For an atom in a driven cavity we find that the atom-cavity entanglement is maximized for an intermediate driving field strength. We find that entanglement can be transiently enhanced by a measurement.
For an atom in an externally driven cavity, we show that special initial states lead to near-disentangled atom-field evolution, and superpositions of these can lead to near maximally entangled states. Somewhat counterintutively, we find that (moderate) spontaneous emission in this system actually leads to a transient increase in entanglement beyond the steady-state value. We also show that a particular field correlation function could be used, in an experimental setting, to track the time evolution of this entanglement.
We investigate steady state entanglement in an open quantum system, specifically a single atom in a driven optical cavity with cavity loss and spontaneous emission. The system reaches a steady pure state when driven very weakly. Under these conditions, there is an optimal value for atom-field coupling to maximize entanglement, as larger coupling favors a loss port due to the cavity enhanced spontaneous emission. We address ways to implement measurements of the entanglement and find that normalized cross-correlation functions are indicators of the entanglement in the system. The equal time intensity-field cross correlation between the transmitted field of the cavity and the fluorescence intensity is proportional to the entanglement of formation for weak driving fields.
We explore the entanglement between a single atom and a single, resonant field mode of a driven optical cavity, focusing on the strong driving regime. We show that, in the absence of spontaneous emission, there are special initial conditions that lead to approximately disentangled trajectories, whereas spontaneous emission results in coherent superpositions of such trajectories that may lead to (transient) near-maximally entangled atom-field states. We also discuss the possibility of using a special "asymmetric" field correlation function to track the time evolution of this entanglement.
We investigate a two-level atom coupled to a cavity with a strong classical driving field in a dissipative environment and find an analytical expression for the time evolution density matrix for the system. The analytical density operator is then used to study the entanglement between the atom and cavity by considering the competing process between the atom–field interactions and the field–environment interactions. It is shown that there is an optimal interaction time for generating atom–cavity entanglement.