Manceau Mathieu, Leuchs Gerd, Khalili Farid, Chekhova Maria
Max-Planck-Institute for the Science of Light, Staudtstraße 2, 91058 Erlangen, Germany.
University of Erlangen-Nürnberg, Staudtstrasse 7/B2, 91058 Erlangen, Germany.
Phys Rev Lett. 2017 Dec 1;119(22):223604. doi: 10.1103/PhysRevLett.119.223604. Epub 2017 Nov 29.
In an unseeded SU(1,1) interferometer composed of two cascaded degenerate parametric amplifiers, with direct detection at the output, we demonstrate a phase sensitivity overcoming the shot noise limit by 2.3 dB. The interferometer is strongly unbalanced, with the parametric gain of the second amplifier exceeding the gain of the first one by a factor of 2, which makes the scheme extremely tolerant to detection losses. We show that by increasing the gain of the second amplifier, the phase supersensitivity of the interferometer can be preserved even with detection losses as high as 80%. This finding can considerably improve the state-of-the-art interferometry, enable sub-shot-noise phase sensitivity in spectral ranges with inefficient detection, and allow extension to quantum imaging.
在一个由两个级联简并参量放大器组成的非种子注入SU(1,1)干涉仪中，在输出端进行直接探测，我们展示了一种相位灵敏度，其超过散粒噪声极限2.3分贝。该干涉仪严重失衡，第二个放大器的参量增益比第一个放大器的增益高2倍，这使得该方案对探测损耗具有极强的耐受性。我们表明，通过增加第二个放大器的增益，即使探测损耗高达80%，干涉仪的相位超灵敏度仍可保持。这一发现可显著改进现有干涉测量技术，在探测效率低下的光谱范围内实现亚散粒噪声相位灵敏度，并可扩展至量子成像领域。
