From quantum pulse gate to quantum pulse shaper -- enigneered frequency conversion in nonlinear optical waveguides

TL;DR

This paper advances the control of quantum light pulse modes by engineering nonlinear waveguides, introducing devices like the quantum pulse gate and quantum pulse shaper for arbitrary manipulation of ultrafast pulsed quantum states.

Contribution

It generalizes spatio-spectral engineering techniques for $ ext{chi}^{(2)}$ processes, proposing new integrated devices for complete pulse-mode control in quantum optics.

Findings

Development of the quantum pulse shaper (QPS) for specific mode generation

Analysis of sum-frequency and difference-frequency generation processes

Demonstration of arbitrary pulse-mode manipulation capabilities

Abstract

Full control over the spatio-temporal structure of quantum states of light is an important goal in quantum optics, to generate for instance single-mode quantum pulses or to encode information on multiple modes, enhancing channel capacities. Quantum light pulses feature an inherent, rich spectral broadband-mode structure. In recent years, exploring the use of integrated optics as well as source-engineering has led to a deep understanding of the pulse-mode structure of guided quantum states of light. In addition, several groups have started to investigate the manipulation of quantum states by means of single-photon frequency conversion. In this paper we explore new routes towards complete control of the inherent pulse-modes of ultrafast pulsed quantum states by employing specifically designed nonlinear waveguides with adapted dispersion properties. Starting from our recently proposed quantum pulse gate (QPG) we further generalize the concept of spatio-spectral engineering for arbitrary $\chitwo$-based quantum processes. We analyse the sum-frequency generation based QPG and introduce the difference-frequency generation based quantum pulse shaper (QPS). Together, these versatile and robust integrated optics devices allow for arbitrary manipulations of the pulse-mode structure of ultrafast pulsed quantum states. The QPG can be utilized to select an arbitrary pulse mode from a multimode input state, whereas the QPS enables the generation of specific pulse modes from an input wavepacket with Gaussian-shaped spectrum.