, the optimization problem is convex. In the current paper, quantum tomography in fibres based on this convex optimization method is presented, and its generalization to more complicated situations like the introduction of losses in the modelling is discussed.
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| 30. |
- Nilsson, Börje, et al.
(författare)
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Long distance source localization in waveguides with complicated structure
- 2012
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Ingår i: 2012 International Conference on Mathematical Methods in Electromagnetic Theory (MMET). - Los Almitos : IEEE. - 9781467344784 ; , s. 415-418
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- With the purpose of source localization in high voltage direct current submarine power cables general layered waveguide models are investigated. It is concludes that the non-discrete modes can usually be ignored in comparison with the least attenuated discrete mode. Only a finite number of discrete modes are of importance for a band limited signal. Accurate analytical expressions are derived in the time domain for both discrete and non-discrete electromagnetic waveguide modes for large distances together with an error analysis.
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