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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2800
DTSTART:20121029T213000Z
DURATION:PT1H0M0S
DTSTAMP:20260416T215136Z
LAST-MODIFIED:20121026T170328Z
LOCATION:5310 Chamberlin
SUMMARY:Progress in Superconducting Quantum Circuits\, Condensed Matte
 r Theory Group Seminar\, Robert McDermott
DESCRIPTION:Superconducting integrated circuits incorporating Josephso
 n junctions are an attractive candidate for scalable quantum computing
  in the solid state. Currently\, fidelity of multiqubit operations is 
 limited by decoherence and by added noise of the qubit measurement. In
  this talk I describe work to improve qubit coherence and measurement 
 fidelity. First\, I describe the incorporation of crystalline silicon 
 into phase qubit circuits\; the improved qubits display energy relaxat
 ion times that are a factor 2-3 greater than those achieved with the b
 est available amorphous materials. Next\, I will describe efforts to u
 nderstand and eliminate pure dephasing. We have shown that the dephasi
 ng is due to flux noise induced by surface magnetic states at the supe
 rconductor-insulator interface\; in recent work we have demonstrated a
  fabrication process that has led to a noise suppression by more than 
 an order of magnitude. Finally (and if time permits)\, I will discuss 
 development of a novel microwave amplifier based on a variant of the d
 c Superconducting QUantum Interference Device (dc SQUID). With these d
 evices we have achieved noise performance within a factor of 2 of the 
 standard quantum limit at 8 GHz. Preliminary measurements show a signi
 ficant improvement in single-shot quantum nondemolition measurement fi
 delity.  
URL:https://www.physics.wisc.edu/events/?id=2800
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