Bell-state tomography in a silicon many-electron artificial molecule.
Ross C C Leon, Chih Hwan Yang, Jason C C Hwang, Julien Camirand Lemyre, Tuomo Tanttu, Wei Huang, Jonathan Y Huang, Fay E Hudson, Kohei M Itoh, Arne Laucht, Michel Pioro-Ladrière, Andre Saraiva, Andrew S Dzurak
Author Information
Ross C C Leon: School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia. ross@quantummotion.tech. ORCID
Chih Hwan Yang: School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia. ORCID
Jason C C Hwang: School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia. ORCID
Julien Camirand Lemyre: Institut Quantique et Département de Physique, Université de Sherbrooke, Sherbrooke, Québec, Canada. ORCID
Tuomo Tanttu: School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia. ORCID
Wei Huang: School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia. ORCID
Jonathan Y Huang: School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia.
Fay E Hudson: School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia. ORCID
Kohei M Itoh: School of Fundamental Science and Technology, Keio University, Yokohoma, Japan. ORCID
Arne Laucht: School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia. ORCID
Michel Pioro-Ladrière: Institut Quantique et Département de Physique, Université de Sherbrooke, Sherbrooke, Québec, Canada.
Andre Saraiva: School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia. a.saraiva@unsw.edu.au.
Andrew S Dzurak: School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, NSW, Australia. a.dzurak@unsw.edu.au. ORCID
An error-corrected quantum processor will require millions of qubits, accentuating the advantage of nanoscale devices with small footprints, such as silicon quantum dots. However, as for every device with nanoscale dimensions, disorder at the atomic level is detrimental to quantum dot uniformity. Here we investigate two spin qubits confined in a silicon double quantum dot artificial molecule. Each quantum dot has a robust shell structure and, when operated at an occupancy of 5 or 13 electrons, has single spin-[Formula: see text] valence electron in its p- or d-orbital, respectively. These higher electron occupancies screen static electric fields arising from atomic-level disorder. The larger multielectron wavefunctions also enable significant overlap between neighbouring qubit electrons, while making space for an interstitial exchange-gate electrode. We implement a universal gate set using the magnetic field gradient of a micromagnet for electrically driven single qubit gates, and a gate-voltage-controlled inter-dot barrier to perform two-qubit gates by pulsed exchange coupling. We use this gate set to demonstrate a Bell state preparation between multielectron qubits with fidelity 90.3%, confirmed by two-qubit state tomography using spin parity measurements.
