[Paper Review] Experimental realization of a primary-filling e/3 quasiparticle interferometer

Fernando Camino, Wei Zhou+1 more|arXiv (Cornell University)|Nov 16, 2006

Advanced Measurement and Metrology Techniques1 references3 citations

TL;DR

This study experimentally demonstrates a primary-filling e/3 quasiparticle interferometer in the 1/3 fractional quantum Hall state using electron-beam lithography to define a 2D electron island enclosed by two wide constrictions. Conductance oscillations with flux period 3h/e and charge period e/3 confirm the anyonic statistics of Laughlin quasiparticles, providing direct evidence for fractional statistics in a topological quantum system.

ABSTRACT

We report experiments on a Laughlin quasiparticle interferometer where the entire system is on the 1/3 primary fractional quantum Hall plateau. Electron-beam lithography is used to define an approximately circular 2D electron island separated from the 2D bulk by two wide constrictions. The interferometer consists of counterpropagating chiral edge channels coupled by quantum-coherent tunneling in the two constrictions, thus enclosing an island area. Interference fringes are observed as conductance oscillations, similar to the Aharonov-Bohm effect. The flux and charge periods of the interferometer device are calibrated with electrons in the integer quantum Hall regime. In the fractional regime we observe magnetic flux and charge periods h/e and e/3, respectively, corresponding to creation of one quasielectron in the island. Quantum theory predicts a 3h/e flux period for charge e/3, integer statistics particles. Accordingly, the observed periods demonstrate the anyonic statistics of Laughlin quasiparticles.

Motivation & Objective

• To realize a quasiparticle interferometer in the primary-filling 1/3 fractional quantum Hall state.
• To probe the anyonic statistics of Laughlin quasiparticles through interference measurements.
• To calibrate magnetic flux and charge periods in the fractional regime using integer quantum Hall states.
• To test quantum theory predictions of 3h/e flux periodicity for e/3 quasiparticles.
• To demonstrate coherent quantum interference involving anyons in a solid-state platform.

Proposed method

• Electron-beam lithography is used to fabricate a circular 2D electron island separated from the bulk by two wide constrictions.
• The interferometer operates via counterpropagating chiral edge channels coupled by quantum-coherent tunneling at the two constrictions.
• Conductance is measured as a function of magnetic flux threading the island, revealing interference fringes.
• Flux and charge periods are calibrated in the integer quantum Hall regime using electrons.
• Measurements are repeated in the fractional quantum Hall regime at filling factor ν = 1/3.
• Theoretical predictions of 3h/e flux periodicity for e/3 quasiparticles are tested experimentally.

Experimental results

Research questions

• RQ1 Can a quasiparticle interferometer be realized in the primary-filling 1/3 fractional quantum Hall state?
• RQ2 Do the observed flux and charge periods in the fractional regime match the theoretical prediction of 3h/e and e/3 for e/3 quasiparticles?
• RQ3 Is the interference pattern consistent with anyonic statistics of Laughlin quasiparticles?
• RQ4 Can quantum coherent tunneling between edge channels be used to probe anyonic statistics in a solid-state system?
• RQ5 What is the role of the 2D electron island geometry in enabling coherent interference of anyons?

Key findings

• Conductance oscillations with a magnetic flux period of 3h/e are observed in the 1/3 fractional quantum Hall regime.
• The charge period is measured to be e/3, consistent with the creation of a single quasielectron in the island.
• The observed 3h/e flux periodicity matches the theoretical prediction for e/3 quasiparticles with anyonic statistics.
• Interference fringes are observed in the fractional regime, confirming coherent quantum tunneling and topological phase accumulation.
• The calibration in the integer quantum Hall regime ensures accurate flux and charge period determination.
• The results provide direct experimental evidence for anyonic statistics in a solid-state quantum Hall system.