Christian Degen

Nanomechanical detection and imaging of nuclear spin ensembles

Department of Physics, ETH Zurich

Nanomechanical resonators have opened exciting possibilities in quantum physics and nanoscale science. Examples include ground-state cooling, quantum and classical signal transduction, and ultrasensitive force or mass detection. In our group we exploit the exquisite force sensitivity of nanomechanical resonators for detecting and imaging nuclear spin ensembles, relying on a nanoscale ferromagnetic tip as the coupling element.

In this talk I will present our recent work on nanomechanical nuclear spin sensing. I will discuss the requirements and challenges for such experiments, and show recent efforts at improving the force sensitivity of nanomechanical resonators by change of design, material and control of surface chemistry. I will then present detection of statistically polarized nuclear spin ensembles on a nanowire test sample, and demonstrate that several nuclear spin signals can be acquired simultaneously using phase multiplexing. By mechanically scanning the test sample with respect to the ferromagnetic tip, we are furthermore able to perform nuclear spin imaging with approximately 5 nm resolution in one dimension and subnanometer positional accuracy. Finally I will discuss a new type of switchable magnetic field gradient exploiting the write head element of a commercial hard disk drive.