Welcome to the Complex Systems Group!
The Complex Systems group is a strongly interdisciplinary group,
conducting research under the umbrella of probabilistic modeling of
complex systems. The group expertise includes statistical physics,
nonlinear dynamics, quantum physics, as well as applied
mathematics. These capabilities are applied to problems in
hydrodynamics, soft matter, nanoscience, validation and verification,
computational biology, and information science in support of the
laboratory national security mission. The group has a mission, and
strong tradition, of serving as a nucleation center for vanguard
interdisciplinary research. Present and future directions include
science based prediction, complex networks, epidemiological modeling,
social dynamics, quantum technologies, and algorithms.
New!
Complex Systems 2007 Overview
LALP-07-052
Congratulations!
- Eli Ben-Naim, elected APS Fellow.
- Peter Milonni, Max Born Award, Optical Society of America
- Harvey Rose, named Los Alamos Fellow
- David Roberts, named Feynman Distinguished Postdoctoral Fellow
- Moran Wang, named Oppenheimer Distinguished Postdoctoral Fellow
Research Nuggets
Towards individualized medicine
Each person reacts differently to different medications - what helps
some may harm others. Researchers are actively working to take the
guess work out. In an ideal world, and hopefully not-to-distant
future, doctors will prescribe medicine based not only on the symptoms
and side effects of an average person, but will be able prescribe
medicine that is tailored to one's individual genetic makeup. In a
recent Nature Genetics article, a collaboration of biologists,
computer scientists, bio-chemists, and Physicists at Princeton,
Harvard, and Los Alamos took a step towards realizing this possibility. Specifically, these researchers discovered many genetic
linkages that affect drug response in yeast. Los Alamos Director's
funded postdoc, David Roberts of the Complex Systems Group (T-13) and
the Center for Nonlinear Studies (T-CNLS) participated in this
research.
EO Perlstein, DM Ruderfer, DC Roberts, SL Schreiber, L Kruglyak,
Nature Genetics 39, 496 (2007).
Universal scaling in anisotropic materials
Recent theoretical work Matthew Hastings (T-13) established new
theoretical laws governing structured materials. His research
establishes universal scaling relations that relate the susceptibility
and the inter-plane coupling in anisotropic layered antiferromagnetic
materials. These results explain and extend previous computational
work and offer new possibilities for using neutron scattering to
experimentally determine the coupling constants in important materials
such as the cuprate superconductor La2CuO4. Ongoing experimental,
theoretical, and computational research at several institutes
worldwide focuses on testing and applying these results to a number of
structured materials. This work was done in collaboration with
Christopher Mudry of the Paul Scherrer Institut in Switzerland and
published in Physical Review Letters 96, 027215 (2006).
Granular flow: experiments confirm Los Alamos theory
Granular flows underly a broad range of natural and industrial
processes from propagation of sand dunes to transportation of
plastics. Recently, Eli Ben-Naim, a theoretical physicist at the
Complex Systems Group (T-13), extended James Clerk Maxwell's classic
theory of gases to granular flows. The major prediction of this theory
is that the energy distribution does not adhere to the
Maxwell-Boltzmann equilibrium distribution law. Recent experiments at
Argonne National Laboratory using electrostatically charged magnetic
particles, confirm the Los Alamos theory. The agreement between the
theoretical predictions and the experimental data, down to one part in
100,000 in the energy distribution, are remarkable. This research is a
collaboration between Los Alamos and Argonne National labs. The
results are published in Physical Review Letters 95, 068001 (2005).
Mathematics of Quantum Decoherence
G.P. Berman (T-13, LANL) in collaboration with Prof. I.M. Sigal
(Department of Mathematics, University of Toronto, Canada) and
Prof. Marco Merkli (Department of Mathematics and Statistics Memorial,
University of Newfoundland, Canada) examined rigorously the phenomenon
of quantum decoherence and thermalization for N-level systems coupled
to reservoirs. So far, this phenomenon has been analyzed rigorously
only for explicitly solvable models. The reservoirs are described by
free massless bosonic fields. They applied their general results to
the specific cases of the qubit and the quantum register. Their
research provides a picture for the dynamics of reduced density matrix
elements and for averages of observables. They compared our results
with the explicitly solvable case of systems whose interaction with
the environment does not allow for energy exchange (non-demolition, or
energy conserving interactions). The results are published in
Phys. Rev. Lett., 98, 130401 (2007).
European conference dedicated to the work of T-13 staff member
The Institute of Theoretical Physics in Vienna is organizing an
international conference on Lied-Robinson bounds and its wealth of
applications in condensed matter physics and quantum information. This
conference will take place February 20 to February 24, 2007 at the
Erwin Schrodinger International Institute for Mathematical Physics in
Vienna, Austria. The focus of this conference is recent advances that
revolve around a series of contributions by Matthew Hastings
(T-13). Matthew extended the seminal work of Elliott Lieb from one
dimension to general spatial dimension, and his work has inspired a
number of advances in mathematical physics of gapped hamiltonians.
New Book: Magnetic Resonance Force Microscopy and a Single-Spin Measurement
Magnetic resonance force microscopy (MRFM) is a rapidly evolving
field which originated in 1990s and matured recently with the first
detection of a single electron spin below the surface of a
non-transparent solid. Further development of MRFM techniques will
have a great impact on many areas of science and technology including
physics, chemistry, biology, and even medicine. Scientists, engineers,
and students from various backgrounds will all be interested in this
promising field.
The objective of this “multi-level” book is to describe the basic
principles, applications, and the advanced theory of MRFM. Focusing on
the experimental oscillating cantilever-driven adiabatic reversals
(OSCAR) detection technique for single electron spin, this book
contains valuable research data for scientists working in the field of
quantum physics or magnetic resonance. Readers unfamiliar with quantum
mechanics and magnetic resonance will be able to obtain an
understanding and appreciation of the basic principles of MRFM.
