0308164v2

related topics
{classical, space, random}
{algorithm, log, probability}
{qubit, qubits, gate}
{energy, state, states}
{state, algorithm, problem}
{measurement, state, measurements}
{information, entropy, channel}
{spin, pulse, spins}
{vol, operators, histories}
{states, state, optimal}
{state, phys, rev}
{phase, path, phys}
{level, atom, field}

Estimation of the Local Density of States on a Quantum Computer

Joseph Emerson, Seth Lloyd, David Poulin, David Cory

abstract: We report an efficient quantum algorithm for estimating the local density of states (LDOS) on a quantum computer. The LDOS describes the redistribution of energy levels of a quantum system under the influence of a perturbation. Sometimes known as the ``strength function'' from nuclear spectroscopy experiments, the shape of the LDOS is directly related to the survivial probability of unperturbed eigenstates, and has recently been related to the fidelity decay (or ``Loschmidt echo'') under imperfect motion-reversal. For quantum systems that can be simulated efficiently on a quantum computer, the LDOS estimation algorithm enables an exponential speed-up over direct classical computation.

oai_identifier:
oai:arXiv.org:quant-ph/0308164
categories:
quant-ph cond-mat.other nlin.CD nucl-th
comments:
4 pages (revtex) including 1 figure
doi:
10.1103/PhysRevA.69.050305
arxiv_id:
quant-ph/0308164
journal_ref:
Phys.Rev. A69 (2004) 050305
created:
2003-08-28
updated:
2003-08-29

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