Accuracy of circular polarization as a measure of spin polarization in quantum dot qubits
Abstract
A quantum dot (QD) spin LED provides a test of spin injection into a QD qubit. The polarization of the observed light is, however, influenced by the geometry of the dot so the spin may be more polarized than the emitted light would naively suggest. We have calculated polarization dependent optical matrix elements using 8-band strain-dependent k.p theory for InAs/GaAs self-assembled QDs for a range of sizes, shapes, and emission directions. We find the QD geometry and emission direction strongly influence the observed circular polarization. For typical QD geometries with emission along the 110 direction, the light is only 4circularly polarized for spin states 100110. Therefore observed polarizations[1] of 0.01 imply a spin polarization within the dot of 0.25. [1] Y. Chye, M. E. White, E. Johnston-Halperin, B. D. Gerardot, D. D. Awschalom, and P. M. Petroff, Phys. Rev. B Vol. 66, 201301(R)
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2003
- Bibcode:
- 2003APS..MARX19015P