5,572 research outputs found
NMR Quantum Computation
In this article I will describe how NMR techniques may be used to build
simple quantum information processing devices, such as small quantum computers,
and show how these techniques are related to more conventional NMR experiments.Comment: Pedagogical mini review of NMR QC aimed at NMR folk. Commissioned by
Progress in NMR Spectroscopy (in press). 30 pages RevTex including 15 figures
(4 low quality postscript images
Quantum computation with phase drift errors
We present results of numerical simulations of the evolution of an ion trap
quantum computer made out of 18 ions which are subject to a sequence of nearly
15000 laser pulses in order to find the prime factors of N=15. We analyze the
effect of random and systematic phase drift errors arising from inaccuracies in
the laser pulses which induce over (under) rotation of the quantum state.
Simple analytic estimates of the tolerance for the quality of driving pulses
are presented. We examine the use of watchdog stabilization to partially
correct phase drift errors concluding that, in the regime investigated, it is
rather inefficient.Comment: 5 pages, RevTex, 2 figure
Universality in Quantum Computation
We show that in quantum computation almost every gate that operates on two or
more bits is a universal gate. We discuss various physical considerations
bearing on the proper definition of universality for computational components
such as logic gates.Comment: 11 pages, LaTe
Improving the purity of one- and two-qubit gates by AC fields
We investigate the influence of AC driving fields on the coherence properties
of one- and two-qubit gate operations. In both cases, we find that for suitable
driving parameters, the gate purity improves significantly. A mapping of the
time-dependent system-bath model to an effective static model provides
analytical results. The resulting purity loss compares favorably with numerical
results.Comment: 16 pages, 7 figures, style file include
Quantum Computing: Pro and Con
I assess the potential of quantum computation. Broad and important
applications must be found to justify construction of a quantum computer; I
review some of the known quantum algorithms and consider the prospects for
finding new ones. Quantum computers are notoriously susceptible to making
errors; I discuss recently developed fault-tolerant procedures that enable a
quantum computer with noisy gates to perform reliably. Quantum computing
hardware is still in its infancy; I comment on the specifications that should
be met by future hardware. Over the past few years, work on quantum computation
has erected a new classification of computational complexity, has generated
profound insights into the nature of decoherence, and has stimulated the
formulation of new techniques in high-precision experimental physics. A broad
interdisciplinary effort will be needed if quantum computers are to fulfill
their destiny as the world's fastest computing devices. (This paper is an
expanded version of remarks that were prepared for a panel discussion at the
ITP Conference on Quantum Coherence and Decoherence, 17 December 1996.)Comment: 17 pages, LaTeX, submitted to Proc. Roy. Soc. Lond. A, minor
correction
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