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CATEGORIES:Semiconductor Physics Group Seminars
SUMMARY:Probing the limits of gate-based charge sensing -
Dr. M. Fernando Gonzalez Zalba\, Hitachi Cambridge
Laboratory
DTSTART;TZID=Europe/London:20141020T141500
DTEND;TZID=Europe/London:20141020T151500
UID:TALK55389AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/55389
DESCRIPTION:Quantum computation requires a qubit-specific meas
urement capability to readout the final state of i
ndividual qubits. In the promising solid-state app
roaches based on superconducting and semiconductin
g nano-devices experiments are increasing in compl
exity and it becomes important to simplify the cir
cuit layout and decrease the number of components.
One of the components of solid-state quantum comp
uters are the qubit readout electrometers. They ar
e made redundant by the introduction of in-situ ga
te sensors based on a resonant readout. This techn
ique couples the gate to a resonant circuit and pr
obes the qubit's radio-frequency polarisability. H
ere\, we investigate the ultimate performance of s
uch resonant readout schemes and the noise sources
that limit their operation.\n\nWe find a charge s
ensitivity of 37 ue/\\sqrt{Hz}\, the best value re
ported for this technique\, using the example of a
gate-sensor strongly coupled to a double quantum
dot at the corner states of a silicon nanowire tra
nsistor.\n\nWe model the charge and phase noise by
solving the dynamical master equation of the fast
-driven electronic transitions and determine the l
imits of charge and phase sensitivity of resonant
readout. We find comparable performance to standar
d charge sensors and our model predicts limits of
order ne/\\sqrt{Hz} and urad/\\sqrt{Hz}. We discus
s the experimental factors limiting gate detection
and highlight ways to optimise its sensitivity. I
n total\, resonant gate-based detection has advant
ages over external electrometers not only in terms
of reduced number of circuit elements\, but also
in terms of absolute charge sensitivity.\n
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Departm
ent of Physics
CONTACT:Teri Bartlett
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