Spring 2020

The first part of this talk will introduce generalized Jordan–Wigner transformation on arbitrary triangulation of any manifold in 2d, 3d, and general dimensions. This gives a duality between all fermionic systems and a new class of Z2 lattice gauge theories. This map preserves the locality and has an explicit dependence on the second Stiefel–Whitney class and a choice of spin structure on the manifold. In the Euclidean picture, this mapping is equivalent to introducing topological terms (Chern-Simon term in 2d or the Steenrod square term in general) to the Euclidean action.

 Intro.  Physics and statistics  (a) where theory and experiment meet, (b) divergent world views, (c) underlying probabilistic nature of the world:  Bell's theorem and random number generation.
The calibration of a few photon detector.  (a) What is a Transition Edge Sensor?  What needs to be calibrated?  (b) The K-means algorithm as maximum likelihood.  (c) Adaptation of the K-means algorithm to Poisson statistics:  a new maximum likelihood objective function: PIKA.  (d) Application of PIKA to calibration of an attenuator at near-ideal quantum efficiency.

Abstract: Quantum photonics provides a powerful toolbox with vastapplications ranging from quantum simulation, photonic informationprocessing, all optical universal quantum computation, secure quantuminternet as well as quantum enhanced sensing. Many of theseapplications require the integration of several complex opticalelements and material systems which pose a challenge in scalability.Integration of linear and non-linear photonics on a chip is essentialto tackle this issue leading to more compact, high bandwidth devices.

(pizza and drinks served at 12pm; talk starts at 12:10pm)
 

The position states of the harmonic oscillator describe the location of a particle moving on the real line. Similarly, the phase difference between two superconductors on either side of a Josephson junction takes values in the configuration space of a particle on a circle. More generally, many physical systems can be described by a basis of "position states," describing a particle moving on a more general configuration or state space. Most of this space is usually ignored due to the energy cost required to pin a particle to a precise "position".

(pizza and drinks served at 12pm; talk starts at 12:10pm)

The interaction of a single photon with an individual two-level system is the textbook example of quantum electrodynamics. Achieving strong coupling in this system has so far required confinement of the light field inside resonators or waveguides. Experiments with Rydberg superatoms [1,2] have demonstrated the ability to realize strong coupling to a propagating light pulse containing only a few photons in free space.

Dissertation Committee Chair: Luis Orozco
Committee:
Alicia Kollar
Mohammad Hafezi (Dean’s rep)
William D. Phillips
Ian Spielman (Advisor)
Abstract:

Quantum dots formed in silicon heterostructures have emerged as a promising candidate for creating qubits, the building blocks of quantum computing. Their small size, ease of control, and compatibility with modern semiconductor processes make them especially enticing. However, the intrinsic near-degeneracy (valley splitting) of the conduction band electrons that form these quantum dots poses a serious concern for the viability of these qubits, but may also hold the solution.

I will present our recent advances in the formal verification of post-quantum security. Our framework includes a logic for reasoning about quantum programs (qRHL, quantum relational Hoare logic) and a tool for computer-aided verification in qRHL. We have used this framework to verify the post-quantum security of the Fujisaki-Okamoto transform for building encryption schemes. I will give an overview of the logical foundations and of our experiences when verifying a real-life cryptosystem.