The Goal

Systems which are not in thermodynamic equilibrium are all around us: life itself is a non-equilibrium phenomenon, with live cells and organisms evolving in time. This research aims at applying to detectors of Gravitational Waves (GW) the most recent techniques of statistical mechanics, like those, in particular, that describe the fluctuations of physical observables in nonequilibrium systems. The research will determine to which extent detectors of GW are non-equilibrium systems.

RareNoise is a 5 year project; the official start date is 1st July 2008.

The project is funded by the European Research Council (ERC) under the 7th work programme of the European Union, via a Starting Independent Researcher Grant  (ERC grant agreement no. 202680). The activity is led by Dr. Livia Conti at Istituto Nazionale di Fisica Nucleare (Italy).

The Research

To study nonequilibrium phenomena the RareNoise project investigates the statistical properties of very-low loss mechanical oscillators in nonequilibrium steady-states. The study is performed via two mutually reinforcing approaches: numerical and mathematical analysis and laboratory experiments. These will be performed at 3 temperature ranges (about 300K, 77K and 4K) and with two low-loss materials (a metal, namely the aluminum alloy Al5056, and a semiconductor, namely single-crystal Silicon): the large variation of material properties thus accessible allows a systematic investigation of the nonequilibrium phenomena. Moreover silicon is the material of many micro and nanomechanical devices and high precision instruments, such as 3rd generation gravitational wave detectors: thus a direct application is possible of the knowledge acquired from the RareNoise project to these instruments. The theoretical work will develop  in parallel to the experiments, with the aim of developing models that can realistically simulate the behavior of the experimental setup: these models will be investigated numerically by means of nonequilibrium molecular dynamics techniques.

The project will result in refinements of the nonequilibrium theory and novel applications to the interferometric gravitational wave detectors: non-equilibrium fluctuations will be estimated and their effect on the detection capabilities will be clarified. From the theoretical viewpoint, this research would offer the unique opportunity of studying non-equilibrium thermodynamics with macroscopic systems limited by intrinsic losses. As common in the field of science, it is expected that new theoretical results would be reachable from the outcome of the experiment.

Interdisciplinarity

Trying to account for non-modeled noise in gravitational wave experiments, this research connects widely separated fields of science: that of experimentalists engaged in the noise hunting of the most sensitive displacement sensors that human beings can build, that of theoreticians looking for microscopic descriptions of irreversible thermodynamics and that of scientists developing molecular machines.