Quantum Sensing

Quantum sensing is a rapidly emerging frontier in measurement and imaging technologies, leveraging quantum principles such as entanglement to attain sensitivity and resolution unattainable with classical methods.

In our projects we are focusing on quantum imaging, quantum communications, and quantum telescopy, aiming to dramatically improve performance in multiple applications.

Quantum approach, by employing spatial, spectral and temporal correlations of multiple photons from quantum sources offers advantages and provides additional opportunities such as low light imaging or new sensing approaches in optical interferometers.

Quantum Astrometry project explores how quantum technologies can push the limits of astronomical imaging. In traditional interferometry, multiple telescopes are used together to simulate a much larger one, with their separation – called the baseline – determining the finest detail they can resolve: the longer the baseline, the sharper the image. However, current optical interferometers are limited by the need for a direct optical connection between telescopes, which constrains how far apart they can be placed.

We are developing quantum-assisted methods that utilize quantum interference of photon pairs to effectively extend the baseline, in principle, by order of magnitude without such physical links. Building on ideas from quantum information science, including protocols that mimic teleportation of astronomical photon states, our goal is to demonstrate two-photon interference techniques that could one day enable extremely precise measurements of the positions and motions of stars and galaxies.

KEY TASKS

Quantum telescopy – we are testing bench-top implementations of two-photon interferometers which can also be employed at astronomical observatories. The main focus of the study is temporal and spectral correlations of photons, which allow to reconstruct the photon phase information. Spectral binning employs fast spectrometers developed in the group with resolution almost at the Heisenberg-Gabor limit, 40 ps & 40 pm.

(Left): Performing an interference measurement between two telescopes using an entangled state emitted from a central entangled photon source (EPS), adapted from Gottesman, D., Jennewein, T., Croke, S., Longer-baseline telescopes using quantum repeaters, Phys.Rev.Lett. 109, 070503 (2012); (Right): adapted from Wikimedia Commons

Quantum communications beyond astronomy, the fast spectrometers under development have the potential to significantly advance quantum communication networks, particularly because practical entangled-photon sources typically emit across broad spectral bandwidths.

A key application is Hong–Ou–Mandel (HOM) interference, which serves as the fundamental mechanism for the entanglement-swapping protocol – an essential process for linking distant quantum nodes, connecting quantum computers, and enabling device independent quantum key distribution (QKD).

We are exploring how entanglement swapping can be optimized for broadband sources by utilizing multiple spectral bins, thereby substantially improving the efficiency, scalability, and robustness of quantum communication systems.

Achieving excellent temporal and spectral resolution is critical for maintaining photon coherence within each temporal and spectral bin, thus enabling high-visibility two-photon interference measurements essential for reliable entanglement swapping protocols.

KEY TASKS

Entanglement swapping – we are developing novel approaches to quantum communications and quantum key distribution (QKD) to scale up their throughput by doing it in spectral bins. The research involves implementing and testing practical swapping schemes with single photon sources and two-photon interferometers based on Hong-Ou-Mandel effect.

Quantum imaging, by employing spatial, spectral and temporal correlations of multiple photons from quantum sources offers advantages and provides additional opportunities such as low light imaging or new sensing approaches in optical interferometers..

KEY TASKS

Quantum imaging – with our international collaborators we are working on several projects which utilize spatial, spectral and temporal correlations of photon pairs from quantum sources for a variety of imaging schemes including ghost spatial and ghost spectral imaging, and quantum microscopy concepts. Our main role is typically in enabling fast single photon imaging with sub-nanosecond temporal resolution.