399 research outputs found
Application of aerospace-generated technology to water pollution and other public sector problems Quarterly report, 1 Sep. - 30 Nov. 1968
Aerospace technology utilization to water pollution and weather modification
On free loop spaces of toric spaces
Growth of the Hilbert-Poincar\"e series for the rational homology of the free
loop space of a toric space is addressed. In case the toric space is a
manifold, the structure of the fan dictates whether the Hilbert-Poincar\"e
series has exponential growth. Applications are made to the existence of
infinitely many geometrically distinct periodic geodesics
Application of aerospace-generated technology to water pollution and other public sector problems Quarterly report, 1 Dec. 1968 - 28 Feb. 1969
Aerospace-generated technology considered for solving 22 specific problems in water pollutio
Selective and Efficient Quantum Process Tomography
In this paper we describe in detail and generalize a method for quantum
process tomography that was presented in [A. Bendersky, F. Pastawski, J. P.
Paz, Physical Review Letters 100, 190403 (2008)]. The method enables the
efficient estimation of any element of the --matrix of a quantum process.
Such elements are estimated as averages over experimental outcomes with a
precision that is fixed by the number of repetitions of the experiment.
Resources required to implement it scale polynomically with the number of
qubits of the system. The estimation of all diagonal elements of the
--matrix can be efficiently done without any ancillary qubits. In turn,
the estimation of all the off-diagonal elements requires an extra clean qubit.
The key ideas of the method, that is based on efficient estimation by random
sampling over a set of states forming a 2--design, are described in detail.
Efficient methods for preparing and detecting such states are explicitly shown.Comment: 9 pages, 5 figure
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