# Real-Time Ramsey Interferometry in Fractional Quantum Hall States

## TL;DR

This paper demonstrates a method using Ramsey interferometry to probe the dynamical phase, fractional charge, and edge quasiparticle velocities in fractional quantum Hall states, including distinguishing between Pfaffian and anti-Pfaffian states.

## Contribution

It introduces a novel Ramsey interferometry technique to analyze fractional quasiparticles' dynamical phases and edge properties in quantum Hall systems.

## Key findings

- Interference patterns reveal fractional charge in quantum Hall states.
- The method distinguishes between Pfaffian and anti-Pfaffian states at 5/2 filling.
- Edge quasiparticle velocities can be extracted from the Ramsey signal.

## Abstract

We study the time-dependent dynamical phase of fractional quasiparticles in quantum Hall states using Ramsey interferometry. A Ramsey two-pulse voltage modulation generates an interference term in the current noise of a quantum point contact oscillating with the dynamical phase. We show that the interference pattern probes the Green's function of the fractional quasi-particles in the time domain and reveals the fractional charge. We address both the case of a point-like tunnel junction and the case of momentum-resolved tunneling which also provides information on the speed of those quasiparticles propagating along the edge. For the 5/2 fractional quantum Hall case, the Ramsey signal can differentiate between the Pfaffian and anti-Pfaffian states.