title: Internal dynamics of intense twin beams and their coherence.
abstract: The dynamics of intense twin beams in pump-depleted parametric down-conversion is studied. A generalized parametric approximation is suggested to solve the quantum model. Its comparison with a semiclassical model valid for larger twin-beam intensities confirms its applicability. The experimentally observed maxima in the spectral and spatial intensity auto- and cross- correlation functions depending on pump power are explained in terms of different speeds of the (back-) flow of energy between the individual down-converted modes and the corresponding pump modes. This effect is also responsible for the gradual replacement of the initial exponential growth of the down-converted fields by the linear one. Furthermore, it forms a minimum in the curve giving the effective number of twin-beam modes. These effects manifest a tight relation between the twin-beam coherence and its internal structure, as clearly visible in the model. Multiple maxima in the intensity correlation functions originating in the oscillations of energy flow between the pump and down-converted modes are theoretically predicted.
authors.affiliation: RCPTM, Joint Laboratory of Optics of Palacký University and Inst. Phys. CAS, 17. listopadu 12, 77146 Olomouc, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Peřina
authors.affiliation: Institute of Physics CAS, Joint Laboratory of Optics, 17. listopadu 50a, 77146 Olomouc, Czech Republic.
authors.forename: Ondřej
authors.initials: O
authors.lastname: Haderka
authors.affiliation: Dipartimento di Scienza e Alta Tecnologia, Università degli Studi dell'Insubria, Via Valleggio 11, 22100 Como, Italy.|CNISM UdR Como, Via Valleggio 11, 22100 Como, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Allevi
authors.affiliation: Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Via Valleggio 11, 22100 Como, Italy.|CNISM UdR Como, Via Valleggio 11, 22100 Como, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Bondani