Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!mips!dimacs.rutgers.edu!aramis.rutgers.edu!planchet.rutgers.edu!nanotech From: piety@hplred.hpl.hp.com (Bob Piety) Newsgroups: sci.nanotech Subject: Re: Reliability of nanocomputers Message-ID: Date: 13 May 91 21:09:11 GMT Sender: nanotech@planchet.rutgers.edu Organization: Hewlett Packard Labs, Palo Alto CA Lines: 41 Approved: nanotech@aramis.rutgers.edu / merkle@parc.xerox.com (Ralph Merkle) / 11:42 am May 3, 1991 / > parts (stiffness scales with length. Double the size, ^^^^^^ > double the stiffness) hence smaller positional errors. > Because positional errors caused by thermal noise are > described by a gaussian distribution, doubling the > size will result in a dramatic reduction in error rates. > Instead of 10^-12, we'd get (much) better than 10^-24. ^^^^^^ ^^^^^^ > temperatures (77 Kelvins) would reduce thermal noise by > almost a factor of 4, which would result in error rates ^^^^^^^^^^^ > much less than 10^-40. ^^^^^^ I don't understand your mathematics-- please explain how you arrive at these figures. Thanks, Bob piety@hplred.hpl.hp.com (415)857-4759 [In Drexler's paper "Rod Logic and Thermal Noise..." the probability of error (after three pages of calculus) comes out in the form 2 exp [1/2 (sigma phi/kT)^2 -D phi/kT] Where phi is alignment force (a design constant), D is minimum displacement for error (ditto), and sigma is std. dev. of knob displacement, a function of T whose leading term is linear in kT (k is Boltzmann's constant). Thus the first term in the exponential is second-order; ignoring it, if we drop the temperature by a factor of 2 we divide the probability of error by exp(D phi) (which can be arbitrarily large, depending on the design). The whole paper can be found in Molecular Electronic Devices III (1988, Elsevier). --JoSH]