Publié le

Learning efficient erasure protocols for an underdamped memory

Nicolas Barros, Stephen Whitelam, Sergio Ciliberto and Ludovic Bellon, submitted to Phys. Rev. Lett.

[article] arXiv: 2409.15050
[dataset] doi: 10.5281/zenodo.13829199

We apply evolutionary reinforcement learning to a simulation model in order to identify efficient time-dependent erasure protocols for a physical realization of a one-bit memory by an underdamped mechanical cantilever. We show that these protocols, when applied to the cantilever in the laboratory, are considerably more efficient than our best hand-designed protocols. The learned protocols allow reliable high-speed erasure by minimizing the heating of the memory during the operation. More generally, the combination of methods used here opens the door to the rational design of efficient protocols for a variety of physics applications.

Download pdf

Publié le

Probabilistic work extraction on a classical oscillator beyond the second law

Nicolas Barros, Sergio Ciliberto, Ludovic Bellon, Phys. Rev. Lett. 133, 057101 – Editor’s suggestion

[letter] doi: 10.1103/PhysRevLett.133.057101
[dataset] doi: 10.5281/zenodo.10721407

We demonstrate experimentally that, applying optimal protocols which drive the system between two equilibrium states characterized by a free energy difference ΔF, we can maximize the probability of performing the transition between the two states with a work W smaller than ΔF. The second law holds only on average, resulting in the inequality ⟨W⟩≥ΔF. The experiment is performed using an underdamped oscillator evolving in a double-well potential. We show that with a suitable choice of parameters the probability of obtaining trajectories with W≤ΔF can be larger than 90 %. Very fast protocols are a key feature to obtain these results which are explained in terms of the Jarzynski equality.

Download pdf

Our letter was spotted by Karmela Padavic-Callaghan, physics reporter from the New Scientist. Read their interview and presentation of our work for a wide audience : A microscopic diving board can cheat the second law of thermodynamics

Publié le

Temperature mediated back-action in micro- and nanomechanical resonators

Ludovic Bellon and Pierre Verlot, submitted to Phys. Rev. B

arXiv: 2407.20063

We theoretically investigate the thermally induced back-action effects in absorption-sensitive micro- and nanomechanical resonators. We propose a unified approach, enabling to simultaneously address both the effective dynamics and non-equilibrium phononic state, depending on the position of a confined sensing (and heating) probe at the surface of the mechanical device. We present an analytical solution for a unidimensional resonator whose thermomechanical deformation profile generally follows that of the mechanical losses. In particular, we find that both the dynamics and the mechanical fluctuations strongly depend on the loss distribution. The effect of the quantum fluctuations of the heat source is also discussed. Our approach provides a thorough, general platform for analyzing thermal back-action effects and their consequences, which may be of significance for future development in ultrasensitive nanomechanical research.

Download pdf

Publié le

First-passage information engine

Aubin Archambault, Caroline Crauste-Thibierge, Alberto Imparato, Christopher Jarzynski, Sergio Ciliberto and Ludovic Bellon, submitted to Phy. Rev. Lett.

arXiv: 2407.17414

We investigate the thermodynamic properties of an information engine that uses feedback control to extract work from a manipulated mechanical oscillator. The feedback is triggered by the first passage of the system across a fixed threshold. In this setting, we derive and experimentally verify two distinct fluctuation theorems that involve the information associated with the feedback-controlled stochastic trajectories. Our experimental setup consists of a cantilever submitted to an electrostatic feedback force, and our protocol improves the thermodynamic performances of the engine by a factor of 5, compared with previously proposed protocols.

Download pdf

Publié le

Multimode characterization of an optical beam deflection setup

Alex Fontana and Ludovic Bellon, Phys. Rev. Applied 22, 014044 (2024)

[article] doi: 10.1103/PhysRevApplied.22.014044
[dataset] doi: 10.5281/zenodo.11110783

Optical beam deflection is a popular method to measure the deformation of micro-mechanical devices. As it measures mostly a local slope, its sensitivity depends on the location and size of the optical spot. We present a method to evaluate precisely these parameters, using the relative amplitude of the thermal noise induced vibrations. With a case study of a micro-cantilever, we demonstrate the accuracy of the approach, as well as its ability to fully characterize the sensitivity of the detector, and the parameters (mass,
stiffness) of the resonator.

Download pdf

Publié le

Hyperspectral electromechanical imaging at the nanoscale: Dynamical backaction, dissipation and quantum fluctuations

Clément Chardin, Sébastien Pairis, Stéphane Douillet, Mpïra Hocevar, Julien Claudon, Jean-Philippe Poizat, Ludovic Bellon and Pierre Verlot, submitted to Nano Letters

arXiv: 2407.20740

We report a new scanning thermomechanical microscopy platform enabling to both heat and acquire the fluctuations of mechanical nanostructures with nanometric resolution. We use this platform to image the nanomechanical noise response of a 40 nm diameter nanowire while scanning a localized heat source across its surface. We develop a thermal backaction model, which we use to demonstrate a close connection between the structure of the nanowire, its thermal response, its dissipation and its fluctuations. We notably identify the presence of a localized thermoelastic defect, which we demonstrate behaves as a single fluctuation hub, whose e-beam excitation yields a far off-equilibrium vibrational state, largely dominated by the quantum fluctuations of the heating source. Our platform is of interest for future development of ultra-low loss nanophononic devices, and appears as a new playground for investigating quantum thermodynamics in the strongly dissipative regime and at room temperature.

Download pdf

Publié le

Inertial effects in discrete sampling information engines

Aubin Archambault, Caroline Crauste-Thibierge, Sergio Ciliberto, Ludovic Bellon, submitted to EPL

arXiv:2407.06672

We describe an experiment on an underdamped mechanical oscillator used as an information engine. The system is equivalent to an inertial Brownian particle confined in a harmonic potential whose center is controlled by a feedback protocol which measures the particle position at a specific sampling frequency 1/𝜏. Several feedback protocols are applied and the power generated by the engine is measured as a function of the oscillator parameters and the sampling frequency. The optimal parameters are then determined. The results are compared to the theoretical predictions and numerical simulations on overdamped systems. We highlight the specific effects of inertia, which can be used to increase the amount of power extracted by the engine. In the regime of large 𝜏, we show that the produced work has a tight bound determined by information theories.

Download pdf

Publié le

Thermal noise calibration of functionalized cantilevers for force microscopy: effects of the colloidal probe position

Aubin Archambault, Caroline Crauste-Thibierge and Ludovic Bellon, J. Appl. Phys. 135, 094502 (2024)

[article] doi: 10.1063/5.0189480
[dataset]  doi: 10.5281/zenodo.10102664
[software] doi: 10.5281/zenodo.10103601

Colloidal probes are often used in force microscopy when the geometry of the tip-sample interaction should be well controlled. Their calibration requires the understanding of their mechanical response, which is very sensitive to the details of the force sensor consisting of a cantilever and the attached colloid. We present analytical models to describe the dynamics of the cantilever and its load positioned anywhere along its length. The thermal noise calibration of such probes is then studied from a practical point of view, leading to correction coefficients that can be applied in standard force microscope calibration routines. Experimental measurements of resonance frequencies and thermal noise profiles of raw and loaded cantilevers demonstrate the validity of the approach.

Download pdf

Publié le

Experimental study of information engines at the mesoscopic scale

Aubin Archambault, PhD Thesis, Université de Lyon (2023)

hal: tel-04499304

The usual laws of thermodynamics are robust and can be applied to large range of macroscopic systems. However, when thermal fluctuations are on the same scale as the studied phenomena, these laws only describe the average behaviour. While it is impossible to macroscopicaly extract work from thermal fluctuations, this limit can be overcome by adapting the protocols based on the outcome of a measurement. This thesis presents an experimental realisation of information engine, monothermal cycles whose evolution is determined by the result of a measurement on the system. We show that it is then possible to extract energy from thermal fluctuations, and optimise the engine to maximise the work extraction in different regimes. These measurements are used to test recent theoretical works and explore the underdamped regime, usually harder to study. They also highlight specific effects of this underdamped regime. Two supplementary works are presented. The first presents two model for the description of the flexural modes of micro-cantilevers loaded with massive spheres. These models are completed by experiments, made possible by the development of microfabrication process. The second presents the development of force measurement device, adapted to forces in the range of the piconewton. This device is used to measure Casimir forces, up to a distance of 30nm.

Download pdf

Publié le

Role of a capping layer on the crystalline structure of Sn thin films grown at cryogenic temperatures on InSb substrates

A.-H. Chen, C.P. Dempsey, M. Pendharkar, A. Sharma, B. Zhang, S. Tan, L. Bellon, S.M. Frolov, C.J. Palmstrom, E. Bellet-Amalric, and M. Hocevar, Nanotechnology 35 075702

[Article] doi: 10.1088/1361-6528/ad079e
[Data set] doi: 10.5281/zenodo.7581136

Metal deposition with cryogenic cooling is a common technique in the condensed matter community for producing ultra-thin epitaxial superconducting layers on semiconductors. However, a significant challenge arises when these films return to room temperature, as they tend to undergo dewetting. This issue can be mitigated by capping the films with an amorphous layer. In this study, we investigate the influence of different in situ fabricated caps on the structural characteristics of Sn thin films deposited at 80 K on InSb substrates. Regardless of the type of capping, we consistently observe that the films remain smooth upon returning to room temperature and exhibit epitaxy on InSb in the cubic Sn (α-Sn) phase. Notably, we identify a correlation between alumina capping using an electron beam evaporator and an increased presence of tetragonal Sn (β-Sn) grains. This suggests that heating from the alumina source may induce a partial phase transition in the Sn layer. The existence of the β-Sn phase induces superconducting behavior of the films by percolation effect. This study highlights the potential for tailoring the structural properties of cryogenic Sn thin films through in situ capping. This development opens avenues for precise control in the production of superconducting Sn films, facilitating their integration into quantum computing platforms.

Download pdf
Download data