Abstract Harnessing and protecting quantum entanglement from the detrimental effects of local environments is essential for quantum information and computation. With this aim, we present a simple scheme to preserve and control the quantum entanglement. The scheme consists of two coupled single-mode lossy cavities, each containing a qubit, which are in turn connected simultaneously with another two lossy cavities. We examine the protection of entanglement for initially maximal entangled state in both weak and strong coupling regimes. It is found that one can enhance the survival time of the entanglement expeditiously by adjusting the coupling strengths between the relevant cavities and increasing the number of auxiliary cavities. In addition, if the cavities without qubits do not lose photons then after certain damping oscillations the entanglement between two qubits becomes stable. Interestingly, the magnitude of the stable quantum entanglement depends not only on the hopping strengths but also on the number of contributing auxiliary cavities.
Abstract Harnessing and protecting quantum entanglement from the detrimental effects of local environments is essential for quantum information and computation. With this aim, we present a simple scheme to preserve and control the quantum entanglement. The scheme consists of two coupled single-mode lossy cavities, each containing a qubit, which are in turn connected simultaneously with another two lossy cavities. We examine the protection of entanglement for initially maximal entangled state in both weak and strong coupling regimes. It is found that one can enhance the survival time of the entanglement expeditiously by adjusting the coupling strengths between the relevant cavities and increasing the number of auxiliary cavities. In addition, if the cavities without qubits do not lose photons then after certain damping oscillations the entanglement between two qubits becomes stable. Interestingly, the magnitude of the stable quantum entanglement depends not only on the hopping strengths but also on the number of contributing auxiliary cavities.
Quantum technology relies on the utilization of resources, like quantum coherence and entanglement, which allow quantum information and computation processing. This achievement is however jeopardized by the detrimental effects of the environment surrounding any quantum system, so that finding strategies to protect quantum resources is essential. Non-Markovian and structured environments are useful tools to this aim. Here we show how a simple environmental architecture made of two coupled lossy cavities enables a switch between Markovian and non-Markovian regimes for the dynamics of a qubit embedded in one of the cavity. Furthermore, qubit coherence can be indefinitely preserved if the cavity without qubit is perfect. We then focus on entanglement control of two independent qubits locally subject to such an engineered environment and discuss its feasibility in the framework of circuit quantum electrodynamics. With up-to-date experimental parameters, we show that our architecture allows entanglement lifetimes orders of magnitude longer than the spontaneous lifetime without local cavity couplings. This cavity-based architecture is straightforwardly extendable to many qubits for scalability.
Abstract Exploring strategies to protect quantum correlations from the detrimental effects of their surroundings is crucial in the field of quantum computing and information sciences. For this purpose, we consider a simple engineered environment consisting of two noninteracting separated qubits, each embedded in a single-mode lossy cavity which is further connected to another lossy cavity. We investigate the dynamics and protection of quantum discord for the initially maximum entangled state in the weak and strong coupling regimes between the qubits and their corresponding cavities. It is found that the quantum discord can be preserved efficiently for a much longer time by adjusting the hopping strengths between the two coupled cavities. In addition, if the secondary cavity is perfect then a stationary quantum discord between the two qubits arises after certain damping oscillations. Interestingly, the magnitude of the stationary quantum discord can be maximized by increasing the coupling strengths of the two cavities.
Quantum technologies able to manipulating single quantum systems, are presently developing. Among the dowries of the quantum realm, entanglement is one of the basic resources for the novel quantum revolution. Within this context, one is faced with the problem of protecting the entanglement when a system state is manipulated. In this paper, we investigate the effect of the classical driving field on the generation entanglement between two qubits interacting with a bosonic environment. We discuss the effect of the classical field on the generation of entanglement between two (different) qubits and the conditions under which it has a constructive role in protecting the initial-state entanglement from decay induced by its environment. In particular, in the case of similar qubits, we locate a stationary sub-space of the system Hilbert space, characterized by states non depending on the environment properties as well as on the classical driving-field. Thus, we are able to determine the conditions to achieve maximally entangled stationary states after a transient interaction with the environment. We show that, overall, the classical driving field has a constructive role for the entanglement protection in the strong coupling regime. Also, we illustrate that a factorable initial-state can be driven in an entangled state and, even, in an entangled steady-state after the interaction with the environment.
We investigate the control and protection of two-qubit entanglement through engineered interactions between two auxiliary harmonic oscillators. Each qubit is coupled to a local oscillator via a dephasing interaction, while the oscillators interact through independently tunable position-position and momentum-momentum couplings. Employing the characteristic-function representation, we obtain analytical solutions for the composite-system dynamics and examine how the stability properties of the coupled oscillators determine the evolution of two-qubit concurrence. Our analysis reveals distinct dynamical regimes exhibiting entanglement revivals, suppression, or decay, and identifies configurations in which oscillator interactions effectively reduce entanglement degradation. We further investigate the influence of thermal dissipation using local and global master-equation descriptions, demonstrating that suitable oscillator couplings can preserve substantial two-qubit entanglement under the dissipative conditions considered. These results establish a connection between the dynamical stability of auxiliary bosonic modes and the controllability of entanglement in discrete-variable quantum systems, providing a potential strategy for entanglement protection through engineered oscillator interactions.
Quantum technologies able to manipulating single quantum systems, are presently developing. Among the dowries of the quantum realm, entanglement is one of the basic resources for the novel quantum revolution. Within this context, one is faced with the problem of protecting the entanglement when a system state is manipulated. In this paper, we investigate the effect of the classical driving field on the generation entanglement between two qubits interacting with a bosonic environment. We discuss the effect of the classical field on the generation of entanglement between two (different) qubits and the conditions under which it has a constructive role in protecting the initial-state entanglement from decay induced by its environment. In particular, in the case of similar qubits, we locate a stationary sub-space of the system Hilbert space, characterized by states non depending on the environment properties as well as on the classical driving-field. Thus, we are able to determine the conditions to achieve maximally entangled stationary states after a transient interaction with the environment. We show that, overall, the classical driving field has a constructive role for the entanglement protection in the strong coupling regime. Also, we illustrate that a factorable initial-state can be driven in an entangled state and, even, in an entangled steady-state after the interaction with the environment.
Abstract The nonlocal advantage of quantum coherence (NAQC), quantum coherence (QC), and quantum entanglement are promising quantum resources to achieve various quantum information tasks. However, the decoherence of quantum resource is detrimental to the implementation of quantum information processing, and it brings enormous challenge to the application of quantum resource. Here, consider that Alice and Bob possess a two-qubit X state, and the two-qubit X state is composed of two atoms. Bob’s atom interacts with a reservoir, and Alice's atom is subjected to the influence of amplitude damping channel. We design an effective scheme by coupling auxiliary qubits with reservoir, and this scheme can significantly suppress the dissipation of the NAQC, QC, and quantum entanglement. The results reveal that the NAQC, QC, and quantum entanglement degenerate with the increase of time t in the strong coupling regime or weak coupling regime when absenting auxiliary qubits. If one adds some auxiliary qubits in the reservoir, these quantum resources can be strengthened both in the strong coupling regime and weak coupling regime. Auxiliary qubits can help us effectively resist the dissipation of these quantum resources. In comparison with the QC and quantum entanglement, the NAQC is most fragile and it is most vulnerable to the influences of reservoir and noise channel. One needs introduce more auxiliary qubits to suppress the dissipation of the NAQC, especially in the scenarios of the weak coupling regime and strong channel parameter. In this sense, our investigations may provide a potent technique for restraining decoherence and offer a new platform for quantum resource application.