Quantifying decoherence in continuous variable systems

• Published in: Journal of optics. B, Quantum and semiclassical optics Quantum and semiclassical optics, 2005-04, Vol.7 (4), p.R19-R36
• Main Authors: Serafini, A, Paris, M G A, Illuminati, F, De Siena, S
• Format: Article
• Language: English
• Subjects: Classical and quantum physics: mechanics and fields; Exact sciences and technology; Foundations, theory of measurement, miscellaneous theories (including aharonov-bohm effect, bell inequalities, berry's phase); Fundamental areas of phenomenology (including applications); Nonclassical field states; squeezed, antibunched and sub-poissonian states; operational definitions of the phase of the field; phase measurements; Optics; Physics; Quantum information; Quantum mechanics; Quantum optics
• ISSN: 1464-4266; 1741-3575
• DOI: 10.1088/1464-4266/7/4/R01

We present a detailed report on the decoherence of quantum states of continuous variable systems under the action of a quantum optical master equation resulting from the interaction with general Gaussian uncorrelated environments. The rate of decoherence is quantified by relating it to the decay rates of various, complementary measures of the quantum nature of a state, such as the purity, some non-classicality indicators in phase space, and, for two-mode states, entanglement measures and total correlations between the modes. Different sets of physically relevant initial configurations are considered, including one- and two-mode Gaussian states, number states, and coherent superpositions. Our analysis shows that, generally, the use of initially squeezed configurations does not help to preserve the coherence of Gaussian states, whereas it can be effective in protecting coherent superpositions of both number states and Gaussian wavepackets.