Broadband quantum spectroscopy for biophysics and beyond: a single-measurement approach to capturing stochastic dynamics

Stochastic, time-varying processes are ubiquitous in nature, arising in diverse contexts such as protein interactions, magnetization dynamics, charge transport in semiconductors, and more. Accessing the information encoded in these processes is critical to fully realizing underlying energy landscapes, yet often presents a significant experimental challenge. Here, I will discuss our success in developing a novel frequency-domain method that senses dynamics present in the DC – MHz range, resulting in an information-rich spectrum acquired in a single experiment. This method exploits the excellent sensitivity and nanoscale spatial resolution of a solid-state quantum sensor– namely, the nitrogen-vacancy center in diamond– to detect local magnetic fields. This approach combines high spectral resolution (distinguishing test signals separated by only a few Hertz) with broad detection bandwidth. I will demonstrate how detection of the spectral components of a two-state telegraph noise signal – a test case for many stochastic biophysical processes – allows us to probe the dynamics of this process. This novel sensing approach can accurately measure both spectrally-sparse and congested responses in single experiments, motivating its future use in e.g., probing the local dynamics of few to single biomolecules or detection of low-frequency communication bands.