Imaging with Single Photons
Seeing more with less light.
At the Quantum Imaging Laboratory at the University of Warsaw, we explore new ways of seeing the world by studying light at the level of individual photons.
Led by Dr Radek Łapkiewicz, our team develops optical imaging methods that combine highly sensitive photon detection with computational analysis. From revealing fine structures beyond the diffraction limit to recovering images through scattering layers, we investigate how carefully measuring light can unlock information that conventional imaging methods struggle to capture.
Our research brings together quantum optics, fluorescence microscopy, single-photon detection and computational imaging to push the boundaries of what can be measured with light.
Read popular articles about our previous research:
1. Photon Correlations and Single-Photon Detection
We use single-photon avalanche diode (SPAD) arrays and precise photon time-tagging to study correlations between detected photons. These measurements help us characterize entangled photon sources and develop imaging techniques that exploit the statistical and quantum properties of light.
2. Super-Resolution Fluorescence Microscopy
How can we reveal details smaller than conventional optical resolution allows? Our work explores methods that analyse fluctuations and correlations in fluorescence light. SOFISM combines image scanning microscopy with fluorescence fluctuation correlations to reveal finer structures using standard fluorescent labels.
- Sroda et al., Optica 7, 1308–1316 (2020). DOI: 10.1364/OPTICA.399600
- Krupinski-Ptaszek et al., Biomedical Optics Express 16, 910–921 (2025). DOI: 10.1364/BOE.533263
3. Imaging Through Dynamic Scattering Media
Scattering can scramble light and make objects difficult to image. We investigate how sensitive photon-counting cameras and computational reconstruction can recover images through changing diffusers, even in extremely low-light conditions where fewer than one photon per pixel is recorded per frame on average.
- Makowski et al., “Low Photon Number Non-Invasive Imaging Through Time-Varying Diffusers” (2024). Read on arXiv
4. Super-Resolution Imaging Through Scattering Layers
Scattering normally creates complex speckle patterns that obscure fine structures. Our NISE approach, Nonlinear Imaging with Speckle Excitation, uses highly nonlinear luminescent labels to selectively respond to the brightest regions of these patterns. This enables super-resolution imaging without wavefront shaping.
- Szczypkowski et al., “Non-invasive super-resolution imaging through scattering media using highly nonlinear labels” (2025). Read on arXiv
From photons to images
At QIL, we approach imaging as both an experimental and a computational challenge. Detecting light is only the beginning: by analysing when and where photons arrive, and how their detection events are correlated, we seek to extract information that would otherwise remain hidden.
Under the leadership of Dr Radek Łapkiewicz, our team brings together expertise in quantum optics, microscopy, photon-counting detectors and image reconstruction. We work across the boundary between fundamental research and new imaging techniques, exploring how the physics of light can lead to better ways of observing complex samples.
Our goal is simple: to discover how much more we can learn from light when we measure it in new ways.