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Related Concept Videos

Woodward–Hoffmann Selection Rules and Microscopic Reversibility01:34

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Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...
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Gradient Echo Quantum Memory in Warm Atomic Vapor
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Published on: November 11, 2013

Reversibility and energetics in optical computing.

H J Caulfield, J Shamir, J E Ludman

    Optics Letters
    |September 23, 2009
    PubMed
    Summary
    This summary is machine-generated.

    Energy-conserving computer operations do not increase entropy and have no minimum energy cost. Reversible optical gates, crucial for information conservation, incur unavoidable energy losses, despite negligible photon energy costs.

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    Published on: February 6, 2014

    Area of Science:

    • Information theory
    • Thermodynamics
    • Optical computing

    Background:

    • The relationship between computation, energy, and entropy is a fundamental question in physics and computer science.
    • Understanding the minimum energy cost of computation is crucial for developing energy-efficient computing technologies.
    • Information-conserving operations are theoretically linked to reversibility, but practical implementations face challenges.

    Purpose of the Study:

    • To analyze the energy costs associated with information-conserving computer operations.
    • To investigate the implications of reversibility on energy expenditure in optical computing.
    • To clarify the different meanings of 'energy per calculation' in the context of physical limits.

    Main Methods:

    • Theoretical analysis of information-conserving operations based on thermodynamic principles.
    • Examination of energy losses in reversible optical gate designs.
    • Comparison of theoretical energy costs with practical limitations.

    Main Results:

    • Information-conserving operations do not inherently increase entropy, thus lacking a fundamental minimum energy cost from an information perspective.
    • Reversible optical gates, while theoretically information-conserving, inevitably incur energy losses.
    • The energy expended by a single photon in a conservative optical operation is significantly less than kT (thermal energy).

    Conclusions:

    • The theoretical minimum energy cost of computation is linked to information irreversibility, not energy conservation alone.
    • Practical implementations of reversible computing, particularly optical, face energy loss challenges.
    • Further research is needed to bridge the gap between theoretical energy efficiency and practical optical computing.