Diffusive molecules share the 1/3 shot noise suppression of quantum conductors
Electrical noise measurement, especially shot noise, which arises from the discreteness of charge, is an indispensable tool in quantum transport for probing the nature of charge carriers beyond simple conductance measurements. Diffusive conductors share a universal shot noise reduction of 1/3, a result obtained independently from quantum scattering theory, semi-classical kinetics, or by classical exclusion processes8. Until now, however, experimental tests of this universality have been limited to cryogenic conditions, leaving its origin incompletely understood. Here we show that ferrocene redox cycling in a microfluidic gap is a room temperature realization of this universality. We derive the full counting statistics of diffusing single-electron molecular shuttles and verify the predicted current noise experimentally, showing that the universal 1/3 shot noise suppression is recovered in the diffusion-limited regime. Our result identifies diffusion and sequential charge transfer as sufficient ingredients for this universal noise reduction, rather than quantum coherence, fermionic statistics or cryogenic conditions. We anticipate that this study will establish electrochemical microfluidics as a room-temperature platform for mesoscopic counting statistics and bring noise-based probes to molecular transport and reaction kinetics. Furthermore, this liquid-based quantum-inspired study will provide a novel insight on the yet to be understood links between quantum and biology.