Horacio S. Wio

Noise Induced Phase Transitions and Coupled Brownian Motors: Non Standard Hysteretic Cycles

"Recent work [1,2,3] have shown the possibility, through a noise induced symmetry breaking leading to a nonequilibrium phase transition, of obtaining a set of coupled Brownian motors. It was also shown [4] that in some parameter region such a system could show negative mobility (that is motion opposed to the applied force) and anomalous hysteretic behavior (clockwise in opposition to the usual counter-clockwise). Using an explicit mean-field approximation and colored multiplicative noises, it was found a contraction of the ordered phase (and re-entrance as a function of the coupling) on one hand, and a shift from anomalous to normal hysteretic behavior on the other [5].
This behavior was obtained in systems presenting a noise induced phase transition that originates from a short time instability. Here we discuss a similar system, but where the noise induced phase transition is originated in an entropic mechanism [6].
Some preliminary studies that exploits such a mechanism indicate the possibility of obtaining no standard hysteretic cycles: anti-clockwise but showing a staircase-like structure. Depending on the parameter region, the hysteresis diagram could have one or more blocks, that can be explored as a whole or step by step, opening the possibility of exploiting it as a noise-controlled multipurpose logic gate[7].

[1] Sagués et al, Rev. Mod. Phys. 79, 829 (2007)
[2] van den Broeck et al, Phys. Rev. E 55, 4084 (1997)
[3] Mangioni et al, Phys. Rev. E 61, 223 (2000)
[4] Reimann et al, Europhys.Lett. 45, 545 (1999)
[5] Mangioni et al, Phys. Rev. E 66, 051106 (2002)
[6] Carrillo et al, Phys. Rev. E 67, 04611 (2003)
[7] Wio, Proc. .ICNF2013,IEEE Conf.Pub.(2013)