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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-4064
DTSTART:20160311T160000Z
DTEND:20160311T170000Z
DTSTAMP:20260419T144848Z
LAST-MODIFIED:20160304T190119Z
LOCATION:5310 Chamberlin Hall
SUMMARY:Microwave response and photon emission of a voltage baised Jos
 ephson junction\, R. G. Herb Condensed Matter Seminar\, Salha Jebari\,
  CEA Grenoble
DESCRIPTION:The readout of superconducting qubits and other quantum de
 vices operating at microwave frequencies requires amplifiers combining
  noise close to the quantum limit[1 ]\, high gain\, large bandwidth\, 
 and sufficient dynamic range[2 ]. Josephson parametric amplifiers usin
 g Josephson junctions in the 0-voltage state\, driven by a large micro
 wave signals\, begin to perform sufficiently well in all 4 of these as
 pects to be of practical use\, but remain difficult to optimize and us
 e. Recent experiments with superconducting circuits consisting of a DC
  voltage-biased Josephson junction in series with a resonator\, showed
  that a tunneling Cooper pair can emit one or several photons with a t
 otal energy of 2e times the applied voltage[3 ]. We present microwave 
 reflection measurements on this device in [3]\, indicating that amplif
 ication is possible with a simple DC voltage-biased Josephson junction
 .<br><br>
\nWe compare these measurements with the noise power emitted
  by the junction and show that\, for low Josephson energy\, transmissi
 on and noise emission can be explained within the framework of P(E) th
 eory of inelastic Cooper pair tunneling. Combined with a theoretical m
 odel\, our results indicate that voltage-biased Josephson junctions mi
 ght be useful for amplification near the quantum limit\, offering simp
 ler design and a different trade-off between gain\, bandwidth and dyna
 mic range\, which could be advantageous in some situations.
URL:https://www.physics.wisc.edu/events/?id=4064
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