Mechanical manipulation of molecular spins in CNT resonators
Tim Althuon – Hector Fellow Wolfgang Wernsdorfer
Carbon nanotube (CNT) resonators will be designed and fabricated to exploit their sensing properties. We will graft a single-molecule magnet (SMM) on such a CNT resonator in order to manipulate its spin states via the mechanical motion of the CNT. Using this nanomechanical approach, single-molecule magnets will be investigated with the long-term prospect of applying them in future quantum technologies.
Building a functional quantum computer is one of the most ambitious technological goals of our century. A key challenge consists in finding quantum systems that are sufficiently protected from the environment while being easily accessible. As a promising candidate, single-molecule magnets (SMMs) will be the object of this project.
Strong spin-phonon coupling between molecular spins and the mechanical motion in carbon nanotube (CNT) resonators will be exploited to perform coherent manipulations of nuclear spin states in molecular magnets. The basic platform (cf. figure 1) consists of a suspended CNT which is contacted by source and drain electrodes, while mechanical motion can be driven by multiple capacitively coupled gate electrodes. A SMM grafted on a suspended CNT can then be used to investigate different properties of molecular magnetism. First, the direct electrical manipulation of molecular spin states in CNT resonators could be studied with the prospect of achieving long relaxation and decoherence times due to the mechanical isolation from the substrate. Second, following the strategy of cavity-QED experiments, where the state of an atom is manipulated and read-out using cavity photons, in this work CNT phonons could be used to manipulate and read-out nuclear spins of SMMs.
This project adresses fundamental physical questions regarding molecular magnetism, whereas on the other hand, it can provide a first step towards quantum technologies based on SMMs.
Figure 1: Single-molecule magnet (red arrow: magnetization axis) grafted on suspended CNT. V_SD: applied bias between source and drain, V_G1,...,V_G5: bias applied to gate electrodes 1 to 5, I: measured current through the CNT.
Tim AlthuonKarlsruhe Institute of Technology
Wolfgang WernsdorferPhysics & Chemistry
Hector Fellow since 2019