Irreversible information loss: Fundamental notions and entropy costs

Anderson, Neal G.

doi:10.1142/s2010194514603548

Cited by 5 publications

(1 citation statement)

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“…Incidentally, the above argument isn't novel, in the sense that, in its broad outlines, and/or at an intuitive level, it has already been well understood by myself and others in the thermodynamics of computing community for at least the last 20 years, if not longer. In terms of explicit discussion of these ideas in the literature, our concept of "independent entropy" was previously called noninformation-bearing entropy by Anderson, as distinguished from informationbearing entropy or mutual information; Anderson discusses these concepts, and the importance of correlations for understanding Landauer's Principle and the thermodynamics of computation in a number of papers [34,35,36,37].…”

Section: Physical Time-evolution and Computational Operationsmentioning

confidence: 99%

Reversible Computation

2018

Lecture Notes in Computer Science

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We review the physical foundations of Landauer's Principle, which relates the loss of information from a computational process to an increase in thermodynamic entropy. Despite the long history of the Principle, its fundamental rationale and proper interpretation remain frequently misunderstood. Contrary to some misinterpretations of the Principle, the mere transfer of entropy between computational and noncomputational subsystems can occur in a thermodynamically reversible way without increasing total entropy. However, Landauer's Principle is not about general entropy transfers; rather, it more specifically concerns the ejection of (all or part of) some correlated information from a controlled, digital form (e.g., a computed bit) to an uncontrolled, non-computational form, i.e., as part of a thermal environment. Any uncontrolled thermal system will, by definition, continually re-randomize the physical information in its thermal state, from our perspective as observers who cannot predict the exact dynamical evolution of the microstates of such environments. Thus, any correlations involving information that is ejected into and subsequently thermalized by the environment will be lost from our perspective, resulting directly in an irreversible increase in total entropy. Avoiding the ejection and thermalization of correlated computational information motivates the reversible computing paradigm, although the requirements for computations to be thermodynamically reversible are less restrictive than frequently described, particularly in the case of stochastic computational operations. There are interesting possibilities for the design of computational processes that utilize stochastic, many-to-one computational operations while nevertheless avoiding net entropy increase that remain to be fully explored.

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Section: Physical Time-evolution and Computational Operationsmentioning

confidence: 99%