丹麦哥本哈根大学Eugene Simon Polzik团队研究了声学频率范围内传感的混合量子网络。相关论文于2025年7月2日发表在《自然》杂志上。

感测场和力的极限由传感器的量子噪声设定。纠缠允许抑制这种噪声，并实现超出标准量子极限的灵敏度。量子光学传感的适用性通常受到可用光子量子源固定波长的限制。另一个普遍存在的限制与多种应用相关的声学噪声频率范围内实现量子噪声限制灵敏度的挑战有关。 

研究组演示了一种用于宽带量子传感的工具，该工具通过执行可应用于宽范围光谱的量子态处理，并通过抑制声学频率范围内倍频程内的量子噪声来实现。原子自旋系综与爱因斯坦-波多尔斯基-罗森（EPR）光源的频率可调光束之一强耦合。另一束EPR光束与第一束纠缠在一起，被调谐到不同的波长。 

通过将自旋系综设计为负质量或正质量振荡器，研究组展示了在不同波长下测量的频率相关量子噪声降低。自旋系综的可调性使得能够在动态范围从kHz到MHz的各种系统中靶向量子噪声。作为声频范围内宽带量子降噪的一个例子，研究组分析了该方法对引力波探测器（GWD）的适用性。其他可能的应用包括连续可变量子中继器和分布式量子传感。

附：英文原文

Title: Hybrid quantum network for sensing in the acoustic frequency range

Author: Novikov, Valeriy, Jia, Jun, Brasil, Tlio Brito, Grimaldi, Andrea, Bocoum, Mamouna, Balabas, Mikhail, Mller, Jrg Helge, Zeuthen, Emil, Polzik, Eugene Simon

Issue&Volume: 2025-07-02

Abstract: Ultimate limits for the sensing of fields and forces are set by the quantum noise of a sensor1,2,3. Entanglement allows for suppression of such noise and for achieving sensitivity beyond standard quantum limits4,5,6,7. Applicability of quantum optical sensing is often restricted by fixed wavelengths of available photonic quantum sources. Another ubiquitous limitation is associated with challenges of achieving quantum-noise-limited sensitivity in the acoustic noise frequency range relevant for several applications. Here we demonstrate a tool for broadband quantum sensing by performing quantum state processing that can be applied to a wide range of the optical spectrum and by suppressing quantum noise over an octave in the acoustic frequency range. An atomic spin ensemble is strongly coupled to one of the frequency-tunable beams of an Einstein–Podolsky–Rosen (EPR) source of light. The other EPR beam of light, entangled with the first one, is tuned to a disparate wavelength. Engineering the spin ensemble to act as a negative-mass or positive-mass oscillator, we demonstrate frequency-dependent quantum noise reduction for measurements at the disparate wavelength. The tunability of the spin ensemble enables targeting quantum noise in a variety of systems with dynamics ranging from kHz to MHz. As an example of broadband quantum noise reduction in the acoustic frequency range, we analyse the applicability of our approach to gravitational-wave detectors (GWDs). Other possible applications include continuous-variable quantum repeaters and distributed quantum sensing.

DOI: 10.1038/s41586-025-09224-3

Source: https://www.nature.com/articles/s41586-025-09224-3