Observation of ballistic upstream modes at fractional quantum Hall edges of graphene

Abstract

The structure of edge modes at the boundary of quantum Hall (QH) phases forms the basis for understanding low energy transport properties. In particular, the presence of ``upstream'' modes, moving against the direction of charge current flow, is critical for the emergence of renormalized modes with exotic quantum statistics. Detection of excess noise at the edge is a smoking gun for the presence of upstream modes. Here we report on noise measurements at the edges of fractional QH (FQH) phases realized in dual graphite-gated bilayer graphene devices. A noiseless dc current is injected at one of the edge contacts, and the noise generated at contacts at $L=4\mu$m or $10\mu$m away along the upstream direction is studied. For integer and particle-like FQH states, no detectable noise is measured. By contrast, for ``hole-conjugate'' FQH states, we detect a strong noise proportional to the injected current, unambiguously proving the existence of upstream modes. The noise magnitude remaining independent of length together with a remarkable agreement with our theoretical analysis demonstrates the ballistic nature of upstream energy transport, quite distinct from the diffusive propagation reported earlier in GaAs-based systems. Our investigation opens the door to the study of upstream transport in more complex geometries and in edges of non-Abelian phases in graphene.

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Cited by in corpus (29)

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• Full Classification of Transport on an Equilibrated 5/2 Edge via Shot Noise
• Does delta-$T$ noise probe quantum statistics?
• Half-integer conductance plateau at the $\nu =2/3$ fractional quantum Hall state in a quantum point contact
• Thermal conductance and noise of Majorana modes along interfaced $\nu =5/2$ fractional quantum Hall states
• Absence of edge reconstruction for quantum Hall edge channels in graphene devices
• Shot noise as a diagnostic in the $\nu =2/3$ fractional quantum Hall edge zoo
• Emergence of Neutral Modes in Laughlin-like Fractional Quantum Hall Phases
• Coherent-Incoherent Crossover of Charge and Neutral Mode Transport as Evidence for the Disorder-Dominated Fractional Edge Phase
• Fingerprints of anti-Pfaffian topological order in quantum point contact transport
• Absence of heat flow in ν = 0 quantum Hall ferromagnet in bilayer graphene
• Multiple Mechanisms for Emerging Conductance Plateaus in Fractional Quantum Hall States
• The Monte Carlo simulation of the topological quantities in FQH systems
• Impact of potential and temperature fluctuations on charge and heat transport in quantum Hall edges in the heat Coulomb blockade regime
• Role of scaling dimensions in generalized noises in fractional quantum Hall tunneling due to a temperature bias
• Electrical noise spectroscopy of magnons in a quantum Hall ferromagnet
• Transport Signatures of Fractional Quantum Hall Binding Transitions
• Experimentally Motivated Order of Length Scales Affect Shot Noise
• Half-integer thermal conductance in the absence of Majorana mode
• Landscapes of an out-of-equilibrium anyonic sea
• Exchange-phase erasure in anyonic Hong-Ou-Mandel interferometry
• Time-dependent transport in Graphene Mach-Zender Interferometers
• Quantized heat flow in graphene quantum Hall phases: Probing the topological order
• Edge reconstruction of compressible Quantum Hall fluid in the filling fraction range 1/3 to 2/3
• Manifestation of edge-bulk incompatibility in fractional quantum Hall platform
• Collapse of edge reconstruction in compressible Quantum Hall fluid within filling fraction range 2/3 to 1
• Shot noise signatures of candidate states for the fractional quantum Hall $\nu =12/5$ state
• Extracting the scaling dimension of quantum Hall quasiparticles from current correlations