Dynamics Of Nonclassical Correlations Research Articles

Generating non-classical correlations between two superconductor qubits confined in a transmission cavity in dispersive limit under intrinsic noise

Abstract An analytical solution of the dynamical evolution of two qubits confined in a transmission line cavity is obtained in dispersive limit under intrinsic noise. The dynamics of non-classical correlations are investigated by using different measures based on the skew information quantifiers [including local quantum uncertainty and uncertainty-induced non-locality], the Bell function and logarithmic negativity for experimentally chosen parameters. It is found that the generation of the non-classical correlations and its robustness depend crucially on the transverse exchange interaction, the dissipation rate, the mean photon number, and the frequency shift. The phenomena of sudden disappearance and sudden appearance of entanglement are observed. The stationary correlations appear due to the intrinsic decoherence, which depends on the parameters of the chosen initial states.

Non-Classical Correlations and Transfer of Quantum Information in a Superconducting Qubit System with Dynamical Decoupling Pulses

We investigate the dynamics of non-classical correlations(entanglement and quantum discord) of the system consisting of two non-interacting superconducting qubits coupling with a common data bus, where the system is driven by the dynamical decoupling pulses. It is found that the non-classical correlations between two superconducting qubits can be increased by appling a train of dynamical decoupling pulses. Furthermore, we also explore the influence of the dynamical decoupling pulses on the information flowing between superconducting qubits and data bus by making use of the trace distance. It is shown that the dynamical decoupling pulses can protect quantum information of two superconducting qubits and force information to flow back to the superconducting qubits from the data bus.

Sudden transitions of trace distance discord of dipole–dipole coupled two qubits

We investigate the exact dynamics of trace distance discord (TDD) by considering two qubits under dephasing whose states belong to a class of X states beyond Bell diagonal form. The necessary condition for the occurrence of freezing TDD is found and compared with that of entropic discord. For an illustration, we consider two interacting qubits coupled to independent reservoirs and demonstrate these dynamical properties of TDD. It is interesting to find that the freezing TDD exists even for X states without maximally mixed marginals and can be tuned by dipole–dipole coupling of two qubits. Moreover, we consider the initial extended Werner-like (EWL) states and investigate the differences between TDD and entanglement. The influences of initial state and the dipole–dipole coupling of the two qubits on the dynamics of nonclassical correlations are explored.

Dynamics of Nonclassical Correlations with an Initial Correlation

We investigate the dynamics of nonclassical correlations including concurrence and local quantum uncertainty in the damped Jaynes–Cummings model with an initial system–reservoir correlation. The dynamics of qubit–reservoir correlation and the influence of non-Markovian effect are studied. Furthermore, we consider the double damped Jaynes–Cummings model consisting of two noninteracting qubits locally coupled to independent reservoirs and explore the properties of both qubit–qubit and reservoir–reservoir correlations. The influences of initial correlation and non-Markovian effect on the dynamics of nonclassical correlations are analyzed. It is found that the dynamics for both qubit–qubit and reservoir–reservoir correlations can be significantly changed by the initial correlation and the non-Markovian effect. Finally, we explore the sudden changes of local quantum uncertainty and find that they are closely related to the initial system–environment entanglement.

Decoherent dynamics of two nonclassically correlated particles

We investigate the dynamics of nonclassical correlations between two particles in a harmonic trap which interact in a pointlike manner. Via a quantum-jump approach we add a specific damping model. The correlations between the particles are quantified using a Bell-type correlation function, adapted for the continuous-variable case. They clearly exceed the classical border and show collapses and revivals. Their destruction due to decoherence strongly depends on the initial separation of the particles and on the damping constant.