Computerized Tomography of Electron Spins

Quantum-enhanced sensing techniques allow us to detect single spins, both nuclear and electron. This capability is promising not only because it is necessarily impressive from a technological point of view, but also because it enables us to “peek” under the hood of the ensemble average employed by the more “traditional” methods. Recent studies, making use of NMR-based dynamical decoupling schemes, have shown how to estimate both range and solid angle of the detected spin with respect to the sensor, or in other words its precise position. In the first part of the seminar, I will present a method extended and developed in my group, which makes use of simple radio pulses to perform nanoscale tomography of electron spins. The sectioning is implemented using a rotating magnetic field with varying strengths. For our lab, this is the first step towards nanoMRI, and allows us to pinpoint the location of spins in sample space. In the second part of the seminar, I will discuss one exciting direction we are pursuing to improve the sensitivity of our technique, with the aim of reaching the Heisenberg limit. This method makes use of what is currently known as adaptive Bayesian estimation. I will show our current state in this endeavor and explain how the use of such means is projected to improve the signal-to-noise ratio in quantum sensing setups.