Dear Editor,

please find enclosed a manuscript on a combined theoretical/experimental work
on a what we believe is a new approach to assess the quantumness of a physical
system. While the combination of quantum physics with computer science led to
the emergence of many ideas how to possibly do some useful computation using
quantum physics, there have been many exciting inspirations to traditional
physics as well.

In the combined theoretical and experimental work we present in this
manuscript, we tried to use very elementary computer science concepts like the
compressibility of data sets to evaluate the "quantumness" of a real physical
system. We find that this plan seems to work, at least for  a maximally
entangled bipartite system, in the sense that the equivalent of an entropic
Bell inequality can be tested and found violated with relatively simple
computational tools applied to measured data.

To us, this looks like a funny combination of computer science and quantum
physics that may even help to "understand" entanglement not only in a
statistical, but perhaps algorithmic way. As this aspect may have reasonably
far reaching consequences, and this demonstration lies somewhere between
physics and computer science, we felt that PNAS may be a suitable platform
to present this work.

We are new to the editorial process with PNAS, so let me just go through the
required suggestions in the submission process:

For the editorial board members, we believe Anthony Leggett from Urbana
(Physics)  would be most suitable, as he has worked on various tests on the
foundation of quantum physics;  David Donoho from Stanford (Applied
Mathematical Sciences) may have an interest in this work from a point of view
of data complexity description; William Bialek from Princeton (Physics) may be
interested due to his work of connecting physical principles with more
complex systems.

As NAS members who are experts in the area of our work, we would like to
recommend Anton Zeilinger from Vienna, who has done many experiments on
foundational quantum physics, and knows the experimental aspects of our work
very well. Further, for his cross-links between physics and computer science,
Andrew Yao at Tsinghua University in Beijing, China seems quite appropriate,
and similarly John Preskill for his expertise on quantum information at
large.

Potential reviewers could be Andrew G. White from University of Queensland in
Brisbane, Australia, and Gregor Weihs from the University of Innsbruck,
Austria; both of them are experimental physicists with a track record of
foundational tests of quantum physics. Carlton M. Caves at the University of
New Mexico, and Samuel L. Braunstein at the University of York, UK, have both
developed entropic Bell inequalities that are at the root of the test we carry
out in our experiment. Nicolas Cerf at the  Ecole Polytechnique de Bruxelles,
Belgium, a theoretical physicist at the boundary to quantum optical experiments
and expertise in quantum information science would be another suggestion.

With this, we hope to have provided the necessary information, and would
kindly ask you for consideration of a publication in the Proceedings of the
National Academy of Sciences.


With Best Regards on behalf of all authors,

Christian Kurtsiefer