Generalizing Landauer’s principle

Maroney, O. J. E.

doi:10.1103/physreve.79.031105

Cited by 85 publications

(123 citation statements)

References 30 publications

(32 reference statements)

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“…This idea was made quantitative by Szilard, who showed, by means of a simple one-molecule gas, that information acquisition, for example, by a Maxwell demon, is necessarily accompanied by an entropy increase of not less than k ln(2) [4], where k is Boltzmann's constant. A closely related phenomenon is the demonstration, due to Landauer, that erasing an unknown bit of information requires energy to be dissipated as heat, amounting to not less than kT ln(2) [5][6][7], where T is the temperature of the environment surrounding the bit.…”

Section: Introductionmentioning

confidence: 99%

Beyond Landauer Erasure

Barnett

Vaccaro

2013

Entropy

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In thermodynamics, one considers thermal systems and the maximization of entropy subject to the conservation of energy. A consequence is Landauer's erasure principle, which states that the erasure of one bit of information requires a minimum energy cost equal to kT ln(2), where T is the temperature of a thermal reservoir used in the process and k is Boltzmann's constant. Jaynes, however, argued that the maximum entropy principle could be applied to any number of conserved quantities, which would suggest that information erasure may have alternative costs. Indeed, we showed recently that by using a reservoir comprising energy degenerate spins and subject to conservation of angular momentum, the cost of information erasure is in terms of angular momentum rather than energy. Here, we extend this analysis and derive the minimum cost of information erasure for systems where different conservation laws operate. We find that, for each conserved quantity, the minimum resource needed to erase one bit of memory is λ −1 ln(2), where λ is related to the average value of the conserved quantity. The costs of erasure depend, fundamentally, on both the nature of the physical memory element and the reservoir with which it is coupled.

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Section: Introductionmentioning

confidence: 99%

Beyond Landauer Erasure

Barnett

Vaccaro

2013

Entropy

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“…In the original protocol, erasing one bit of entropy originally associated with the logical degrees of freedom-localizing the particle to a single well-transfers an equivalent amount of heat in the bath in a way that does not increase the entropy of the Universe. Reversing the process merely removes the same amount of heat from the bath and moves its equivalent to the logical degrees of freedom-creating infor- mation in the "information-bearing degrees of freedom" [25], a point often forgotten [50].…”

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confidence: 99%

Erasure without Work in an Asymmetric Double-Well Potential

Gavrilov

Bechhoefer

2016

Phys. Rev. Lett.

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According to Landauer's principle, erasing a memory requires an average work of at least kT ln 2 per bit. Recent experiments have confirmed this prediction for a one-bit memory represented by a symmetric double-well potential. Here, we present an experimental study of erasure for a memory encoded in an asymmetric double-well potential. Using a feedback trap, we find that the average work to erase can be less than kT ln 2. Surprisingly, erasure protocols that differ subtly give measurably different values for the asymptotic work, a result we explain by showing that one protocol is symmetric with the respect to time reversal, while the other is not. The differences between the protocols help clarify the distinctions between thermodynamic and logical reversibility.Introduction. Landauer's principle states that erasing a one-bit memory requires an average work of at least kT ln 2 [1, 2], with the lower bound achieved in the quasistatic limit. It plays a key role in sharpening our understanding of the second law of thermodynamics and of the interplay between information and thermodynamics, an issue first raised Maxwell [3], developed in important contributions by Szilard [4] and Bennett [5] but also subject to a long, sometimes confused discussion [6]. Recent experiments have confirmed Landauer's prediction in simple systems: in a one-bit memory represented by a symmetric double-well potential [7, 8], in memory encoded by nanomagnetic bits [9, 10], and even in quantum bits [11]. These successes have helped to create an extended version of stochastic thermodynamics [12, 13] that views information as another kind of thermodynamic resource, on the same footing as heat, chemical energy, and other sources of work [14]. This new way of looking at thermodynamics has led to experimental realizations of information engines ("Maxwell demons") [15][16][17][18].Despite its success in simple situations, Landauer's principle remains untested in more complex cases, such as systems where the symmetry between states is broken. This case, briefly mentioned but not pursued in Landauer's original paper [1], was followed up in later theoretical work [2,[19][20][21][22][23][24][25]. In addition, erasure in asymmetric states can be interpreted as situations where the initial system is out of global thermodynamic equilibrium. Since nonequilibrium settings are ubiquitous in biological systems, it is important to establish basic scenarios in simpler settings to understand more clearly, for example, why common biological systems may not be able to reach ultimate thermodynamic limits [26].Here, we explore the broken-symmetry case experimentally by studying erasure in a memory represented by an asymmetric, double-well potential. While we find broad agreement with the main predictions of theoretical work,

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“…Explicit physical processes by which the operations UFZ and RND can be constructed and optimised are given in [18] and for generic operations in [19,29].…”

Section: Logical Reversalmentioning

confidence: 99%

Does a Computer Have an Arrow of Time?

Maroney

2009

Found Phys

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Schulman (Entropy 7(4): [221][222][223][224][225][226][227][228][229][230][231][232][233] 2005) has argued that Boltzmann's intuition, that the psychological arrow of time is necessarily aligned with the thermodynamic arrow, is correct. Schulman gives an explicit physical mechanism for this connection, based on the brain being representable as a computer, together with certain thermodynamic properties of computational processes. Hawking (Physical Origins of Time Asymmetry, Cambridge University Press, Cambridge, 1994) presents similar, if briefer, arguments. The purpose of this paper is to critically examine the support for the link between thermodynamics and an arrow of time for computers. The principal arguments put forward by Schulman and Hawking will be shown to fail. It will be shown that any computational process that can take place in an entropy increasing universe, can equally take place in an entropy decreasing universe. This conclusion does not automatically imply a psychological arrow can run counter to the thermodynamic arrow. Some alternative possible explanations for the alignment of the two arrows will be briefly discussed.

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Generalizing Landauer’s principle

Cited by 85 publications

References 30 publications

Beyond Landauer Erasure

Beyond Landauer Erasure

Erasure without Work in an Asymmetric Double-Well Potential

Does a Computer Have an Arrow of Time?

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