Decay rate and decoherence control in coupled dissipative cavities

We give a detailed account of the derivation of a master equation for two coupled cavities in the presence of dissipation. The analytical solution is presented and physical limits of interest are discussed. Firstly we show that the decay rate of initial coherent states can be significantly modified if the two cavities have different decay rates and are weakly coupled through a wire. Moreover, we show that also decoherence rates can be substantially altered by manipulation of physical parameters. Conditions for experimental realizations are discussed.Comment: 19 pages, 1 table, accepted by Physica

Analysing a complementarity experiment on the quantum-classical boundary

The complementarity experiment reported in Bertet [{\it{et al.}} (2001), {\it{Nature}} {\bf{411}}, 166.] is discussed. The role played by entanglement in reaching the classical limit is pointed out. Dissipative and thermal effects of the cavity are calculated and a simple modification of the experiment is proposed in order to observe the progressive loss of the capacity of ``quantum erasing''as a manifestation of the classical limit of quantum mechanics.Comment: 7 pages, 4 figure

Non-equilibrium entangled steady state of two independent two-level systems

We determine and study the steady state of two independent two-level systems weakly coupled to a stationary non-equilibrium environment. Whereas this bipartite state is necessarily uncorrelated if the splitting energies of the two-level systems are different from each other, it can be entangled if they are equal. For identical two-level systems interacting with two bosonic heat baths at different temperatures, we discuss the influence of the baths temperatures and coupling parameters on their entanglement. Geometric properties, such as the baths dimensionalities and the distance between the two-level systems, are relevant. A regime is found where the steady state is a statistical mixture of the product ground state and of the entangled singlet state with respective weights 2/3 and 1/3

Teleportation of a quantum state of a spatial mode with a single massive particle

Mode entanglement exists naturally between regions of space in ultra-cold atomic gases. It has, however, been debated whether this type of entanglement is useful for quantum protocols. This is due to a particle number superselection rule that restricts the operations that can be performed on the modes. In this paper, we show how to exploit the mode entanglement of just a single particle for the teleportation of an unknown quantum state of a spatial mode. We detail how to overcome the superselection rule to create any initial quantum state and how to perform Bell state analysis on two of the modes. We show that two of the four Bell states can always be reliably distinguished, while the other two have to be grouped together due to an unsatisfied phase matching condition. The teleportation of an unknown state of a quantum mode thus only succeeds half of the time.Comment: 12 pages, 1 figure, this paper was presented at TQC 2010 and extends the work of Phys. Rev. Lett. 103, 200502 (2009

Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter

Climate change and human pressures are changing the global distribution and the ex‐ tent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (precon‐ ditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experi‐ mentally simulated, under standard laboratory conditions, rewetting of leaves, river‐ bed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative character‐ istics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dis‐ solved substances during rewetting events (56%–98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contrib‐ uted most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental vari‐ ables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached sub‐ stances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying event

Effects Of Finite Temperature In Ballistic Quantum Dots

We studied the effects of finite temperature in the magnetic susceptibility of a system of N non-interacting electrons in a homogeneous magnetic field and in a smooth confinement potential: the two-dimensional harmonic oscillator. Different exact ensemble calculations are considered and discussed: canonical (N fixed), canonical via grand-canonical (N average fixed) and partial canonical ensembles. We compute a Gaussian average of the susceptibility over the number of particles and another one over the size of system in order to compare our results with data of mesoscopic systems experiments. We conclude that it is fundamental to consider interactions between the particles in the theoretical analysis to obtain the temperature dependence of the experimental results. © 1998 Elsevier Science B.V. All rights reserved.2571-4542546Gutzwiller, M.C., (1990) Chaos in Classical and Quantum Mechanics, , Springer, New YorkBerry, M.V., (1991) Chaos and Quantum Physics, Les Houches Lecture Series 52, , M.J. Gianoni, A. Voros, J. Zinn-Justin (Eds.), North-Holland, AmsterdamOzorio De Almeida, A.M., (1988) Hamiltonian Systems: Chaos and Quantization, , Cambridge University Press, CambridgeNakamura, K., Thomas, H., (1988) Phys. Rev. Lett., 61, p. 247Levy, L.P., Reich, D.H., Pfeiffer, L., West, K., (1993) Physica B, 189, p. 204Von Oppen, F., (1994) Phys. Rev. B, 50, p. 17151Agam, O., (1994) J. Phys (France), 1 (4), p. 697Prado, S.D., De Aguiar, M.A.M., Keating, J.P., Egydio De Carvalho, R., (1994) J. Phys A, 27, p. 6091Prado, S.D., De Aguiar, M.A.M., (1996) Phys. Rev. E, 54, p. 1369Ulmo, D., Richter, K., Jalabert, R.A., (1995) Phys. Rev. Lett., 74, p. 383Richter, K., Ulmo, D., Jalabert, R.A., (1996) Phys. Rep., 276, p. 1Altshuler, B.L., Gefen, Y., Imry, Y., (1991) Phys. Rev. Lett., 66, p. 88Darwin, C.G., (1930) Proc. Cambridge Phil. Soc., 27, p. 86Schuh, B., (1985) J. Phys. A, 18, p. 803Németh, R., (1990) Z. Phys. B, 81, p. 89Brack, M., Genzken, O., Hansen, K., (1991) Z. Phys. D, 21, p. 65Tiago, M.L., Terra, M.O., De Aguiar, M.A.M., to appea

Analysis of the dynamics of a spacecraft in the vicinity of an asteroid binary system with equal masses

In this work, we performed a dynamical analysis of a spacecraft around a nearly equal-mass binary near-Earth asteroid with application to the asteroid 2017 YE5, which is also a possible dormant Jupiter-family comet. Thus, we investigated the motion of a particle around this binary system using the circular restricted three-body problem. We calculated the locations of the Lagrangian points of the system and their Jacobi constant. Through numerical simulations, using the Poincaré Surface of Sections, it was possible to find several prograde and retrograde periodic orbits around each binary system's primary, some exhibiting significantly-sized higher-order behavior. We also calculated the stability of these orbits. After finding the periodic orbits, we investigated the influence of solar radiation pressure on these orbits. For this analysis, we considered that the area-to-mass ratio equals 0.01 and 0.1. We also performed a spacecraft lifetime analysis considering the physical and orbital characteristics of the 2017YE5 system and investigated the behavior of a spacecraft in the vicinity of this system. We analyzed direct and retrograde orbits for different values of Jacobi's constant. This study investigated orbits that survive for at least six months, not colliding or escaping the system during that time. We also analyze the initial conditions that cause the spacecraft to collide with M1 or M2, or escape from the system. In this work, we take into account the gravitational forces of the binary asteroid system and the solar radiation pressure (SRP). Finally, we calculated optimal bi-impulsive orbital maneuvers between the collinear Lagrangian points. We found a family of possible orbital transfers considering times of flight between 0.1 and 1 day.publishe

Finite Temperature Effects in the NonintegrableSU(3) Lipkin Model

In the present work we use nonrelativistic many body physics techniques to generalize the classical limit of quantum systems in such a way as to incorporate statistical mixtures. Finite temperature effects are thus incorporated in a natural way. We give a detailed account of the thermodynamics of theSU(3) Lipkin model and then derive the classical thermal (chaotic) dynamics of the system. The most remarkable features of our analysis are twofold: firstly the appearance of a new degree of freedom essentially connected to thermal effects, i.e., for high enough temperatures. Secondly we give a quantitative characterization of the temperature effects on the chaotic volume of the system. Thermal effects are shown to be responsible for novel nonlinear contributions to the dynamics and to consistently counterbalance the inter- action part of the dynamics. This is the case in the context both of thermodynamics and of the thermal dynamics and we believe it to be true in general.http://www.sciencedirect.com/science/article/B6WB1-45K1844-21/1/a9efa81f47d76e6c3b8fff7bb405f3e