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.
Critical behavior in ultrastrong-coupled oscillators
M.G. Genoni;
2012
Abstract
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.File | Dimensione | Formato | |
---|---|---|---|
PRA_CriticalOscillators.pdf
accesso riservato
Tipologia:
Publisher's version/PDF
Dimensione
262.99 kB
Formato
Adobe PDF
|
262.99 kB | Adobe PDF | Visualizza/Apri Richiedi una copia |
Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.