Ultrafast All-Optical Measurement of Squeezed Vacuum in a Lithium Niobate Nanophotonic Circuit

TL;DR

This paper demonstrates ultrafast, all-optical measurement and tomography of squeezed vacuum states in a lithium niobate nanophotonic circuit, enabling quantum information processing at THz speeds.

Contribution

It introduces a novel integrated photonic platform for ultrabroadband, all-optical quantum state measurement using dispersion-engineered femtosecond pulses in lithium niobate.

Findings

Achieved all-optical Wigner tomography of squeezed vacuum.

Demonstrated ultrabroad bandwidth operation up to 6.5 THz.

Enabled ultrafast quantum measurements beyond electronic speed limits.

Abstract

Squeezed vacuum, a fundamental resource for continuous-variable quantum information processing, has been used to demonstrate quantum advantages in sensing, communication, and computation. While most experiments use homodyne detection to characterize squeezing and are therefore limited to electronic bandwidths, recent experiments have shown optical parametric amplification (OPA) to be a viable measurement strategy. Here, we realize OPA-based quantum state tomography in integrated photonics and demonstrate the generation and all-optical Wigner tomography of squeezed vacuum in a nanophotonic circuit. We employ dispersion-engineering to enable the distortion-free propagation of femtosecond pulses and achieve ultrabroad operation bandwidths, effectively lifting the speed restrictions imposed by traditional electronics on quantum measurements with a theoretical maximum clock speed of 6.5 THz. We implement our circuit on thin-film lithium niobate, a platform compatible with a wide variety of active and passive photonic components. Our results chart a course for realizing all-optical ultrafast quantum information processing in an integrated room-temperature platform.