Quantum Squeezing Enhanced Photothermal Microscopy

TL;DR

The paper introduces a quantum microscopy technique called squeezing-enhanced photothermal (SEPT) microscopy that significantly improves sensitivity beyond the shot-noise limit, enabling detailed imaging of nanoparticles and subcellular structures.

Contribution

SEPT combines continuous-wave squeezing with photothermal modulation, achieving 3.5 dB noise suppression and enhancing imaging sensitivity and throughput in label-free microscopy.

Findings

Achieved 3.5 dB noise suppression beyond the standard quantum limit.

Enabled 2.5-fold increase in imaging throughput or 31% reduction in pump power.

Successfully characterized nanoparticles and visualized subcellular structures like cytochrome c.

Abstract

Label-free optical microscopy through absorption or scattering spectroscopy provides fundamental insights across biology and materials science, yet its sensitivity remains fundamentally limited by photon shot noise. While recent demonstrations of quantum nonlinear microscopy show sub-shot-limited sensitivity, they are intrinsically limited by availability of high peak-power squeezed light sources. Here, we introduce squeezing-enhanced photothermal (SEPT) microscopy, a quantum imaging technique that leverages twin-beam quantum correlations to detect absorption induced signals with unprecedented sensitivity. SEPT achieves 3.5 dB noise suppression beyond the standard quantum limit, enabling a 2.5-fold increase in imaging throughput or 31% reduction in pump power, while providing an unmatched versatility through the intrinsic compatibility between continuous-wave squeezing and photothermal modulation. We showcase SEPT applications by providing high-precision characterization of nanoparticles and revealing subcellular structures, such as cytochrome c, that remain undetectable under shot-noise-limited imaging. By combining label-free contrast, quantum-enhanced sensitivity, and compatibility with existing microscopy platforms, SEPT establishes a new paradigm for molecular absorption imaging with far-reaching implications in cellular biology, nanoscience, and materials characterization.