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SUMMARY:Phonon–mediated non-equilibrium interactions between mesoscopic 
 devices - Stefan Ludwig\, Ludwig-Maximilians-Universit
DTSTART:20081205T110000Z
DTEND:20081205T120000Z
UID:TALK15480@talks.cam.ac.uk
CONTACT:Dr Andrew Ferguson
DESCRIPTION:Charge detection utilizing a biased quantum point contact (QPC
 ) has become an essential probe for studying the electronic properties of 
 nanoscale devices such as coupled few electron quantum dots. In order to r
 each a sufficient sensitivity to detect at least single electron charging 
 events\, the detector QPC is usually strongly biased at VQPC » 1meV and I
 QPC ~ 1 nA. As a result the QPC emits energy quanta that can be reabsorbed
  in the device components. This back–action ultimatively results in deco
 herence limiting possible applications for instance in the field of quantu
 m information processing. In the presentation I will discuss recent experi
 ments in which the non–equilibrium back–action of a biased QPC onto se
 rially coupled double or triple quantum dots is explored. Back-action can 
 be observed as a ratchet current through a double quantum dot or as telegr
 aph noise in the detector current. In the case of two adjacent but electri
 cally separate QPCs\, a strong bias applied to one QPC results in a counte
 rflow current flowing in the opposite direction through the second unbiase
 d QPC. In all these experiments\, energy quanta are emitted by a biased QP
 C and absorbed in a second unbiased nanostructure.
LOCATION:Microelectronics Group Seminar Room
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