Ultrafast Tunneling Dynamics in Nanoscale Systems

Ultrafast tunnelling dynamics in nanoscale systems explore the motion of electrons across atomic-scale barriers on timescales ranging from femtoseconds to attoseconds. By harnessing intense, phase-stable light pulses—often in the terahertz region—to modulate the tunnelling junction of a scanning tunnelling microscope, researchers attain simultaneous sub-picosecond temporal and sub-ångström spatial resolution. This approach reveals fundamental processes such as transient barrier deformation, state-selective charge injection and coherent wavepacket evolution in low-dimensional materials, single molecules and semiconductor interfaces. Advances in pulse synchronisation, carrier-envelope phase control and optical pump–probe integration have transformed our ability to track and manipulate electronic, excitonic and plasmonic excitations in real time. Such insights underpin the development of next-generation optoelectronic devices operating at optical clock rates, quantum information platforms based on coherent charge motion and novel spectroscopic tools for material characterisation. The technique’s versatility, from direct imaging of wavefunction dynamics in graphene nanoribbons to the control of two-level population kinetics in molecular junctions, underscores its central role in bridging ultrafast photonics and nanoscale electronics.

Research from Nature Portfolio

Recent studies have demonstrated an externally triggered optical pump–probe scanning tunnelling microscope capable of tens-picosecond time resolution under stable laser illumination. By electrically controlling pulse timing and employing a piezo-actuated aspheric lens for junction stability, this system captures carrier decay dynamics at specific surface features of GaAs with ∼170 ps resolution. In parallel, lightwave-driven terahertz scanning tunnelling spectroscopy of seven-atom-wide armchair graphene nanoribbons has achieved coherent control of single-cycle field transients at ultralow tip heights. Tomographic mapping of local wavefunctions revealed position-dependent decay profiles and energy-resolved spectra inaccessible to conventional methods, paving the way for ultrafast probing of electronic properties in atomically precise structures.

Ultrafast Tunneling Dynamics in Nanoscale Systems publication trend

The graph below shows the total number of articles in ultrafast tunneling dynamics in nanoscale systems across all publications each year (not limited to Nature Index journals).

Technical terms

Ultrafast tunnelling: Electron transmission through a nanoscale barrier on femtosecond to attosecond timescales driven by transient fields.

Scanning tunnelling microscopy (STM): A technique that measures quantum tunnelling current between a conductive tip and sample to image surfaces with atomic resolution.

Terahertz (THz) pulses: Electromagnetic transients in the 0.1–10 THz range used to apply ultrafast bias voltages in tunnelling junctions.

Pump–probe spectroscopy: A method that uses one pulse to excite a system and a delayed pulse to interrogate its transient state.

Carrier–envelope phase (CEP): The relative phase between the peak of an optical pulse envelope and its underlying carrier wave, critical for waveform control.

References

1. Origin of photoinduced DC current and two-level population dynamics in a single molecule. Science Advances (2024).
2. Efficient and Continuous Carrier-Envelope Phase Control for Terahertz Lightwave-Driven Scanning Probe Microscopy. ACS Photonics (2023).
3. Externally-triggerable optical pump-probe scanning tunneling microscopy with a time resolution of tens-picosecond. Scientific Reports (2023).
4. Lightwave-driven scanning tunnelling spectroscopy of atomically precise graphene nanoribbons. Nature Communications (2021).
5. Ultrafast state-selective tunneling in two-dimensional semiconductors with a phase- and amplitude-controlled THz-scanning tunneling microscope. APL Materials (2024).