Event Details

Condensed Matter webinar

Some types of machine are fundamentally limited by the laws of thermodynamics. Two famous thermodynamic constraints are the Carnot bound, which limits the efficiency with which heat can be converted to work, and the Landauer bound, which imposes an energy cost for rewriting information. Does an analogous constraint apply to clocks? Recently, separate theoretical analyses of chemical clocks and quantum clocks have suggested that it does, and that it imposes an entropy cost to timekeeping that depends on a clock’s tick rate and accuracy.

We have built, tested, and analysed a simple optomechanical clock in which the accuracy and intrinsic energy dissipation can be measured. The clock consists of a vibrating micromechanical membrane, monitored using a radio-frequency circuit. We find, both experimentally and theoretically, that the entropy generated is proportional to the clock’s accuracy, and that the relationship between them is similar to that previously predicted for both chemical and quantum clocks.

This is suggestive but not conclusive evidence that some clocks are indeed thermodynamic machines. However, I will show that some existing clocks are much more efficient than ours. The ultimate thermodynamic limit on timekeeping - if indeed such a thing exists - therefore remains an unknown quantity.

References:

Anna Pearson et al. Measuring The Thermodynamic Cost of Timekeeping. Physical Review X 11, 21029 (2021)

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.11.021029

“Clocks that tell time more accurately use more energy – new research"

https://theconversation.com/clocks-that-tell-time-more-accurately-use-more-energy-new-research-161120

If someone from outside of the Condensed Matter Physics group would like to join the webinar, please send a request to m.thompson@lancaster.ac.uk