We explore the quantum correlations, fidelity and quantum thermodynamics of two coupled double quantum dots containing two excess electrons. In this regard, we investigate and compare the evolution of those measures under thermal effects and tunneling coupling. We find the hierarchy of quantum correlations, and one-way steering between the two quantum dots. We found, as expect that the quantum correlations are diminishes by increasing the values of temperature. We show that this state can be used for quantum teleportation. On the other, we address the extracting work and efficiency of the state. We compare the extraction work with the bare energies. Our results show that quantum dots states have a reliable and better capacity to preserve quantum correlations and remain one of the good resources for the deployment of quantum information processing protocols.
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.
Optimal procedures and appropriate designs of transmitting channels are required to preserve quantum correlations (QCs) in quantum teleportation schemes. In pursuit of this objective, a comprehensive investigation into the intricate dynamics of a quantum channel comprising two singular Cooper-pair charge qubits, mutually coupled and influenced by Josephson energy, has been undertaken. The use of the Gibbs density operator has provided valuable insights into the thermal quantum characteristics and teleportation fidelity of the system. Furthermore, this study underscores the critical interplay between the energy parameters and the utilization of quantum features to establish conducive conditions for the preservation of nonclassicality and the success of the teleportation scheme. Additionally, the study reveals that trace distance discord is the most resilient in the thermal output state, surpassing both concurrence and the degree of violation of Bell’s inequality. Notably, precise control of the input state amplitude and adept manipulation of the energy parameters have enhanced QCs and resulted in the teleportation fidelity exceeding the classical limit.
We present a model of quantum teleportation protocol based on a double quantum dot array. The unknown qubit is encoded using a pair of quantum dots, with one excess electron, coupled by tunneling. It is shown how to create a maximally entangled state using an adiabatically increasing Coulomb repulsion between different dot pairs. This entangled state is exploited to perform teleportation again using an adiabatic coupling between itself and the incoming unknown state. Finally, a sudden separation of Bob’s qubit allows a time evolution of Alice’s which amounts to a modified version of standard Bell measurement. A transmission over a long distance could be obtained by considering the entangled state of a chain of N coupled double quantum dots. The system is shown to be increasingly robust with N against decoherence due to phonons.
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.
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.