Energetics of critical oscillators in active bacterial baths

We investigate the nonequilibrium energetics near a critical point of a non-linear oscillator immersed in an active bacterial bath. At the critical point, we reveal a scaling exponent of the average power exerted by a constant non-conservative torque <(W)over dot similar to(D-a/tau)(1/4), where D-a is the effective diffusivity and tau the correlation time of the bacterial bath described by a Gaussian colored noise. Other features that we investigate are the average stationary power and the variance of the work both below and above the saddle-node bifurcation. Above the bifurcation, the average power attains an optimal, minimum value for finite tau that is below its zero-temperature limit. Furthermore, we reveal a finite-time uncertainty relation for active matter which leads to values of the Fano factor of the work that can be below 2k(B)T(eff), with T-eff the effective temperature of the oscillator in the bacterial bath. We analyze different Markovian approximations to describe the nonequilibrium stationary state of the system. Finally, we illustrate our results in the experimental context by considering the example of driven colloidal particles in periodic optical potentials within an E. Coli bacterial bath.

Automated summary

In this study, nonequilibrium energetics near a critical point of a non-linear oscillator immersed in an active bacterial bath was investigated. The average power exerted by a constant non-conservative torque was found to follow a scaling exponent relationship. Additionally, an optimal minimum value for the average power was observed above the saddle-node bifurcation, along with a finite-time uncertainty relation for active matter.