5,193 research outputs found
Readout scheme of the fullerene-based quantum computer by a single electron transistor
The readout of the quantum spin state is a challenge for any spin-based
quantum computing implementation. We propose a scheme, based on the achieved
technique of single electron transistor (SET), to implement the readout of
electronic spin state inside a doped fullerene by means of the
magnetic dipole-dipole coupling and spin filters. In the presence of an
external magnetic field, we show how to perform the spin state detection by
transforming the information contained in the spin state into the tunneling
current. The robustness of our scheme against sources of error is discussed.Comment: RevTex, 1 table and two figures. Latest versio
Geodetic results from ISAGEX data
Laser and camera data taken during the International Satellite Geodesy Experiment (ISAGEX) were used in dynamical solutions to obtain center-of-mass coordinates for the Astro-Soviet camera sites at Helwan, Egypt, and Oulan Bator, Mongolia, as well as the East European camera sites at Potsdam, German Democratic Republic, and Ondrejov, Czechoslovakia. The results are accurate to about 20m in each coordinate. The orbit of PEOLE (i=15) was also determined from ISAGEX data. Mean Kepler elements suitable for geodynamic investigations are presented
Intelligent process development of foam molding for the Thermal Protection System (TPS) of the space shuttle external tank
A knowledge based system to assist process engineers in evaluating the processability and moldability of poly-isocyanurate (PIR) formulations for the thermal protection system of the Space Shuttle external tank (ET) is discussed. The Reaction Injection Molding- Process Development Advisor (RIM-PDA) is a coupled system which takes advantage of both symbolic and numeric processing techniques. This system will aid the process engineer in identifying a startup set of mold schedules and in refining the mold schedules to remedy specific process problems diagnosed by the system
Squashed States of Light: Theory and Applications to Quantum Spectroscopy
Using a feedback loop it is possible to reduce the fluctuations in one
quadrature of an in-loop field without increasing the fluctuations in the
other. This effect has been known for a long time, and has recently been called
``squashing'' [B.C. Buchler et al., Optics Letters {\bf 24}, 259 (1999)], as
opposed to the ``squeezing'' of a free field in which the conjugate
fluctuations are increased. In this paper I present a general theory of
squashing, including simultaneous squashing of both quadratures and
simultaneous squeezing and squashing. I show that a two-level atom coupled to
the in-loop light feels the effect of the fluctuations as calculated by the
theory. In the ideal limit of light squeezed in one quadrature and squashed in
the other, the atomic decay can be completely suppressed.Comment: 8 pages plus one figure. Submitted to JEOS-B for Dan Walls Special
Issu
Tunable joint measurements in the dispersive regime of cavity QED
Joint measurements of multiple qubits have been shown to open new
possibilities for quantum information processing. Here, we present an approach
based on homodyne detection to realize such measurements in the dispersive
regime of cavity/circuit QED. By changing details of the measurement, the
readout can be tuned from extracting only single-qubit to only multi-qubit
properties. We obtain a reduced stochastic master equation describing this
measurement and its effect on the qubits. As an example, we present results
showing parity measurements of two qubits. In this situation, measurement of an
initially unentangled state can yield with near unit probability a state of
significant concurrence.Comment: 4 pages, 4 figure
- …