Opportunities for detecting ring currents using an attoclock setup

Strong field ionization by circularly polarized laser fields from initial states with internal orbital momentum has an interesting propensity rule: electrons counter-rotating with respect to the laser field can be liberated more easily than co-rotating electrons [Barth and Smirnova, Phys. Rev. A 84, 063415 (2011)]. Here we show that application of few-cycle IR pulses allows one to use this propensity rule to detect ring currents associated with such quantum states, by observing angular shifts of the ejected electrons. Such shifts present the main observable of the attoclock method. We use time-dependent analytical R-matrix theory to show that the attoclock measured angular shifts of an electron originating from two counter-rotating orbitals (p(+) and p(-)) are noticeably different. Our work opens opportunities for detecting ring currents excited in atoms and molecules, using the attoclock setup.