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Photoelectric effect with a twist


Photons have fixed spin and unbounded orbital angular momentum (OAM). While the former is manifested in the polarization of light, the latter corresponds to the spatial phase distribution of its wavefront1. The distinctive way in which the photon spin dictates the electron motion upon light–matter interaction is the basis for numerous well-established spectroscopies. By contrast, imprinting OAM on a matter wave, specifically on a propagating electron, is generally considered very challenging and the anticipated effect undetectable2. In refs. 3,4, the authors provided evidence of OAM-dependent absorption of light by a bound electron. Here, we seek to observe an OAM-dependent dichroic photoelectric effect, using a sample of He atoms. Surprisingly, we find that the OAM of an optical field can be imprinted coherently onto a propagating electron wave. Our results reveal new aspects of light–matter interaction and point to a new kind of single-photon electron spectroscopy.

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Fig. 1: Experimental set-up and first evidence of OAM-dependent dichroism.
Fig. 2: Theoretical description of the imprinting of light OAM on the matter wave of a single photoelectron released from a He atom.
Fig. 3: Theoretical description of the imprinting of light OAM on the matter waves of photoelectrons released from a sample of He atoms.
Fig. 4: Experimental versus theoretical photoelectron spectra and DCSs for different combinations of infrared spin and OAM.

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Data availability

The plotted data and other information related to this study are available from the corresponding author upon reasonable request.

Code availability

The numerical code supporting the experimental results reported in this paper is available upon reasonable request.


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We acknowledge the support of the project ‘Triggering forbidden phenomena with twisted light and particle beams’ (no. J1–8134), funded by the Slovenian Research Agency (ARRS), and of EU-H2020 project NFFA (grant no. 654360). The theoretical study has been financed by the German Science Foundation (DFG), within the priority programme 1840, ‘Quantum dynamics in tailored intense fields’ (SFB-TRR227 and WA 4352/2-1).

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G.D.N., P.R.R., J.W. and J.B. proposed the experiment, the feasibility of which was discussed with M.C., M.Ž. and C.C. G.D.N. coordinated the experiment. J.W. and J.B. developed the theoretical model and J.W. carried out the simulations. C.C., A.M., B.Ressel, B.Rösner, J.W., K.H., M.C., M.D.F., M.S., O.P., Š.K., P.R.R. and G.D.N. carried out the measurements. P.R.R., E.A., A.D., A.S., B.Rösner, C.D., M.B.D., M.D.F., M.Manfredda, M.Z., N.M. and S.S. prepared the light source. G.D.N., B.Rösner and M.D.F. carried out the data analysis. G.D.N., J.W. and J.B. wrote the first draft of the manuscript, which was first reviewed by A.M., B.Rösner, C.C., M.Meyer, M.Ž. and P.R.R. and then discussed with all co-authors.

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Correspondence to Giovanni De Ninno.

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Supplementary Figs. 1–4 and discussion.

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De Ninno, G., Wätzel, J., Ribič, P.R. et al. Photoelectric effect with a twist. Nat. Photonics 14, 554–558 (2020).

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