Correlated double-electron additions at the edge of a two-dimensional electronic system

Abstract

We create laterally large and low disorder quantum well based quantum dots to study single electron additions to two dimensional electron systems (2DES). Electrons tunnel into these dots across an AlGaAs tunnel barrier from a single $n+$ electrode. Using single-electron capacitance spectroscopy in a dilution refrigerator, we identify capacitance peaks for the addition of the first electron to a dot and record subsequent peaks in the addition spectrum up to occupancies of thousands of electrons. Here, we report two remarkable phenomena that occur in the filling factor range $\nu =2$ to $\nu =5$ while selectively probing electron additions to the edge states of the dot: (1) Coulomb blockade peaks arise from the entrance of two electrons rather than one; (2) at and near filling factor 5/2 and at fixed gate voltage, these double-height peaks appear uniformly with a periodicity of $h/2e$. At other filling factors in the range $\nu =2$ to $\nu =5$, the mean periodicity for the twice-height electron peaks remains $h/2e$, but the twice-height peaks are instead further bunched into pairs of double-height peaks, with pairs spaced $h/e$ apart. The unusual two-electron Coulomb blockade peaks suggest a novel pair tunneling effect that involves electron correlations that arise in the quantum dot, with spectra at $\nu =5/2$ identical to those previously only seen in superconducting dots.

arXiv commentAdded discussion to "bunching phenomena" section in supplement

References in corpus (14)

• Sharp and Smooth Boundaries of Quantum Hall Liquids
• The microscopic nature of localization in the quantum Hall effect
• Quantum Dots in Strong Magnetic Fields: Stability Criteria for the Maximum Density Droplet
• Electron Attraction Mediated by Coulomb Repulsion
• Cooper Instability of Composite Fermions
• Periodic and Aperiodic Bunching in the Addition Spectra of Quantum Dot
• High Resolution Spectroscopy of Two-Dimensional Electron Systems
• Charging Spectrum and Configurations of a Wigner Crystal Island
• Robust Electron Pairing in the Integer Quantum Hall Effect Regime
• The Localization-Delocalization Transition in Quantum Dots
• Localization in Artificial Disorder - Two Coupled Quantum Dots
• Two-electron state in a disordered 2D island: pairing caused by the Coulomb repulsion
• Interaction-induced interference in the integer quantum Hall effect
• Gate-Sensing Charge Pockets in the Semiconductor Qubit Environment

Cited by in corpus (5)

• Impact of bulk-edge coupling on observation of anyonic braiding statistics in quantum Hall interferometers
• Strongly coupled edge states in a graphene quantum Hall interferometer
• Electron Pairing of Interfering Interface-Based Edge Modes
• Evidence for correlated electron pairs and triplets in quantum Hall interferometers
• Three-electron bunches in occupation of a 5-site Coulomb cluster