Eckart, S., Kunitski, M., Richter, M., Hartung, A., Rist, J., Trinter, F., Fehre, K., Schlott, N., Henrichs, K., Schmidt, L. Ph. H., Jahnke, T., Schöffler, M., Liu, K., Barth, I., Kaushal, J., Morales, F., Ivanov, M., Smirnova, O., Dörner, R.
Ultrafast preparation and detection of ring
currents in single atoms
Nature Physics 14, (7),pp 701-704 (2018)
Quantum particles can penetrate potential barriers by tunnelling.
If that barrier is rotating, the tunnelling process
is modified. This is typical for electrons in atoms, molecules
or solids exposed to strong circularly polarized laser
pulses. Here we measure how the transmission probability
through a rotating tunnel depends on the sign of the magnetic
quantum number m of the electron and thus on the initial
direction of rotation of its quantum phase. We further
show that our findings agree with a semiclassical picture,
in which the electron keeps part of that rotary motion on its
way through the tunnel by measuring m-dependent modification
of the electron emission pattern. These findings
are relevant for attosecond metrology as well as for interpretation
of strong-field electron emission from atoms and
molecules and directly demonstrate the creation of ring
currents in bound states of ions with attosecond precision.
In solids, this could open a way to inducing and controlling
ring-current-related topological phenomena.
TH-2018-29