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Selected Projects & Collaborations

Optical beam-deflection atomic force microscopy system at low temperature

Research Project | 2 Project Members

This project aims to develop an advanced optical beam-deflection atomic force microscope (AFM) integrated in a low-temperature cryostat and an ultra-high vacuum system. The system will enable precise study of individual molecules and complex 2D molecular systems. The cryostat, optimized for low helium consumption and long hold times, will support extended experiments, while the vacuum environment will allow in-situ preparation of samples through methods like thermal evaporation and electrospray deposition. The AFM, built at the University of Basel, will include a preamplifier to extend bandwidth and enable faster data acquisition, supporting advanced AFM modes such as multimode AFM. The system will also feature precise positioning of the AFM probe on 2D materials and quantum dot devices, using optical microscopy and large-area scanning. Controlled electrostatic potentials and back-gate voltages will allow for quantum dot confinement and charge density manipulation, facilitating experiments like 2D or 3D force spectroscopy. Molecules will be studied at submolecular resolution, allowing for manipulation and measurement of lateral forces. Examples include investigating molecular knots and nanographene, with a focus on processes like dehydrogenation. Frictional forces on different substrates will also be explored. Finally, high-resolution AFM and Kelvin probe force microscopy (KPFM) will be used to map charge distributions in electron donor-acceptor systems, including those in excited states, offering new insights into molecular interactions and dynamics.

Q-AFM / Quantum Limited Atomic Force Microscopy

Research Project | 2 Project Members

We aim to make a radical improvement in the speed of acquisition and information content of Scanning Probe Microscopy (SPM) images by developing a new type of resonant mechanical force sensor. By the end of the project we realize a Quantum-limited Atomic Force Microscope (Q-AFM), where the force sensor is working at the fundamental limit of action and reaction set by quantum physics. Achieving this limit will result in three orders of magnitude improvement in force sensitivity and five orders of magnitude in measurement bandwidth, beyond the current state-of-the-art. This huge gain in performance will translate to a radical increase in imaging speed and in the information content of images. Our sensor will lead to a revolution in SPM, where multi-dimensional data sets are acquired in seconds, as opposed to several days as is the current practice. The key to reaching quantum-limited sensitivity lies in the the electro-mechanical coupling between the resonant mechanical force transducer and the readout circuit. While our ideas are based on well-established theories and some proof-of-concept measurements, but there is still a high risk that we can not reach the desired strong-coupling regime with an appropriate SPM sensor design. To mitigate this high risk we will pursue two different sensor designs, one based on electrostatic coupling and the other based on piezoelectric coupling. Our work plan includes medium and low risk stages of development, each of will result in major gains in performance SPM. The project brings together three university research groups from KTH, Uni Basel and TU Wien, with one SME Intermodulation Products. Together they bring the diverse and complementary expertise necessary to carry out this project such as: superconducting quantum circuits, low temperature AFM, piezoelectric MEMS, and advanced analog and digital electronic design and low-level programming.