add note about steady state fluctuations

src/thermo.tex

@@ -753,8 +753,11 @@ system enters a periodic steady state after the time \(n_0τ\) for some
 \(n_0\in\NN\) so that \(ρ_\sys((n + n_0)τ)= ρ_\sys(n_0τ)\) for all
 \(n\in\NN\). This assumption is linked to the notion of a ``finite
 memory'' of the baths which implies an infinite bath\footnote{Or, as
-  we have remarked earlier, a suitably large bath.}. In the same
-spirit, we \emph{assume} that the energy change of each bath
+  we have remarked earlier, a suitably large bath.}. Note that even in
+the absence of modulation, the steady state can exhibit periodic
+dynamics as can be seen in \cref{fig:markov_analysis_steady} on page
+\pageref{fig:markov_analysis_steady}. In the same spirit, we
+\emph{assume} that the energy change of each bath
 \(ΔE_{\bath^i}^\cyc =ΔE_{\bath^i}((n+1)τ)-ΔE_{\bath^i}(nτ) =
 E_{\bath^i}((n+1)τ)-E_{\bath^i}(nτ)\) is constant once the system is
 in the periodic steady state. This behavior, at least on the system