Investigating quantum characteristics in a solid-state system is a crucial focus for advanced exploration. Within this scenario, double quantum dots emerge as a flexible and promising framework with the capability of bringing about significant progress in the fields of quantum computation and nanotechnology. The study presented in this work conducts a comprehensive examination of the capabilities embedded in two charge qubits residing within quantum dots, particularly focusing on their ability to generate essential quantum information resources within a thermal environment. The investigation delves into the assessment of local quantum Fisher information at the individual qubit level, local quantum uncertainty, and the quantification of entanglement through negativity. Through this meticulous exploration of quantum characteristics, the study aims to provide valuable insights into the complex interplay of thermal dynamics and quantum correlations inherent in the charge qubits within the semiconductor framework. A noteworthy revelation from our study is the discernible dependence of non-classical resources on intrinsic parameters, such as Coulomb interaction parameters, as well as extrinsic factors, including temperature. This highlights the nuanced influence of both intrinsic and extrinsic variables on the quantum properties, opening avenues for a more profound comprehension of the complex interactions that mold the quantum landscape in solid-state systems.
Investigating quantum characteristics in a solid-state system is a crucial focus for advanced exploration. Within this scenario, double quantum dots emerge as a flexible and promising framework with the capability of bringing about significant progress in the fields of quantum computation and nanotechnology. The study presented in this work conducts a comprehensive examination of the capabilities embedded in two charge qubits residing within quantum dots, particularly focusing on their ability to generate essential quantum information resources within a thermal environment. The investigation delves into the assessment of local quantum Fisher information at the individual qubit level, local quantum uncertainty, and the quantification of entanglement through negativity. Through this meticulous exploration of quantum characteristics, the study aims to provide valuable insights into the complex interplay of thermal dynamics and quantum correlations inherent in the charge qubits within the semiconductor framework. A noteworthy revelation from our study is the discernible dependence of non-classical resources on intrinsic parameters, such as Coulomb interaction parameters, as well as extrinsic factors, including temperature. This highlights the nuanced influence of both intrinsic and extrinsic variables on the quantum properties, opening avenues for a more profound comprehension of the complex interactions that mold the quantum landscape in solid-state systems.
This work examines the thermal dynamics of basis-independent quantum coherence and correlation-based quantum resources for two dipole-dipole-coupled electrons confined in spatially separated quantum-dot (QD) molecules. Single-dot quantum superpositions and inter-subsystem coherence are characterized by using localized and collective coherence. Quantum correlations between the two double quantum dots are quantified by employing Bures distance entanglement, Local quantum uncertainty (LQU), and local quantum Fisher Information (LQFI). The findings show that dipole-dipole coupling K is the most effective protective parameter, extending the entanglement sudden death temperature, diminishing the local quantum superpositions and enhancing the collective coherence. The dipole-dipole interaction has also a crucial impact on protecting LQU and LQFI beyond the entanglement sudden death temperature. Coulomb repulsion J reinforces this protection through an independent channel, projecting the thermal state onto the entangled {∣0A1B⟩,∣1A0B⟩} subspace; their combined action is required to approach the entanglement maximum, and it enhances collective coherence and extends the temperature range over which LQU and LQFI remain appreciable. Energy detuning ε can enhance localized coherence but paradoxically accelerates the entanglement sudden death and quenches LQU and LQFI by weakening two-body correlations. Inter-dot tunneling Γ enhances local superpositions at low temperature, but it reduces collective coherence, lowers the entanglement sudden death temperature, and disrupts other nonclassical correlations.
This study investigates the progression of thermal entanglement and quantum coherence in a system composed of two superconducting charge qubits connected through a fixed capacitor. Superconducting materials play a central role in modern quantum technologies due to their ability to sustain coherent states over long timescales, making them an ideal platform for quantum information processing. We employ metrics such as logarithmic negativity and relative entropy of coherence to precisely evaluate these quantum resources. In particular, we analyze how thermal noise affects entanglement and quantum coherence in this capacitively coupled system. A central aspect of this work is the interaction between the reservoir's temperature at equilibrium and various intrinsic parameters of the system. The results show that increasing temperature leads to a gradual degradation of entanglement and coherence. However, these quantum resources are highly sensitive to system variables, and careful tuning of these variables can reduce the harmful impact of absolute temperature. These findings offer promising perspectives for optimizing two-qubit superconducting charge systems, with the aim of enhancing their robustness and fully exploiting the advantages offered by quantum technologies.
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.
Abstract Our work explores the time evolution of entanglement, local quantum uncertainty, and correlated coherence within a system modeled by two coupled double quantum dots. The dynamics is described using a time-fractional Schrödinger equation, which is treated here as a phenomenological effective framework introducing temporal nonlocality and memory-like effects, rather than as a first-principles open-system reduction. We vary the fractional parameter τ , the tunneling amplitudes δ A and δ B , and the inter-dot Coulomb interaction strength V , in order to investigate how these key parameters govern the generation, stabilization, and decay of quantum resources within the system. The obtained results reveal that, for both initial states (separable and partially entangled), fractional dynamics with a small τ rapidly generates entanglement reaching maximal values LN ≈ 1 together with strong non-classical correlations quantified by the local quantum uncertainty. Conversely, when τ is closer to unity, entanglement builds up more slowly but the memory-like effects allow quantum resources to remain significant for a longer time, with the negativity remaining above ≈ 0.6 . We also find that higher Coulomb-interaction frequencies V accelerate the build-up of correlations and stabilize coherence, while a strong tunneling asymmetry degrades entanglement and coherence despite the initial benefits of increasing quantum resources. We find that the standard unitary Schrödinger evolution is recovered analytically at τ = 1 , where the Mittag–Leffler functions reduce to ordinary exponentials, while decreasing τ progressively introduces fractional-time nonlocal (memory-like) effects.
Our work explore the time evolution of entanglement, local quantum uncertainty, and correlated coherence, within a system modeled by two double quantum dots. The dynamics is represented using a time-fractional Schrödinger equation, which includes memory effects in a non-Markovian regime. We vary the fractional parameter τ, the tunneling amplitudes δA and δB, as well as the inter-dot interaction strength V, to investigate how these key parameters govern the generation, stabilization, and decay of quantum resources within the system. The obtained results reveal that, for both initial states, fractional dynamics with a low τ rapidly generates entanglement expecting maximal values LN≈1 and non-classical correlations quantified by local quantum uncertainty. Conversely, higher values of τ lead to slower entanglement but memory effects allow quantum resources to remain significant for a longer time, with the negativity remaining above (≈0.6). We also find that higher interaction frequencies V accelerate correlations and stabilize coherence, while a strong tunneling asymmetry degrades entanglement and coherence despite the initial benefits of increasing quantum resources.
Abstract Superconducting charge qubits represent a cutting-edge technology in the field of quantum computing, offering a promising platform for quantum processing. This study delves into the behaviors of thermal coherence and quantum correlations within a two-superconducting charge qubit system coupled by a fixed capacitance. Specifically, we investigate the effects of thermal noise on entanglement (measured by concurrence), nonclassical correlations (quantified by local quantum uncertainty), and quantum coherence (measured by correlated coherence) within the two-superconducting charge qubit capacitively coupled. Our analysis takes into account the interplay between the equilibrium temperature of the reservoir and various system parameters. Our findings demonstrate that an increase in temperature leads to a decrease in coherence and quantum correlations within the considered system. However, the behavior of these quantum resources is heavily dependent on the system parameters, and a careful selection of these parameters can help mitigate the negative effects of absolute temperature. Additionally, we observe that local quantum uncertainty and correlated coherence are more resilient than thermal entanglement to rising temperatures. These results provide insight into how a two-superconducting charge qubit system can be optimized for achieving quantum advantages.