1,552 research outputs found
A single-electron inverter
A single-electron inverter was fabricated that switches from a high output to
a low output when a fraction of an electron is added to the input. For the
proper operation of the inverter, the two single-electron transistors that make
up the inverter must exhibit voltage gain. Voltage gain was achieved by
fabricating a combination of parallel-plate gate capacitors and small tunnel
junctions in a two-layer circuit. Voltage gain of 2.6 was attained at 25 mK and
remained larger than one for temperatures up to 140 mK. The temperature
dependence of the gain agrees with the orthodox theory of single-electron
tunneling.Comment: 3 pages, 4 figures (1 color), to be published in Appl. Phys. Let
Quantum corrections in Higgs inflation: the real scalar case
We present a critical discussion of quantum corrections, renormalisation, and
the computation of the beta functions and the effective potential in Higgs
inflation. In contrast with claims in the literature, we find no evidence for a
disagreement between the Jordan and Einstein frames, even at the quantum level.
For clarity of discussion we concentrate on the case of a real scalar Higgs. We
first review the classical calculation and then discuss the back reaction of
gravity. We compute the beta functions for the Higgs quartic coupling and
non-minimal coupling constant. Here, the mid-field regime is
non-renormalisable, but we are able to give an upper bound on the 1-loop
corrections to the effective potential. We show that, in computing the
effective potential, the Jordan and Einstein frames are compatible if all mass
scales are transformed between the two frames. As such, it is consistent to
take a constant cutoff in either the Jordan or Einstein frame, and both
prescriptions yield the same result for the effective potential. Our results
are extended to the case of a complex scalar Higgs.Comment: 28 pages, 1 figure. v2: minor changes, updated references, published
versio
Alternative Systems of Business Tax in Europe: An applied analysis of ACE and CBIT Reforms
This paper explores the economic implications of an allowance for corporate equity (ACE), a comprehensive business income tax (CBIT) and a combination of the two in the EU. We illustrate the key trade-offs in designing ACE and CBIT in the presence of tax distortions at various decision margins of firms, such as its financial structure, investment, profit allocation and discrete location. Using an applied general equilibrium model for Europe, we quantitatively assess the effects of ACE, CBIT and combined reforms in EU countries. The results suggest that ACE is welfare improving as long as corporate tax rates are not used to cover the cost of base narrowing. CBIT typically reduces welfare by exacerbating marginal investment distortions. When governments adjust statutory corporate tax rates to balance their budget, however, CBIT reforms become more attractive while ACE reforms are welfare reducing in a number of countries. European coordination of reforms mitigates fiscal spillovers within the EU and renders ACE reforms more, and CBIT reforms less, attractive for welfare. A combination of ACE and CBIT reforms can be designed to be revenue neutral and welfare improving through smaller financial distortions.European Union, corporate taxation
Negative differential resistance due to single-electron switching
We present the multilevel fabrication and measurement of a Coulomb-blockade
device displaying tunable negative differential resistance (NDR). Applications
for devices displaying NDR include amplification, logic, and memory circuits.
Our device consists of two Al/AlO islands that are strongly coupled
by an overlap capacitor. Our measurements agree excellently with a model based
on the orthodox theory of single-electron transport.Comment: 3 pages, 3 figures; submitted to AP
Quantum state detection of a superconducting flux qubit using a DC-SQUID in the inductive mode
We present a readout method for superconducting flux qubits. The qubit
quantum flux state can be measured by determining the Josephson inductance of
an inductively coupled DC superconducting quantum interference device
(DC-SQUID). We determine the response function of the DC-SQUID and its
back-action on the qubit during measurement. Due to driving, the qubit energy
relaxation rate depends on the spectral density of the measurement circuit
noise at sum and difference frequencies of the qubit Larmor frequency and SQUID
driving frequency. The qubit dephasing rate is proportional to the spectral
density of circuit noise at the SQUID driving frequency. These features of the
backaction are qualitatively different from the case when the SQUID is used in
the usual switching mode. For a particular type of readout circuit with
feasible parameters we find that single shot readout of a superconducting flux
qubit is possible.Comment: 11 pages, 3 figures; submitted to Phys. Rev.
Detection of a persistent-current qubit by resonant activation
We present the implementation of a new scheme to detect the quantum state of
a persistent-current qubit. It relies on the dependency of the measuring
Superconducting Quantum Interference Device (SQUID) plasma frequency on the
qubit state, which we detect by resonant activation. With a measurement pulse
of only 5ns, we observed Rabi oscillations with high visibility (65%).Comment: 4 pages, 4 figures, submitted to PRB Rapid Co
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