8,855 research outputs found
Thermodynamics of Information Processing Based on Enzyme Kinetics: an Exactly Solvable Model of Information Pump
Motivated by the recent proposed models of the information engine [D. Mandal
and C. Jarzynski, Proc. Natl. Acad. Sci. 109, 11641 (2012)] and the information
refrigerator [D. Mandal, H. T. Quan, and C. Jarzynski, Phys. Rev. Lett. 111,
030602 (2013)], we propose a minimal model of the information pump and the
information eraser based on enzyme kinetics. This device can either pump
molecules against the chemical potential gradient by consuming the information
encoded in the bit stream or (partially) erase the information encoded in the
bit stream by consuming the Gibbs free energy. The dynamics of this model is
solved exactly, and the "phase diagram" of the operation regimes is determined.
The efficiency and the power of the information machine is analyzed. The
validity of the second law of thermodynamics within our model is clarified. Our
model offers a simple paradigm for the investigating of the thermodynamics of
information processing involving the chemical potential in small systems
Maxwell's Refrigerator: An Exactly Solvable Model
We describe a simple and solvable model of a device that -- like the
"neat-fingered being" in Maxwell's famous thought experiment -- transfers
energy from a cold system to a hot system by rectifying thermal fluctuations.
In order to accomplish this task, our device requires a memory register to
which it can write information: the increase in the Shannon entropy of the
memory compensates the decrease in the thermodynamic entropy arising from the
flow of heat against a thermal gradient. We construct the nonequilibrium phase
diagram for this device, and find that it can alternatively act as an eraser of
information. We discuss our model in the context of the second law of
thermodynamics.Comment: 9 pages (Main Text + Supplemental Material), 3 figures, to appear in
Physical Review Letter
The quantum-classical correspondence principle for work distributions
For closed quantum systems driven away from equilibrium, work is often
defined in terms of projective measurements of initial and final energies. This
definition leads to statistical distributions of work that satisfy
nonequilibrium work and fluctuation relations. While this two-point measurement
definition of quantum work can be justified heuristically by appeal to the
first law of thermodynamics, its relationship to the classical definition of
work has not been carefully examined. In this paper we employ semiclassical
methods, combined with numerical simulations of a driven quartic oscillator, to
study the correspondence between classical and quantal definitions of work in
systems with one degree of freedom. We find that a semiclassical work
distribution, built from classical trajectories that connect the initial and
final energies, provides an excellent approximation to the quantum work
distribution when the trajectories are assigned suitable phases and are allowed
to interfere. Neglecting the interferences between trajectories reduces the
distribution to that of the corresponding classical process. Hence, in the
semiclassical limit, the quantum work distribution converges to the classical
distribution, decorated by a quantum interference pattern. We also derive the
form of the quantum work distribution at the boundary between classically
allowed and forbidden regions, where this distribution tunnels into the
forbidden region. Our results clarify how the correspondence principle applies
in the context of quantum and classical work distributions, and contribute to
the understanding of work and nonequilibrium work relations in the quantum
regime.Comment: 22 pages, 9 figure
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