No description available.

No description available.

No description available.

No description available.

No description available.

In this work we mainly focus on two main aspects of interest within the field of Relativistic Quantum Information. We first expand on the current knowledge of the effects of relativity on entanglement between global field modes. Within this aspect, we focus on two topics: we address and revise the single mode approximation commonly used in the literature. We study the nonlocal correlations of charged bosonic field modes and the degradation of entanglement initially present in maximally entangled states as a function of acceleration, when one observer is accelerated. In the second part of this work we introduce, develop and exploit a method for confining quantum fields within one (or two) cavities and analyzing the effects of motion of one cavity on the entanglement initially present between cavity field modes. One cavity is always allowed to undergo arbitrary trajectories composed of segments of inertial motion and uniform acceleration. We investigate how entanglement is degraded, conserved and created as a function of the parameters describing the motion and we provide the analytical tools to understand how these effects occur. We conclude this work by analyzing the effects of the change of spatial topology on the nonlocal correlations present in the Hawking-Unruh radiation in the topological geon analogue of black hole spacetimes.

We describe what can be called the “universal” phase space of 2+1 AdS gravity, in which the moduli spaces of globally hyperbolic AdS spacetimes with compact Cauchy surface, as well as the moduli spaces of multi black hole spacetimes are realized as submanifolds. Importantly our phase space also includes all Brown-Henneaux excitations on the conformal boundary of asymptotically AdS spacetimes, with Diff+(S1)/SL(2,R)xDiff+(S1)/SL(2,R) contained as a submanifold. Our description of the universal phase space is obtained from results on the correspondence between maximal surfaces in AdS3 and quasi-symmetric homeomorphisms of the unit circle. We find that the phase space can be parametrized by two copies of the universal Teichmuller space T(D), or equivalently by the cotangent bundle over T(D). This yields a symplectic map from T*T(D) to T(D)xT(D) generalizing the well-known Mess map in the compact spatial surface setting. We also relate our parametrization to the Chern-Simons formulation of 2+1 gravity and, infinitesimally, to the holographic (Fefferman-Graham) description. In particular, we relate the charges arising in the holographic description (such as the mass and angular momentum of asymptotically AdS spacetimes) to the periods of holomorphic quadratic differentials arising via the Bers embedding of T(D)xT(D).

No description available.

In Part I, the electron correlation problem is briefly reviewed and some approaches to its solution are discussed. In Part II, a partitioning technique used previously to examine correlation trends in individual electronic shells for a series of four-electron ions has been extended and applied to a detailed comparison of four well-correlated wavefunctions for the Be atom. The present analysis of a correlated two-particle density, generalized for any N-electron system, retained all contributions from products of all terms in the wavefunction up to and including the pair-correlation effects. For each correlated description of Be, Coulomb holes and shifts have been evaluated and compared for the K(1S), L(1S), KL(1s) and KL(3S) shells. The inverted nature of the intershell holes, relative to the intrashell effects, has been examined and rationalized in terms of the 2s-2p near-degeneracy which exists in Be. The total Coulomb holes for the two energetically best wavefunctions showed a previously unseen structure which was directly attributable to the intershells. The calculation of partial Coulomb holes and shifts, Δg(r12,r1,)vs.r12 & Δg(p12,P1)vs.P12, allowed us to examine changes in the components of correlation as the position r1 or the momentum p1 of a test electron was varied. Selected one- and two-particle radial and momentum expectation values are also reported along with various radial and angular correlation coefficients. In Part III the partitioning technique, discussed in Part II, has been applied to a momentum space study of electron correlation in a molecular system. The correlation effects embedded in a CI wavefunction for LiH has been examined in terms of the intra- and intershell Coulomb shifts and several one- and two-particle expectation values. Finally, in Part IV we present an overview of correlation coefficients as used, quite extensively, in the discussion of electron correlation. We have examined their construction and have reviewed their application towards this subject.

This thesis examines the electrical transport properties of a series of n-type GaAs/(AIGa)As double barrier resonant tunnelling devices with well widths between 50 angstrem and 2400 angstrem . The current-voltage characteristics show peak-to-valley ratios as high as 25:1 and as many as seventy resonances, with clear evidence of quantum interference effects at room temperature. The application of a high magnetic field parallel to the current flow produces magnetooscillations in the transport properties which allow the sheet charge density in the accumulation layer to be determined. The energy level in the well over a wide range of bias is obtained from analysis of thermal activation of resonant tunnelling. The contributions of elastic scattering and LO phonon emission to the valley current are investigated spectroscopically with a magnetic field and two phonon modes of the (AIGa)As barrier are observed. The buildup of space charge in the quantum well at resonance leads to intrinsic bistability in the current and differential capacitance of an asymmetric structure. Magnetoquantum oscillations due to a degenerate electron gas in the well are used to measure this charge buildup and demonstrate that the tunnelling process is truly sequential. The bistability is dramatically enhanced at high magnetic fields when the lowest energy Landau level of the well can accommodate a high electron density. In a strongly asymmetric sample, a new kind of bistability is observed where the off-resonant current exceeds the resonant current due to enhancement of charge buildup by intersubband scattering. The modulation of the scattering rate by a magnetic field produces periodic oscillations in the width of the bistability. In a magnetic field applied perpendicular to the current, the resonances are broadened as a consequence of the conservation of canonical momentum. The transition from electric to magnetic quantisation in wide wells is investigated and tunnelling into interfacial Landau levels is observed. The angular dependence of the resonances is used to probe conduction band anisotropy. In a tilted field, a completely new type of magneto-oscillations is observed.