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Optical emission and coherent control in carbon nanotube quantum dots

Akira Hidaand Koji Ishibashi (Advanced Device Laboratory, Pioneering Research Institute, RIKEN, Japan)

Abstract Single-wall carbon nanotubes (SWCNTs) are an attractive material for quantum dots simply because of their small diameter, so that the energy scales can be larger compared with those fabricated by top-down (lithography) technologies. They can be metallic or semiconducting, depending on how they are rolled up from a graphene sheet. Both electrical and optical applications are possible, but the fabrication and processing difficulties hinder reliable and reproducible realization of potential quantum devices.

We are interested in excitons in the SWCNT quantum dot. Our quantum dot is a short nanotube in which both ends are terminated by molecules. We show that potential profile in the nanotube can be modified by different chemical boings between the nanotube and the molecule, and demonstrate formation of the single and double quantum dots.

The semiconducting SWCNT quantum dot shows exciton emissions. Of our particular interest is to control the exciton states in the double quantum dots for the exciton-based quantum gate application. The single exciton in a dot forms a quantum bit (qubit), and its quantum state can be coherently controlled by the laser pulse. In the double quantum dots formed in a short SWCNT, an interaction between excitons in each dot makes the system to work as a conditional quantum gate. In my talk, formation of quantum dots, basic properties of the exciton emission and the quantum gate (CNOT) operation will be shown.

References

• Akira Hida and Koji Ishibashi, Appl. Phys. Express, 8, 045101 (2015)
• Akira Hida and Koji Ishibashi, ACS Photonics, 9, 3398-3403 (2022)