Beyond quantum linear optics with adaptive boson sampling

Area of Science:

• Quantum Information Science
• Quantum Optics
• Photonic Quantum Computing

Background:

• Universal photon-based quantum computing necessitates optical nonlinearities.
• Linear-optical dynamics impose limitations on photonic state generation.
• Quantitative methods for studying nonlinear dynamics in photonic systems are underdeveloped.

Purpose of the Study:

• To investigate if dynamics beyond linear optics can be accessed with limited resources.
• To develop practical methods for quantifying the emergence of nonlinear dynamics.
• To demonstrate nonlinear dynamics unobtainable within a linear-optical paradigm.

Main Methods:

• Leveraging an adaptive boson sampling architecture with measurement-based feedback.
• Introducing practical methods to quantify the gap with respect to linear optics.
• Deriving nonlinearity witnesses from linear-optical evolution properties.
• Validating methods on a state-of-the-art photonic platform with real-time adaptivity and post-selection emulation.

Main Results:

• Demonstrated a regime where bounds of linear-optical dynamics can be surpassed.
• Successfully quantified the emergence of nonlinear dynamics.
• Validated the developed toolbox within adaptive boson sampling architectures of increasing complexity.
• Probed experimentally a regime with nonlinear dynamics unobtainable in linear optics.

Conclusions:

• Adaptive photonic architectures with limited adaptivity serve as a powerful testbed for exploring new quantum regimes.
• Measurement-based feedback and adaptivity are key to accessing nonlinear dynamics in photonic systems.
• The developed methods provide a quantitative framework for studying nonlinear quantum optics.