A shuttling-based two-qubit logic gate for linking distant silicon quantum processors

Abstract

Control of entanglement between qubits at distant quantum processors using a two-qubit gate is an essential function of a scalable, modular implementation of quantum computation. Among the many qubit platforms, spin qubits in silicon quantum dots are promising for large-scale integration along with their nanofabrication capability. However, linking distant silicon quantum processors is challenging as two-qubit gates in spin qubits typically utilize short-range exchange coupling, which is only effective between nearest-neighbor quantum dots. Here we demonstrate a two-qubit gate between spin qubits via coherent spin shuttling, a key technology for linking distant silicon quantum processors. Coherent shuttling of a spin qubit enables efficient switching of the exchange coupling with an on/off ratio exceeding 1,000 , while preserving the spin coherence by 99.6% for the single shuttling between neighboring dots. With this shuttling-mode exchange control, we demonstrate a two-qubit controlled-phase gate with a fidelity of 93%, assessed via randomized benchmarking. Combination of our technique and a phase coherent shuttling of a qubit across a large quantum dot array will provide feasible path toward a quantum link between distant silicon quantum processors, a key requirement for large-scale quantum computation.

References in corpus (7)

• Single-shot read-out of an individual electron spin in a quantum dot
• An addressable quantum dot qubit with fault-tolerant control fidelity
• Two-qubit silicon quantum processor with operation fidelity exceeding 99%
• Scalable gate architecture for densely packed semiconductor spin qubits
• Loading a quantum-dot based "Qubyte" register
• Radio-frequency detected fast charge sensing in undoped silicon quantum dots
• Robust micro-magnet design for fast electrical manipulations of single spins in quantum dots

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