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Annalen der Physik

Laser‐Induced Optimization of Entanglement and Coherence in a Two‐Qubit Molybdenum Disulfide System

Sabrine El Asri, Fadoua Omari, Kamal Elasri, Fouad Essaadi, Yassine Oussarhan, M. Jakha, Mohamed Ouhammou, S. Mouslih, S. Taj, B. Manaut

Published Nov 12, 2025• 2 citations
Publisher

Abstract

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.

DOI
10.1002/andp.202500421

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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.
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 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 entanglement and quantum coherence between the pseudospin and valley indices of individual electrons in two-dimensional graphene, thermalized at an equilibrium temperature T . The system is modeled by an effective Dirac-like Hamiltonian describing a graphene valley-pseudospin qubit under polarized laser driving, including sublattice-dependent scattering process, while the thermal fluctuations are accounted through the standard Gibbs thermal state. Entanglement between the two degrees of liberty of electrons is quantified using concurrence, and coherence with the system is measured employing the relative entropy of coherence. The findings demonstrate that the behavior of entanglement and coherence under thermal noise strongly depends on the scattering strength, wavevector components, and electromagnetic field. Additionally, our results indicate that the strong polarized fields ( ξ 0 = 8 meV 2 ) with low-frequency ( ω = 0.06 eV ) can be employed to enhance the robustness of thermal entanglement and coherence of the system at intermediate temperatures. We also explore the impact of the other system parameters, like scattering strength and wavevector components, in enhancing and preserving quantum resources within graphene-based systems, noting particularly that the relative entropy of coherence is more resilient than concurrence against thermal decoherence.
Abstract The open quantum dynamics of a two‐qubit quantum dot system is investigated initially prepared as thermal state and exposed to an Ohmic bosonic reservoir, modeling it as a prototype quantum processor. By integrating local and interaction Hamiltonians, field‐induced couplings, and thermal effects, we derive the system's thermal state and analyze its evolution using quantum measures: concurrence, Bell nonlocality, energy fluctuations, and quantum speed limit (QSL) time. Results reveal that strong field‐induced coupling enhances and preserves quantum correlations, which otherwise vanish abruptly beyond a critical coupling strength. Conversely, energy fluctuations and the QSL time are suppressed for weak coupling but increase significantly in the strong coupling regime. Higher temperatures are shown to uniformly accelerate the dissipation of quantum correlations. Furthermore, it is found that while weak splitting strength allows for tunable correlations, strong splitting enhances initial correlations and energy fluctuations at the cost of suppressing the QSL. These findings demonstrate the potential of coupled quantum dots as tunable two‐qubit processors, providing a guide for precise control over their quantum and thermal properties.
Abstract Graphene, with its two-dimensional carbon structure, exhibits unique quantum properties that are crucial for quantum computing. In this paper, we investigate the influence of an external electromagnetic field on quantum coherence and entanglement between two qubits in graphene lattices. Our findings show that an electromagnetic field with high field strength (ξ 0 ∼ 50 meV2) and low frequency (ω = 0.117 eV) significantly enhances quantum entanglement and coherence, even at elevated temperatures (T ∼ 20 meV). By adjusting the frequency and the field strength, these quantum effects can be preserved long enough at high temperatures. Furthermore, circular polarization of the electromagnetic field is found to be more effective than linear and elliptical polarizations in optimizing these effects. These results highlight the critical role of electromagnetic fields in enhancing quantum properties, potentially paving the way for advancements in quantum computing and related technologies.
In this work, we study the thermal quantum coherence and fidelity in a two-level system with spin-orbit coupling. The proposed model involves a single electron in a double quantum dot with Rashba spin-orbit coupling in the presence of an external magnetic field. In our scenario, the thermal entanglement of the single electron is driven by the charge and spin qubits, the latter controlled by Rashba coupling. Analytical expressions are obtained for thermal concurrence and correlated coherence using the density matrix formalism. The main goal of this work is to provide a good understanding of the effects of temperature and several parameters in quantum coherence. In addition, our findings show that we can use the Rashba coupling to tune the thermal entanglement, quantum coherence, and the thermal fidelity behavior of the system. Moreover, we focus on the role played by thermal entanglement and correlated coherence responsible for quantum correlations. We observe that the correlated coherence is more robust than the thermal entanglement in all cases, so quantum algorithms based only on correlated coherence may be stronger than those based on entanglement.