15 research outputs found
Dynamics of Entanglement and Bell-nonlocality for Two Stochastic Qubits with Dipole-Dipole Interaction
We have studied the analytical dynamics of Bell nonlocality as measured by
CHSH inequality and entanglement as measured by concurrence for two noisy
qubits that have dipole-dipole interaction. The nonlocal entanglement created
by the dipole-dipole interaction is found to be protected from sudden death for
certain initial states
Entanglement dynamics of two qubits under the influence of external kicks and Gaussian pulses
We have investigated the dynamics of entanglement between two spin-1/2 qubits
that are subject to independent kick and Gaussian pulse type external magnetic
fields analytically as well as numerically. Dyson time ordering effect on the
dynamics is found to be important for the sequence of kicks. We show that
"almost-steady" high entanglement can be created between two initially
unentangled qubits by using carefully designed kick or pulse sequences
Correlation and nonlocality measures as indicators of quantum phase transitions in several critical systems
We have investigated the quantum phase transitions in the ground states of
several critical systems, including transverse field Ising and XY models as
well as XY with multiple spin interactions, XXZ and the collective system
Lipkin-Meshkov-Glick models, by using different quantumness measures, such as
entanglement of formation, quantum discord, as well as its classical
counterpart, measurement-induced disturbance and the
Clauser-Horne-Shimony-Holt-Bell function. Measurement-induced disturbance is
found to detect the first and second order phase transitions present in these
critical systems, while, surprisingly, it is found to fail to signal the
infinite-order phase transition present in the XXZ model. Remarkably, the
Clauser-Horne-Shimony-Holt-Bell function is found to detect all the phase
transitions, even when quantum and classical correlations are zero for the
relevant ground state
Quantum Correlations in non-Markovian Environments
We have studied the analytical Markovian and non-Markovian dynamics of
quantum correlations, such as entanglement, quantum discord and Bell
nonlocalities for three noisy qubits. Quantum correlation as measured by
quantum discord is found to be immune to death contrary to entanglement and
Bell nonlocality for initial GHZ- or W-type mixed states
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