Entanglement trapping in a non-stationary structured reservoir

We study a single two-level atom interacting with a reservoir of modes defined by a reservoir structure function with a frequency gap. Using the pseudomodes technique, we derive the main features of a trapping state formed in the weak coupling regime. Utilising different entanglement measures we show that strong correlations and entanglement between the atom and the modes are in existence when this state is formed. Furthermore, an unexpected feature for the reservoir is revealed. In the long time limit and for weak coupling the reservoir spectrum is not constant in time.Comment: 10 pages, 16 figure

Population trapping due to cavity losses

In population trapping the occupation of a decaying quantum level keeps a constant non-zero value. We show that an atom-cavity system interacting with an environment characterized by a non-flat spectrum, in the non-Markovian limit, exhibits such a behavior, effectively realizing the preservation of nonclassical states against dissipation. Our results allow to understand the role of cavity losses in hybrid solid state systems and pave the way to the proper description of leakage in the recently developed cavity quantum electrodynamic systems.Comment: 4 pages, 3 figures, version accepted for publication on Phys. Rev.

A preliminary study on cranio-facial characteristics associated with minor neurological dysfunctions (Mnds) in children with autism spectrum disorders (asd)

Background. Craniofacial anomalies and minor neurological dysfunction (MNDs) have been identified, in literature, as risk factors for neurodevelopmental disorders. They represent physical indicators of embryonic development suggesting a possible contributory role of complications during early, even pre-conceptional, phases of ontogeny in autism spectrum disorders (ASD). Limited research has been conducted about the co-occurrence of the two biomarkers in children with ASD. This study investigates the associative patterns of cranio-facial anomalies and MNDs in ASD children, and whether these neurodevelopmental markers correlate with intensity of ASD symptoms and overall functioning. Methods. Caucasian children with ASD (n = 33) were examined. Measures were based on five anthropometric cranio-facial indexes and a standardized and detailed neurological examination according to Touwen. Relationships between anthropometric z-scores, MNDs and participant characteristics (i.e., age, cognitive abilities, severity of autistic symptoms measured using the Childhood Autism Rating Scale (CARS) checklist) were assessed. Results. With respect to specific MNDs, significant positive correlations were found between Cephalic Index and Sensory deficits (p-value < 0.001), which did not correlate with CARS score. Importantly, CARS score was positively linked with Intercanthal Index (p-value < 0.001), and negatively associated with posture and muscle tone (p-value = 0.027) and Facial Index (p-value = 0.004). Conclusion. Our data show a link between a specific facial phenotype and anomalies in motor responses, suggesting early brain dysmaturation involving subcortical structures in cerebro-craniofacial development of autistic children. This research supports the concept of a “social brain functional morphology” in autism spectrum disorders

Environment-dependent dissipation in quantum Brownian motion

The dissipative dynamics of a quantum Brownian particle is studied for different types of environment. We derive analytic results for the time evolution of the mean energy of the system for Ohmic, sub-Ohmic and super-Ohmic environments, without performing the Markovian approximation. Our results allow to establish a direct link between the form of the environmental spectrum and the thermalization dynamics. This in turn leads to a natural explanation of the microscopic physical processes ruling the system time evolution both in the short-time non-Markovian region and in the long-time Markovian one. Our comparative study of thermalization for different environments sheds light on the physical contexts in which non-Markovian dissipation effects are dominant.Comment: 10 pages, 6 figures, v2: added new references and paragraph

Tripartite entanglement dynamics in a system of strongly driven qubits

We study the dynamics of tripartite entanglement in a system of two strongly driven qubits individually coupled to a dissipative cavity. We aim at explanation of the previously noted entanglement revival between two qubits in this system. We show that the periods of entanglement loss correspond to the strong tripartite entanglement between the qubits and the cavity and the recovery has to do with an inverse process. We demonstrate that the overall process of qubit-qubit entanglement loss is due to the second order coupling to the external continuum which explains the exp[-g^2 t/2+g^2 k t^3/6+\cdot] for of the entanglement loss reported previously.Comment: 9 pages, 5 figure

Sudden death and sudden birth of entanglement in common structured reservoirs

We study the exact entanglement dynamics of two qubits in a common structured reservoir. We demonstrate that, for certain classes of entangled states, entanglement sudden death occurs, while for certain initially factorized states, entanglement sudden birth takes place. The backaction of the non-Markovian reservoir is responsible for revivals of entanglement after sudden death has occurred, and also for periods of disentanglement following entanglement sudden birth.Comment: 4 pages, 2 figure

Quantum Zeno Effect in Trapped Ions

A "continuous measurement" Quantum Zeno Effect (QZE) in the context of trapped ions is predicted. We describe the physical system and study its exact time evolution showing the appearance of Zeno Phenomena. New indicators for the occurrence of QZE in oscillatory systems are proposed and carefully discussed.Comment: 12 pages, 4 figure

Microscopic derivation of the Jaynes-Cummings model with cavity losses

In this paper we provide a microscopic derivation of the master equation for the Jaynes-Cummings model with cavity losses. We single out both the differences with the phenomenological master equation used in the literature and the approximations under which the phenomenological model correctly describes the dynamics of the atom-cavity system. Some examples wherein the phenomenological and the microscopic master equations give rise to different predictions are discussed in detail.Comment: 9 pages, 3 figures New version with minor correction Accepted for publication on Physical Review

Dynamics of Entanglement and Bell-nonlocality for Two Stochastic Qubits with Dipole-Dipole Interaction

We have studied the analytical dynamics of Bell nonlocality as measured by CHSH inequality and entanglement as measured by concurrence for two noisy qubits that have dipole-dipole interaction. The nonlocal entanglement created by the dipole-dipole interaction is found to be protected from sudden death for certain initial states