Events

Professor Anthony Leggett - University of Illinois

One of the historically earliest proposals for implementing the idea of (partially) protected topological quantum computing involves the physical braiding of the Majorana fermions believed to exist in two-dimensional Fermi superfluids in which the order parameter has the so-called chiral ("p+ip") symmetry. (For many years a plausible candidate system was single-plane strontium ruthenate, but recent experiments have somewhat muddied the waters). The original theoretical paper on this topic (Ivanov 2001), and most of the subsequent literature on it, uses the Bogoliubov-de Gennes equations, thereby violating the principle of conservation of total particle number. In this informal talk I will report on some work with Yiruo Lin* which inter alia attempts to examine how far the standard conclusions continue to hold when we insist on conserving particle number.

IQC Seminar featuring Michael Wilke, McGill University

The pioneering experiments by Hanbury and Twiss are considered by many as the beginnings of experimental quantum optics. These experiments are now particularly relevant in the context of quantum photonics and the characterization of single photon sources.
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Measuring quantum fields with particle detectors and machine learning

Abstract: The model for measurements used in quantum mechanics (based on the projection postulate) cannot be extended to model measurements of quantum fields, since they are incompatible with relativity. We will see that measurements performed with particle detectors (i.e., localized non-relativistic quantum systems that couple covariantly to quantum fields) are consistent with relativity, and that they allow us to build a consistent measurement theory for QFT. For this measurement framework to be of practical use, we need to understand how can we measure specific properties of the field using a particle detector. I will show that there is a simple fixed measurement protocol that allows us to extract essentially all the information about the field that the detector gathers, and that this information can then be interpreted to study a specific targeted feature using machine learning techniques. Specifically, I will examine two examples in which we use a neural network to extract global information about the field (boundary conditions and temperature) performing local measurements, taking advantage of the fact that this global information is stored locally by the field, albeit in a scrambled way.

Seminar featuring Giampiero Marchegiani - Technology Innovation Institute, Abu Dhabi

Single-particle excitations, known as Bogoliubov quasiparticles, threaten the operation of superconducting qubits. In this presentation, we theoretically revisit and generalize the qubit-quasiparticle interaction, including the gap asymmetry in Josephson junctions, which naturally arises from the deposition of aluminum layers with different thicknesses. ...

IQC Seminar featuring Dr. Stephen Vintskevich

There are multiple challenging issues one must address to boost further the nascent field of quantum technologies. The most common are reducing noises’ affection on a given quantum protocol’s performance, performing well-controlled quantum operations, and developing general frameworks for mapping various practical problems into quantum algorithms performed in different quantum devices. ...

IQC Seminar featuring Ali Assem Mahoud

This talk aims to highlight some mathematical tools that can be used in prob- lems related to quantum computing. We start with monogamy-of-entanglement games and study how to approach them through the Haar measure on unitary matrices. ...

ZOOM online Seminar Featuring Ahmad Farooq, Ph.D. - Kyung Hee University

Reliable and efficient reconstruction of the quantum states under the processing of noisy measurement data is a vital tool in fundamental and applied quantum information sciences owing to communication, sensing, and computing. Noisy intermediate-scale quantum (NISQ) computers are expected to perform tasks that surpass the capability of the most powerful classical computers available today. ...

Categories of Kirchoff Relations

Abstract: I will be talking about the connections between electrical circuits and stabilizer qudit quantum circuits with an eye towards applications to qudit quantum error correction. More formally I will be defining a category dubbed Kirchhoff relations and characterize the maps in this category using parity check matrices. I will then go on to give a universal set of generators for this category and interpret these generators in-terms of electrical elements.

This is work in progress.

Seminar Presentation by Richard Germond, Queen's University

A number of astrophysical and cosmological observations suggest that roughly 85% of the matter in the Universe is composed of dark matter, presumed to be a particle outside the standard model of particle physics. Direct detection experiments look for signatures of a dark matter particle scattering with a sensitive detector; of the different technologies used for this, cryogenic detectors are well-suited for detecting low-mass dark matter due to their low energy thresholds.

Introduction to Majorana Topological Qubits

Abstract: This presentation will introduce some of the experimental approaches to building topological qubits and the theories supporting current research. Beginning from the early toy models that first proposed the formation of Majorana bound states, I aim to convey an understanding of why topological qubits are so resistant to decoherence. I will introduce the “ingredients” necessary to build a Majorana device and some of the challenges involved. Finally, I will discuss the field's current state and what might be next on the journey to making topological quantum computing a reality. Neither an understanding of topology nor quantum algorithms are necessary to enjoy this talk!