732 research outputs found
Charge noise at Cooper-pair resonances
We analyze the charge dynamics of a superconducting single-electron
transistor (SSET) in the regime where charge transport occurs via Cooper-pair
resonances. Using an approximate description of the system Hamiltonian, in
terms of a series of resonant doublets, we derive a Born-Markov master equation
describing the dynamics of the SSET. The average current displays sharp peaks
at the Cooper-pair resonances and we find that the charge noise spectrum has a
characteristic structure which consists of a series of asymmetric triplets of
peaks. The strongest feature in the charge noise spectrum is the triplet of
peaks centered at zero frequency which has a peak spacing equal to the level
separation within the doublets and is similar to the triplet in the spectrum of
a driven, damped, two-level system. We also explore the back-action that the
SSET charge noise would have on an oscillator coupled to the island charge,
measurement of which provides a way of probing the charge noise spectrum.Comment: 14 pages, 7 figure
Leggett-Garg inequalities for the statistics of electron transport
We derive a set of Leggett-Garg inequalities (temporal Bell's inequalities)
for the moment generating function of charge transferred through a conductor.
Violation of these inequalities demonstrates the absence of a macroscopic-real
description of the transport process. We show how these inequalities can be
violated by quantum-mechanical systems and consider transport through normal
and superconducting single-electron transistors as examples.Comment: 5 pages; 3 figure
Effects of defoliation from an outbreak of the teak skeletoniser, Paliga damastesalis walker (Lepidoptera: Crambidae), on the growth of teak, Tectona grandis L.
The effects of defoliation by the teak skeletoniser Paliga damastesalis Walker (Lepidoptera: Crambidae) on a six-month old stand of teak Tectona grandis L. was evaluated on the subsequent year-long growth in the field. Defoliation did not exceed 10%. It had a transient negative effect on post-defoliation height increment and new leaf production of up to two and three months of growth. However, defoliation severity significantly affected collar diameter increment up to the seventh month. A peak in the mean monthly growth increments for new leaf production occurred in April, followed by collar diameter increment in June and height in July. In addition, a peak in one of these three growth parameters also corresponded with a trough in the other or both of the other parameters; as such, the height increment peaked with a concomitant trough in collar diameter increment a month later. As for the remaining period of the dry season after July, new leaf production remained at a constant low level, while increments for both the height and collar diameter were found to decrease. Tree recovery appeared rapid with regard to these growth parameters, thus the impact of defoliation was generally and relatively negligible on the growth parameters measured
One-by-one trap activation in silicon nanowire transistors
Flicker or 1/f noise in metal-oxide-semiconductor field-effect transistors
(MOSFETs) has been identified as the main source of noise at low frequency. It
often originates from an ensemble of a huge number of charges trapping and
detrapping. However, a deviation from the well-known model of 1/f noise is
observed for nanoscale MOSFETs and a new model is required. Here, we report the
observation of one-by-one trap activation controlled by the gate voltage in a
nanowire MOSFET and we propose a new low-frequency-noise theory for nanoscale
FETs. We demonstrate that the Coulomb repulsion between electronically charged
trap sites avoids the activation of several traps simultaneously. This effect
induces a noise reduction by more than one order of magnitude. It decreases
when increasing the electron density in the channel due to the electrical
screening of traps. These findings are technologically useful for any FETs with
a short and narrow channel.Comment: One file with paper and supplementary informatio
The fate of being a ‘distressed asset’: insights into women returners’ experiences in the UK
Building on studies looking into how professionals encounter stigma and negotiate their work lives, this article fills a gap in extant sociological literature on gender and professional work by providing original qualitative data on professional women’s supported re-entry-to-work experiences. Examining the development of returner programmes in the UK, we investigate the supportive factors in the mitigation of stigma threats associated with the returner status, including organisational support and individual stigma-management strategies. We examine how these social processes contribute to alleviating stigmatisation only partially, while maintaining persistent wage and career discrimination for women returners. To explain this mixed result, we explore the way in which women returners inhabit neoliberal feminist subjectivities
Incoherent charge transport in an organic polariton condensate
We study how polariton condensation modifies charge transport in organic
materials. Typically, organic charge transport proceeds via incoherent hopping
of charges. We study how the hopping rate depends on the condensate density,
matter-light coupling, and cavity photon detuning. While hopping may change the
state -- exciting the upper polariton, dark states, or vibrational sidebands --
we find ground state process dominate at all reasonable temperatures. We find
that hopping rates can be exponentially sensitive to detuning and condensate
density, allowing an increase or decrease of hopping rate by two orders of
magnitude due to optical excitation.Comment: 7 pages, 3 figures + Supplemental Material 9 pages, 2 figure
- …