QLS seminar - Tuesday, 3 October 14h00: "Information and thermodynamics: optimizing information processing using underdamped systems" by Salambô Dago

[Quantitative Life Sciences]

Dear All,

Tomorrow, Tuesday, 3 October 2023 at 14:00 CET, Salambô Dago (Univ. 
Lyon, ENS de Lyon, CNRS Lyon, France and Fac. of Physics, Univ. of 
Vienna, Austria)
will give a seminar titled:*

*

*Information and thermodynamics: optimizing information processing using 
underdamped systems*

*
*

*Abstract:*

  The Landauer principle states that at least kBTln2 of energy is 
required to erase a 1-bit memory, with kBT the thermal energy of the 
system. Practical erasure implementations re- quire an overhead to 
Landauer’s Bound (LB), observed to scale as kBT × B/τ, with τ the 
protocol duration and B close to the system relaxation time. Most model 
experiments use overdamped systems, for which minimizing the overhead 
means minimizing the dissipation. Underdamped systems thus sound 
appealing to reduce this energetic cost, and are the object of this 
presentation. Our experiment implements a model 1-bit memory based on a 
micro-mechanical oscillator confined in a double-well potential created 
by a feedback loop [1]. We measure the work and the heat of informa- 
tion processing protocols within the stochastic thermodynamic framework. 
Our research covers all possible operations on a single bit b: HOLD (b → 
b), SET (b → 0 or 1), NOT (b → ¬b).

The logical SET operation is an erasure, logically irreversible, coming 
with an entropic cost which is at least LB. We demonstrate that, in our 
experiment, this bound is reached with a 1% uncertainty, with protocols 
as short as 100 ms [2]. Besides, we show experimentally and 
theoretically that for underdamped systems, fast erasures induce a 
heating of the memory: the work influx is not instantaneously 
compensated by the inefficient heat transfer to the thermostat. This 
temperature rise results in a kinetic and potential energy contribution 
superseding the viscous dissipation term. Our model covering all damping 
regimes paves the way to new optimization strategies in information 
processing [3, 4], including the implementation of more applied logic 
gates performing repeated fast operations [6].

The other logical operations are reversible, and can thus in principle 
be performed at no ther- modynamical cost. We implement the NOT 
operation using the momentum degree of freedom in our underdamped memory 
to perform a bit-flip [5]. Not bounded by any entropic cost this time, 
the energetic cost of the protocol vanishes as the quality factor of the 
oscillator increases, further highlighting the low energy footprint and 
interest of underdamped memories.


References
1. S. Dago, J. Pereda, S. Ciliberto and L. Bellon: JSTAT 5, 053209 (2022)
2. S. Dago, J. Pereda, N. Barros, S. Ciliberto, and L. Bellon: Phys. 
Rev. Lett. 126, 17 (2021)
3. S. Dago and L. Bellon: Phys. Rev. Lett. 128, 7 (2022)
4. S. Dago, S. Ciliberto and L. Bellon: PNAS 120 (39) e2301742120, (2023).
5. S. Dago and L. Bellon: Phys. Rev. E 108, L022101, (2023).
6. S. Dago, S.Ciliberto and L.Bellon: To be published in Advanced 
Physics Research,
arXiv:2306.15573 (2023)

_The seminar will take place in the __*Fibonacci room*__, Galileo Guest 
House, via Beirut 7__

_Indico webpage: https://indico.ictp.it/event/10547/
__
You are all most welcome to attend!

Best regards,
Erica

-- 
Erica Sarnataro
Group Secretary
Quantitative Life Sciences
The Abdus Salam International Centre for Theoretical Physics (ICTP)
Trieste,  Italy
Tel. +39-040-2240623
www.ictp.it/research/qls.aspx
e-mail:qls at ictp.it