Our laboratory is located in the Department of Physics of the University of Basel in Switzerland. Our research is centered around the emerging field of "Quantum sensing", where the use of individual, well-controlled quantum systems as high-performance sensing devices is being explored. We concentrate on implementing various types of such sensors and on applying them to outstanding scientific tasks in mesoscopic physics, nano-science and technology. At the moment, our quantum system of choice for these purposes is the Nitrogen-Vacancy (NV) color center in diamond, whose exceptional quantum-coherent properties allow for high-performance sensing applications (such as single-electron spin detection) even at room temperature.
Patrick's and Brendan's paper entitled "Nanomagnetism of magnetoelectric granular thin-film antiferromagnets" was posted on ArXiv. Since experimental tools to explore antiferromagnetic films on the nanoscale are still sparse, we offer a solution to this technological bottleneck, by addressing the ubiquitous surface magnetisation of magnetoelectic antiferromagnets in a granular thin film sample on the nanoscale using single-spin magnetometry in combination with spin-sensitive transport experiments. Specifically, we quantitatively image the evolution of individual nanoscale antiferromagnetic domains in 200-nm thin-films of Cr2O3 in real space and across the paramagnet-to-antiferromagnet phase transition. These experiments allow us to discern key properties of the Cr2O3 thin film, including the mechanism of domain formation and the strength of exchange coupling between individual grains comprising the film. Our work offers novel insights into Cr2O3's magnetic ordering mechanism and establishes single spin magnetometry as a novel, widely applicable tool for nanoscale addressing of antiferromagnetic thin films.
Patrick Appel and Arne Barfuss successfully defended their PhD thesis. Great job!!!
In collaboration with the group of V. Jacques and the CNRS Thales we were able to demonstrate real-space visualization of non-collinear antiferromagnetic order in a magnetic thin film at room temperature and manipulate the cycloid propagation direction by an electric field. These results demonstrate how our material of choice can be used in the design of reconfigurable nanoscale spin textures.
Daniels's paper "Deterministic enhancement of coherent photon generation from a nitrogen-vacancy center in ultrapure diamond" was published in PRX. We couple NV centers to a tunable microcavity and significantly enhance their photonic properties: i.e. we demonstrate an increase of the phonon-free emission--which is required for entanglement swapping schemes--from 4% to close to 50%. By making a step-change in the NV's optical properties in a deterministic way, these results pave the way for much enhanced spin-photon and spin-spin entanglement rates.
Arne Barfuss has won the Swiss Nanotechnology Award sponsored by Rolic Technologies Ltd. for the outstanding publication "Strong mechanical driving of a single electron spin". For the first time, the Swiss MNT Network presents this award to doctoral students at the Swiss research center. Congrats Arne!
Jean and Arne's paper "Hybrid continuous dynamical decoupling: a photon-phonon doubly dressed spin" studies parametric interaction between a single Nitrogen-Vacancy electronic spin and a diamond mechanical resonator. We present a novel dynamical decoupling scheme, which is based on recently established techniques for dynamical decoupling by concatenated continuous driving. Our work benefits from a robust, drift-free strain-coupling mechanism we have established in the past and from the narrow linewidth of the high-quality diamond mechanical oscillator we employ. We demonstrate prolongation of the relevant spin dephasing times by up to two orders of magnitude, suggesting feasible applications of our decoupling scheme in quantum information processing and sensing.