Two-qubit logic gates based on the ultrafast spin transfer in π-conjugated graphene nanoflakes. (30th June 2022)

• Record Type: Journal Article
• Authors: Zhang, Yiming; Liu, Jing; Jin, Wei; Lefkidis, Georgios; Hübner, Wolfgang; Li, Chun
• Is Part Of: Carbon. Volume 193(2022)
• Page Start: 195
• Page End: 204
• Publication Date: 2022-06-30
• Subjects: Graphene nanoflakes -- Two-qubit logic gate -- Spin transfer -- First principles; Carbon -- Periodicals; Carbone -- Périodiques; Koolstof; Toepassingen; Electronic journals; 546.681
• DOI: 10.1016/j.carbon.2022.03.012
• Languages: English
• ISSNs: 0008-6223

Abstract

Abstract: Ultrafast optical spin control allows gate operations to be performed within picosecond time scale, orders of magnitude faster than microwave or electrical control. Here, using high-level quantum chemical computations, we suggest several two-qubit logic gates based on the optically induced ultrafast spin-flip and spin-transfer processes on rhombic graphene nanoflakes (Co4 -GNF). It is demonstrated that Co atoms chemisorbed on π -conjugated C atoms can significantly influence the spin properties of the system. The spin density of different energy levels is distributed on different Co atoms, thus opening channels for successful spin-transfer processes between the Co atoms. Reversible local spin-flip processes on each Co atom as well as global spin-transfer processes between the Co atoms are realized. By carefully combining the various spin-dynamics processes achieved in our Co4 -GNF structure, both classical (OR, AND, NAND) and quantum (CNOT, SWAP) binary logic gates are constructed. All spin manipulation processes finish at the subpicosecond time scale with fidelities above 96%. This theoretical design, which is exclusively based on laser-induced ultrafast spin dynamics, represents a novel implementation of qubit manipulation and can thus pave the way towards the construction of nano magnetic logic circuits and spintronic devices. Graphical abstract: Image 1