308 research outputs found
Quantum state conversion by cross-Kerr interaction
A generalized Mach-Zehnder-type interferometer equipped with cross-Kerr
elements is proposed to convert N-photon truncated single-mode quantum states
into (N+1)-mode single-photon states, which are suitable for further state
manipulation by means of beam splitter arrays and ON/OFF-detections, and vice
versa. Applications to the realization of unitary and non-unitary
transformations, quantum state reconstruction, and quantum telemanipulation are
studied.Comment: 22 pages, 4 figures, using a4.st
Streamflow and selected precipitation data for Yucca Mountain and vicinity, Nye County, Nevada, water years 1983--85
Streamflow and precipitation data collected at and near Yucca Mountain, Nevada, during water years 1983--85, are presented in this report. The data were collected and compiled as part of the studies the US Geological Survey is making, in cooperation with the US Department of Energy, to characterize surface-water hydrology in the Yucca Mountain area. Streamflow data include daily mean discharges and peak discharges at 4 complete-record gaging stations and peak discharges at 10 crest-stage, partial-record stations and 12 miscellaneous sites. Precipitation data include cumulative totals at 12 stations maintained by the US Geological Survey and daily totals at 17 stations maintained by the Weather Service Nuclear Support Office, National Oceanic and Atmospheric Administration
Imperfect Detectors in Linear Optical Quantum Computers
We discuss the effects of imperfect photon detectors suffering from loss and
noise on the reliability of linear optical quantum computers. We show that for
a given detector efficiency, there is a maximum achievable success probability,
and that increasing the number of ancillary photons and detectors used for one
controlled sign flip gate beyond a critical point will decrease the probability
that the computer will function correctly. We have also performed simulations
of some small logic gates and estimate the efficiency and noise levels required
for the linear optical quantum computer to function properly.Comment: 13 pages, 5 figure
Schrodinger cats and their power for quantum information processing
We outline a toolbox comprised of passive optical elements, single photon
detection and superpositions of coherent states (Schrodinger cat states). Such
a toolbox is a powerful collection of primitives for quantum information
processing tasks. We illustrate its use by outlining a proposal for universal
quantum computation. We utilize this toolbox for quantum metrology
applications, for instance weak force measurements and precise phase
estimation. We show in both these cases that a sensitivity at the Heisenberg
limit is achievable.Comment: 10 pages, 5 figures; Submitted to a Special Issue of J. Opt. B on
"Fluctuations and Noise in Photonics and Quantum Optics" (Herman Haus
Memorial Issue
An atomic boson sampler
A boson sampler implements a restricted model of quantum computing. It is
defined by the ability to sample from the distribution resulting from the
interference of identical bosons propagating according to programmable,
non-interacting dynamics. Here, we demonstrate a new combination of tools for
implementing boson sampling using ultracold atoms in a two-dimensional,
tunnel-coupled optical lattice. These tools include fast and programmable
preparation of large ensembles of nearly identical bosonic atoms
( indistinguishability) by means of rearrangement with
optical tweezers and high-fidelity optical cooling, propagation for variable
evolution time in the lattice with low loss (, independent of
evolution time), and high fidelity detection of the atom positions after their
evolution (typically ). With this system, we study specific
instances of boson sampling involving up to atoms distributed among sites in the lattice. Direct verification of a given boson sampling
distribution is not feasible in this regime. Instead, we introduce and perform
targeted tests to determine the indistinguishability of the prepared atoms, to
characterize the applied family of single particle unitaries, and to observe
expected bunching features due to interference for a large range of atom
numbers. When extended to interacting systems, our work demonstrates the core
capabilities required to directly assemble ground and excited states in
simulations of various Hubbard models.Comment: 20 pages, 7 figures (main text and methods); 8 pages, 2 figures
(supplemental materials
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