Abstract In this paper, we investigate the dynamics of quantum resources (QRs) in a double quantum dot (DQD) system subject to thermal fluctuations. We explore the effects of temperature, Rashba spin–orbit interaction (RSOI), and other system parameters on QR in this system. We use three quantum measures in this context: linear entropy, first-order coherence, and entanglement quantified by concurrence. The results demonstrate the detrimental effects of thermal noise and that an increase in the Zeeman splitting exacerbates this degradation of QR. The findings further reveal that careful tuning of the RSOI can enhance and preserve thermal quantum correlations. Interestingly, first-order coherence persists at higher temperatures than entanglement, indicating that coherence-based tasks and protocols could be more resilient in spin-qubit arrays. Unlike entanglement and coherence, linear entropy increases with temperature and Rashba coupling, suggesting that the RSOI increases the mixedness of the thermal state in the DQD system.
Abstract In this paper, we investigate the dynamics of quantum resources (QRs) in a double quantum dot (DQD) system subject to thermal fluctuations. We explore the effects of temperature, Rashba spin–orbit interaction (RSOI), and other system parameters on QR in this system. We use three quantum measures in this context: linear entropy, first-order coherence, and entanglement quantified by concurrence. The results demonstrate the detrimental effects of thermal noise and that an increase in the Zeeman splitting exacerbates this degradation of QR. The findings further reveal that careful tuning of the RSOI can enhance and preserve thermal quantum correlations. Interestingly, first-order coherence persists at higher temperatures than entanglement, indicating that coherence-based tasks and protocols could be more resilient in spin-qubit arrays. Unlike entanglement and coherence, linear entropy increases with temperature and Rashba coupling, suggesting that the RSOI increases the mixedness of the thermal state in the DQD system.
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.
We study bipartite entanglement, quantum coherence, and linear-entropy-based distance in a semiconductor double quantum dot (DQD) hosting a single electron, subject to longitudinal Zeeman splitting, a transverse magnetic field gradient, and thermal fluctuations. In this single-electron system, modeled as a two-qubit system, intrinsic correlations arise from the interplay between the charge-localization and spin degrees of freedom. Entanglement is quantified via the Bures distance, coherence through the Hellinger distance, and linear-entropy-based distance is used as a quantitative measure to characterize the purity of the corresponding quantum thermal state. Our results demonstrate how temperature T, the strength of applied magnetic fields, and the intrinsic DQD parameters shape the behavior of these quantum resources (QR), revealing that careful adjustment of the DQD parameters and the intensities of the two perpendicular external magnetic fields provides a practical handle for controlling the quantum properties of the system and preserving quantum resources against the detrimental effects of thermal noise. We further show that Hellinger coherence is more robust than entanglement against thermal noise, underscoring its potential as a reliable quantum resource in solid-state quantum information platforms.
This study investigates the dynamics of two-qubit correlations in a double quantum dot (QD) containing an electron and two charge-spin configurations under the influence of Rashba interaction, the Dzyaloshinsky–Moriya interaction, and an external magnetic field. The dynamics of two-qubit correlations, particularly those of local quantum Fisher information (LQFI) and local quantum uncertainty (LQU), are compared with those of log negativity. The correlation dynamics are analysed under the effects of Dzyaloshinsky–Moriya interaction, Rashba spin–orbit coupling, electron tunnelling strength, Zeeman spin-splitting coupling, and intrinsic decoherence. Importantly, in the absence of intrinsic electron QD qubit decoherence, it is found that weak couplings within the electron QD qubit system have a high capacity to create equal LQFI and LQU two-qubit correlations, as well as log-negativity entanglement. Furthermore, it is found that an increase in Zeeman spin splitting and the tunnelling effect of two electrons decreases the ability of the other couplings, DM spin–orbit and Rashba spin–orbit interactions, to generate Wigner–Yanase–Fisher correlation and entanglement, and the opposite is also true. The generation of electron-QD qubit correlations exhibits decaying oscillatory dynamics, especially when decoherence is considered. Additionally, the LQFI and LQU display different correlations, and the sudden death and birth phenomena of entanglement occur. Moreover, the phenomena of decaying oscillatory dynamics, as well as the sudden death and birth of entanglement, depend on the electron-QD-qubit couplings. These electron-QD-qubit correlations provide the quantum dot system with promising features for establishing quantum technologies.
In this paper we investigate the thermal quantum correlations in a semiconductor double-quantum-dot system. The device comprises a single electron in a double quantum dot subjected to a longitudinal-magnetic-field and a transverse-magnetic-field gradient. The thermal entanglement of the single electron is driven by the charge and spin qubits. Employing the density-matrix formalism, we derive analytical expressions for thermal concurrence and correlated coherence, providing a comprehensive analysis of how temperature and various system parameters influence quantum coherence. Our results demonstrate that the transverse magnetic field serves as a tunable parameter for controlling thermal entanglement and quantum coherence. We also highlight the roles of thermal entanglement and correlated coherence in generating quantum correlations, noting that thermal correlated coherence is consistently more robust than thermal entanglement. This suggests that quantum algorithms based solely on correlated coherence might be more resilient than those relying on entanglement.
We investigate thermal quantum correlations in a system of two coupled superconducting spin qubits described by an effective Andreev spin-qubit Hamiltonian in the presence of spin-orbit interaction. Using Local Quantum Fisher Information (LQFI) and Local Quantum Uncertainty (LQU) as quantum-correlation quantifiers, we analyze the effects of the superconducting phase difference, tunneling amplitude, spin-orbit coupling, and temperature on the nonclassical properties of the system. Analytical expressions for the thermal density matrix are obtained and employed to evaluate both quantities. Our results show that quantum correlations decrease monotonically with increasing temperature, while stronger tunneling and spin-orbit interaction significantly enhance their robustness. Moreover, the superconducting phase introduces a pronounced periodic behavior through the modulation of the effective exchange couplings, leading to constructive and destructive interference regimes that strongly influence the correlations. By analyzing the energy spectrum of the effective Hamiltonian, we demonstrate that the enhancement of quantum correlations is closely associated with an increased energy gap between the ground and first excited states, which suppresses thermal excitations and stabilizes the correlated ground state. Furthermore, LQFI is consistently larger than LQU throughout the investigated parameter space, reflecting its higher sensitivity to quantum fluctuations and local parameter estimation. These findings reveal the microscopic mechanism governing thermal quantum correlations in Andreev spin qubits and highlight the important roles of phase engineering, spin-orbit interaction, and tunneling in protecting quantum resources in hybrid superconducting quantum devices.
Abstract In this work, the thermal quantum correlations in two coupled double semiconductor charge qubits are investigated. This is carried out by deriving analytical expressions for both the thermal concurrence and the correlated coherence. The effects of the tunneling parameters, the Coulomb interaction, and the temperature on the thermal entanglement and on the correlated coherence are studied in detail. It is found that the Coulomb potential plays an important role in the thermal entanglement and in the correlated coherence of the system. The results also indicate that the Coulomb potential can be used for significant enhancement of the thermal entanglement and quantum coherence. One interesting aspect is that the correlated coherence capture all the thermal entanglement at low temperatures, that is, the local coherences are totally transferred to the thermal entanglement. Finally, the role played by thermal entanglement and the correlated coherence responsible for quantum correlations are focused on. It is shown that in all cases, the correlated coherence is more robust than the thermal entanglement so that quantum algorithms based only on correlated coherence may be more robust than those based on entanglement.