Decoherence of a tunneling two level system in a superconducting qubit due to spectral diffusion

by Shlomi Matityahu

at Condensed Matter Theory Seminar

Wed, 13 Apr 2016, 13:30
Physics building (#54) room 207

Abstract

The low temperature physics of amorphous and disordered solids has been a subject of great interest for more than four decades Below about 1K the acoustic and thermodynamic properties of a large variety of glasses are not only qualitatively different compared to their crystalline counterparts but show a remarkable degree of universality This universal behavior was explained by the existence of low energy excitations with two level structure known as tunneling two level systems TLSs Recent progress with microfabricated quantum devices has revealed that an ubiquitous source of noise originates in such TLSs In this talk I will describe how individual TLSs in the Jospehson junction of a superconducting qubit can be probed and manipulated and discuss a recent experiment in which Ramsey and spin echo dephasing rates of individual TLSs were measured I will show that most features of the Ramsey dephasing can be understood within the standard model of tunneling TLSs whereas the spin echo dephasing rate suggests the existence of some white noise environment I will discuss a two TLS model as a possible explanation for such an environment

Created on 07-04-2016 by Bar Lev, Yevgeny (ybarlev)
Updaded on 07-04-2016 by Bar Lev, Yevgeny (ybarlev)