Optically Controlled Spin Gate Using GaN Quantum Dots

• Published in: ACS photonics 2022-05, Vol.9 (5), p.1529-1534
• Main Authors: Kim, Juhyeon, Croft, Zachary, Steel, Duncan G., Ku, Pei-Cheng
• Format: Article
• Language: English
• ISSN: 2330-4022; 2330-4022
• DOI: 10.1021/acsphotonics.2c00083

Two laterally positioned quantum dot single-photon emitters in different semiconductor heterostructures were analyzed. A controlled phase gate between two quantum dot spins was shown based on the Coulomb interaction between the two quantum dot trions. The interaction shifts the bitrion energy manifold, enabling a π-phase shift to be acquired depending on the state of the control qubit. The gate fidelity increases with an increasing bitrion coupling which in turn depends on the spacing between the quantum dots. In practical applications, this spacing needs to be sufficiently large to allow the two-quantum-dot system to be fabricated. An enhanced bitrion coupling was shown in In­(Ga)N quantum dots both in a bulk GaN matrix and in a dot-in-wire geometry, compared to that in In­(Ga)As dots. The enhanced bitrion coupling in In­(Ga)N dots increases the edge-to-edge interdot spacing needed to achieve the same gate performance, allowing a deterministic spin–spin gate to be designed based on site-controlled dot-in-wire In­(Ga)N quantum dots that can be readily fabricated with an interdot spacing of 10 nm using state-of-the-art lithography.