8,251 research outputs found
Simulating chemistry using quantum computers
The difficulty of simulating quantum systems, well-known to quantum chemists,
prompted the idea of quantum computation. One can avoid the steep scaling
associated with the exact simulation of increasingly large quantum systems on
conventional computers, by mapping the quantum system to another, more
controllable one. In this review, we discuss to what extent the ideas in
quantum computation, now a well-established field, have been applied to
chemical problems. We describe algorithms that achieve significant advantages
for the electronic-structure problem, the simulation of chemical dynamics,
protein folding, and other tasks. Although theory is still ahead of experiment,
we outline recent advances that have led to the first chemical calculations on
small quantum information processors.Comment: 27 pages. Submitted to Ann. Rev. Phys. Che
Introduction to Quantum Algorithms for Physics and Chemistry
In this introductory review, we focus on applications of quantum computation
to problems of interest in physics and chemistry. We describe quantum
simulation algorithms that have been developed for electronic-structure
problems, thermal-state preparation, simulation of time dynamics, adiabatic
quantum simulation, and density functional theory.Comment: 44 pages, 5 figures; comments or suggestions for improvement are
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Digital Quantum Simulation of the Statistical Mechanics of a Frustrated Magnet
Many interesting problems in physics, chemistry, and computer science are
equivalent to problems of interacting spins. However, most of these problems
require computational resources that are out of reach by classical computers. A
promising solution to overcome this challenge is to exploit the laws of quantum
mechanics to perform simulation. Several "analog" quantum simulations of
interacting spin systems have been realized experimentally. However, relying on
adiabatic techniques, these simulations are limited to preparing ground states
only. Here we report the first experimental results on a "digital" quantum
simulation on thermal states; we simulated a three-spin frustrated magnet, a
building block of spin ice, with an NMR quantum information processor, and we
are able to explore the phase diagram of the system at any simulated
temperature and external field. These results serve as a guide for identifying
the challenges for performing quantum simulation on physical systems at finite
temperatures, and pave the way towards large scale experimental simulations of
open quantum systems in condensed matter physics and chemistry.Comment: 7 pages for the main text plus 6 pages for the supplementary
material
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
Simulations in Early Universe Theory
We give an impression of the type of results that have been obtained with
numerical lattice simulations of field theory in the early universe.Comment: 19 pages, contribution to Lattice 200
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