Magnetic-Field Resilient Microwave Quantum Squeezer

The squeezed state is an important resource for quantum information processing and quantum sensing. In the microwave domain, the Josephson parametric amplifier (JPA) is widely used to generate squeezed states. However, due to their sensitivity to the magnetic field, such squeezers are not suitable for sensing tasks such as searching for dark matter Axion and addressing magnetic resonance detection. Here we demonstrate high-degree microwave vacuum squeezing using a magnetic-field resilient amplifier made from NbN thin films. With the second-order correlation characterization, we show our squeezer can generate microwave photon pairs with high g² (0).