Quantum noise from a piece of Teflon: macroscopic magnetic resonance at the standard quantum limit

In measurements on spin ensembles, the standard quantum limit on sensitivity is set by spin projection noise and scales as the inverse square root of the number of spins. Cold atoms, atomic vapor cells, and color centers in solids reach this regime with ensembles of up to 10¹³ spins. Increasing the ensemble size further is a direct route to higher sensitivity, provided all other noise sources are reduced correspondingly. I will present nuclear magnetic resonance measurements on a finger-sized piece of Teflon containing 10²¹ fluorine nuclei, with sensitivity limited by the quantum spin projection noise of the sample. I will also describe our work towards the generation of spin squeezing in this macroscopic ensemble and discuss implications for axion dark matter searches.

Speaker: Alexander Sushkov, Johns Hopkins University