Attosecond quantum uncertainty dynamics and ultrafast squeezed light for quantum communication.

Advancements in quantum optics and squeezed light generation have revolutionized various fields of quantum science over the past three decades, with notable applications such as gravitational wave detection. Here, we extend the use of squeezed light to the realm of ultrafast quantum science. We demonstrate the generation of the shortest ultrafast synthesized quantum light pulses spanning 0.33 to 0.73 PHz by a degenerate four-wave mixing nonlinear process. Experimental metrology results confirm that these pulses exhibit amplitude squeezing, which is consistent with theoretical predictions. Moreover, we observe the temporal dynamics of amplitude uncertainty of the squeezed light, demonstrating that quantum uncertainty of light is controllable and tunable in real time. Additionally, we demonstrate control over the quantum state of light by switching between amplitude and phase squeezing. Our ability to generate and manipulate ultrafast, squeezed, synthesized light waveforms with attosecond resolution unlocks exciting possibilities for quantum technologies, including petahertz-scale secure quantum communication, quantum computing, and ultrafast spectroscopy. As an example, we introduce an attosecond quantum encryption protocol leveraging squeezed synthesized light for secure digital communication at unprecedented speeds. This work paves the way for exploring quantum uncertainty dynamics and establishes the foundation for the emerging ultrafast and attosecond quantum science fields.