Nanowire Force Sensors

to measure weak forces and as scanning probes

Bottom-up nanowires are extremely promising as sensitive mechanical transducers. We have integrated such nanowire force sensors into a low-temperature scanning probe apparatus. Our ability to scan such force sensors is now opening are variety of scanning force measurements including measurements of weak lateral forces, atomic-scale friction, and vectorial force sensing.

Scanning SQUID-on-tip Microscopy

for imaging nanoscale magnetic fields

We use state-of-the-art nanometer-scale SQUIDs as sensitive scanning probes of magnetic field and thermal dissipation. Our SQUID-on-tip sensors are sensitive local probes, which – unlike global magnetization or transport measurements – overcome inhomogeneity in systems ranging from magnetic nanotubes, to superconducting films, to van der Waals heterostructures.

Sensitive Torque Magnetometry

using dynamic cantilever magnetometry

Our study of magnetic nanostructures is motivated both by fundamental questions about the effects of miniaturization on magnetic properties and by their potential applications. Nanometer-scale magnets can be used as elements in dense magnetic memories, logical devices, magnetic sensors, and as probes in high resolution imaging applications.





Magnetic Resonance Force Microscopy

for nano-NMR and nano-MRI

The proposal of magnetic resonance force microscopy (MRFM) and its subsequent realization combine the physics of magnetic resonance imaging (MRI) with the techniques of scanning probe microscopy. Driven by the ultimate goal of imaging a single nuclear spin and the promise of a molecular structure microscope, such work is being pursued in a handful of laboratories world-wide.

Quantum States of Motion

and hybrid mechanical systems

Experiments with nanomechanical oscillators are now addressing what were once purely theoretical questions: the initialization, control, and readout of the quantum state of a mechanical oscillator. Researchers are able both to initialize the fundamental vibrational mode of a mechanical resonator into its ground state and even to produce nonclassical coherent states of motion.

Scanning Quantum Dot Microscopy

with optically addressable quantum dots

We have developed a fiber-coupled quantum dot (QD) in a tip as a scanning probe for electric-field imaging. By optically monitoring the probe QD’s quantum-confined Stark effect, we sensitively map the the electric field of a nearby sample. Such sensors are promising for the imaging of single charges, measuring individual tunneling events, and monitoring charging dynamics in mesoscopic systems.





Project with Tübingen, Zaragoza, and IBM Zürich

Our vision is to enable a new era in scanning probe microscopy (SPM), in which nanometer-scale sensing devices – specifically superconducting devices – can be directly patterned on-tip and used to reveal new types of contrast. To realize this vision, we will use focused ion beam (FIB) techniques to produce sensors with unprecedented size, functionality, and sensitivity directly on the tips of custom-designed cantilevers.

Floris Braakman: Quantum Interfaces

Qubit optomechanics and hole spin qubits

We study coupling of qubits to an optomechanical system. Through their nonlinear character, qubits can generate very large enhancement of the radiation pressure interaction between light and matter. We also investigate hole spin qubits defined Ge- and Si-based nanodevices. In particular, we aim to make use of their strong and highly tunable spin-orbit interaction.