Generation of Single-Mode and Multimode Bright Squeezed Vacuum above 10 ¹⁴ Photons

Squeezed states of light and entangled photon source are fundamental resources for quantum science and technology, enabling advances in quantum communication, computation, and precision metrology. Here, we experimentally demonstrate the generation of ultrabright squeezed vacuum and entangled photon pairs via type-I high-gain parametric down-conversion. Using femtosecond pump pulses at 1,030 nm, we produce ultrabright squeezed vacuum with pulses energies on the order of 10 μJ at a central wavelength of 2,060 nm, corresponding to a photon number exceeding 10 14 . By implementing SU(1,1) interferometric configuration, we achieve flexible control over the mode structure, allowing the transition between multimode entangled photon pairs and nearly single-mode squeezed states. This results provide a high-intensity quantum light source that facilitates the study of nonclassical ultrafast dynamics.