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arXiv · 2507.16357

Modulation of sub-optical cycle photocurrents in an ultrafast near-infrared scanning tunnelling microscope

Andrea Rossetti·Florian Pagnini·Majdi Assaid·Christoph Schoenfeld·Alfred Leitenstorfer·Markus Ludwig·Daniele Brida
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Abstract

Lightwave-driven scanning tunnelling microscopy (STM) at near-IR frequencies promises an unprecedented combination of atomic spatial resolution and temporal resolution approaching the attosecond range. To achieve this goal, high-sensitivity optical control and detection of sub-cycle tunnelling currents must be achieved at the STM junction. Here, we demonstrate the generation and detection of coherent ultrafast currents across the junction of an STM illuminated by near-infrared single-cycle pulses. We introduce a novel modulation scheme that avoids time-dependent thermal loading while selectively isolating carrier-envelope phase (CEP)-dependent photocurrents. All artifacts arising from periodic modulation of laser power and thermal coupling are efficiently suppressed, enabling a clean readout of the coherent portion of the ultrafast tunneling current.

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Andrea Rossetti, Florian Pagnini, Majdi Assaid, Christoph Schoenfeld, Alfred Leitenstorfer, Markus Ludwig, Daniele Brida. 2025-07-22. Modulation of sub-optical cycle photocurrents in an ultrafast near-infrared scanning tunnelling microscope. https://arxiv.org/abs/2507.16357

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