The manipulation of quantum states of light¹ holds the potential to enhance searches for fundamental physics. Only recently has the maturation of quantum squeezing technology coincided with the emergence of fundamental physics searches that are limited by quantum uncertainty^2,3. In particular, the quantum chromodynamics axion provides a possible solution to two of the greatest outstanding problems in fundamental physics: the strong-CP (charge–parity) problem of quantum chromodynamics⁴ and the unknown nature of dark matter^5,6,7. In dark matter axion searches, quantum uncertainty manifests as a fundamental noise source, limiting the measurement of the quadrature observables used for detection. Few dark matter searches have approached this limit^3,8, and until now none has exceeded it. Here we use vacuum squeezing to circumvent the quantum limit in a search for dark matter. By preparing a microwave-frequency electromagnetic field in a squeezed state and near-noiselessly reading out only the squeezed quadrature⁹, we double the search rate for axions over a mass range favoured by some recent theoretical projections^10,11. We find no evidence of dark matter within the axion rest energy windows of 16.96–17.12 and 17.14–17.28 microelectronvolts. Breaking through the quantum limit invites an era of fundamental physics searches in which noise reduction techniques yield unbounded benefit compared with the diminishing returns of approaching the quantum limit.

对光¹的量子态的操纵具有增强对基础物理学的搜索的潜力。直到最近，量子压缩技术的成熟才与受到量子不确定性限制的基础物理搜索的出现相吻合^2,3。特别是，量子色动力学轴子为基础物理学中两个最大的突出问题提供了可能的解决方案：量子色动力学的强 CP（电荷奇偶校验）问题⁴和暗物质的未知性质^5,6,7. 在暗物质轴子搜索中，量子不确定性表现为基本噪声源，限制了用于检测的正交可观测量的测量。很少有暗物质搜索接近这个极限^3,8，直到现在还没有一个超过它。在这里，我们使用真空挤压来绕过量子极限来寻找暗物质。通过在压缩状态下准备微波频率电磁场并几乎无声地读出压缩正交⁹，我们在最近的一些理论预测^{10,11 所}支持的质量范围内将轴子的搜索率提高了一倍. 我们在 16.96-17.12 和 17.14-17.28 微电子伏特的轴子静止能量窗口内没有发现暗物质的证据。突破量子极限带来了一个基础物理研究的时代，在这个时代，与接近量子极限的收益递减相比，降噪技术产生了无限的好处。