524 research outputs found
Fidelity of Optically Controlled Single- and Two-Qubit Operations on Coulomb-Coupled Quantum Dots
We investigate the effect of the Coulomb interaction on the applicability of
quantum gates on a system of two Coulomb-coupled quantum dots. We calculate the
fidelity for a single- and a two-qubit gate and the creation of Bell states in
the system. The influence of radiative damping is also studied. We find that
the application of quantum gates based on the Coulomb interaction leads to
significant input state-dependent errors which strongly depend on the Coulomb
coupling strength. By optimizing the Coulomb matrix elements via the material
and the external field parameters, error rates in the range of can be
reached. Radiative dephasing is a more serious problem and typically leads to
larger errors on the order of for the considered gates. In the
specific case of the generation of a maximally entangled Bell state, error
rates in the range of can be achieved even in the presence of
radiative dephasing.Comment: 8 pages, 10 figures; final versio
Bovine teeth as a novel matrix for the control of the food chain: liquid chromatography–tandem mass spectrometry detection of treatments with prednisolone, dexamethasone, estradiol, nandrolone and seven β2-agonists
A Liquid Chromatography-Tandem Mass Spectrometry Method for the Detection of Antimicrobial Agents from Seven Classes in Calf Milk Replacers: Validation and Application
Quantum information processing in bosonic lattices
We consider a class of models of self-interacting bosons hopping on a
lattice. We show that properly tailored space-temporal coherent control of the
single-body coupling parameters allows for universal quantum computation in a
given sector of the global Fock space. This general strategy for encoded
universality in bosonic systems has in principle several candidates for
physical implementation.Comment: 4 pages, 2 figs, RevTeX 4; updated to the published versio
Evaluation of nandrolone and ractopamine in the urine of veal calves: liquid chromatography-tandem mass spectrometry approach
Tunneling and Electric-Field Effects on Electron-Hole Localization in Artificial Molecules
We theoretically investigate the Stark shift of the exciton goundstate in two
vertically coupled quantum dots as a function of the interdot distance. The
coupling is shown to enhance the tuneability of the linear optical properties,
including energy and oscillator strength, as well as the exciton
polarizability. The coupling regime that maximizes these properties results
from the detailed balance between the effects of the single-particle tunneling,
of the electric field and of the carrier-carrier interaction. We discuss the
relevance of these results to the possible implementation of
quantum-information processing based on semiconductor quantum dots: in
particular, we suggest the identification of the qubits with the exciton levels
in coupled- rather than single-dots
Spin-based quantum information processing with semiconductor quantum dots and cavity QED
A quantum information processing scheme is proposed with semiconductor
quantum dots located in a high-Q single mode QED cavity. The spin degrees of
freedom of one excess conduction electron of the quantum dots are employed as
qubits. Excitonic states, which can be produced ultrafastly with optical
operation, are used as auxiliary states in the realization of quantum gates. We
show how properly tailored ultrafast laser pulses and Pauli-blocking effects,
can be used to achieve a universal encoded quantum computing.Comment: RevTex, 2 figure
The human cytomegalovirus tegument protein pp65 (pUL83): a key player in innate immune evasion
Spin-based optical quantum gates via Pauli blocking in semiconductor quantum dots
We present a solid-state implementation of ultrafast conditional quantum
gates. Our proposal for a quantum-computing device is based on the spin degrees
of freedom of electrons confined in semiconductor quantum dots, thus benefiting
from relatively long decoherence times. More specifically, combining Pauli
blocking effects with properly tailored ultrafast laser pulses, we are able to
obtain sub-picosecond spin-dependent switching of the Coulomb interaction,
which is the essence of our conditional phase-gate proposal. This allows us to
realize {\it a fast two qubit gate which does not translate into fast
decoherence times} and paves the road for an all-optical spin-based quantum
computer.Comment: 14 Pages RevTeX, 3 eps figures include
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