Fig. 4.

Stochastic microswimmer dynamics from noisy memory readings for noise level $\xi =2\cdot 10^{-4}{c}_0$. (A) Sample trajectories in the absence (blue) and in the presence (green) of a linear chemical field. (B and C) Run time distributions for moving the field upward ($\mathrm{\Delta }{t}_R$) and downward ($\mathrm{\Delta }{t}_L$) in the absence (B) and in the presence (C) of a field. Note that the run time axis starts at the minimal possible run time $\mathrm{\Delta }t/T_0=1$ because of the used discretization. (D) Chemotactic drift velocity $v_c$ as a function of noise-to-signal ratio $\xi /\left(kR\right)$ for different values of gradient steepness $k$. Each data point corresponds to a simulation time of $10^6{T}_0$. (E) Sample trajectories in time-dependent Gaussian profiles $c\left(x,t\right)$ (see color bar) centered at $x_{0\pm }=\pm 10R$ of width $\sigma =8R$ and height $a=4c_0$ and modulated with period $T=461T_{\mathrm{S}}$.