9 research outputs found
Corrigendum: Coherent creation and destruction of orbital wavepackets in Si:P with electrical and optical read-out
The ability to control dynamics of quantum states by optical interference, and subsequent
electrical read-out, is crucial for solid state quantum technologies. Ramsey interference has
been successfully observed for spins in silicon and nitrogen vacancy centres in diamond, and
for orbital motion in InAs quantum dots. Here we demonstrate terahertz optical excitation,
manipulation and destruction via Ramsey interference of orbital wavepackets in Si:P with
electrical read-out. We show milliradian control over the wavefunction phase for the two-level
system formed by the 1s and 2p states. The results have been verified by all-optical echo
detection methods, sensitive only to coherent excitations in the sample. The experiments
open a route to exploitation of donors in silicon for atom trap physics, with concomitant
potential for quantum computing schemes, which rely on orbital superpositions to, for
example, gate the magnetic exchange interactions between impurities
Understanding resonant charge transport through weakly coupled single-molecule junctions
Off-resonant charge transport through molecular junctions has been
extensively studied since the advent of single-molecule electronics and it is
now well understood within the framework of the non-interacting Landauer
approach. Conversely, gaining a qualitative and quantitative understanding of
the resonant transport regime has proven more elusive. Here, we study resonant
charge transport through graphene-based zinc-porphyrin junctions. We
experimentally demonstrate an inadequacy of the non-interacting Landauer theory
as well as the conventional single-mode Franck-Condon model. Instead, we model
the overall charge transport as a sequence of non-adiabatic electron transfers,
the rates of which depend on both outer and inner-sphere vibrational
interactions. We show that the transport properties of our molecular junctions
are determined by a combination of electron-electron and electron-vibrational
coupling, and are sensitive to the interactions with the wider local
environment. Furthermore, we assess the importance of nuclear tunnelling and
examine the suitability of semi-classical Marcus theory as a description of
charge transport in molecular devices.Comment: version accepted in Nature Communications; SI available at
https://researchportal.hw.ac.uk/en/publications/understanding-resonant-charge-transport-through-weakly-coupled-s
Understanding resonant charge transport through weakly coupled single-molecule junctions
Off-resonant charge transport through molecular junctions has been
extensively studied since the advent of single-molecule electronics and it is
now well understood within the framework of the non-interacting Landauer
approach. Conversely, gaining a qualitative and quantitative understanding of
the resonant transport regime has proven more elusive. Here, we study resonant
charge transport through graphene-based zinc-porphyrin junctions. We
experimentally demonstrate an inadequacy of the non-interacting Landauer theory
as well as the conventional single-mode Franck-Condon model. Instead, we model
the overall charge transport as a sequence of non-adiabatic electron transfers,
the rates of which depend on both outer and inner-sphere vibrational
interactions. We show that the transport properties of our molecular junctions
are determined by a combination of electron-electron and electron-vibrational
coupling, and are sensitive to the interactions with the wider local
environment. Furthermore, we assess the importance of nuclear tunnelling and
examine the suitability of semi-classical Marcus theory as a description of
charge transport in molecular devices.Comment: version accepted in Nature Communications; SI available at
https://researchportal.hw.ac.uk/en/publications/understanding-resonant-charge-transport-through-weakly-coupled-s
Sodium replacement and fluid shifts during prolonged exercise in humans
Contains fulltext :
149473.pdf (publisher's version ) (Open Access
Picosecond dynamics of a silicon donor based terahertz detector device
We report the characteristics of a simple complementary metal-oxide-semiconductor compatible terahertz detector device with low response time (nanoseconds) determined using a short-pulse, high intensity free-electron laser. The noise equivalent power was 1 x 10(-11) W Hz(-1/2). The detector has an enhanced response over narrow bands, most notably at 9.5 THz, with a continuum response at higher frequencies. Using such a device, the dynamics of donors in silicon can be explored, a system which has great potential for quantum information processing. (C) 2014 AIP Publishing LLC.Physics, AppliedSCI(E)[email protected]; [email protected]