Effects of Parity and Symmetry on the Aharonov–Bohm Phase of a Quantum Ring

Abstract

We experimentally investigate the properties of one-dimensional quantum rings that form near the surface of nanowire quantum dots. In agreement with theoretical predictions, we observe the appearance of forbidden gaps in the evolution of states in a magnetic field as the symmetry of a quantum ring is reduced. For a twofold symmetry, our experiments confirm that orbital states are grouped pairwise. Here, a π-phase shift can be introduced in the Aharonov–Bohm relation by controlling the relative orbital parity using an electric field. Studying rings with higher symmetry, we note exceptionally large orbital contributions to the effective g-factor (up to 300), which are many times higher than those previously reported. These findings show that the properties of a phase-coherent system can be significantly altered by the nanostructure symmetry and its interplay with wave function parity.

Epitaxial growth of crystal phase quantum dots in III–V semiconductor nanowires

“…Quantum rings can also be employed to explore the Aharonov–Bohm (AB) effect as reported in 2022 by Debbarma and co-workers. 181 The AB effect is a quantum mechanical phenomenon in which an electrically charged particle is affected by an electromagnetic potential, despite being confined to a region in which both the magnetic and electric fields are zero. 182 In their work, they investigated two different kinds of crystal phase ZB-InAs (4–5 nm thick) ring-like QD structures (A and B).…”

Nuclear versus electronic ring currents in oriented torsional molecules induced by magnetic fields. I. Nuclear currents of toluene

“…The coupling of the two electrons in the quantum rings is mediated by the repulsive Coulomb interaction leading to a different interaction potential. We also apply a homogeneous co-axial magnetic field, whereas in studies of quantum-ring systems the rings are usually exposed to inhomogeneous magnetic fields [18][19][20][21].…”

Perfect Zeeman Anisotropy in Rotationally Symmetric Quantum Dots with Strong Spin–Orbit Interaction

“…In a system with rotationally symmetric confinement, such as in a quantum ring, − the coupling of the electron’s spin to its angular momentum from SOI can give rise to a particularly strong magnetic anisotropy. If the electric field responsible for SOI is symmetric around the ring axis, then SOI will suppress Zeeman splitting of levels for any external magnetic ( B ) field oriented in the ring plane.…”

“…During growth of a zinc blende (ZB) InAs nanowire core, two segments (∼20 nm) of wurtzite (WZ) crystal structure are introduced. They provide both axial confinement and symmetry-preserving tunnel barriers to the QD for noninvasive electron transport spectroscopy. , The core is surrounded by a ∼20 nm thick shell of InAs 1– x Sb x ( x = 0.1–0.2), followed by a thin layer of InAs, and finally an outer, sacrificial shell of GaSb that selectively deposits on ZB and provides an indicator of the QD position . The purpose of the InAsSb shell, with a slightly reduced band gap relative to InAs, is to create a radial well where SOI is enhanced .…”

“…Although no solid-state system can attain the infinite symmetry of an ideal quantum ring, as long as the system has a periodic and rotationally symmetric potential, bands of orbital states form where orbital interactions can be completely suppressed. ,, Carbon nanotubes are an interesting example with an inherently high radial symmetry, and where SOI emerges from the curved graphene lattice. Weak interaction of counter-propagating electron states has been observed, evidencing a low, although finite, disorder. , However, as the electron momentum in a tubular structure is not axially restricted, electron–electron interactions and orbital separation are very different from those in a ring or a two-dimensional disk.…”