Quantum Input-Output Modeling in the Ultra-Fast Domain: Theoretical Foundations and Experimental Validation

Stanford University, Stanford CA

Investigators

Abstract

The primary aims of this project are to develop new theory and new laboratory tools for analyzing the quantum-mechanical properties of ultrafast (very short) pulses of light. The project will push beyond familiar conditions, which is largely limited to long timescales and slowly-varying patterns of light (optical modes). The advances made will support future quantum engineering efforts to utilize ultrafast light pulses for computing, communication, and sensing. In the context of quantum technology, ultrafast quantum light may be expected to provide advantages over slowly-varying light by increasing the speed of computation, the rate at which information can be transmitted through a communication channel, or the bandwidth (response speed) of a sensor. The major themes of the project are the exploration of practical approaches to generating ultrafast light pulses with manifestly quantum properties (distinguished from conventional light pulses, for example, by exhibiting extremely low noise), the improvement of methods for analyzing quantum entanglement among ultrafast light pulses, and the development of a new class of laser-like optical devices called ultrafast optical parametric oscillators, which are of great interest to a broad spectrum of engineering research for potential use in future quantum technologies. Technically speaking, the theoretical component of this project is structured around concrete studies of new device concepts for nanophotonic devices and circuits to generate and manipulate few-photon states of ultrafast optical pulses with non-Gaussian quantum states. The work will address fundamental issues in the modeling of quantum nonlinearities in nanophotonic devices with ultrafast pump and signal fields, motivated by applications such as the synthesis of cubic phase gates (for quantum computing) and realizing ultrafast optical parametric oscillators with pump thresholds in the few-photon regime. The latter devices are expected to require significant advances in efficiently modeling the quantum dynamics of optical systems with many (tens of thousands) of relevant optical modes. The experimental component of this project aims at the development and validation of measurement methods for characterizing time-domain entanglement among signal pulses in synchronously-pumped optical parametric oscillators, which is expected to develop strong connections with concepts from condensed matter physics (such as tensor network states). The experimental component will also include further work on a prototype synchronously-pumped optical parametric oscillator in which coherent feedback is utilized to establish programmable structures of entanglement across the output pulse train. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.