Publication

Observation of e/4 charge at ν=1/2 in GaAs

2026

Abstract

Even-denominator fractional quantum Hall states (FQHSs) fall outside the standard Laughlin's and Jain's odd-denominator hierarchy. In this work, we study the FQHS 𝜈 = 1/2 in the lowest Landau level. The state is confined within a 70 nm-wide GaAs quantum well, where the electrons exhibit a bilayer-like charge distribution. Inter-layer interactions stabilize the 𝜈 = 1/2 FQHS, which is predicted to host quasiparticles with charge e/4-with either Abelian or non-Abelian topological order. Here, we report on shot-noise measurements of partitioned quasiparticles at 𝜈 = 1/2, where charge partitioning is generated by a unique etch-defined quantum point contact. Our measurements were performed on two nominally identical devices, at two independent experimental setups. Analysis of shot noise in the weak-backscattering regime in each device reveals quasiparticles with charge e/4. These observations provide a clear benchmark for future studies aimed at probing the topological order of the 𝜈 = 1/2 FQHS and its quasiparticles' exchange statistics.

Official source

https://infoscience.epfl.ch/entities/publication/327cad4b-6813-4acd-854a-547ee76777e1

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2026

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/327cad4b-6813-4acd-854a-547ee76777e1

About this result

Related concepts (32)

Fractional quantum Hall effect

The fractional quantum Hall effect (FQHE) is a physical phenomenon in which the Hall conductance of 2-dimensional (2D) electrons shows precisely quantized plateaus at fractional values of . It is a property of a collective state in which electrons bind magnetic flux lines to make new quasiparticles, and excitations have a fractional elementary charge and possibly also fractional statistics.

Topological order

In physics, topological order is a kind of order in the zero-temperature phase of matter (also known as quantum matter). Macroscopically, topological order is defined and described by robust ground state degeneracy and quantized non-Abelian geometric phases of degenerate ground states. Microscopically, topological orders correspond to patterns of long-range quantum entanglement. States with different topological orders (or different patterns of long range entanglements) cannot change into each other without a phase transition.

Noise (electronics)

In electronics, noise is an unwanted disturbance in an electrical signal. Noise generated by electronic devices varies greatly as it is produced by several different effects. In particular, noise is inherent in physics and central to thermodynamics. Any conductor with electrical resistance will generate thermal noise inherently. The final elimination of thermal noise in electronics can only be achieved cryogenically, and even then quantum noise would remain inherent. Electronic noise is a common component of noise in signal processing.

Related publications (32)

Observation of e/4 charge at ν=1/2 in GaAs

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