Dynamic charge oscillation in a quantum conductor driven by ultrashort voltage pulses

TL;DR

This paper generalizes the understanding of dynamic charge oscillations in quantum conductors driven by ultrashort voltage pulses, showing their robustness even in strongly correlated systems like fractional quantum Hall states.

Contribution

It extends the theory of charge oscillations beyond interferometers to generic conductors, including strongly correlated ones, under the assumption of sublinear DC current.

Findings

Charge oscillations occur in various quantum conductors driven by ultrashort pulses.

These oscillations are robust against strong Coulomb interactions.

The phenomenon can be interpreted via photo-assisted probabilities.

Abstract

Time-dependent driving with ultrashort voltage pulses brings quantum conductors into the non-adiabatic transport regime, where novel dynamical effects emerge. An example of this physics occurs in interferometric systems, where the transmitted charge oscillates as a function of the charge injected by an ultrashort voltage pulse. This behavior has been predicted in a variety of setups, including Fabry-P\'erot and Mach-Zehnder interferometers, and more recently in quantum dots. It is commonly interpreted as resulting from interference between different propagating paths taken by the injected excitation. In this letter, we fully generalize the derivation of such dynamic charge oscillations beyond interferometric devices for a generic quantum conductor with the single assumption that its DC current is sublinear at large bias. Strikingly, they also extend perturbatively to strongly correlated conductors, showing in particular their robustness against arbitrarily strong Coulomb interactions. To illustrate the generality of our approach, we analyze in detail the case of a quantum point contact in the fractional quantum Hall regime, which fulfills the sublinearity condition. We demonstrate that this non-interferometric system exhibit dynamic charge oscillation. Finally, we propose a complementary interpretation of this phenomenon, rooted in the photo-assisted probabilities associated with the voltage pulse.