GRAvitational-waves Science&technology Symposium (GRASS 2019)

Session

Thermal noise in and out of thermodynamic equilibrium

THERM

25 Oct 2019, 08:05

Sala Paladini (Palazzo Moroni, Padova)

2. Faster than Nature: Engineered swift equilibration of small systems.

Dr Ignacio A. Martínez (Universidad Complutense de Madrid)

25/10/2019, 08:30

A fundamental and intrinsic property of any device or natural system is its relaxation time \tau_{\rm relax}, which is the time it takes to return to equilibrium after the sudden change of a control parameter. Reducing \tau_{\rm relax} is frequently necessary, and is often obtained by a complex feedback process. To overcome the limitations of such an approach, alternative methods based on...

3. Operating high sensitivity measurement apparata out of equilibrium

Dr Igor Neri

25/10/2019, 09:05

In this work we present an approach aimed at operating high sensitivity measurement apparata out of equilibrium with the purpose to enhance their sensitivity. We show, with an experiment, that selective cooling of thermally activated single modes of a mechanical structure, is capable of positively impacting the measurement sensitivity improving significantly the signal-to-noise ratio in the...

17. Thermal fluctuations in an out-of-equilibrium state

Mr Alex Fontana (Univ Lyon, ENS de Lyon, UCBL, CNRS, Laboratoire de Physique, F-69342 Lyon, France)

25/10/2019, 09:30

Thermal noise manifests itself as a tiny variance around the mean value of an observable $x$ of a physical system. Usually too small to be noticed, it becomes important in an increasing number of applications, such as quantum systems operated close to their ground state, MEMS and NEMS, frequency standards, or the next generation of gravitational wave detectors$^1$. Its understanding is thus...

41. Measuring (excess?) thermal noise on a macroscopic oscillator in non-equilibrium conditions

Giacomo Ciani (PD)

25/10/2019, 09:55

Past measurements performed by our group on a macroscopic mechanical oscillator subject to a thermal gradient/heat flow have found increased mechanical thermal noise levels with respect to what is calculated from the fluctuation-dissipation theorem, even assuming equilibrium at the highest temperature present in the system.
We have recently upgraded the experimental facility with an optical...

32. Thermal gradients and Energy equipartition - numerical and theoretical

Dr Paolo De Gregorio (Dipartimento di Scienze Matematiche "Luigi Lagrange" (DISMA), Politecnico di Torino)

25/10/2019, 10:15

We discuss a one-dimensional model of a vibrating rigid rod, in and out of equilibrium. We study stationary states when the system is subject to temperature gradients, which is the nonequilibrium scenario, as compared to constant temperature for the equilibrium situations. While some thermomechanical properties remain substantially unchanged comparing in and out of equilibrium situations, the...

18. A thermoelastic extension of the fluctuation dissipation theorem in nonequilibrium states

Dr Gianmaria Falasco (University of Luxembourg)

25/10/2019, 10:40

We build a continuous fluctuating description of elastic, conductive and dissipative solids
subject to heat fluxes, which takes fully into account linear thermoelastic couplings.
Under the assumption of local equilibrium, we derive an extension of the fluctuation-dissipation theorem
and obtain the strain fluctuations in the nonequilibrium steady state.
We outline next steps towards the...