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Universal Quantum Cloning and Macroscopic Superposition in Parametric Amplification
Author(s) -
De Martini Francesco,
Mussi Valentina
Publication year - 2000
Publication title -
fortschritte der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.469
H-Index - 71
eISSN - 1521-3978
pISSN - 0015-8208
DOI - 10.1002/(sici)1521-3978(200005)48:5/7<413::aid-prop413>3.0.co;2-3
Subject(s) - physics , quantum mechanics , spontaneous parametric down conversion , quantum entanglement , superposition principle , qubit , quantum amplifier , quantum , quantum error correction
The new process of quantum‐injection into an optical parametric amplifier operating in entangled configuration is adopted to amplify into a large dimensionality spin‐½ Hilbert space the quantum entanglement and superposition properties of the photon‐couples generated by parametric down‐conversion. The invariance properties of the OPA interaction hamiltonian show that, under certain conditions, the device may act as a Universal Quantum Cloning Machine (UQCM) of the input qubits. Preliminary results here reported show the first experimental realization of such a device. The structure of the Wigner function and of the field's correlation functions shows a multiphoton Schrödinger‐cat behaviour of the emitted field which is largely detectable against the squeezed‐vacuum noise.