R. G. Herb Condensed Matter Seminars |
Events During the Week of April 3rd through April 10th, 2022
Monday, April 4th, 2022
- No events scheduled
Tuesday, April 5th, 2022
- Quantum stochastic resonance of individual Fe atoms
- Time: 10:00 am - 11:00 am
- Place: 5310 Chamberlin
- Speaker: Sue Coppersmith, UNSW Sydney
- Abstract: Stochastic resonance, where noise synchronizes a system’s response to an external drive, is a phenomenon that occurs in a wide variety of noisy systems ranging from the dynamics of neurons to the periodicity of ice ages. This talk will present theory and experiments on a quantum system that exhibits stochastic resonance — the quantum tunneling of the magnetization of a single Fe atom measured using spin-polarized scanning tunneling microscopy. Stochastic resonance is shown deep in the quantum regime, where fluctuations are driven by tunneling of the magnetization, as well as in a semi-classical crossover region where thermal excitations set in. An analytic theory with no adjustable parameters agrees quantitatively with experiment, and provides a path towards probing dynamics on time scales shorter than can be resolved experimentally.
- Host: Mark Eriksson
Wednesday, April 6th, 2022
- No events scheduled
Thursday, April 7th, 2022
- Encoded Silicon Qubits: A High-Performance & Scalable Platform for Quantum Computing
- Time: 10:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Dr. Nathan Holman
- Abstract: For quantum computers to achieve their promise, regardless of the qubit technology, significant improvements to both performance and scale are required. Quantum-dot-based qubits in silicon have recently enjoyed dramatic advances in fabrication and control techniques. The “exchange-only” modality is of particular interest, as it avoids control elements that are difficult to scale such as microwave fields, photonics, or ferromagnetic gradients. In this control scheme, the entirety of quantum computation may be performed using only asynchronous, baseband voltage pulses on straightforwardly tiled arrays of quantum dots. The pulses control only a single physical mechanism, the exchange interaction, which exhibits low control crosstalk and exceptionally high on/off ratios. Exchange enables universal logic within a qubit encoding that is robust against certain correlated errors. These aspects collectively provide a compelling path toward fault-tolerance. HRL Laboratories has recently demonstrated universal quantum logic of encoded exchange-only Si spin qubits, including two-qubit gates performed on arrays of six quantum dots. In this talk, we will introduce the fabrication and operation principles of these encoded Si qubit devices, and we will show recent experimental results.
- Host: Mark Eriksson
Friday, April 8th, 2022
- No events scheduled