Researchers from the University of Portsmouth have unveiled a quantum sensing scheme that achieves the pinnacle of quantum sensi­tivity in measuring the transverse dis­placement between two inter­fering photons. This new technique has the potential to enhance super­resolution imaging techniques that already employ single-photon sources as probes for the locali­zation and tracking of biological samples, such as single-molecule locali­zation micro­scopy with quantum dots.

Traditionally, achieving ultra-high precision in nanoscopic techniques has been constrained by the limi­tations of standard imaging methods, such as the diffraction limit of cameras and highly magnifying objectives. However, this new quantum sensing scheme circum­vents these obstacles, paving the way for unpre­cedented levels of precision.

At the heart of this innovation lies an interferometric technique that not only achieves unparalleled spatial precision, but also maintains its effectiveness regardless of the overlap between displaced photonic wave packets. The precision of this technique is only marginally reduced when dealing with photons differing in nonspatial degrees of freedom, marking a signi­ficant advancement in quantum-enhanced spatial sensitivity.

Vincenzo Tamma, Director of the Quantum Science and Technology Hub, said: “These results shed new light on the metrological power of two-photon spatial interference and can pave the way to new high-precision sensing techniques. Other potential appli­cations for the research could be found in the development of quantum sensing techniques for high-precision refracto­metry and astro­physical bodies locali­zation, as well as high-precision multi-parameter sensing schemes, including 3D quantum locali­zation methods.” (Source: U. Portsmouth)

Reference: D. Triggiani & V. Tamma: Estimation with Ultimate Quantum Precision of the Transverse Displacement between Two Photons via Two-Photon Interference Sampling Measurements, Phys. Rev. Lett. 132, 180802 (2024); DOI: 10.1103/PhysRevLett.132.180802

Link: Quantum Science and Technology Hub, University of Portsmouth, Portsmouth, UK