R. G. Herb Condensed Matter Seminars |
Events During the Week of March 17th through March 24th, 2024
Monday, March 18th, 2024
- Quantum skyrmion Hall effect
- Time: 12:00 pm - 1:00 pm
- Place: 5310 Chamberlin Hall
- Speaker: Ashely Cook, Max Planck Institutes for the Physics of Complex Systems and the Chemical Physics of Solids
- Abstract: In the quantum Hall effect, a two-dimensional gas of electrons is subjected to an out-of-plane magnetic field and electron transport quantises: the Hall conductivity plateaus at values proportional to integers and rational numbers in units of fundamental constants, with remarkably low error. Shortly after experimental discovery of the quantum Hall effect in 1980, theorists developed a framework explaining this quantization as a consequence of topological phases of matter, or those phases with signatures unaffected by sufficiently small perturbations. In particular, a theory in terms of point charges coupling to external fields beautifully described this physics. A great variety of topological phases have been classified as a consequence of discovery of the quantum Hall effect, but this work has recently led to discovery of topological skyrmion phases of matter, multiplicative topological phases of matter, and finite-size topological phases of matter, which contradict key assumptions of established classification schemes. The discovery of these three sets of topological states necessitates a paradigm shift from the quantum Hall effect framework to that of the quantum skyrmion Hall effect, in which the point charges of the quantum Hall effect are generalised to truly quantum counterparts of topological textures in observable fields, called skyrmions.
- Host: Alex Levchenko
Tuesday, March 19th, 2024
- No events scheduled
Wednesday, March 20th, 2024
- Protecting Qubits from High-energy Impacts
- Time: 12:00 pm - 1:00 pm
- Place: 5310 Chamberlin Hall
- Speaker: Britton Plourde, Syracuse University
- Abstract: Superconducting circuits are an attractive system for forming qubits in a quantum computer because of the natural energy gap to excitations in the superconductor. However, experimentally it is observed that superconducting qubits have dissipative excitations above the superconducting ground state, known as quasiparticles, that can be generated in bursts, leading to correlated errors between qubits across an array. Such correlated errors pose a significant challenge for current quantum error correction schemes. Quasiparticle bursts can be produced by a range of energy-deposition sources, including the impact of high-energy particles from background radioactivity. These events result in a significant number of energetic phonons that travel efficiently throughout the substrate and generate quasiparticles when they impinge on the qubits. I will describe experiments measuring correlated phonon-mediated quasiparticle poisoning in multi-qubit chips in the aftermath of high-energy particle impacts, as well as numerical modeling of the phonon and quasiparticle dynamics. In addition, I will discuss strategies for protecting qubits from these poisoning effects for the implementation of future fault-tolerant quantum processors.
- Host: Robert McDermott
Thursday, March 21st, 2024
- No events scheduled
Friday, March 22nd, 2024
- No events scheduled