Evidence of the Quantum-Optical Nature of High-Harmonic Generation

High-harmonic generation (HHG) is a process in which a strong laser field converts light to higher frequencies, creating ultrashort attosecond and broadband radiation. LOA’s QUANTUM group now published an article that explores the potential of HHG to produce non-classical light states, which are crucial for advancements in quantum technology, addressing issues such as scalability and decoherence. They have experimentally demonstrated the nonclassical nature of light generated through HHG in semiconductors using a femtosecond infrared laser. By analyzing the intensity correlations, they observed nonclassical features in the photon statistics, such as the violation of the Cauchy-Schwarz inequality and signatures of two-mode squeezing.

These findings suggest that HHG can be used as a quantum-optics platform to produce unique nonclassical light states, exhibiting multipartite broadband entanglement and multimode squeezing. The presented method operates at room temperature, using standard semiconductors and commercial fiber lasers, making it accessible and practical for quantum applications such as optical quantum computing, communication, and imaging.