Harvesting Brownian Motion: Zero Energy Computational Sampling

Fuente: arXiv
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Main Authors: Doty, David, Kornerup, Niels, Luchsinger, Austin, Orshansky, Leo, Soloveichik, David, Woods, Damien
Format: Preprint
Published: 2023
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author Doty, David
Kornerup, Niels
Luchsinger, Austin
Orshansky, Leo
Soloveichik, David
Woods, Damien
author_facet Doty, David
Kornerup, Niels
Luchsinger, Austin
Orshansky, Leo
Soloveichik, David
Woods, Damien
contents The key factor currently limiting the advancement of computational power of electronic computation is no longer the manufacturing density and speed of components, but rather their high energy consumption. While it has been widely argued that reversible computation can escape the fundamental Landauer limit of $k_B T\ln(2)$ Joules per irreversible computational step, there is disagreement around whether indefinitely reusable computation can be achieved without energy dissipation. Here we focus on the relatively simpler context of sampling problems, which take no input, so avoids modeling the energy costs of the observer perturbing the machine to change its input. Given an algorithm $A$ for generating samples from a distribution, we desire a device that can perpetually generate samples from that distribution driven entirely by Brownian motion. We show that such a device can efficiently execute algorithm $A$ in the sense that we must wait only $O(\text{time}(A)^2)$ between samples. We consider two output models: Las Vegas, which samples from the exact probability distribution every $4$ tries in expectation, and Monte Carlo, in which every try succeeds but the distribution is only approximated. We base our model on continuous-time random walks over the state space graph of a general computational machine, with a space-bounded Turing machine as one instantiation. The problem of sampling a computationally complex probability distribution with no energy dissipation informs our understanding of the energy requirements of computation, and may lead to more energy efficient randomized algorithms.
format Preprint
id arxiv_https___arxiv_org_abs_2309_06957
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Harvesting Brownian Motion: Zero Energy Computational Sampling
Doty, David
Kornerup, Niels
Luchsinger, Austin
Orshansky, Leo
Soloveichik, David
Woods, Damien
Data Structures and Algorithms
Emerging Technologies
60J28
G.3; F.1.m
The key factor currently limiting the advancement of computational power of electronic computation is no longer the manufacturing density and speed of components, but rather their high energy consumption. While it has been widely argued that reversible computation can escape the fundamental Landauer limit of $k_B T\ln(2)$ Joules per irreversible computational step, there is disagreement around whether indefinitely reusable computation can be achieved without energy dissipation. Here we focus on the relatively simpler context of sampling problems, which take no input, so avoids modeling the energy costs of the observer perturbing the machine to change its input. Given an algorithm $A$ for generating samples from a distribution, we desire a device that can perpetually generate samples from that distribution driven entirely by Brownian motion. We show that such a device can efficiently execute algorithm $A$ in the sense that we must wait only $O(\text{time}(A)^2)$ between samples. We consider two output models: Las Vegas, which samples from the exact probability distribution every $4$ tries in expectation, and Monte Carlo, in which every try succeeds but the distribution is only approximated. We base our model on continuous-time random walks over the state space graph of a general computational machine, with a space-bounded Turing machine as one instantiation. The problem of sampling a computationally complex probability distribution with no energy dissipation informs our understanding of the energy requirements of computation, and may lead to more energy efficient randomized algorithms.
title Harvesting Brownian Motion: Zero Energy Computational Sampling
topic Data Structures and Algorithms
Emerging Technologies
60J28
G.3; F.1.m
url https://arxiv.org/abs/2309.06957