Date/Time
Date(s) - 17/09/2014
3:30 pm - 4:30 pm

Title: Artificial Atoms Based on Superconductors: From Quantum Information to Measurements of Noise in Solid-State Mesoscopic Systems

Speaker: Dr. Adrian Lupascu

Institute: University of Waterloo

Location: ABB 102

Description:

At low temperature, nanoscale electrical circuits based on superconductors behave as artificial atoms. Their dynamics is described by a small number of degrees of freedom, and their properties can be tailored by circuit design.
Superconducting artificial atoms are currently one of the main candidates for the implementation of quantum bits (qubits), the basic units of a quantum computer. In this talk I will show how advances in the understanding of the properties of superconducting artificial atoms find applications as a new tool to investigate noise in mesoscopic systems with unprecedented sensitivity.
I will present our recent work using a particular type of superconducting artificial atom, the flux qubit. This system is very sensitive to magnetic flux noise. This source of noise has been known for decades in the field of superconducting quantum interference devices (SQUIDs), however its microscopic origin remains unclear. Flux qubits bring a new opportunity to investigate flux noise, with much higher sensitivity than it was possible using SQUID based devices. I will present our experiment where we characterize magnetic flux noise over ten orders of magnitude in frequency.
In the next part of the talk, I will discuss the application of a flux qubit to the measurement of tunneling dynamics of non-equilibrium quasiparticles in superconductors.
I will close the talk with a discussion of the prospects brought by noise measurements for further developments of quantum information processors, and also of new types of detectors.