Quantum Hall Fabry-Pérot Interferometer Detects Phase Slips at And, Revealing Quasiparticle Properties

Quantum Hall interferometers represent powerful tools for investigating the fundamental properties of electrons in strong magnetic fields, and recent work by N. L. Samuelson, L. A. Cohen, W. Wang, et al. from various institutions including those led by T. Taniguchi and K. Watanabe, reveals new insights into how these devices respond to individual quasiparticles. The team demonstrates that these interferometers exhibit distinct ‘phase slips’, sudden changes in the interference pattern, caused by quasiparticles entering the device, and importantly, they observe that the time it takes for the system to settle after each event can extend to several minutes. This extended equilibration time allows researchers to differentiate between two types of phase slips, revealing that quasiparticles can either spread out across the interferometer or become trapped at specific defects, offering a new level of control and understanding of these quantum systems and their behaviour. This ability to distinguish between these behaviours represents a significant step towards harnessing quasiparticles for future quantum technologies.

Non-Equilibrium Quasiparticle Dynamics in Interferometers

Quantum Hall Fabry-Pérot interferometers provide a sensitive means of investigating quasiparticles confined within a device, revealing information about their fundamental characteristics and interactions. This work explores the behaviour of quasiparticles when they are not in equilibrium, focusing on their response to an applied voltage pulse and developing a theoretical framework that accounts for both smooth, wave-like evolution and the disruptive effects of electron-hole puddle formation and scattering. The results demonstrate that the transient interference signal serves as a sensitive probe of quasiparticle lifetime and the strength of their mutual interactions, offering new insights into these exotic states of matter.

Anyon Dynamics in Graphene Interferometry Experiments

Researchers investigated the properties of edge states in a two-dimensional electron system, likely graphene, within the fractional quantum Hall regime using a graphene-based interferometer. By observing the interference patterns created by these edge states, scientists reveal information about their fundamental properties and the dynamics of anyons, quasiparticles exhibiting unique exchange statistics. Telegraph noise, random fluctuations in current, provides further insight into these quasiparticles.

Quasiparticle Dynamics Observed in Quantum Hall Interferometer

Scientists achieved detailed observation of quasiparticles within a quantum Hall interferometer, revealing insights into their behaviour and interactions. Experiments demonstrate that the time it takes for quasiparticles to equilibrate within the interferometer can extend to several minutes, allowing for precise measurement of their dynamics. The team traced the dependence of phase slips on magnetic field, establishing a connection between equilibration time and the properties of the interferometer and identifying two distinct classes of phase slips linked to different quasiparticle behaviours. One class arises from quasiparticles adding to a uniformly coupled puddle, while the second is associated with quasiparticles trapped by defects and interacting with only a localized portion of the edge. Measurements confirm that the characteristic time for quasiparticle entry varies significantly with magnetic field, and analysis of the interferometer phase reveals that individual phase slips exhibit magnitudes within a specific range, supporting a scenario where quasiparticles occupy a compressible puddle. By carefully observing interference phase slips, the team successfully measured the time it takes for localized quasiparticles to charge, revealing timescales that can extend to several minutes in their graphene devices and allowing them to directly observe the stochastic behaviour expected in clean quantum Hall systems. The study further distinguished between two types of quasiparticles: those trapped at defects and those entering larger, more diffuse regions of accumulated charge, achieved through a multi-gated geometry. The findings suggest a complex interplay between quasiparticle interactions and the presence of disorder within van der Waals heterostructures, providing new insight into the behaviour of these exotic states of matter. Future work could benefit from employing faster radio-frequency impedance reflectometry to overcome limitations imposed by readout time, particularly when investigating more complex quantum Hall states.