28 research outputs found
Creation of quantum correlations between two atoms in a dissipative environment from an initial vacuum state
We have investigated the effect of counter-rotating terms on the dynamics of
entanglement and quantum discord between two identical atoms interacting with a
lossy single mode cavity field for a system initially in a vacuum state. The
counter-rotating terms are found to lead to steady states in the long time
limit which can have high quantum discord, but have no entanglement. The effect
of cavity decay rate on this steady state quantum discord has been also
investigated, surprisingly, the increase in cavity decay rate is found to both
enhance and maximize the steady quantum discord for separable states.Comment: Effects of counter-rotating interaction terms on quantum discor
Control and manipulation of entanglement between two coupled qubits by fast pulses
We have investigated the analytical and numerical dynamics of entanglement
for two qubits that interact with each other via Heisenberg XXX-type
interaction and subject to local time-specific external kick and Gaussian
pulse-type magnetic fields in x-y plane. The qubits have been assumed to be
initially prepared in different pure separable and maximally entangled states
and the effect of the strength and the direction of external fast pulses on
concurrence has been investigated. The carefully designed kick or pulse
sequences are found to enable one to obtain constant long-lasting entanglement
with desired magnitude. Moreover, the time ordering effects are found to be
important in the creation and manipulation of entanglement by external fields.Comment: 18 pages, 6 figure