Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Phys Rev Lett. 2013 Apr 19;110(16):163602. doi: 10.1103/PhysRevLett.110.163602. Epub 2013 Apr 15.
We demonstrate unconditional quantum-noise suppression in a collective spin system via feedback control based on quantum nondemolition measurement. We perform shot-noise limited collective spin measurements on an ensemble of 3.7×10(5) laser-cooled (171)Yb atoms in their spin-1/2 ground states. Correlation between two sequential quantum nondemolition measurements indicates -0.80(-0.12)(+0.11) dB quantum-noise suppression in a conditional manner. Our feedback control successfully converts the conditional quantum-noise suppression into the unconditional one without significant loss of the noise reduction level.
我们通过基于量子非破坏测量的反馈控制，在一个集体自旋系统中实现了无条件量子噪声抑制。我们在一个由 3.7×10(5)个激光冷却的（171）Yb 原子组成的集合中进行了集体自旋 1/2 基态的量子噪声限制的自旋测量。两次连续的量子非破坏测量之间的相关性表明，在有条件的情况下，量子噪声抑制达到-0.80(-0.12)(+0.11) dB。我们的反馈控制成功地将条件量子噪声抑制转换为无条件量子噪声抑制，而不会显著降低噪声降低水平。
