Scattering theory of plasmon-assisted entanglement transfer and distillation

We analyse the quantum mechanical limits to the plasmon-assisted entanglement transfer observed by E. Altewischer, M.P. van Exter, and J.P. Woerdman [Nature, 418, 304 (2002)]. The maximal violation S of Bell's inequality at the photodetectors behind two linear media (such as the perforated metal films in the experiment) can be described by two ratio's tau_1, tau_2 of polarization-dependent transmission probabilities. A fully entangled incident state is transferred without degradation for tau_1=tau_2, but a relatively large mismatch of tau_1 and tau_2 can be tolerated with a small reduction of S. We predict that fully entangled Bell pairs can be distilled out of partially entangled radiation if tau_1 and tau_2 satisfy a pair of inequalities.Comment: 4 pages including 2 figures; two references added, plasmon model include

Dephasing of entangled electron-hole pairs in a degenerate electron gas

A tunnel barrier in a degenerate electron gas was recently discovered as a source of entangled electron-hole pairs. Here, we investigate the loss of entanglement by dephasing. We calculate both the maximal violation E_max of the Bell inequality and the degree of entanglement (concurrence) C. If the initially maximally entangled electron-hole pair is in a Bell state, then the Bell inequality is violated for arbitrary strong dephasing. The same relation E_max=2\sqrt{1+C^{2}} then holds as in the absence of dephasing. More generally, for a maximally entangled superposition of Bell states, the Bell inequality is satisfied for a finite dephasing strength and the entanglement vanishes for somewhat stronger (but still finite) dephasing strength. There is then no one-to-one relation between E_max and C.Comment: 7 pages with 3 figures, special style file included; To appear in a special issue on "Quantum Computation at the Atomic Scale" in Turkish Journal of Physic

Entangling ability of a beam splitter in the presence of temporal which-path information

We calculate the amount of polarization-entanglement induced by two-photon interference at a lossless beam splitter. Entanglement and its witness are quantified respectively by concurrence and the Bell-CHSH parameter. In the presence of a Mandel dip, the interplay of two kinds of which-path information -- temporal and polarization -- gives rise to the existence of entangled polarization-states that cannot violate the Bell-CHSH inequality.Comment: 8 pages including 2 figure

On the production and transfer of entangled electrons and photons

UBL - phd migration 201

Quantum state tomography with quantum shotnoise

We propose a scheme for a complete reconstruction of one- and two-particle orbital quantum states in mesoscopic conductors. The conductor in the transport state continuously emits orbital quantum states. The orbital states are manipulated by electronic beamsplitters and detected by measurements of average currents and zero frequency current shotnoise correlators. We show how, by a suitable complete set of measurements, the elements of the density matrices of the one- and two-particle states can be directly expressed in terms of the currents and current correlators.Comment: 4 pages, 2 figure

Entanglement detection for electrons via witness operators

We discuss an implementation of the entanglement witness, a method to detect entanglement with few local measurements, in systems where entangled electrons are generated both in the spin and orbital degrees of freedom. We address the efficiency of this method in various setups, including two different particle-hole entanglement structures, and we demonstrate that it can also be used to infer information on the possible dephasing afflicting the devices.Comment: 12 pages, 5 figures; published versio

Virus thermotherapy effects on the performance of a Muscadelle selection

Virus thermotherapy of a clonally selected, high yielding but leaf-roll infected Muscadelle selection resulted in significantly greater yield and vegetative growth. There were more berries per bunch and heavier bunches in each year and a greater weight of annual prunings of heat treated propagules in 3 of the 4 years reported. No consistent differences in selected maturity components were observed

An Interoperable eHealth Reference Architecture for Primary Care

eHealth is still not widely used in primary care, because barriers still exist around integrated and interoperable technological infrastructures for eHealth. This paper describes the design of an interoperable eHealth reference architecture for primary care and its evaluation with experts. This reference architecture aims to facilitate IT specialists in setting up interoperable eHealth infrastructures within primary healthcare organizations. The design of the reference architecture was based on the results of 14 working sessions with 10 eHealth Small and Medium sized Enterprises (SMEs) and the theory behind the Refined eHealth European Interoperability Framework (ReEIF). The evaluation with experts revealed additional conditions that – next to the reference architecture – are needed before interoperable eHealth in primary care can actually be achieved