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UID:UW-Physics-Event-8475
DTSTART:20231109T163000Z
DTEND:20231109T180000Z
DTSTAMP:20260414T031201Z
LAST-MODIFIED:20231023T144350Z
LOCATION:2104 Chamberlin
SUMMARY:Extracting Contributions to Qubit Loss from Superconducting Mi
 crowave Resonators\, Graduate Program Event\, Shravan Patel\, Departme
 nt of Physics Graduate Student
DESCRIPTION:Superconducting coplanar waveguide resonators play a criti
 cal role in information storage and qubit state measurement in superco
 nducting quantum information processing. At the same time\, these reso
 nators are a versatile testbed for characterizing the various contribu
 tions to qubit loss. Ideally\, the internal quality factors Qi of thes
 e resonators should reach ten million or higher\, limited only by the 
 loss tangent of the silicon or sapphire substrate. However\, in real d
 evices\, Qi is limited by the presence of various loss channels\, incl
 uding two-level state (TLS) defects at amorphous interfaces\, trapped 
 magnetic flux vortices\, and nonequilibrium quasiparticles. In this wo
 rk\, we measure Qi as a function of photon occupation in Al and Nb thi
 n-film microwave resonators with different center conductor and gap wi
 dths. This allows us to extract the contribution to loss from interfac
 ial TLS defects. We have also implemented novel resonator designs\, in
 cluding tapered resonators to study the relative contributions to loss
  from TLS and quasiparticles. We have characterized devices fabricated
  on different substrates\, used several methods to deposit the Al and 
 Nb films\, and explored surface cleaning techniques to remove the nati
 ve silicon oxide immediately prior to cooling the resonators.
URL:https://www.physics.wisc.edu/events/?id=8475
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