We have computed the global quantum discord (GQD) and von Neumann entropy (VNE) of multipartite two-level atomic systems interacting with a single-mode Fock field. We use Tavis–Cumming model. We have explored how quantum correlations and quantum entanglement evolve with time in such systems. The quantum system is prepared initially in a mixed state and different parameters are varied to see how they affect the information processing in the system. The dynamical character of the GQD and VNE show an interplay between classical and nonclassical correlations. Photons in this model play an important role to assist the GQD and VNE and we observed that the effects of the field on the GQD and VNE reside in the time evolution of the system indicating that both atom and field states have become entangled. The GQD is assisted in a nonlinear fashion with the number of photons in the system. The GQD and VNE show linear behavior with each other in the dynamics of the system. The effects of intrinsic decoherence on the dynamics of the GQD and VNE are also studied. We have extrapolated the results for a large photon number on the system. We have studied the effect of the change in the size of the system on the maximum value of GQD and VNE and we have estimated the scaling coefficients for this behavior.
We have computed the global quantum discord (GQD) and von Neumann entropy (VNE) of multipartite two-level atomic systems interacting with a single-mode Fock field. We use Tavis–Cumming model. We have explored how quantum correlations and quantum entanglement evolve with time in such systems. The quantum system is prepared initially in a mixed state and different parameters are varied to see how they affect the information processing in the system. The dynamical character of the GQD and VNE show an interplay between classical and nonclassical correlations. Photons in this model play an important role to assist the GQD and VNE and we observed that the effects of the field on the GQD and VNE reside in the time evolution of the system indicating that both atom and field states have become entangled. The GQD is assisted in a nonlinear fashion with the number of photons in the system. The GQD and VNE show linear behavior with each other in the dynamics of the system. The effects of intrinsic decoherence on the dynamics of the GQD and VNE are also studied. We have extrapolated the results for a large photon number on the system. We have studied the effect of the change in the size of the system on the maximum value of GQD and VNE and we have estimated the scaling coefficients for this behavior.
Abstract Dynamical evolution of global quantum discord (GQD) and von Neumann entropy (VNE) is studied for N two-level atomic system (TLS) (two, three and four TLS). The system interacts with the single mode Fock field and the cavity is filled with the non-linear Kerr medium (NLKM). It is seen that for large values of the Kerr parameter, the GQD and VNE show periodic behavior which leads to the sudden death and birth of the quantum entanglement (QE). It is found that the oscillations of the GQD is suppressed for the initial mixed state. The VNE has non-zero values of quantum interference throughout the dynamics of the system for initial mixed states. It is also found that the multipartite systems show sustained response to the QE during the time evolution. Moreover, the GQD and VNE are notably affected in the presence of the NLKM and affected for the entire range of Kerr values as we increase the number of photons in the cavity. Furthermore, for both initial pure and mixed states, the periodic behavior of the GQD and VNE is almost the same for the case of moving TLS. The sudden death and birth of QE is more prominent for moving TLS case. The atomic motion is favorable to sustain the QE in the atomic systems in a NLKM.
This paper investigates the evolution of global quantum discord (GQD) and quantum Fisher information (QFI) of the interaction of multiple two-level atomic systems (TLS) with a single thermal field mode and a non-linear Kerr medium (NLKM) considering the cases of intrinsic decoherence and its absence. Results indicate that increasing the number of atomic systems (N) while maintaining the NLKM parameter constant ? leads to higher GQD and QFI values for both intrinsic intrinsic decoherence cases. With rising ?, the GQD values decrease but the oscillation rate of the GQD increases. The presence of intrinsic decoherence does not significantly reduce the GQD quasi-static value compared to the no-decoherence scenario for certain ? values. At the same time, a different trend is observed for higher ? values. The average QFI value rises with reduced oscillation amplitudes for higher ? values and larger N subsystems. Unlike the GQD, higher ? values aid in maintaining average QFI in the presence of intrinsic decoherence. For moving TLS, changing ? does not alter the oscillation periods of the GQD and QFI. The GQD values decrease with increased ? in the moving system case, while the QFI improves with higher ? values. Additionally, higher average thermal photons within the system suppress the GQD and QFI values and decrease oscillation amplitudes for both quantifiers.
In this paper, we investigate the interplay between quantum correlations, quantified by global quantum discord (GQD), and quantum Fisher information (QFI) within a multipartite two-level system interacting with a single-mode Fock field. Our model incorporates Kerr-like nonlinearity, parametric amplification, and intrinsic decoherence. By varying the photon-number cutoff, system dimensionality, and parametric amplification strength under different magnitudes of the Kerr effect, we analyze how these factors influence correlation dynamics and parameter estimation precision. We observe a threshold-like behavior in the photon number during the transition from a decoherence-dominated regime to a coherence-enhanced regime. These results show a balance between the amplification strength and Kerr effects, and reveal that GQD and QFI exhibit different levels of robustness. These findings provide valuable insights for optimizing nonlinear atom-field configurations in quantum information and quantum metrology applications.
In this work, we study the dynamics of global quantum discord and quantum Fisher information in a multipartite system of two-level atoms interacting with a coherent field. The model includes parametric amplification, Kerr-type nonlinearity, and intrinsic decoherence to examine how these effects control quantum correlations and parameter-estimation sensitivity. The results show that, without intrinsic decoherence, both quantities exhibit rapid oscillations with clear collapse and revival behavior. Strong Kerr nonlinearity and strong parametric amplification enhance global quantum discord, while quantum Fisher information becomes maximum under a suitable balance of Kerr nonlinearity and amplification strength. Increasing the number of atoms generally strengthens global quantum discord but does not always improve quantum Fisher information. Intrinsic decoherence damps the oscillations and drives the system toward steady-state behavior.
We investigate the quantum correlation between light and matter in bipartite quantum systems, drawing on the Jaynes–Cummings model and the Tavis–Cummings model, which are well-established in cavity quantum electrodynamics. Through the resolution of the quantum master equation, we can derive the dissipative dynamics in open systems. To assess the extent of quantum correlation, several measures are introduced: von Neumann entropy, concurrence and quantum discord. The effects of initial entanglement and dissipation intensity on quantum discord are carefully examined. Furthermore, we examined the dynamics of quantum discord within the O H + model.
Quantum correlations characterized by quantum entanglement and quantum discord play important roles in many quantum information processing. We study the relations among the entanglement of formation, concurrence, tangle, linear entropy-based classical correlation and von Neumann entropy-based classical correlation . We present analytical formulae of linear entropy-based classical correlation for arbitrary d⊗2 quantum states and von Neumann entropy-based classical correlation for arbitrary 2⊗2 rank-2 quantum states. From the von Neumann entropy-based classical correlation, we derive an explicit formula of quantum discord for arbitrary rank-2 two-qubit quantum states.