83 research outputs found
Generation of Superposition States and Charge-Qubit Relaxation Probing in a Circuit
We demonstrate how a superposition of coherent states can be generated for a
microwave field inside a coplanar transmission line coupled to a single
superconducting charge qubit, with the addition of a single classical magnetic
pulse for chirping of the qubit transition frequency. We show how the qubit
dephasing induces decoherence on the field superposition state, and how it can
be probed by the qubit charge detection. The character of the charge qubit
relaxation process itself is imprinted in the field state decoherence profile.Comment: 6 pages, 4 figure
Temperature Measurement and Phonon Number Statistics of a Nanoelectromechanical Resonator
Measuring thermodynamic quantities can be easy or not, depending on the
system that is being studied. For a macroscopic object, measuring temperatures
can be as simple as measuring how much a column of mercury rises when in
contact with the object. At the small scale of quantum electromechanical
systems, such simple methods are not available and invariably detection
processes disturb the system state. Here we propose a method for measuring the
temperature on a suspended semiconductor membrane clamped at both ends. In this
method, the membrane is mediating a capacitive coupling between two
transmission line resonators (TLR). The first TLR has a strong dispersion, that
is, its decaying rate is larger than its drive, and its role is to pump in a
pulsed way the interaction between the membrane and the second TLR. By
averaging the pulsed measurements of the quadrature of the second TLR we show
how the temperature of the membrane can be determined. Moreover the statistical
description of the state of the membrane, which is directly accessed in this
approach is significantly improved by the addition of a Josephson Junction
coupled to the second TLR.Comment: 9 pages, 5 figures. To appear in New Journal of Physic
Capacitive Coupling of Two Transmission Line Resonators Mediated by the Phonon Number of a Nanoelectromechanical Oscillator
Detection of quantum features in mechanical systems at the nanoscale
constitutes a challenging task, given the weak interaction with other elements
and the available technics. Here we describe how the interaction between two
monomodal transmission-line resonators (TLRs) mediated by vibrations of a
nano-electromechanical oscillator can be described. This scheme is then
employed for quantum non-demolition detection of the number of phonons in the
nano-electromechanical oscillator through a direct current measurement in the
output of one of the TLRs. For that to be possible an undepleted field inside
one of the TLR works as a amplifier for the interaction between the mechanical
resonator and the remaining TLR. We also show how how the non-classical nature
of this system can be used for generation of tripartite entanglement and
conditioned mechanical coherent superposition states, which may be further
explored for detection processes.Comment: 6 pages, 5 figure
Quantum simulation of the Anderson Hamiltonian with an array of coupled nanoresonators: delocalization and thermalization effects
The possibility of using nanoelectromechanical systems as a simulation tool
for quantum many-body effects is explored. It is demonstrated that an array of
electrostatically coupled nanoresonators can effectively simulate the
Bose-Hubbard model without interactions, corresponding in the single-phonon
regime to the Anderson tight-binding model. Employing a density matrix
formalism for the system coupled to a bosonic thermal bath, we study the
interplay between disorder and thermalization, focusing on the delocalization
process. It is found that the phonon population remains localized for a long
time at low enough temperatures; with increasing temperatures the localization
is rapidly lost due to thermal pumping of excitations into the array, producing
in the equilibrium a fully thermalized system. Finally, we consider a possible
experimental design to measure the phonon population in the array by means of a
superconducting transmon qubit coupled to individual nanoresonators. We also
consider the possibility of using the proposed quantum simulator for realizing
continuous-time quantum walks.Comment: Replaced with new improved version. To appear in EPJ Q
Prospecção de moléculas de extratos vegetais do bioma cerrado para o controle de Colletotrichum gossypii var. cephalosporioides e Meloidogyne incognita.
bitstream/CENARGEN/29683/1/doc228.pd
Variação sazonal de parâmetros relacionados à duração do fluxo de látex em seringueira (Hevea brasiliensis Muell. ARG.) no planalto paulista.
Expressão relativa do gene ovu em vários estádios de desenvolvimento de botão floral de algodoeiro.
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