Title

Three-dimensional topological insulator quantum dot for optically controlled quantum memory and quantum computing

Authors

Authors

H. P. Paudel;M. N. Leuenberger

Comments

Authors: contact us about adding a copy of your work at STARS@ucf.edu

Abbreviated Journal Title

Phys. Rev. B

Keywords

SINGLE-HOLE SPIN; ELECTRON-SPIN; RESONANCE FLUORESCENCE; SEMICONDUCTOR; SURFACE; PHASE; STATE; SPINTRONICS; FERMIONS; CRYSTAL; Physics, Condensed Matter

Abstract

We present the model of a quantum dot (QD) consisting of a spherical core-bulk heterostructure made of three-dimensional (3D) topological insulator (TI) materials, such as PbTe/Pb0.31Sn0.69Te, with bound massless and helical Weyl states existing at the interface and being confined in all three dimensions. The number of bound states can be controlled by tuning the size of the QD and the magnitude of the core and bulk energy gaps, which determine the confining potential. We demonstrate that such bound Weyl states can be realized for QD sizes of few nanometers. We identify the spin locking and the Kramers pairs, both hallmarks of 3D TIs. In contrast to topologically trivial semiconductor QDs, the confined massless Weyl states in 3D TI QDs are localized at the interface of the QD and exhibit a mirror symmetry in the energy spectrum. We find strict optical selection rules satisfied by both interband and intraband transitions that depend on the polarization of electron-hole pairs and therefore give rise to the Faraday effect due to the Pauli exclusion principle. We show that the semiclassical Faraday effect can be used to read out spin quantum memory. When a 3D TI QD is embedded inside a cavity, the single-photon Faraday rotation provides the possibility to implement optically mediated quantum teleportation and quantum information processing with 3D TI QDs, where the qubit is defined by either an electron-hole pair, a single electron spin, or a single hole spin in a 3D TI QD. Remarkably, the combination of interband and intraband transition gives rise to a large dipole moment of up to 450 Debye. Therefore, the strong-coupling regime can be reached for a cavity quality factor of Q approximate to 10(4) in the infrared wavelength regime of around 10 mu m.

Journal Title

Physical Review B

Volume

88

Issue/Number

8

Publication Date

1-1-2013

Document Type

Article

Language

English

First Page

17

WOS Identifier

WOS:000323487100003

ISSN

1098-0121

Share

COinS