Events

Stacey Jefferey - QuSoft

While the quantum query complexity of k-distinctness is known to be O(n^{3/4−1/4(2k−1)}) for any constant k≥4, the best previous upper bound on the time complexity was ~O(n^{1−1/k}). We give a new upper bound of ~O(n^{3/4−1/4(2k−1)}) on the time complexity, matching the query complexity up to polylogarithmic factors. In order to achieve this upper bound, we give a new technique for designing quantum walk search algorithms, which is an extension of the electric network framework. We also show how to solve the welded trees problem in O(n) queries and O(n^2) time using this new technique, showing that the new quantum walk framework can achieve exponential speedups.

The ability to engineer the electrical, optical and magnetic properties of advanced materials on the nanoscale is of increasing importance to the development of future technologies. One approach to achieving this is through impurity doping, with increased control over the spatial resolution and isotopic purity enabled by the development of dedicated tools. In this talk the 'P-NAME' tool will be described, and the underlying principle surrounding its application for the development of doped systems for quantum technologies including qubits presented. cont.

The Quantum Innovators in Computer Science and Mathematics workshop brings together promising researchers working on theoretical aspects of quantum information and computation in computer science and mathematics. Guests are invited for a three-day conference aimed at exploring the frontier of our field. 

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.

There's growing awareness of the lack of diversity in science and the presence of barriers to inclusion. What factors lead to disparities in representation? Why should we be motivated to effect change? What can we do to change things? Will our actions really make a difference? 

This presentation will focus on ideas to challenge the status quo – actions to advance equity, diversity, and inclusion (EDI). We will discuss recent research to illustrate and raise awareness of the many EDI challenges in science, then explore various practical ways to take action to advance EDI. These practical actions stem from our recently released "Science is For Everyone" Teaching toolkit, which provides an abundance of ideas to diversify science education and further support recruitment, retention, and advancement of all students. We will touch on the importance of diversifying content and talk about how Indigenous content is being brought into post-secondary science courses. Finally, we will give an overview of other exciting science EDI initiatives across research and academic life.

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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Meet graduate student researchers from science, engineering, and mathematics and hear how they discovered quantum information science, found their way into research, and how the skills they gained in their undergraduate studies are helping them develop the next generation of quantum technology.

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. ...