Eur. Phys. J. D 22, 441-451 (2003)
https://doi.org/10.1140/epjd/e2003-00049-1

Quantum correlations close to a square pattern forming instability

¹ Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, 7600 Mar del Plata, Argentina
² Department of Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG, UK
³ Instituto Mediterráneo de Estudios Avanzados () , IMEDEA (CSIC-UIB), Campus Universitat Illes Balears, 07071 Palma de Mallorca, Spain

Corresponding author: ^a pere@imedea.uib.es

Received: 17 September 2002
Revised: 11 November 2002
Published online: 26 February 2003

Abstract

We analyze the quantum fluctuations of the degenerate optical parametric oscillator close to an instability for the formation of a square pattern. While strong correlations between the fluctuations of the signal modes emitted at the critical wave number and with opposite wave vector are present both below and above threshold, no features signaling the square character of the pattern forming above threshold have been identified below threshold in the spatio-temporal second-order coherence. We also explore in which regimes a reduced few mode model gives meaningful results.