Abstract
The interplay between non-Markovian dynamics and driving fields in the survival of entanglement between two non-degenerate oscillators is considered here. Based on exact analytical results for the non-Markovian dynamics of two parametrically coupled non-degenerate oscillators in contact with non-identical independent thermal baths, the out-of-equilibrium quantum limit derived in [Phys. Rev. Lett. 105 180501 (2010)] is generalised to the non-Markovian regime. Specifically, it is shown that non-Markovian dynamics, when compared to the Markovian case, allow for the survival of stationary entanglement at higher temperatures, with larger coupling strength to the baths and at smaller driving rates. The effect of the asymmetry of the (i) coupled oscillators, (ii) coupling strength to the baths at equal temperature, and (iii) temperature at equal coupling strength is discussed. In particular, it is shown that the non-Markovian character of the dynamics is capable of beating the resonant condition that states that the driving frequency equals the sum of the natural frequencies for the maximum rate of squeezing generation; hence, squeezing generation is more robust under non-Markovian dynamics.
Highlights
The survival of quantum features in hot environments is restricted by decoherence [1]. For quantum features such as entanglement to survive in the presence of the environment, the typical energy scale of the system ω must be larger than the energy scale kBT associated to thermal fluctuations [2]
The undriven non-Markovian dynamics for this degenerate case was previously analyzed in Ref. [37] and it was found that when ω falls inside the spectral density, entanglement persists for a longer time than in the Markovian case
There is evidence that non-Markovian dynamics may allow for the survival of entanglement at temperatures higher than the corresponding Markovian case provided by the interaction with a common bath [27, 38]
Summary
The survival of quantum features in hot environments is restricted by decoherence [1]. To discuss the way how this condition is relaxed, let γTB be the time scale associated to the non-unitary dynamics induced by the thermal bath and γp the pumping rate of the driving field In terms of these time scales, the quantum limit for driven out-of-equilibrium quantum systems reads ω/kBTeff > 1, where Teff = T γTB/γp is an effective temperature [4, 5]. Results derived here are valid for any parameter regime and allow for predicting that, when compared with the Markovian case, non-Markovian dynamics (i) decrease the time needed to generate entanglement, (ii) increase the temperature and the coupling-strength-to-the-environment limits at which steady state entanglement can be found, (iii) decrease the pumping rate for reaching a particular amount of entanglement and (iv) relax the resonant driving condition
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
