Exciton Controlled-NOT Gate Using Coupled Quantum Dots in Carbon Nanotube

Abstract

A four-level system is a prerequisite for the controlled-NOT (CNOT) gate and is realized with excitons confined in the coupled quantum dots (QDs). The coupled QDs are fabricated by chemically bonding the collagen model peptides to a single-walled carbon nanotube. An interdot exciton–exciton interaction and an exciton four-level system based on it are confirmed through photoluminescence measurements. Rabi oscillations of the exciton populations are observed, which allow the manipulations of the exciton four-level system with designed laser-pulse sequences. The tests on whether the exciton four-level system operates as a CNOT gate are conducted, and the quantum process fidelity is estimated to be approximately 0.7–0.8. The SWAP operation is also demonstrated by employing the CNOT gate three times.