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Physics and Computation, 1994. PhysComp '94, Proceedings., Workshop on

17-20 Nov 1994

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Displaying Results 1 - 25 of 35
  • Space, time, logic, and things

    Publication Year: 1994, Page(s):36 - 43
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (620 KB)

    We examine the fundamental origins of logic and show how these fundamentals are related to basic concepts of space, time, objects, and events used in both physics and computing. We attempt to show how a universe can be constructed beginning not from first principles, but from no principles. Several possible implications for physics and mathematics are also discussed View full abstract»

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  • Space and time in computation, topology and discrete physics

    Publication Year: 1994, Page(s):44 - 53
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (772 KB)

    A step can be regarded as an elementary ordering of two objects (or operators). A step is a distinction combined with an action that crosses the boundary of that distinction. The elementary step can be seen as a reference, as a division of space or as a tick of a clock. By looking at the structure of a step, we provide a context that unifies specific aspects of special relativity, Laws of Form, to... View full abstract»

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  • Zig-zag path to understanding [physical limits of information handling]

    Publication Year: 1994, Page(s):54 - 59
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (420 KB)

    Our understanding of the fundamental physical limits of information handling has developed along a very convoluted path. Most of the initially plausible physical conjectures have turned out to be wrong. A participant's personal view of these events as not a disciplined contribution to the history of science. The author does, however, list his own mistakes along with those of others View full abstract»

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  • The stabilisation of quantum computations

    Publication Year: 1994, Page(s):60 - 62
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (180 KB)

    A quantum computer is a device capable of performing computational tasks that depend on characteristically quantum mechanical effects, in particular coherent quantum superposition. Such devices can efficiently perform classes of computation (e.g. factorisation) which are believed to be intractable on any classical computer. This makes it highly desirable to construct such devices. In this paper, w... View full abstract»

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  • Statistical mechanics of combinatorial search

    Publication Year: 1994, Page(s):196 - 202
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (520 KB)

    The statistical mechanics of combinatorial search problems is described using the example of the well-known NP-complete graph coloring problem. A simple parameter describing the problem structure predicts the difficulty of solving the problem, on average. However, because of the large variance associated with this prediction, it is of limited direct use for individual instances. Additional paramet... View full abstract»

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  • Reversible logic issues in adiabatic CMOS

    Publication Year: 1994, Page(s):111 - 118
    Cited by:  Papers (25)  |  Patents (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (580 KB)

    Power dissipation in CMOS circuits has become increasingly important for the design of portable, embedded and high-performance computing systems. Our VLSI research group has investigated a novel form of energy-conserving logic suitable for CMOS. Through small chip-building experiments, we have demonstrated the low-power operation of simple logic functions. These chips have used logical reversibili... View full abstract»

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  • Can quantum computers have simple Hamiltonians?

    Publication Year: 1994, Page(s):63 - 68
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (432 KB)

    Recently, P. Shor (1994) has shown that quantum computers (computers which can operate simultaneously on a quantum superposition of inputs) permit efficient (i.e. polynomial-time) solutions of problems for which no efficient classical-mechanical solution is known. This has led to renewed interest in the question of whether or not quantum computers can be physically realized. One kind of quantum co... View full abstract»

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  • Phase transitions and coarse-grained search

    Publication Year: 1994, Page(s):203 - 208
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (404 KB)

    Abstraction is a method for solving a variety of computational search problems that uses coarse-graining to simplify the search. When a coarse-grained, or abstract, solution is found, it is then refined to give a complete solution. We present a model of this abstraction process for constraint satisfaction problems, a well-known class of NP-complete search problems. This model is then used to ident... View full abstract»

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  • Thermal logic circuits

    Publication Year: 1994, Page(s):119 - 127
    Cited by:  Papers (2)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (728 KB)

    Thermal logic is a hypothetical device technology that allows one to analyze the energetics of computing machines in a simpler setting than real device technologies. The paper describes the rudiments of thermal logic, and uses it to analyze reversible logic pipelines. The similarity between thermal logic and electronic logic is explained, and thermal analogs of electronic devices and circuits are ... View full abstract»

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  • Quantum oblivious transfer is secure against all individual measurements

    Publication Year: 1994, Page(s):69 - 77
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (604 KB)

    Shows that the BBCS-protocol (Bennett, Brassard, Cre´peau and Skubiszewska, CRYPTO'91, 1992) implementing one of the most important cryptographic primitives-`oblivious transfer'-is secure against any individual measurement allowed by quantum mechanics. We analyze the common situation where successive measurements on the same photon could be used to cheat in the protocol. We model this situat... View full abstract»

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  • The Boltzmann entropy and randomness tests

    Publication Year: 1994, Page(s):209 - 216
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (672 KB)

    In the context of the dynamical systems of classical mechanics, we introduce two new notions called “algorithmic fine-grain and coarse-grain entropy”. The fine-grain algorithmic entropy is, on the one hand, a simple variant of the Martin-Lof (and other) randomness tests, and, on the other hand, a connecting link between description (Kolmogorov) complexity, Gibbs entropy and Boltzmann e... View full abstract»

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  • Research toward nanoelectronic computing technologies in Japan

    Publication Year: 1994, Page(s):1 - 4
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    A perspective of the research activities in Japan aimed at the development of new computing technologies based on structures with ultra-small dimensions is presented. Examples are given of work toward the development of resonant tunneling circuits, electron-wave interference and single-electron tunneling devices, and atomic-scale fabrication technologies View full abstract»

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  • Some results on invertible cellular automata

    Publication Year: 1994, Page(s):143 - 150
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (604 KB)

    Addresses certain questions concerning invertible cellular automata, and presents new results in this area. Specifically, we explicitly construct a cellular automaton in a class (a residual class) previously known not to be empty only via a nonconstructive existence proof. This class contains cellular automata that are invertible on every finite support but not on an infinite lattice. Moreover, we... View full abstract»

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  • A reversible instruction set architecture and algorithms

    Publication Year: 1994, Page(s):128 - 134
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (400 KB)

    We describe a reversible instruction set architecture using recently developed reversible logic design techniques. Such an architecture has the dual advantage of being able to run backwards and of being, in theory, implementable so as to dissipate less than log 2 kT joules per bit operation. We analyze several basic control structures and algorithms on the architecture, showing that, for example, ... View full abstract»

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  • Physical computation and parallelism (constructive postmodern physics)

    Publication Year: 1994, Page(s):78 - 87
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (504 KB)

    There is increasing evidence that information may be the basic stuff of the universe. We consider this proposition in the light of Bohm and Hiley's (1993) quantum potential, the work of the ANPA group on the combinatorial hierarchy, and the natural philosophies of G. Kron (1963) and M. Jessel (1962). We compare and contrast the philosophical backgrounds of both these and the more conventional Cope... View full abstract»

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  • Entropy cost of information

    Publication Year: 1994, Page(s):217 - 226
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (592 KB)

    An entropy analysis of Szilard's (1929) one-molecule Maxwell's demon suggests a general theory of the entropy cost of information. The entropy of the demon increases due to the decoupling of the molecule from the measurement information. In general, neither measurement nor erasure is fundamentally a thermodynamically costly operation; however, the decorrelation of the system from the information m... View full abstract»

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  • Quantum cellular automata: the physics of computing with arrays of quantum dot molecules

    Publication Year: 1994, Page(s):5 - 13
    Cited by:  Papers (50)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (632 KB)

    We discuss the fundamental limits of computing using a new paradigm for quantum computation, cellular automata composed of arrays of coulombically coupled quantum dot molecules, which we term quantum cellular automata (QCA). Any logical or arithmetic operation can be performed in this scheme. QCA's provide a valuable concrete example of quantum computation in which a number of fundamental issues c... View full abstract»

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  • Computational spacetimes

    Publication Year: 1994, Page(s):239 - 245
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (544 KB)

    The execution of an algorithm is limited by physical constraints rooted in the finite speed of signal propagation. To optimize the usage of the physical degrees of freedom provided by a computational engine, one must apply all relevant technological and physical constraints to the temporal and spatial structure of a computational procedure. Computational spacetimes make explicit both technological... View full abstract»

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  • On the average-case complexity of the reversibility problem for finite cellular automata

    Publication Year: 1994, Page(s):151 - 155
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (444 KB)

    Of particular relevance in the theory and applications of cellular automata is the concept of invertibility. We study the computational complexity of deciding whether or not a given finite cellular automata is invertible. This problem is known to be CoNP-complete, we prove that the expected-time complexity of its randomized version is “hard”: the problem is CoRNP-complete. Finally, we ... View full abstract»

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  • Impact of locality and dimensionality limits on architectural trends

    Publication Year: 1994, Page(s):30 - 35
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (480 KB)

    Since computing is a physical activity, all forms of computing must obey locality constraints imposed by physics. Unknowingly, many software abstractions violate locality constraints because they represent high dimensional topologies that have higher degrees of freedom than is uniformly implementable by the underlying physical architecture. This semantic gap between abstractions implemented in the... View full abstract»

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  • Chu spaces: automata with quantum aspects

    Publication Year: 1994, Page(s):186 - 195
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (896 KB)

    Chu spaces are a model of concurrent computation extending automata theory to express branching time and true concurrency. They exhibit in a primitive form the quantum mechanical phenomena of complementarity and uncertainty. The complementarity arises as the duality of information and time, automata and schedules, and states and events. Uncertainty arises when we define a measurement to be a morph... View full abstract»

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  • Toward an information mechanics

    Publication Year: 1994, Page(s):95 - 110
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1372 KB)

    Presents a chain of reasoning that makes an information mechanics a plausible goal. A radically new model of distributed computation that exceeds Turing's sequential model refutes the perception that quantum mechanics cannot be captured computationally. Our new model, called the `phase web paradigm', is itself captured naturally by a physically relevant mathematics, that of a Clifford algebra. The... View full abstract»

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  • Analog computation with continuous ODEs

    Publication Year: 1994, Page(s):265 - 274
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (836 KB)

    Demonstrates simple, low-dimensional systems of ODEs that can simulate arbitrary finite automata, push-down automata, and Turing machines. We conclude that there are systems of ODEs in R3 with continuous vector fields possessing the power of universal computation. Further, such computations can be made robust to small errors in coding of the input or measurement of the output.... View full abstract»

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  • Encoded arithmetic for reversible logic

    Publication Year: 1994, Page(s):135 - 142
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (556 KB)

    The CCD based implementations of reversible logic consume a constant amount of energy per switching event which depends only on the charge packet size and not on the interconnect length. Within this model of computation, it seems possible to leverage data, encoding to reduce the number of switching events for the computation, resulting in lower overall computation energy. We explore the applicabil... View full abstract»

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  • A fast algorithm for entropy estimation of grey-level images

    Publication Year: 1994, Page(s):233 - 238
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (448 KB)

    Examines an efficient approach to the calculation of the entropy of long binary and nonbinary 1D information sequences. The entropy calculation is accomplished in a time which is linear in the sequence length. The method is expanded to estimate the entropy of grey-level images which, under raster scanning, may be represented as 1D information sequences. The entropy estimate obtained depends on the... View full abstract»

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