In this article, we investigate the hierarchy of quantum correlations between two gravitational cats states (modeled by two qubits). We use concurrence to quantify the entanglement between the two gravitational cat states. Quantum steering is employed to measure the steerabilities. We consider geometric quantum discord to quantify quantum correlations beyond entanglement. We show that the concurrence persists even when steerability is lost under thermal effects. We also show that the temperature influences the degree of quantum correlations between the two gravitational cat states. Besides, when the energy difference between the ground state and the first excited level becomes significant, the states become separable.
In this article, we investigate the hierarchy of quantum correlations between two gravitational cats states (modeled by two qubits). We use concurrence to quantify the entanglement between the two gravitational cat states. Quantum steering is employed to measure the steerabilities. We consider geometric quantum discord to quantify quantum correlations beyond entanglement. We show that the concurrence persists even when steerability is lost under thermal effects. We also show that the temperature influences the degree of quantum correlations between the two gravitational cat states. Besides, when the energy difference between the ground state and the first excited level becomes significant, the states become separable.
We explore the quantum features of two gravitational cats (gravcats) modeled by two qubits, focusing on quantum steerability, concurrence, and geometric quantum discord under varying conditions of gravitational interaction strength, temperature, and excitation energy. We first analyze the system without dephasing effects, revealing that two-way quantum steering occurs at lower temperatures and higher gravitational interaction strengths. As temperature increases, thermal noise reduces steerability, though gravitational effects remain significant, indicating a non-monotonic behavior dependent on energy and mass scales. Furthermore, quantum correlations exhibit a hierarchy, with geometric quantum discord persisting even when steering and entanglement vanish. We then explore the impact of environmental dephasing and classical correlations on the system's dynamics. Our findings demonstrate that classical correlations in correlated dephasing channels can protect quantum resources, enhancing their stability in both Markovian and non-Markovian regimes. This work highlights the intricate interplay between gravitational interactions, thermal effects, and environmental noise in preserving quantum resources.
We consider the effect of a thermal bath on quantum correlations induced by the gravitational interaction in the weak field limit between two massive cat states, called gravitational cat (gravcat) states. The main goal of this paper is to provide a good understanding of the effects of temperature and several parameters in the entanglement (measured by the concurrence) and quantum coherence (measured by the l1-norm that is defined from the minimal distance between the quantum state and the set of incoherent states) which are derived from the thermal quantum density operator. Our results show that the thermal concurrence and l1-norm can be significantly optimized by increasing the masses or decreasing the distance between them. We investigate and discuss the behavior of these quantities under temperature variations in different regimes, including some that are expected to be experimentally feasible in the future. In particular, we observe that thermal fluctuations raise non-entangled quantum correlations when entanglement suddenly drops.
We investigate how resourceful gravitational cat states are to preserve quantum correlations. In this regard, we explore the dynamics of gravitational cat states under different situations such as thermal, classical stochastic, general decaying, and power-law noisy fields. In particular, the one-way steerability, Bell nonlocality, entanglement, and purity in two qubits are our main focus. We also address the weak measurement protocol on the dynamics of quantum correlations and purity of the state. Our results show that the gravitational cat 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. Additionally, two independent channels are also employed, and it is observed that only the weaker coupling regimes are effective in preserving quantum correlations. Notably, in terms of non-Markovian dynamics implication, quantum correlations are found to be longer preserved because of the information feedback phenomenon between the system and environment. Finally, we present a brief analysis to extend our gravitational model to include the electrostatic notion, providing insight into the key differences between the considered configurations.
Abstract We study the quantumness of gravitational cat states in correlated dephasing channels. Our focus is on exploring how classical correlations between successive actions of a dephasing channel influence the decoherence of two gravitational cats (two qubits) at a thermal regime. The results show that the quantum coherence, local quantum Fisher information, and Bell non-locality can be significantly enhanced by augmenting classical correlations throughout the entire duration when the two qubits pass the channel. However, the gravitational interaction and energy gap between states exhibit intricate impacts on the quantum characteristics of gravitational cats. New features are reported that can be significant for both gravitational physics and quantum information processing.
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.
We study the distribution of quantum correlations and basis-independent coherence in a pair of massive particles confined in a double-well potential and coupled through their mutual Newtonian gravitational interaction. Non-classical correlations are characterized using Bures distance of entanglement and quantum discord, while coherence is quantified through the square root of the quantum Jensen--Shannon divergence (QJSD) from the maximally mixed state, yielding a measure that is invariant under arbitrary unitary transformations and is therefore genuinely basis-independent. The total coherence CT decomposes into two operationally distinct contributions: the collective coherence CC, which captures quantum correlations between the two subsystems, and the localized coherence CL, which captures the intrinsic quantum coherence of each individual subsystem. We analyze how temperature T, the gravitational coupling Δ, and the single-particle energy scale w govern the redistribution of coherence between its collective and localized components. Our results show that CL is more robust against thermal fluctuations than CC, and that increasing Δ preferentially enhances collective coherence by strengthening gravitationally induced inter-particle correlations.