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arXiv · 2502.03116

Attosecond Optical Orientation

Lauren B Drescher·Nicola Mayer·Kylie Gannan·Jonah R Adelman·Stephen R Leone
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Abstract

Circularly polarized light offers opportunities to probe symmetry-dependent properties of matter such as chirality and spin. Circular dichroism measurements typically require further intrinsic or extrinsic breaking of symmetry by e.g. enantiomeric excess, orientation, magnetic fields or direction-sensitive detectors. Here we introduce circular-dichroic attosecond transient absorption spectroscopy by leveraging the angular momentum of two circular-polarized pulses, both pump and probe, in an isotropic medium, optically orienting the angular momentum of excited states on an attosecond timescale. We investigate a circular-dichroic measurement of the attosecond transient absorption of He Rydberg states. By limiting the allowed pathways via dipole selection rules for co- and counter-rotating circular polarized NIR and XUV pulses, different spectral reshapings of the XUV transient absorption due to the AC Stark effect are observed. Paired with time-dependent Schr\"odinger equation calculations, the results show the role of selection and propensity rules and open up new opportunities to study coupling pathways of excited states as well as spin-dependent dynamics in atoms and beyond via attosecond optical orientation.

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Lauren B Drescher, Nicola Mayer, Kylie Gannan, Jonah R Adelman, Stephen R Leone. 2025-02-05. Attosecond Optical Orientation. https://arxiv.org/abs/2502.03116

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