47,397 research outputs found
Gate-Level Simulation of Quantum Circuits
While thousands of experimental physicists and chemists are currently trying
to build scalable quantum computers, it appears that simulation of quantum
computation will be at least as critical as circuit simulation in classical
VLSI design. However, since the work of Richard Feynman in the early 1980s
little progress was made in practical quantum simulation. Most researchers
focused on polynomial-time simulation of restricted types of quantum circuits
that fall short of the full power of quantum computation. Simulating quantum
computing devices and useful quantum algorithms on classical hardware now
requires excessive computational resources, making many important simulation
tasks infeasible. In this work we propose a new technique for gate-level
simulation of quantum circuits which greatly reduces the difficulty and cost of
such simulations. The proposed technique is implemented in a simulation tool
called the Quantum Information Decision Diagram (QuIDD) and evaluated by
simulating Grover's quantum search algorithm. The back-end of our package,
QuIDD Pro, is based on Binary Decision Diagrams, well-known for their ability
to efficiently represent many seemingly intractable combinatorial structures.
This reliance on a well-established area of research allows us to take
advantage of existing software for BDD manipulation and achieve unparalleled
empirical results for quantum simulation
Present and Future CP Measurements
We review theoretical and experimental results on CP violation summarizing
the discussions in the working group on CP violation at the UK phenomenology
workshop 2000 in Durham.Comment: 104 pages, Latex, to appear in Journal of Physics
Opportunities, Challenges, and Fantasies in Lattice QCD
Some important problems in quantitative QCD will certainly yield to hard work
and adequate investment of resources, others appear difficult but may be
accessible, and still others will require essentially new ideas. Here I
identify several examples in each class.Comment: 10 pages, 2 figures; Keynote talk at Lattice 2002, Boston, June 2002.
(Text unchanged; figure formatting corrected.) Email correspondence to
[email protected]
Quantum information and precision measurement
We describe some applications of quantum information theory to the analysis
of quantum limits on measurement sensitivity. A measurement of a weak force
acting on a quantum system is a determination of a classical parameter
appearing in the master equation that governs the evolution of the system;
limitations on measurement accuracy arise because it is not possible to
distinguish perfectly among the different possible values of this parameter.
Tools developed in the study of quantum information and computation can be
exploited to improve the precision of physics experiments; examples include
superdense coding, fast database search, and the quantum Fourier transform.Comment: 13 pages, 1 figure, proof of conjecture adde
Multiplicative scale uncertainties in the unified approach for constructing confidence intervals
We have investigated how uncertainties in the estimation of the detection
efficiency affect the 90% confidence intervals in the unified approach for
constructing confidence intervals. The study has been conducted for experiments
where the number of detected events is large and can be described by a Gaussian
probability density function. We also assume the detection efficiency has a
Gaussian probability density and study the range of the relative uncertainties
between 0 and 30%. We find that the confidence intervals
provide proper coverage over a wide signal range and increase smoothly and
continuously from the intervals that ignore scale uncertainties with a
quadratic dependence on .Comment: 22 pages, 7 figures, 2 table
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