Showing papers on "Quantum error correction published in 1985"
TL;DR: The construction of a quantum-mechanical Hamiltonian describing a computer generates a dynamical evolution which mimics a sequence of elementary logical steps if each logical step is locally reversible (global reversibility is insufficient).
Abstract: This article is concerned with the construction of a quantum-mechanical Hamiltonian describing a computer. This Hamiltonian generates a dynamical evolution which mimics a sequence of elementary logical steps. This can be achieved if each logical step is locally reversible (global reversibility is insufficient). Computational errors due to noise can be corrected by means of redundancy. In particular, reversible error-correcting codes can be embedded in the Hamiltonian itself. An estimate is given for the minimum amount of entropy which must be dissipated at a given noise level and tolerated error rate.
835 citations
TL;DR: In this paper, a parallel development of the semiclassical and quantum statistics of multispatiotemporal mode direct, homodyne, and heterodyne detection using an ideal (except for its subunity quantum efficiency) photon detector is presented.
Abstract: A parallel development of the semiclassical and quantum statistics of multispatiotemporal mode direct, homodyne, and heterodyne detection using an ideal (except for its subunity quantum efficiency) photon detector is presented. Particular emphasis is placed on the latter two coherent detection Configurations. The primary intent is to delineate the semiclassical theory's regime of validity and to show, within this regime of validity, how the quantum theory's signal quantum noise, local oscillator quantum noise, the quantum noise incurred because of subunity detector quantum efficiency, plus (for heterodyning only) image band quantum noise produce the quantitative equivalent of the semiclassical theory's local oscillator shot noise. The effects of classical fluctuations on the local oscillator, and the recently suggested dual-detector arrangement for suppressing these fluctuations, are treated. It is Shown that previous studies of this arrangement have neglected a potentially significant noise contribution.
135 citations
TL;DR: This paper examines various finite-element schemes, construct the effective lattice Hamiltonian, and calculate eigenvalues of discrete time-lattice quantum systems that accurately approximate continuum quantum systems.
Abstract: The finite-element (collocation) method enables us to construct discrete time-lattice quantum systems that accurately approximate continuum quantum systems The discrete quantum systems so generated are fully consistent quantum-mechanical systems in their own right This paper gives a comprehensive treatment of such quantum systems We examine various finite-element schemes, construct the effective lattice Hamiltonian, and calculate eigenvalues Numerical results are extremely easy to obtain and are very accurate
54 citations
15 Jun 1985-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the effects of both classical and quantum noise on the operation of free electron lasers are analyzed from both a classical and a quantum mechanical perspective, and it is shown that shot noise can be reduced in some devices in order to study the quantum fluctuations but there are limits below which the shot noise cannot be reduced due to the Heisenberg uncertainty principle.
Abstract: We present an analysis of the effects of both classical and quantum noise on the operation of free electron lasers. Shot noise is considered from both classical and quantum mechanical perspectives. The photon number fluctuations due to shot noise are thermal in nature and should mask quantum effects in most conceivable devices. It is found that shot noise could be reduced in some devices in order to study the effects of quantum fluctuations but there are limits below which the shot noise cannot be reduced due to the Heisenberg uncertainty principle. It is possible to introduce both shot and quantum noise into classical models. The results of some simulations carried out to study the effects of noise on pulse propagation are shown.
27 citations