Measurement of quantum back action in the audio band at room temperature
Measurement of quantum back action in the audio band at room temperature
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DOI：
10.1038/s41586-019-1051-4
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发表时间：
2019-04-18
期刊：
影响因子：
64.8
通讯作者：
Corbitt, Thomas
中科院分区：
文献类型：
--
作者：
Cripe, Jonathan;Aggarwal, Nancy;Corbitt, Thomas
量子力学对连续测量的精度有一个基本的限制。海森堡测不准原理指出，随着对可观察物（例如位置）测量精度的提高，反作用力会增加共轭变量（例如动量）的不确定性。在干涉引力波探测器中，更高的激光功率减少了由散粒噪声（由激光的量子特性引起的光子计数误差）造成的位置不确定性，但这样做必然以牺牲量子辐射压力噪声（QRPN）形式的反向作用为代价(1)。一旦达到设计灵敏度，引力波探测器Advanced LIGO(2)、VIRGO(3)和KAGRA(4)将受到QRPN的限制，频率在10赫兹到100赫兹之间。有几个建议通过降低QRPN（5-10）来提高引力波探测器的灵敏度，但到目前为止，还没有平台允许对这些想法进行实验测试。在这里，我们提出了一种在室温下以引力波探测器相关频率测量QRPN的宽带方法。得到的噪声谱显示，QRPN的影响范围在2 ~ 100千赫兹之间，QRPN的测量幅度与我们的模型一致。我们现在有了一个试验台来研究减轻量子反向作用的技术，比如变分读出和压缩光注入(7)，目的是提高未来引力波探测器的灵敏度。
Quantum mechanics places a fundamental limit on the precision of continuous measurements. The Heisenberg uncertainty principle dictates that as the precision of a measurement of an observable (for example, position) increases, back action creates increased uncertainty in the conjugate variable (for example, momentum). In interferometric gravitational-wave detectors, higher laser powers reduce the position uncertainty created by shot noise (the photon-counting error caused by the quantum nature of the laser) but necessarily do so at the expense of back action in the form of quantum radiation pressure noise (QRPN)(1). Once at design sensitivity, the gravitational-wave detectors Advanced LIGO(2), VIRGO(3) and KAGRA(4) will be limited by QRPN at frequencies between 10 hertz and 100 hertz. There exist several proposals to improve the sensitivity of gravitational-wave detectors by mitigating QRPN(5-10), but until now no platform has allowed for experimental tests of these ideas. Here we present a broadband measurement of QRPN at room temperature at frequencies relevant to gravitationalwave detectors. The noise spectrum obtained shows effects due to QRPN between about 2 kilohertz and 100 kilohertz, and the measured magnitude of QRPN agrees with our model. We now have a testbed for studying techniques with which to mitigate quantum back action, such as variational readout and squeezed light injection(7), with the aim of improving the sensitivity of future gravitational-wave detectors.