2,076 research outputs found
Stamping single wall nanotubes for circuit quantum electrodynamics
We report on a dry transfer technique for single wall carbon nanotube devices
which allows to embed them in high finesse microwave cavity. We demonstrate the
ground state charge readout and a quality factor of about 3000 down to the
single photon regime. This technique allows to make devices such as double
quantum dots which could be instrumental for achieving the strong spin photon
coupling. It can easily be extended to generic carbon nanotube based microwave
devices.Comment: Version similar to the one accepte
The inter-relation between policy and practice for transitions from hospital to home: An ethnographic case study in England’s National Health Service
© 2014 Shaw et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.No abstract available (poster presentation)
0-pi oscillations in nanostructured Nb/Fe/Nb Josephson junctions
The physics of the phase shift in ferromagnetic Josephson junctions may
enable a range of applications for spin-electronic devices and quantum
computing. We investigate transitions from ``0'' to ``'' states in
Nb/Fe/Nb Josephson junctions by varying the Fe barrier thickness from 0.5 nm to
5.5 nm. From magnetic measurements we estimate for Fe a magnetic dead layer of
about 1.1 nm. By fitting the characteristic voltage oscillations with existing
theoretical models we extrapolate an exchange energy of 256 meV, a Fermi
velocity of m/s and an electron mean free path of 6.2 nm, in
agreement with other reported values. From the temperature dependence of the
product we show that its decay rate exhibits a nonmonotonic
oscillatory behavior with the Fe barrier thickness.Comment: 7 pages, 5 figures, accepted for publication in Eur. Phys. J.
Photon mediated interaction between distant quantum dot circuits
Engineering the interaction between light and matter is an important goal in
the emerging field of quantum opto-electronics. Thanks to the use of cavity
quantum electrodynamics architectures, one can envision a fully hybrid
multiplexing of quantum conductors. Here, we use such an architecture to couple
two quantum dot circuits . Our quantum dots are separated by 200 times their
own size, with no direct tunnel and electrostatic couplings between them. We
demonstrate their interaction, mediated by the cavity photons. This could be
used to scale up quantum bit architectures based on quantum dot circuits or
simulate on-chip phonon-mediated interactions between strongly correlated
electrons
Thermal shot noise in top-gated single carbon nanotube field effect transistors
The high-frequency transconductance and current noise of top-gated single
carbon nanotube transistors have been measured and used to investigate hot
electron effects in one-dimensional transistors. Results are in good agreement
with a theory of 1-dimensional nano-transistor. In particular the prediction of
a large transconductance correction to the Johnson-Nyquist thermal noise
formula is confirmed experimentally. Experiment shows that nanotube transistors
can be used as fast charge detectors for quantum coherent electronics with a
resolution of in the 0.2- band.Comment: 3 pages, 4 figure
Shot noise in carbon nanotube based Fabry-Perot interferometers
We report on shot noise measurements in carbon nanotube based Fabry-Perot
electronic interferometers. As a consequence of quantum interferences, the
noise power spectral density oscillates as a function of the voltage applied to
the gate electrode. The quantum shot noise theory accounts for the data
quantitatively. It allows to confirm the existence of two nearly degenerate
orbitals. At resonance, the transmission of the nanotube approaches unity, and
the nanotube becomes noiseless, as observed in quantum point contacts. In this
weak backscattering regime, the dependence of the noise on the backscattering
current is found weaker than expected, pointing either to electron-electron
interactions or to weak decoherence
Coherent coupling of a single spin to microwave cavity photons
Electron spins and photons are complementary quantum-mechanical objects that
can be used to carry, manipulate and transform quantum information. To combine
these resources, it is desirable to achieve the coherent coupling of a single
spin to photons stored in a superconducting resonator. Using a circuit design
based on a nanoscale spin-valve, we coherently hybridize the individual spin
and charge states of a double quantum dot while preserving spin coherence. This
scheme allows us to achieve spin-photon coupling up to the MHz range at the
single spin level. The cooperativity is found to reach 2.3, and the spin
coherence time is about 60ns. We thereby demonstrate a mesoscopic device
suitable for non-destructive spin read-out and distant spin coupling.Comment: minor differences with published versio
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