Speaker
Description
Spin-based searches for new fundamental particles and fields use spin ensembles as transducers that are sensitive to spin interactions with fields beyond the standard model. The Cosmic Axion Spin Precession Experiment (CASPEr) is one example. For such searches, the standard quantum limit on sensitivity scales with the inverse square root of the number of spins. Consequently, increasing the size of the spin ensemble presents a compelling approach to improving sensitivity. However, this enhancement demands a proportional reduction in other sources of noise. We detect with quantum-limited sensitivity the spin dynamics of macroscopic ensembles of $5\times10^{21}$ nuclear spins in a solid. We measure the angular spectral density of the collective spin quantum fluctuations with the amplitude $5\times10^{−11}\,$rad$/\sqrt{\rm Hz}$. The root-mean-squared collective spin quantum fluctuation angle is 9 nano-radians. This sensitivity enables us to place new laboratory limits on the EDM and the gradient interactions of ultralight axion-like dark matter.
| Primary Abstract Topic | Experiment: Axions and Wave-Like-DM |
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