Quantum metrology methods for dark matter searches

Can emerging quantum technologies speed up the search for dark matter? For the case of utlralight dark matter particles with rest mass energies of an meV or less, they can. In particular, laboratory searches for such hypothetical particles attempt to sense a persistent, oscillatory, and classical dark matter signal acting on a quantum harmonic oscillator. Not only can emerging quantum technologies measure the oscillator's motion at the quantum limit, but they can also circumvent that quantum noise in an inference of the classical signal. I will describe the particular case of axionic dark matter, in which superconducting quantum circuits can be used to search for dark matter at a rate exceeding the quantum-limited value.