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Coherent spin manipulation of individual atoms on a surface

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Science  25 Oct 2019:
Vol. 366, Issue 6464, pp. 509-512
DOI: 10.1126/science.aay6779

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Coherent surface spin manipulation

Spin-based quantum information processing requires coherent spin manipulation. Yang et al. demonstrate coherent control of surface titanium and iron atom spins on a magnesium oxide surface with a magnetic scanning tunneling microscope tip. Arbitrary sequences of fast electrical pulses delivered to the top induced large electric fields. These fields drove metal-atom movement, which then modulated the tip-atom exchange interaction to create an oscillating effective magnetic field. Advanced spin-control protocols such as Ramsey fringes and Hahn spin echoes revealed quantum dynamics, such as coherent oscillations in a titanium atom dimer assembled on the surface with the tip.

Science, this issue p. 509

Abstract

Achieving time-domain control of quantum states with atomic-scale spatial resolution in nanostructures is a long-term goal in quantum nanoscience and spintronics. Here, we demonstrate coherent spin rotations of individual atoms on a surface at the nanosecond time scale, using an all-electric scheme in a scanning tunneling microscope (STM). By modulating the atomically confined magnetic interaction between the STM tip and surface atoms, we drive quantum Rabi oscillations between spin-up and spin-down states in as little as ~20 nanoseconds. Ramsey fringes and spin echo signals allow us to understand and improve quantum coherence. We further demonstrate coherent operations on engineered atomic dimers. The coherent control of spins arranged with atomic precision provides a solid-state platform for quantum-state engineering and simulation of many-body systems.

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