Bright Pulsed Squeezed Light for Quantum-Enhanced Precision Microscopy

TL;DR

This paper demonstrates a highly efficient method to generate bright, pulsed squeezed light with record-high squeezing levels suitable for quantum-enhanced nonlinear microscopy, advancing biological imaging techniques.

Contribution

The authors introduce a novel waveguide-based optical parametric amplification technique to produce high levels of bright pulsed squeezing, surpassing previous records.

Findings

Achieved -3.2 dB of bright squeezing compatible with microscopy

Measured -3.6 dB of vacuum squeezing

Corrected squeezing levels up to -15.4 dB in the waveguide

Abstract

Squeezed states of light enable enhanced measurement precision by reducing noise below the standard quantum limit. A key application of squeezed light is nonlinear microscopy, where state-of-the-art performance is limited by photodamage and quantum-limited noise. Such microscopes require bright, pulsed light for optimal operation, yet generating and detecting bright pulsed squeezing at high levels remains challenging. In this work, we present an efficient technique to generate high levels of bright picosecond pulsed squeezed light using a $\chi^2$ optical parametric amplification process in a waveguide. We measure $-3.2~\mathrm{dB}$ of bright squeezing with optical power compatible with nonlinear microscopy, as well as $-3.6~\mathrm{dB}$ of vacuum squeezing. Corrected for losses, these squeezing levels correspond to $-15.4^{+2.7}_{-8.7}~\mathrm{dB}$ of squeezing generated in the waveguide. The measured level of bright amplitude pulsed squeezing is to our knowledge the highest reported to date, and will contribute to the broader adoption of quantum-enhanced nonlinear microscopy in biological studies.