Free coherent evolution of a coupled atomic spin system initialized by electron scattering

Science, vol. 372, pp. 964–968

Abstract

Full insight into the dynamics of a coupled quantum system depends on the ability to follow the effect of a local excitation in real-time. Here, we trace the free coherent evolution of a pair of coupled atomic spins by means of scanning tunneling microscopy. Rather than using microwave pulses, we use a direct-current pump-probe scheme to detect the local magnetization after a current-induced excitation performed on one of the spins. By making use of magnetic interaction with the probe tip, we are able to tune the relative precession of the spins. We show that only if their Larmor frequencies match, the two spins can entangle, causing angular momentum to be swapped back and forth. These results provide insight into the locality of electron spin scattering and set the stage for controlled migration of a quantum state through an extended spin lattice.

Authors 7

1. Lukas M. Veldman

   Delft University of Technology

   Affiliation as printed

   Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands

2. Laëtitia Farinacci

   Delft University of Technology

   Affiliation as printed

   Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands

3. Rasa Rejali

   Delft University of Technology

   Affiliation as printed

   Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands

4. Rik Broekhoven

   Delft University of Technology

   Affiliation as printed

   Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands

5. J. Gobeil

   Delft University of Technology

   Affiliation as printed

   Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands

6. Markus Ternes Aachen Institute of Physics (IA)

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Peter-Grünberg-Institute, Forschungszentrum Jülich, D-52425 Jülich, Germany

   RWTH Aachen University, Institute of Physics, D-52074 Aachen, Germany

7. Alexander F. Otte corresponding

   Delft University of Technology

   Affiliation as printed

   Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands