We investigate the time evolutions of purity, coherence and entanglement in two superconducting qubits coupled through Josephson junctions. The system is modeled by coupling strength, energy, Josephson energy and phase difference. Meanwhile, the structure is under the action of thermal field and classical Ornstein–Uhlenbeck (OU) noise. According to our findings, quantum correlations are notably developed governed by the system parameters. Purity and entanglement generally increase for the energetic qubit regimes. The state’s entanglement and purity degrade with increased coupling strength and temperature. On the other hand, the optimal preservation of quantum correlations reqires the adjustment to intermediate Josephson energies ([Formula: see text]) and phase differences ([Formula: see text]). The coherence measurement shows completely opposite traits compared to the entanglement and purity in the system. These results reveal that quantum states need proper parametrization for the considered state while providing optimization for the higher performance of superconducting qubits in quantum information processing.
We investigate the time evolutions of purity, coherence and entanglement in two superconducting qubits coupled through Josephson junctions. The system is modeled by coupling strength, energy, Josephson energy and phase difference. Meanwhile, the structure is under the action of thermal field and classical Ornstein–Uhlenbeck (OU) noise. According to our findings, quantum correlations are notably developed governed by the system parameters. Purity and entanglement generally increase for the energetic qubit regimes. The state’s entanglement and purity degrade with increased coupling strength and temperature. On the other hand, the optimal preservation of quantum correlations reqires the adjustment to intermediate Josephson energies ([Formula: see text]) and phase differences ([Formula: see text]). The coherence measurement shows completely opposite traits compared to the entanglement and purity in the system. These results reveal that quantum states need proper parametrization for the considered state while providing optimization for the higher performance of superconducting qubits in quantum information processing.
In this paper, we examine the dynamics of Entropic Uncertainty (EU) and concurrence entanglement (CN) in a two-qubit superconducting system influenced by external parameters such as energy biases, coupling strength, and an oscillating external magnetic field. The Hamiltonian includes a Josephson junction coupling term along the [Formula: see text]-direction. Our results show an inverse relationship between EU and CN: stronger coupling reduces EU and enhances CN, while higher energy biases increase EU and decrease CN. The intrinsic magnetic field strength modulates EU and CN, with higher magnetic field reducing EU and enhancing CN at specific phase angles. Temperature variations significantly impact quantum measures, with higher temperatures increasing EU and reducing CN, indicating that lower temperatures favor entanglement and minimize uncertainty. These findings highlight the sensitivity of quantum properties to external parameters, providing optimization for the quantum state control in superconducting qubit systems.
We address the dynamics of quantum coherence, quantum correlations, quantum steering and Bell nonlocality in a model of two interacting qubits, initially prepared in a thermal state. The two qubit are coupled via a dipolar interaction and exposed to Dzyaloshinskii–Moriya (DM) interaction and classical fluctuating fields influenced by Ornstein–Uhlenbeck (OU)-Static (ST) mixed noise in common environments. We analyse the dynamics effects on quantum resources, as Bell nonlocality, quantum steering, quantum entanglement, quantum discord and quantum coherence. We find that the dynamics of quantum correlations are not only strongly affected by the type of system-environment coupling but also by the kind of the considered noise. The entanglement diminution is over time, accompanied by damped oscillations, indicative of coherent dynamics. The DM interaction induces a decrease in quantum coherence and correlations with increasing values, leading to complete maximizing at critical thresholds. The effects of thermal effects destroy the quantum correlation. The variations in state noise disorder parameters reveal enhanced preservation and reduced oscillations as the noise disorder parameter decreases, emphasizing its crucial role in shaping quantum correlations.
Abstract We address entanglement, coherence, and information protection in a system of four non-interacting qubits coupled with different classical environments, namely: common, bipartite, tripartite, and independent environments described by Ornstein–Uhlenbeck (ORU) noise. We show that quantum information preserved by the four qubit state is more dependent on the coherence than the entanglement using time-dependent entanglement witness, purity, and Shannon entropy. We find these two quantum phenomena directly interrelated and highly vulnerable in environments with ORU noise, resulting in the pure exponential decay of a considerable amount. The current Markovian dynamical map, as well as suppression of the fluctuating character of the environments, are observed to be entirely attributable to the Gaussian nature of the noise. The increasing number of environments are witnessed to speed up the amount of decay. Unlike other noises, the current noise parameter’s flexible range is readily exploitable, ensuring long enough preserved memory properties. The four-qubit GHZ state, besides having a large information storage potential, stands partially entangled and coherent in common environments for an indefinite duration. In addition, we derive computational values for each system-environment interaction, which will help quantum practitioners to optimize the related classical environments.
This study examines the influence of temperature and Josephson energy on the quantum properties of superconducting qubits, specifically Bell non-locality and quantum coherence. Our results demonstrate that increasing temperature induces a degradation of both of these essential properties for quantum computing. In contrast, Josephson energy is revealed to be an adjustable parameter allowing for the modulation of non-locality and coherence. However, we observe a trade-off in the simultaneous optimization of these two quantum resources via Josephson energy. This study underscores the crucial importance of thermal control and precise engineering of qubit parameters for the development of high-performance and robust superconducting quantum technologies.
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.
Abstract We investigate quantum coherence, quantum correlations (steering, entanglement, and geometric quantum discord (GQD)), and quantum thermodynamics between two superconducting qubits, examining both steady and dynamical states. Our findings reveal that GQD is more robust to thermal effects than entanglement, which surpasses steerability in robustness. We also show that quantum correlations are more sensitive to thermal noise than coherence. The impact of coupling and Josephson energies on these quantum properties is analyzed. Moreover, we investigate these resources in Markovian and in non-Markovian regimes. Finally, we discuss and compare the extracted work and efficiency in relation to quantum coherence and correlations, focusing on the influence of thermal noise, Josephson energy, and coupling energy.