Entanglement transformation at dielectric four-port devices
S. Scheel, L. Knoll, T. Opatrny, D. -G. Welsch
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4 pages, 2 eps figures, Paper presented at the Fifth International Conference on Quantum Communication Measurement & Computing, Capri, Italy - July 3-8 2000
Quantum communication schemes widely use dielectric four-port devices as basic elements for constructing optical quantum channels. Since for causality reasons the permittivity is necessarily a complex function of frequency, dielectrics are typical examples of noisy quantum channels in which quantum coherence will not be preserved. Basing on quantization of the phenomenological electrodynamics, we construct the transformation relating the output quantum state to the input quantum state without placing frequency restrictions. Knowledge of the full transformed quantum state enables us to compute the entanglement contained in the output quantum state. We apply the formalism to some typical examples in quantum communication.
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Dielectric four-port devices play an important role in optical quantum information processing. Since for causality reasons the permittivity is a complex function of frequency, dielectrics are typical examples of noisy quantum channels, which cannot preserve quantum coherence. To study the effects of quantum decoherence, we start from the quantized electromagnetic field in an arbitrary Kramers--Kronig dielectric of given complex permittivity and construct the transformation relating the output quantum state to the input quantum state, without placing restrictions on the frequency. We apply the …
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Quantum Beam Splitter as a Deterministic Entanglement Source: Exact Photon-Number Statistics, Hong-Ou-Mandel Interference, and von Neumann Entropy Scaling from Balanced Inputs
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Applying the recently developed formalism of quantum-state transformation at absorbing dielectric four-port devices [L.~Knöll, S.~Scheel, E.~Schmidt, D.-G.~Welsch, and A.V.~Chizhov, Phys. Rev. A {\bf 59}, 4716 (1999)], we calculate the quantum state of the outgoing modes of a two-mode squeezed vacuum transmitted through optical fibers of given extinction coefficients. Using the Peres--Horodecki separability criterion for continuous variable systems [R.~Simon, Phys. Rev. Lett. {\bf 84}, 2726 (2000)], we compute the maximal length of transmission of a two-mode squeezed vacuum through an absorbin…
Entanglement recycling in two-step port-based teleportation
University of Wrocław（弗罗茨瓦夫大学）；QuSoft, Amsterdam, The Netherlands（荷兰阿姆斯特丹 QuSoft）；Institute for Logic, Language, and Computation, University of Amsterdam（阿姆斯特丹大学逻辑、语言与计算研究所）；Korteweg-de Vries Institute for Mathematics, University of Amsterdam（阿姆斯特丹大学科特韦格-德弗里斯数学研究所）；Centrum Wiskunde & Informatica (CWI)（数学与计算机科学中心 (CWI)）；International Centre for Theory of Quantum Technologies (ICTQT), University of Gdańsk（格但斯克大学量子技术理论国际中心 (ICTQT)）
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