1,785 research outputs found
Designing optimal discrete-feedback thermodynamic engines
Feedback can be utilized to convert information into useful work, making it
an effective tool for increasing the performance of thermodynamic engines.
Using feedback reversibility as a guiding principle, we devise a method for
designing optimal feedback protocols for thermodynamic engines that extract all
the information gained during feedback as work. Our method is based on the
observation that in a feedback-reversible process the measurement and the
time-reversal of the ensuing protocol both prepare the system in the same
probabilistic state. We illustrate the utility of our method with two examples
of the multi-particle Szilard engine.Comment: 15 pages, 5 figures, submitted to New J. Phy
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
Information heat engine: converting information to energy by feedback control
In 1929, Leo Szilard invented a feedback protocol in which a hypothetical
intelligence called Maxwell's demon pumps heat from an isothermal environment
and transduces it to work. After an intense controversy that lasted over eighty
years; it was finally clarified that the demon's role does not contradict the
second law of thermodynamics, implying that we can convert information to free
energy in principle. Nevertheless, experimental demonstration of this
information-to-energy conversion has been elusive. Here, we demonstrate that a
nonequilibrium feedback manipulation of a Brownian particle based on
information about its location achieves a Szilard-type information-energy
conversion. Under real-time feedback control, the particle climbs up a
spiral-stairs-like potential exerted by an electric field and obtains free
energy larger than the amount of work performed on it. This enables us to
verify the generalized Jarzynski equality, or a new fundamental principle of
"information-heat engine" which converts information to energy by feedback
control.Comment: manuscript including 7 pages and 4 figures and supplementary material
including 6 pages and 8 figure
Microscopic shell-model description of the exotic nucleus ^{16}C
The structure of the neutron-rich carbon nucleus ^{16}C is described by
introducing a new microscopic shell model of no-core type. The model space is
composed of the 0s, 0p, 1s0d, and 1p0f shells. The effective interaction is
microscopically derived from the CD-Bonn potential and the Coulomb force
through a unitary transformation theory. Calculated low-lying energy levels of
^{16}C agree well with the experiment. The B(E2;2_{1}^{+} \to 0_{1}^{+}) value
is calculated with the bare charges. The anomalously hindered B(E2) value for
^{16}C, measured recently, is well reproduced.Comment: 14 pages, 4 figures, considerable results and discussion are added,
but the main conclusion is unchanged, accepted for publication in Phys. Lett.
Widths of Isobaric Analog Resonances: a microscopic approach
A self-consistent particle-phonon coupling model is used to investigate the
properties of the isobaric analog resonance in Bi. It is shown that
quantitative agreement with experimental data for the energy and the width can
be obtained if the effects of isospin-breaking nuclear forces are included, in
addition to the Coulomb force effects. A connection between microscopic model
predictions and doorway state approaches which make use of the isovector
monopole resonance, is established via a phenomenological ansatz for the
optical potential.Comment: 18 pages, 1 figure. To appear on Phys. Rev. C (tentatively scheduled
for June 1998
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