We investigate the strong-coupling regime of a linear x-x coupled harmonic-oscillator system by performing a direct diagonalization of the Hamiltonian. It is shown that the x-x coupled Hamiltonian can be equivalently described by a Mach-Zehnder-type interferometer with a quadratic unitary operation in each of its arms. We show a sharp transition of the unitary operation from an elliptical phase rotator to an elliptical squeezer as the coupling gets stronger, leading to the continuous generation of entanglement, even for a significantly thermal state in the ultrastrong-coupled regime. It is also shown that this critical regime cannot be achieved by a classical Hookian coupling. Finally, the effect of a finite-temperature environment is analyzed, showing that entanglement can still be generated from a thermal state in the ultrastrong-coupled regime but is destroyed rapidly.
Critical behavior in ultrastrong-coupled oscillators / V. Sudhir, M.G. Genoni, J. Lee, M..S. Kim. - In: PHYSICAL REVIEW A. - ISSN 1050-2947. - 86:1(2012 Jul), pp. 012316.1-012316.5.
|Titolo:||Critical behavior in ultrastrong-coupled oscillators|
|Parole Chiave:||atomic and molecular physics; optics|
|Settore Scientifico Disciplinare:||Settore FIS/03 - Fisica della Materia|
|Data di pubblicazione:||lug-2012|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1103/PhysRevA.86.012316|
|Appare nelle tipologie:||01 - Articolo su periodico|