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Double-slit time diffraction at optical frequencies

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Double-slit experiments—where a wave is transmitted through a thin double aperture in space—have confirmed the wave–particle duality of quantum objects, such as single photons, electrons, neutrons, atoms and large molecules. Yet, the temporal counterpart of Young’s double-slit experiment—a wave interacting with a double temporal modulation of an interface—remains elusive. Here we report such a time-domain version of the classic Young’s double-slit experiment: a beam of light twice gated in time produces an interference in the frequency spectrum. The ‘time slits’, narrow enough to produce diffraction at optical frequencies, are generated from the optical excitation of a thin film of indium tin oxide near its epsilon-near-zero point. The separation between time slits determines the period of oscillations in the frequency spectrum, whereas the decay of fringe visibility in frequency reveals the shape of the time slits. Surprisingly, many more oscillations are visible than expected from existing theory, implying a rise time that approaches an optical cycle. This result enables the further exploration of time-varying physics, towards the spectral synthesis of waves and applications such as signal processing and neuromorphic computation.

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Fig. 1: Concept and realization of the double-slit diffraction experiment in time.
Fig. 2: Observation of a spectral diffraction pattern from temporal double slits.

Data availability

Source data are available for this paper and are available via a public repository at All other data that support the plots within this paper and other findings of this study are available from the corresponding authors upon request.

Change history

  • 11 April 2023

    In the version of this article initially published, x-axis labels were omitted for Figure 2e, which are now restored in the HTML and PDF versions of the article.


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E.G. acknowledges support from the Simons Foundation (855344). R.S., S.V., J.B.P. and S.A.M. acknowledge support from UKRI (EP/V048880). J.B.P. acknowledges support from the Gordon and Betty Moore Foundation. S.A.M. acknowledges the Lee-Lucas Chair in Physics.

Author information

Authors and Affiliations



Conceptualization: R.S., S.V., J.B.P., R.T. and E.G. Methodology: S.V., R.T., R.S., E.G. and J.B.P. Software: R.T., I.R., D.M. and E.G. Investigation: R.T., S.V., I.R., D.M. and E.G. Visualization: R.T., R.S., I.R. and D.M. Funding acquisition: R.S., J.B.P., S.A.M. and S.V. Project administration: R.S., J.B.P. and S.A.M. Supervision: R.S. and J.B.P. Writing (original draft): R.S., J.B.P., S.V., R.T. and E.G. Writing (review and editing): R.S., J.B.P., S.V., R.T., E.G., S.A.M. and B.T.

Corresponding authors

Correspondence to Romain Tirole or Riccardo Sapienza.

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The authors declare no competing interests.

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Nature Physics thanks Humeyra Caglayan and Francisco Rodríguez-Fortuño for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Characterization of the temporal double slit with a short (225 fs) probe pulse.

a, Experimental intensity reflectivity (blue line) for a 2.3 ps separation between the time slits, as a function of the probe delay. This is fitted with the model in Fig. S2A (dashed red line). b, Reflectivity for a linear variation of the slit separation (horizontal axis) measured as a function of the probe delay with one of the pumps (vertical axis). c, Intensity dependence of the maximum achievable reflectivity for the two time slits driven by pump 1 (incident at 54°) and pump 2 (incident at 66°). The reflectivity saturates reaching a maximum value of 0.6.

Source data

Extended Data Fig. 2 Modelled reflection coefficient.

a, Amplitude reflection coefficient r(t) corresponding to a realistic modulation of the time-varying mirror (see Fig. S3A). b, Amplitude reflection coefficient in the asymptotic limit.

Source data

Extended Data Fig. 3 Comparison of the models against experimental data.

ac, Signal against frequency and slit separation for experiment (a), the time diffraction model (b) and the adiabatic, dispersive time-varying model (c). The plots are color-saturated to ensure a fair quantitative comparison between the fringe visibility of the respective datasets. d, Experimental oscillation spectrum on a logarithmic scale at a slit separation of 800 fs compared to the theoretical one for various material response times.

Source data

Supplementary information

Supplementary Information

Supplementary figs. 1–4.

Source data

Source Data Fig. 1

Measured data.

Source Data Fig. 2

Measured data, smoothed data and modelling.

Source Data Extended Data Fig. 1

Measured data.

Source Data Extended Data Fig. 2


Source Data Extended Data Fig. 3

Measured data, smoothed data and modelling.

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Tirole, R., Vezzoli, S., Galiffi, E. et al. Double-slit time diffraction at optical frequencies. Nat. Phys. (2023).

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