Chiral symmetry breaking in a reaction-diffusion system

Abstract

The emergence of order in far-from-equilibrium systems is often accompanied by the formation of spatially asymmetric patterns. About 30 years ago, a general mechanism to select a chiral solution by coupling a reaction-diffusion system to an external chiral electric field was proposed by Nicolis and Prigogine [Proc. Natl. Acad. Sci. USA 78, 659 (1981)]. However, no experimental or even numerical evidence in reaction-diffusion systems has been reported yet. Here we report a chiral symmetry-breaking phenomenon in a reaction-diffusion system coupled to a circularly polarized electric field (CPEF). Specifically, we show that the CPEF breaks the zero-rotation chiral symmetry between clockwise and counterclockwise spiral defects and that ordered spiral waves with preferred chirality arise from defect-mediated turbulence. The occurrence of such chiral symmetry breaking can be understood by the competition between spiral defects with opposite chirality.

Chiral selection and frequency response of spiral waves in reaction-diffusion systems under a chiral electric field

“…For example, in the complex Ginzburg-Laudau equation (CGLE) with a broken chiral symmetry breaking term, Nam et al 33 showed that this chiral term would cause a shift in the frequency of spiral waves and the sign of this shift depends on the chirality of the spiral waves. In our recent work 38 , such chirality-dependent frequency response was also observed in RD systems coupled to the CPEF. However, a quantitative description of the chirality-dependent frequency response to the CPEF in such RD systems is still lacking.…”

“…Recently, a circularly polarized electric field (CPEF) that possesses chirality was theoretically proposed 34 and was implemented in the BZ experiment 35 , which allows us to study the response of spiral waves to a chiral electric field in RD systems. Indeed, it has been shown that the CPEF has some pronounce effects on spiral waves [36][37][38] that were not observed in RD systems subject to achiral fields such as a dc or ac electric field.…”

Phase-locked scroll waves defy turbulence induced by negative filament tension

“…Recently, a circularly polarized electric field (CPEF) that possesses chirality was theoretically proposed 34 a) Electronic mail: bwli@hznu.edu.cn and was implemented in the BZ experiment, 35 which allows us to study the response of spiral waves to a chiral electric field in RD systems. Indeed, it has been shown that the CPEF has some pronounce effects on spiral waves [36][37][38] that were not observed in RD systems subject to achiral fields such as a dc or ac electric field.…”

“…41 In Rayleigh-Bénard convection, chiral symmetry breaking in spiral-defect populations was observed when the system rotated along the vertical axis, and the chirality of the dominant spirals relies on the rotation sense of the system. 32 By subjecting a RD system to the CPEF, 38 we recently found that the zero-rotation chiral symmetry between CW and CCW spiral defects breaks and that ordered spiral waves with preferred chirality arise from the spiral turbulence state. Here too, the preferred chirality was only determined by the chirality of the CPEF.…”

“…Here too, the preferred chirality was only determined by the chirality of the CPEF. 38 On the other hand, due to the presence of chiral terms, the frequency response of spiral waves with opposite chirality is different. For example, in the complex Ginzburg-Landau equation (CGLE) with a broken chiral symmetry breaking term, Nam et al 33 showed that this chiral term would cause a shift in the frequency of spiral waves and the sign of this shift depends on the chirality of the spiral waves.…”