Fast spin flips for entangled atoms

Spin Physics The integration of pump-probe spectroscopy with scanning tunneling microscopy (STM) tools has allowed studies of spin relaxation in atoms on the nanosecond time scale. However, following the free evolution of a pair of entangled spins requires faster initial excitation than can be delivered with microwave pulses. Veldman et al. sequentially combined electron spin resonance–STM and direct-current pump-probe techniques to instantaneously flip spins while preserving spin coherence. They used this method to follow free, coherent flip-flop evolution of two coupled spin-1/2 atoms (hydrogenated titanium atom dimers) on a magnesium oxide surface. Science , abg8223, this issue p. [964][1] [1]: /lookup/doi/10.1126/science.abg8223