Ratchet Current Research Articles

Langevin simulation approach to a two-dimensional coupled flashing ratchet

We study the directed motion of a Brownian particle moving in a two-dimensional coupled flashing ratchet driven by Gaussian white noise. The temperature dependence of the current is evaluated numerically in terms of Langevin simulation and discussed by means of a heuristic analytical ad hoc approximation. The current can be enhanced or reversed due to the coupling effects between two degrees of freedom. Our results show that the noise is rectified even in the absence of a true activation energy barrier and the two-dimensional ratchet current does not vanish as the temperature approaches infinity.

The theory of ratchet writing in multipath magnetic cores

Ratchet writing is a method of writing information into certain nondestructive-readout (NDRO) magnetic memory elements. Writing is accomplished by reversing (or "ratcheting") the flux about one hole of the element with a word-oriented wire while simultaneously applying information-determined bit current to another hole called the storage hole. The effect of ratcheting is a threshold reduction for switching about the storage hole. It is established that ratchet writing is possible because some of the flux switched by the ratchet current closes by returning around the storage hole rather than through the "common volume" between the two holes. The detailed switching properties of a simple thin-wall core are computed and compared with experiment. The results are in excellent agreement within the limitations of the approximations made. It is found that there is a region where the bit-current threshold declines linearly with unit slope as ratchet current is increased. In this region there is a direct transfer of flux from the ratcheted hole to the storage hole, the common volume remaining an open circuit.