Location
Hybrid
M3 4206/email amgrad for link
Candidate
Ireneo James Membrere | Applied Mathematics, University of Waterloo
Title
Time-Dependent Particle Detectors and Phase Space Methods for Entanglement Harvesting
Abstract
A key prediction of quantum field theory that has yet to be tested experimentally is the existence of entanglement between spacelike separated regions of quantum fields. It is hypothesized that this phenomenon can be measured using the entanglement harvesting protocol, a process by which entanglement between detectors is induced due to their interaction with a quantum field in its vacuum state. Proposals for implementing the entanglement harvesting protocol using superconducting quantum circuits are extremely promising for achieving this feat. Motivated by this, we outline three research studies in this thesis focused on modelling entanglement harvesting in experimental regimes.
We begin with a perturbative entanglement harvesting model for two superconducting flux qubits tunably coupled to a superconducting transmission line. We find a regime in which this model reduces to the previously derived VGSD model. Then we turn our focus to non-perturbative methods to present results on entanglement harvesting in the regimes of finite interaction times, strong coupling, as well as amplitude and derivative coupling. We found that the breakdown of leading order perturbation theory varies for different switching functions and couplings. We also observe that in most cases, there exists an optimal coupling strength and measurement time for maximizing the entanglement harvested from the vacuum. In an effort to extend non-perturbative methods to other particle detector models, we end this thesis with an analysis of the discrete Heisenberg-Weyl and Stratonovich-Weyl Wigner functions for quantum spin-$j$ systems. In stark contrast to the discrete Heisenberg-Weyl formalism, we show that Stratonovich-Weyl Wigner negativity emerges for thermal states at sufficiently cold temperatures. Furthermore, we find stabilizer states with non-zero Stratonovich-Weyl Wigner negativity.