arXiv subjects

Frederick H. Willeboordse

Publications and source records attributed to Frederick H. Willeboordse.

8 recordsLinked to original sources

arXiv2013

Classical Inversion of the CHSH Inequality

In general, the CHSH inequality $S \le 2$ is considered to provide an \textit{upper} bound for classical correlations. In this note it is shown that if incoming particles are allowed to be delayed ever so briefly, the inequality can be inverted to $S \ge 2$ thus becoming a \textit{lower} bound for classical correlations (maximum S=3). All interaction is strictly local and events are neither dropped nor re-sequenced thus strictly conforming to the standard CHSH setup. The key notion is that a (brief) delay in front of a detector is not a causative intervention.

quant-ph↗

arXiv2008

Bell correlations and equal time measurements

According to the Bell theorem, local hidden variable theories cannot reproduce all the predictions of quantum mechanics. An important consequence is that under physically reasonable assumptions quantum mechanics predicts correlations that seem impossible to obtain from a realistic system. In this paper, two simple binary apparatuses are discussed that can accurately mimic correlations predicted by quantum mechanics \textit{if} the correlations are determined by a coincidence measurement as is commonly done. It is argued that in order to exclude local hidden variables, coincidence monitors should be avoided.

quant-ph↗

arXiv2005

Quantum Correlations with a Classical Apparatus

A deterministic, relativistically local and thus classical Bell-type apparatus is reported that violates the Bell-CHSH inequality by introducing a simple local memory element in the detector and by requiring the detector combinations to switch with unequal probabilities. This indicates that the common notion of the fundamental impossibility of a classical-type theory underlying quantum mechanics may need to be re-evaluated.

quant-ph↗

arXiv2005

Quantum Tomographic Cryptography with a Semiconductor Single Photon Source

In this paper we analyze the security of the so-called quantum tomographic cryptography with the source producing entangled photons via an experimental scheme proposed in Phys. Rev. Lett. 92, 37903 (2004). We determine the range of the experimental parameters for which the protocol is secure against the most general incoherent attacks.

quant-ph↗

arXiv2004

Quantum tomographic cryptography with Bell diagonal states: non-equivalence of classical and quantum distillation protocols

We present a generalized tomographic quantum key distribution protocol in which the two parties share a Bell diagonal mixed state of two qubits. We show that if an eavesdropper performs a coherent measurement on many quantum ancilla states simultaneously, classical methods of secure key distillation are less effective than quantum entanglement distillation protocols. We also show that certain Bell diagonal states are resistant to any attempt of incoherent eavesdropping.

quant-ph↗

arXiv1994

Pattern Dynamics of a Coupled Map Lattice for Open Flow

The pattern dynamics of the one-way coupled logistic lattice which can serve as a phenomenological model for open flow is investigated and shown to be extremely rich. For medium and large coupling strengths, we find spatially periodic, quasiperiodic and chaotic patterns with temporal periodicity and analyze their stability with the help of a newly introduced spatial map. Criteria are established for predicting the down-flow bifurcation behavior of the coupled map lattice, and for selecting attractors through modulation of the boundary. For smaller coupling strengths we find a novel regime in which chaotic defects form a periodic lattice that is shown to be the result of a boundary crisis.

chao-dyn↗

arXiv1994

Self-organized Periodic Lattices of Chaotic Defects

A novel type of self-organized lattice in which chaotic defects are arranged periodically is reported for a coupled map model of open flow. We find that temporally chaotic defects are followed by spatial relaxation to an almost periodic state when suddenly a next defect appears. The distance between successive defects is found to be generally predetermined and diverging logarithmically when approaching a certain critical point. The phenomena are analyzed and shown to be explicable as the results of a boundary crisis for the spatially extended system.

chao-dyn↗

arXiv1993

Bifurcations and Spatial Chaos in an Open Flow Model

It is shown that a coupled map model for open flow may exhibit spatial chaos and spatial quasiperiodicity with temporal periodicity. The locations of these patterns, which cover a substantial part of parameter space, are indicated in a comprehensive phase diagram. In order to analyze the encountered phenomena, a novel class of spatial maps is introduced which is very efficient in accurately reproducing the original spatial patterns. It is found that temporally period one spatial chaos is convectively unstable, and that it is possible to predict an essential aspect of the bifurcation behavior of the coupled system solely by considering its corresponding spatial map.

chao-dyn↗