  A fundamental requirement for quantum technologies is the ability to
coherently control the interaction between electrons and photons. However, in
many scenarios involving the interaction between light and matter, the exchange
of linear or angular momentum between electrons and photons is not feasible, a
condition known as the dipole-approximation limit. An example of a case beyond
this limit that has remained experimentally elusive is when the interplay
between chiral electrons and vortex light is considered, where the orbital
angular momentum of light can be transferred to electrons. Here, we present a
novel mechanism for such an orbital angular momentum transfer from optical
vortex beams to electronic quantum Hall states. Specifically, we identify a
robust contribution to the radial photocurrent, in an annular graphene sample
within the quantum Hall regime, that depends on the vorticity of light. This
phenomenon can be interpreted as an optical pumping scheme, where the angular
momentum of photons is transferred to electrons, generating a radial current,
and the current direction is determined by the vorticity of the light. Our
findings offer fundamental insights into the optical probing and manipulation
of quantum coherence, with wide-ranging implications for advancing quantum
coherent optoelectronics.
