Auzinsh M, Budker D, Kimball D F, Rochester S M, Stalnaker J E, Sushkov A O, Yashchuk V V
Department of Physics, University of Latvia, 19 Rainis blvd, Riga, LV-1586, Latvia.
Phys Rev Lett. 2004 Oct 22;93(17):173002. doi: 10.1103/PhysRevLett.93.173002. Epub 2004 Oct 19.
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 N atomic spins by detecting optical rotation of far-detuned light. We show that for very short measurement times, the optimal sensitivity scales as N(-3/4); if strongly squeezed probe light is used, the Heisenberg limit of N-1 scaling can be achieved. However, if the measurement time exceeds tau(rel)/N(1/2) in the former case, or tau(rel)/N in the latter, where tau(rel) is the spin relaxation time, the scaling becomes N(-1/2), as for a standard shot-noise-limited magnetometer.
我们考虑了噪声（例如量子投影噪声和光子散粒噪声）对理想化原子磁力计灵敏度的限制，该磁力计利用连续量子非破坏测量诱导的自旋压缩。这种磁力计通过检测远失谐光的光学旋转来测量N个原子自旋的自旋进动。我们表明，对于非常短的测量时间，最佳灵敏度按N^(-3/4)缩放；如果使用强压缩探测光，则可以达到N^(-1)缩放的海森堡极限。然而，在前一种情况下，如果测量时间超过τ(rel)/N^(1/2)，或者在后一种情况下超过τ(rel)/N，其中τ(rel)是自旋弛豫时间，则缩放变为N^(-1/2)，这与标准散粒噪声限制的磁力计情况相同。
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