Engineering the Eigenstates of Coupled Spin- 1 / 2 Atoms on a Surface

YANG, KAI; BAE, YUJEONG; PAUL, WILLIAM; NATTERER, FABIAN D.; WILLKE, PHILIP; LADO, JOSE L.; FERRÓN, ALEJANDRO; CHOI, TAEYOUNG; FERNÁNDEZ-ROSSIER, JOAQUÍN; HEINRICH, ANDREAS J.; LUTZ, CHRISTOPHER P.

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Lugar: New York; Año: 2017 vol. 119 p. 227206 - 227206

0031-9007

Quantum spin networks having engineered geometries and interactions are eagerly pursued for quantum simulation and access to emergent quantum phenomena such as spin liquids. Spin-1/2 centers are particularly desirable because they readily manifest coherent quantum fluctuations. Here we introduce a controllable spin-1/2 architecture consisting of titanium atoms on a magnesium oxide surface. We tailor the spin interactions by atomic-precision positioning using a scanning tunneling microscope (STM), and subsequently perform electron spin resonance (ESR) on individual atoms to drive transitions into and out of quantum eigenstates of the coupled-spin system. Interactions between the atoms are mapped over a range of distances extending from highly anisotropic dipole coupling, to strong exchange coupling. The local magnetic field of the magnetic STM tip serves to precisely tune the superposition states of a pair of spins. The precise control of the spin-spin interactions and ability to probe the states of the coupled-spin network by addressing individual spins will enable exploration of quantum many-body systems based on networks of spin-1/2 atoms on surfaces.