Spectrally multimode integrated SU(1,1) interferometer

TL;DR

This paper proposes a theoretical design for an integrated multimode SU(1,1) interferometer on a KTP platform, demonstrating near-perfect interference and supersensitivity below classical limits, advancing quantum-enhanced on-chip measurement technologies.

Contribution

It introduces a novel integrated architecture for multimode SU(1,1) interferometers applicable to various platforms, with analysis of phase sensitivity and strategies for enhancement.

Findings

Achieves near-perfect destructive interference at the output.

Demonstrates regions of phase supersensitivity below the classical limit.

Explores methods to improve phase sensitivity through filtering and seeding.

Abstract

Nonlinear SU(1,1) interferometers are fruitful and promising tools for spectral engineering and precise measurements with phase sensitivity below the classical bound. Such interferometers have been successfully realized in bulk and fiber-based configurations. However, rapidly developing integrated technologies provide higher efficiencies, smaller footprints, and pave the way to quantum-enhanced on-chip interferometry. In this work, we theoretically realised an integrated architecture of the multimode SU(1,1) interferometer which can be applied to various integrated platforms. The presented interferometer includes a polarization converter between two photon sources and utilizes a continuous-wave (CW) pump. Based on the potassium titanyl phosphate (KTP) platform, we show that this configuration results in almost perfect destructive interference at the output and supersensitivity regions below the classical limit. In addition, we discuss the fundamental difference between single-mode and highly multimode SU(1,1) interferometers in the properties of phase sensitivity and its limits. Finally, we explore how to improve the phase sensitivity by filtering the output radiation and using different seeding states in different modes with various detection strategies.