The Smallest Stepping Stone: Quantum Dot Physics Using Atomic Defects by Prof Hadar Steinberg

On 24 September 2025, Prof Hadar Steinberg (Racah Institute of Physics, Hebrew University of Jerusalem), delivered a thought-provoking colloquium at SPMS LT4 in NTU, titled “The Smallest Stepping Stone: Quantum Dot Physics Using Atomic Defects.”

Prof Steinberg introduced his group’s pioneering work on atomically sized quantum dots (QDs) realised in defects of two-dimensional insulators such as hexagonal boron nitride (hBN). By integrating these defect-based QDs with graphene electrodes, his team achieved precise electrical coupling and tunable energy levels through external fields.

Prof Steinberg showcases atom-sized quantum dots in 2D materials with tunable energy control.

From Defects to Devices — Engineering Quantum Dots at Atomic Scale

Prof Steinberg explained how quantum dots act as tiny conducting regions where only a few electrons can reside, giving rise to discrete energy levels dominated by Coulomb repulsion. In his lab, such QDs are created by exploiting atomic defects in hBN, stacked with graphene to form hybrid van der Waals devices. This architecture enables external field penetration through graphene, allowing energy tuning without damaging the atomically thin layers.

He highlighted how these defect-defined QDs open opportunities for ultra-sensitive quantum measurements, including single-electron transistors and local field sensors, all within a few nanometers.

Exploring defect-defined quantum dots for ultra-sensitive, nanoscale measurements and energy-tunable quantum devices.

Quantum Sensing and Future Prospects

The talk sparked engaging discussions on defect placement, fabrication challenges, and the potential of using QDs as quantum sensors. Prof Steinberg emphasised how atomic precision in material stacking can bridge the gap between quantum metrology and integrated nanodevices, paving the way for new sensing paradigms.

The colloquium concluded with active participation from NTU students and researchers, who appreciated Prof Steinberg’s clear explanations and inspiring vision for atomic-scale quantum technologies. The event underscored NTU’s commitment to fostering dialogue between global leaders in nanoscience and the next generation of quantum researchers.

Written by: Gong Xiangxin | NTU School of Electrical and Electronic Engineering Graduate Students' Club

“I enjoyed the energy and enthusiasim of the speaker!” - Sutonu Sadhukhan (PhD student, MSE)

"Learning about the defects and quantum dots.” - Yeo Yi Xuan (PhD student, EEE)

Watch the recording here