We show that fast technical fluctuations of microwave signals can be strongly suppressed by cryogenic resonators. The experiments were carried out with sapphire resonators cooled to approximately 6 K at frequencies around 11 GHz. Each sapphire crystal was shaped like a spindle with the rotational and crystal axes aligned within a degree. Noise suppression factors in excess of 50 dB were measured at 10-kHz offset from the carrier. This was achieved by rotating the sapphire spindle and moving the coupling probes relative to its surface. Microwave signals with reduced fast technical fluctuations allow the high-precision tests of fundamental physics, as well as the development of better radars.

中文翻译：

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低温谐振器的噪声抑制

我们表明，低温谐振器可以强烈抑制微波信号的快速技术波动。实验是在11 GHz左右的频率下将蓝宝石谐振器冷却到大约6 K进行的。每个蓝宝石晶体都像纺锤形，其旋转轴和晶体轴在一定范围内对齐。在距载波10kHz处测得的噪声抑制因子超过50 dB。这是通过旋转蓝宝石主轴并相对于其表面移动耦合探针来实现的。减少了快速技术波动的微波信号可以对基础物理进行高精度测试，也可以开发出更好的雷达。