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SUMMARY:(SP Wednesday Workshop) - Charge Locking Quantum Multiplexer and T
 riple Addressing Gate System - Mr Chi Han Chong\, University of Cambridge
DTSTART:20140521T131500Z
DTEND:20140521T141500Z
UID:TALK52467@talks.cam.ac.uk
CONTACT:Teri Bartlett
DESCRIPTION:This presentation discusses how charge can potentially be stor
 ed in quantum multiplexers. Two types of charge quantum multiplexers will 
 be introduced\, the two-way multiplexer (2wMUX)and the three-way multiplex
 er(3wMUX). Attempts of storing charges in the 2wMUX were not successful an
 d the underlying reasons for it are unknown. Adding a top gate on the mult
 iplexer increases the total capacitance of the device\, in order to enhanc
 e charge stability on the multiplexer. However\, the modified device exper
 ienced problems such as charge leakages to other contacts and non-responsi
 ve gate contacts. These problems are believed to be related to baking gold
  contacts at high temperatures. Meanwhile\, UV-exposed Polyimide was found
  to be removable using a microwave asher. However\, a brown shadow corresp
 onding to the removed Polyimide was observed after depositing gold on that
  area. The exact cause for that is unknown\, but it is very likely that th
 in layers of Polyimide got charred by the high power plasma created in the
  ashing process. Compared to the 2wMUX\, the 3wMUX has a split gate fixed 
 to the midpoint of each addressing lead\, allowing three pathways to be ad
 dressed with only two addressing leads. The effects of split gate length L
  on the 2DEG were investigated. Pinch off voltage increases with decreasin
 g L. The polarity of the DC bias voltage affects the pinch off threshold b
 ecause the relative difference between the gate voltage and DC bias dictat
 es the height of the potential barrier imposed onto the system.
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Department of Physics
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