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VERSION:2.0
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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-1879
DTSTART:20100916T150000Z
DURATION:PT1H0M0S
DTSTAMP:20260422T092240Z
LAST-MODIFIED:20100909T132523Z
LOCATION:5310 Chamberlin
SUMMARY:A Macroscopic Mechanical Resonator Driven by Mesoscopic Electr
 ical Backaction\, R. G. Herb Condensed Matter Seminar\, Alex Rimberg\,
  Dartmouth College
DESCRIPTION:We have recently discovered that the driven classical dyna
 mics of a macroscopic mechanical object can be dominated by the quantu
 m statistical fluctuations of tunneling electrons\, i.e.\, by shot noi
 se.  Furthermore\, coupling between the object and the electrons modif
 ies the electron-electron correlations\, resulting in strongly super- 
 and sub-Poissonian current noise.  In particular\, we have found that 
 a GaAs-based quantum point contact (QPC) can be viewed as a macroscopi
 c mechanical oscillator (a normal mode of the host crystal) whose posi
 tion is continuously monitored by a mesoscopic electrical detector (th
 e QPC). Furthermore\, electrons tunneling through the QPC cause the ho
 st crystal to vibrate by means of quantum mechanical backaction.  This
  effect is similar to Brownian motion\, in which the motion of a grain
  of pollen in water is determined by the classical equilibrium statist
 ical fluctuation of molecules.  In our case\, however\, the motion of 
 the oscillator is determined by the quantum non-equilibrium statistica
 l fluctuations of tunneling electrons.  Furthermore\, the size dispari
 ty between the oscillator (a semiconducting chip containing 10^20 atom
 s) and the source of the fluctuations driving them (fundamental subato
 mic particles) is truly extreme\, and provides a dramatic example of i
 nteraction between the quantum and classical worlds.
URL:https://www.physics.wisc.edu/events/?id=1879
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