Abstract
We consider the limitations due to noise (e.g., quantum projection noise and photon shot-noise) on the sensitivity of an idealized atomic magnetometer that utilizes spin squeezing induced by a continuous quantum nondemolition measurement. Such a magnetometer measures spin precession of atomic spins by detecting optical rotation of far-detuned light. We show that for very short measurement times, the optimal sensitivity scales as ; if strongly squeezed probe light is used, the Heisenberg limit of scaling can be achieved. However, if the measurement time exceeds in the former case, or in the latter, where is the spin relaxation time, the scaling becomes , as for a standard shot-noise-limited magnetometer.
- Received 25 March 2004
DOI:https://doi.org/10.1103/PhysRevLett.93.173002
©2004 American Physical Society