Studies on the periodically kicked pendulum and on the periodically kicked top have shown that Husimi-Wigner wave packets and their corresponding classical ensembles exhibit exponential growth of variable covariances with growth rates determined by the largest classical Lyapunov exponent. Consequently, a quantum measurement of the variance growth rate yields the classical Lyapunov exponent. This method permits a direct connection between wave packets and phase space concepts including the Lyapunov exponent. The biophysics work has covered energy transduction, especially chemosmosis, the origin of protein biosynthesis, and the origin of energy metabolism. Two monographs on these ideas have been published.
Recent work covers ion channel fluctuations, and the mechanism of molecular motors.
The ion channel fluctuation work provides a first principles account of the noise in voltage gated potassium and sodium channels in nerve membrane as described by the Hodgkin-Huxley equations. Both small patches and spatially dependent action potential propagation have been considered. The molecular motor work covers ubiquinone energy transduction, rotary enzyme complexes, ion transporters and the mechanism of actin-myosin dynamics in muscle fibers. The central idea is the distinction between chemo-mechanical energy conversion and energy driven rectification of Brownian motion.