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Non-equilibrium statistics for electronic systems in low dimension
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Zhang, Jin (2010) Non-equilibrium statistics for electronic systems in low dimension. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b2341439~S15
Abstract
The charge fluctuations in electronic devices are becoming increasingly important
as the device size decreases. In this thesis, I first focus on the theory of the
Full Counting Statistics (FCS) of the charge transferred across a quantum point contact,
which can have a general time-dependent transparency with arbitrary pulses
applied between the leads. I present two methods, one analytical and one numerical,
for computing the FCS for non-interacting electrons at zero temperature. For the
case of a barrier with time-dependent profile but no bias, a mapping onto the case of
a biased barrier with constant transmission and reflection amplitudes is derived. For
the general case, which corresponds to applying both a bias and varying the barrier
profile with time, a numerical scheme for computing exactly the FCS for a device
has been developed. With these tools, I discuss two applications of the FCS, both of
which offer the possibility of suppressing the quantum equilibrium noise from logarithmically
divergent down to constant level: an optimal electronic entangler and an
on-demand low noise single electron source, which could have potential application
in electronic quantum computation/information. How the deviation from an ideal
pulse affects the quality of operation of a device with low noise single electron source
or an entangler is discussed in depth.
The response of a many-body system driven away from equilibrium is of fundamental
interest. The second topic I present in this thesis is the study of probably
the simplest non-trivial many-body system out of equilibrium—the non-equilibrium
Fermi-edge singularity (NFES) in tunneling junctions. I first show a method which
maps the NFES problem onto the problem of calculating the FCS for a fictitious
system, where various methods are available. Then I focus on an interpretation on
an experimental data obtained by Cobden which shows the first clear experimental
observation of the NFES in tunneling devices. A generalisation of the NFES in the
constant bias voltage case to non-zero temperature and low-frequency ac signal is
presented. Two factors, namely the Fumi shift and the exponent, both of which are
complex when the system is driven away from equilibrium, are identified to account
for the measured data. Good agreement between the theory and the measured data
is achieved.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QC Physics | ||||
Library of Congress Subject Headings (LCSH): | Charge transfer, Mesoscopic phenomena (Physics), Low-dimensional semiconductors, Quantum theory | ||||
Official Date: | August 2010 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Department of Physics | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | D'Ambrumenil, Nicholas ; Muzykantskii, Boris | ||||
Sponsors: | Engineering and Physical Sciences Research Council (EPSRC) (EP/D065135/1) ; University of Warwick | ||||
Extent: | x, 148 leaves : ill., charts | ||||
Language: | eng |
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