Speaker
Jonas Johansson
(Lund University)
Description
In two letters and in his book “Theory of Heat”, Maxwell
mentioned a thought experiment about “a being whose
faculties are so sharpened that he can follow every
molecule”. The being was later referred to as a demon.
In this presentation I will give a brief historical
introduction to Maxwell’s Demon and discuss some of the
attempts to resolve the paradox of Maxwell’s Demon. The
accepted solution is known as “Landauer’s erasure principle”
and it is based on the observation that the demon needs to
store information and it is the erasure of this information
that compensates for the entropy decrease – the second law
is saved.
During the last few years, spurred by the developments in
stochastic thermodynamics, a few realizations of devices
that transform information to energy, that is, Maxwell’s
Demons, have been demonstrated. I will describe some of
these and continue with our own ideas for the implementation
of a Maxwell’s Demon, which is based on a microbead in a
feedback controlled, linear optical trap. So far, we have
theoretically analyzed a general and idealized version of
our set up. The demon can operate as a feedback controlled
Brownian ratchet, or as a power stroke motor, or as a
mixture of both. The main result of our modeling is that the
efficiency has a maximum when the two modes of operation are
at work simultaneously.
In the context of biological molecular motors, there is a
general discussion whether such motors are mainly operating
as Brownian ratchets or utilizing power stroke. Our modeling
results suggest the possibility that the highest efficiency
and robustness of biological molecular motors can be reached
when both mechanisms are simultaneously active.
