We investigate the dynamics of local quantum Fisher information and quantum coherence in a two‐qubit system hosted in a molybdenum disulfide monolayer and coupled to a thermal Markovian environment. Initially prepared in a thermal state at temperature T s , the system is connected to a reservoir at a different temperature, allowing the study of quantum‐resource dynamics under thermal nonequilibrium conditions. We show that the electron wave‐vector magnitude k affects the transient regime by enhancing the off‐diagonal elements of the initial density matrix, which increases quantum coherence and, more moderately, local quantum Fisher information. This dependence is progressively suppressed by decoherence, so that the long‐time stationary state becomes independent of k and T s . Moreover, quantum coherence decays monotonically to zero, whereas local quantum Fisher information first decreases and then saturates at a finite asymptotic value. This contrast reflects their different physical nature: coherence depends on off‐diagonal density‐matrix elements, while local quantum Fisher information is sensitive to both populations and coherences. Overall, within the Markovian description, the steady state is controlled by the reservoir, while transient dynamics preserve signatures of the initial state and intrinsic system parameters.
We investigate the dynamics of local quantum Fisher information and quantum coherence in a two‐qubit system hosted in a molybdenum disulfide monolayer and coupled to a thermal Markovian environment. Initially prepared in a thermal state at temperature T s , the system is connected to a reservoir at a different temperature, allowing the study of quantum‐resource dynamics under thermal nonequilibrium conditions. We show that the electron wave‐vector magnitude k affects the transient regime by enhancing the off‐diagonal elements of the initial density matrix, which increases quantum coherence and, more moderately, local quantum Fisher information. This dependence is progressively suppressed by decoherence, so that the long‐time stationary state becomes independent of k and T s . Moreover, quantum coherence decays monotonically to zero, whereas local quantum Fisher information first decreases and then saturates at a finite asymptotic value. This contrast reflects their different physical nature: coherence depends on off‐diagonal density‐matrix elements, while local quantum Fisher information is sensitive to both populations and coherences. Overall, within the Markovian description, the steady state is controlled by the reservoir, while transient dynamics preserve signatures of the initial state and intrinsic system parameters.
ABSTRACT We study quantum resources in tilted‐Dirac materials using a thermal state and reservoir‐driven dynamics in dissipative weak‐coupling and memory‐bearing strong‐coupling regimes. In contrast to the usual treatments based on the Bellomo formalism and relying on Bell or Werner states, the present approach starts from a physically motivated thermal state of two qubits whose initial properties are determined by the system temperature and the velocity parameters of the underlying Dirac material. The subsequent dynamics is modeled using the Bellomo formalism for two independent qubits, each locally coupled to an independent reservoir. To characterize the evolution, we analyze coherence quantified by the ‐norm and local quantum Fisher information. Weak, effectively Markovian coupling yields monotonic coherence decay, while local quantum Fisher information depends more strongly on parameters, especially at low reservoir temperatures; varying velocity parameters together obscures their individual effects. With strong, memory‐bearing coupling, coherence remains suppressed at long times, whereas local quantum Fisher information decreases then recovers to a large asymptotic value. The two measures thus respond differently to thermal, material, and reservoir effects, without implying general practical metrological superiority of local quantum Fisher information.
ABSTRACT We study the steady‐state quantum Fisher information (QFI) and several quantum resources entanglement, quantum coherence, and quantum discord for a pair of coupled qubits interacting with either bosonic or fermionic reservoirs. Using the Bloch–Redfield master equation beyond the secular approximation, we derive analytical expressions for the steady‐state density matrix and analyze how equilibrium and nonequilibrium conditions shape the resulting quantum correlations. In thermal equilibrium, the quantum resources display distinct behaviors depending on the bath statistics, with fermionic reservoirs enabling stronger stationary correlations due to particle‐exchange processes. Under nonequilibrium driving, generated either by a temperature imbalance or by a chemical potential difference, the system develops steady‐state coherence and enhanced discord, while entanglement and QFI exhibit non‐monotonic dependence governed by the interplay between coherence generation and population mixing. Our results identify the regimes in which steady‐state metrological performance can be optimized, and they provide general guidelines for enhancing quantum correlations in dissipative two‐qubit platforms.
ABSTRACT The quantum information properties of a monolayer of molybdenum disulfide exposed to a polarized monochromatic electromagnetic field are investigated. Using the density matrix at thermal equilibrium, total and correlated quantum coherence (quantified by the ‐norm) and thermal entanglement (using concurrence) are analyzed. Without external radiation, entanglement is favored at low temperatures and for small band gap, spin‐orbit coupling, and wave vector, but rapidly disappears under thermal fluctuations, while coherence remains robust. Under a laser field, entanglement, although reduced, becomes more resistant to temperature rise, while coherence is strongly amplified. Photon‐assisted transitions renormalize the band structure and introduce new couplings between electronic states, partially stabilizing non‐local correlations and reinforcing quantum superpositions. Field strength, frequency, and polarization are key control parameters, with circular polarization providing the most favorable conditions for simultaneously enhancing coherence and entanglement. The results demonstrate the dual role of electromagnetic radiation as a stabilizer and amplifier of quantum correlations and highlight the potential of molybdenum disulfide for applications in quantum computing, secure communication, and high‐precision detection.
Abstract The thermal behavior of quantum correlations is explored in a two‐qubit system based on nitrogen‐vacancy (NV) centers, using Local Quantum Fisher Information (LQFI), Local Quantum Uncertainty (LQU), and concurrence as quantifiers. These results show that entanglement, measured byconcurrence (CE), decays rapidly with increasing temperature, whereas coherence‐based measures such as LQFI and LQU display greater resilience. The strength of zero‐field splitting plays a key role in shaping quantum correlations, significantly suppressing entanglement at higher values while helping to preserve coherence. External magnetic and electric fields further influence these dynamics–magnetic fields tend to suppress entanglement, while electric fields accelerate its degradation. Dipole–dipole interactions enhance the initial quantum correlations but have a limited effect on their thermal decay. Overall, these findings underscore the robustness of coherence‐based quantum resources and suggest that, while dipole–dipole coupling is more effective at regulating quantum correlations, optimal tuning of system parameters can significantly improve both the generation and preservation of these correlations at finite temperatures.
ABSTRACT We investigate the dynamics of concurrence, correlated coherence, and local quantum Fisher information (LQFI) in a two‐qubit state governed by the effective low‐energy Hamiltonian of buckled silicene under Milburn intrinsic decoherence. Starting from a Werner‐type Bell state, we analyze how the effective wave vector, initial‐state purity, intrinsic decoherence rate, perpendicular electric field, and Rashba coupling affect the redistribution of quantum resources. The results show that concurrence is the most fragile quantity and decays rapidly under intrinsic decoherence. In contrast, correlated coherence exhibits damped oscillations and can remain finite after entanglement is strongly suppressed, indicating the persistence of shared coherence. The LQFI shows a non‐monotonic behavior, including partial recovery and plateau‐like regimes, revealing local metrological sensitivity beyond entanglement. These findings show that buckled silicene offers a tunable platform for controlling different quantum resources in decohering solid‐state environments.
The loss of coherence in a general open quantum system interacting with a bosonic environment is analyzed. The reservoir is initially in a thermal state. The reduced dynamics is described by a non-Markovian time-local master equation. We consider spectral densities that are sub- or super-Ohmic at low frequencies and arbitrarily shaped at high frequencies. In the super-Ohmic regime, for noninteger frequency powers larger than 2, long time survival of coherence appears. In the latter regime, at vanishing temperature, the asymptotic amount of surviving coherence is stabilized to its initial value, up to a phase factor, by properly increasing the bandwidth and decreasing the low-frequency profile of the spectral density. For noninteger positive frequency powers less than 2, stretched exponential-like decoherence is found over long times. The relaxations to the asymptotic configurations become arbitrarily slow by approaching the frequency power 2 of the super-Ohmic regime. The same dependence on temperature, spectral density, and scale frequency appears for purity and concurrence of two qubits and coherence of a qubit.