3,102 research outputs found
Dissipation and lag in irreversible processes
When a system is perturbed by the variation of external parameters, a lag
generally develops between the actual state of the system and the equilibrium
state corresponding to the current parameter values. We establish a
microscopic, quantitative relation between this lag and the dissipated work
that accompanies the process. We illustrate this relation using a model system.Comment: 6 pages, 3 figures, accepted for publication in EP
Asynchronous multiple-access channel capacity
The capacity region for the discrete memoryless multiple-access channel without time synchronization at the transmitters and receivers is shown to be the same as the known capacity region for the ordinary multiple-access channel. The proof utilizes time sharing of two optimal codes for the ordinary multiple-access channel and uses maximum likelihood decoding over shifts of the hypothesized transmitter words
Eavesdropping without quantum memory
In quantum cryptography the optimal eavesdropping strategy requires that the
eavesdropper uses quantum memories in order to optimize her information. What
happens if the eavesdropper has no quantum memory? It is shown that the best
strategy is actually to adopt the simple intercept/resend strategy.Comment: 9 pages LaTeX, 3 figure
Hashing protocol for distilling multipartite CSS states
We present a hashing protocol for distilling multipartite CSS states by means
of local Clifford operations, Pauli measurements and classical communication.
It is shown that this hashing protocol outperforms previous versions by
exploiting information theory to a full extent an not only applying CNOTs as
local Clifford operations. Using the information-theoretical notion of a
strongly typical set, we calculate the asymptotic yield of the protocol as the
solution of a linear programming problem.Comment: 13 pages, 3 figures, RevTeX
Measuring thermodynamic length
Thermodynamic length is a metric distance between equilibrium thermodynamic
states. Among other interesting properties, this metric asymptotically bounds
the dissipation induced by a finite time transformation of a thermodynamic
system. It is also connected to the Jensen-Shannon divergence, Fisher
information and Rao's entropy differential metric. Therefore, thermodynamic
length is of central interest in understanding matter out-of-equilibrium. In
this paper, we will consider how to define thermodynamic length for a small
system described by equilibrium statistical mechanics and how to measure
thermodynamic length within a computer simulation. Surprisingly, Bennett's
classic acceptance ratio method for measuring free energy differences also
measures thermodynamic length.Comment: 4 pages; Typos correcte
Note on exponential families of distributions
We show that an arbitrary probability distribution can be represented in
exponential form. In physical contexts, this implies that the equilibrium
distribution of any classical or quantum dynamical system is expressible in
grand canonical form.Comment: 5 page
Statistical mechanics of lossy compression using multilayer perceptrons
Statistical mechanics is applied to lossy compression using multilayer
perceptrons for unbiased Boolean messages. We utilize a tree-like committee
machine (committee tree) and tree-like parity machine (parity tree) whose
transfer functions are monotonic. For compression using committee tree, a lower
bound of achievable distortion becomes small as the number of hidden units K
increases. However, it cannot reach the Shannon bound even where K -> infty.
For a compression using a parity tree with K >= 2 hidden units, the rate
distortion function, which is known as the theoretical limit for compression,
is derived where the code length becomes infinity.Comment: 12 pages, 5 figure
Generalized Jarzynski Equality under Nonequilibrium Feedback Control
The Jarzynski equality is generalized to situations in which nonequilibrium
systems are subject to a feedback control. The new terms that arise as a
consequence of the feedback describe the mutual information content obtained by
measurement and the efficacy of the feedback control. Our results lead to a
generalized fluctuation-dissipation theorem that reflects the readout
information, and can be experimentally tested using small thermodynamic
systems. We illustrate our general results by an introducing "information
ratchet," which can transport a Brownian particle in one direction and extract
a positive work from the particle
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