Alexander R. H. Smith

Persistence of Tripartite Nonlocality for Non-inertial Observers

We consider the behaviour of bipartite and tripartite non-locality between fermionic entangled states shared by observers, one of whom uniformly accelerates. We find that while fermionic entanglement persists for arbitrarily large acceleration, the Bell/CHSH inequalities cannot be violated for sufficiently large but finite acceleration. However the Svetlichny inequality, which is a measure of genuine tripartite non-locality, can be violated for any finite value of the acceleration.

Spacetime structure and vacuum entanglement

eld play in identifying the spacetime topology, which is not prescribed from rst principles|neither in general relativity or quantum gravity. We analyze how the entanglement and observable correlations acquired between two particle detectors are sensitive to the spatial topology of spacetime. We examine the detector’s time evolution to all orders in perturbation theory and then study the phenomenon of vacuum entanglement harvesting in Minkowski spacetime and two at topologically distinct spacetimes constructed from identications of the Minkowski space. We show that, for instance, if the spatial topology induces a preferred direction, this direction may be inferred from the dependence of correlations between the two detectors on their orientation. We therefore show that vacuum uctuations and vacuum entanglement harvesting makes it, in principle, possible to distinguish spacetimes with identical local geometry that dier only in their topology.

Effect of gravity on localized two-mode Gaussian quantum states

We study how an arbitrary Gaussian state of two localized wave packets, prepared in an inertial frame of reference, is described by a pair of uniformly accelerated observers. We explicitly compute the resulting state for arbitrarily chosen proper accelerations of the observers and independently tuned distance between them. To do so, we introduce a generalized Rindler frame of reference and analytically derive the corresponding state transformation as a Gaussian channel. Our approach provides several new insights into the phenomenon of vacuum entanglement such as the highly non-trivial effect of spatial separation between the observers including sudden death of entanglement. We also calculate the fidelity of the two-mode channel for non-vacuum Gaussian states and obtain bounds on classical and quantum capacities of a single-mode channel. Our framework can be directly applied to any continuous variable quantum information protocol in which the effects of acceleration or gravity cannot be neglected.

Post-Newtonian gravitational effects in optical interferometry

We investigate general optical interferometry in stationary spacetimes focusing on quantum-optical experiments in near-Earth environments. We provide a rigorous expression for the gravitationally induced phase difference and adapt the parametrized post-Newtonian formalism for calculations of polarization rotation. We investigate two optical versions of the Colella-Overhauser-Werner experiment and show that the phase difference is independent of the post-Newtonian parameter

Looking Inside a Black Hole

ensuremath{gamma}

Harvesting entanglement from the black hole vacuum

, making it a possible candidate for an optical test of the Einstein equivalence principle. Polarization rotation provides an example of the quantum clock variable and, while related to the optical Lense-Thirring effects, shows a qualitatively different behavior from them.

Quantum reference frames associated with non-compact groups : the case of translations and boosts, and the role of mass

The cosmic censorship conjecture posits that singularities forming to the future of a regular Cauchy surface are hidden by an event horizon. Consequently any topological structures will ultimately collapse within the horizon of a black hole and so no observer can actively probe them classically. We consider here a quantum analogue of this problem, in which we compare the transition rates of an Unruh–DeWitt detector placed outside the horizon of an eternal BTZ black hole and its associated geon counterpart. We find the transition rates differ, with the latter being time-dependent, implying that we are indeed able to probe the structure of the singularity from outside the horizon.

Determining the effect of spatial resolution in land use classification using optical aerial imagery

We implement the entanglement harvesting protocol, in which two Unruh-DeWitt detectors become entangled through local interactions with a quantum field, for the first time in the vicinity of a black hole. Our study, focusing on the BTZ black hole, reveals that black holes inhibit entanglement harvesting. The entanglement harvested rapidly falls to zero when two detectors with fixed proper separation approach the horizon. This effect is a combination of black hole radiation and gravitational red shift, both generic properties of horizons, suggesting it is a general result for black holes.

Communication between inertial observers with partially correlated reference frames

Quantum communication without a shared reference frame or the construction of a relational quantum theory requires the notion of a quantum reference frame. We analyze aspects of quantum reference frames associated with non-compact groups, specifically the group of spatial translations and Galilean boosts. We begin by demonstrating how the usually employed group average, used to dispense of the notion of an external reference frame, leads to unphysical states when applied to reference frames associated with non-compact groups. However, we show that this average does lead naturally to a reduced state on the relative degrees of freedom of a system, which was previously considered by Angelo et al. [1]. We then study in detail the informational properties of this reduced state for systems of two and three particles in Gaussian states.

Effect of relativistic acceleration on localized two-mode Gaussian quantum states

Unmanned Aircraft System (UAS), a low cost and time efficient remote sensing platform, can help public agencies obtain useful urban aerial imagery of cities and update land use information frequently, especially in natural colour bands. In this paper, a decision tree based land use classification approach using optical aerial imagery is proposed. First, land cover information is extracted through the Maximum Likelihood Classifier and tabulated with an Ownership parcel map. Second, a decision tree is generated to establish the relationship between land cover and land use. Taking advantage of the geometric characteristics of parcels, an organized land use parcel map is produced. Afterwards, by resampling the aerial imagery from 20 cm, 50 cm and 100 cm resolution, effects of spatial resolution in this classification approach are discussed and determined. This land use classification method is flexible and can be widely used in urban planning and landscape monitoring.