Quantum Optics in PCF
Generation and Manipulation of Nonclassical States of Light

Correlated Photon Pairs and Twin Beams in Gas-Filled Fibres [MPL & FAU]

Vishal Choudhury, Markus Lippl, Santiago Lopez-Huidobro
In collaboration with the group of Maria Chekhova at MPL.

We generate correlated photon pairs (low-gain regime) and twin-beams (high-gain regime) in hollow-core photonic crystal fibres filled with noble gases, which suppress Raman scattering and preserve quantum coherence. The necessary phase-matching conditions are adjusted through the pressure of the filling gas, yielding emitted photons with tunable frequencies [1,2,3].

Lately, we demonstrated a photon pair source bridging the ultraviolet C-band and the near-infrared, offering tunability and potential for quantum sensing with undetected photons [1].

[1] S. Lopez-Huidobro et al., Opt. Lett., 48, 13 (2023)
[2] S. Lopez-Huidobro et al., Opt. Lett., 46, 4033 (2021)
[3] M. Finger et al., PRL 115, 143602 (2015)

Towards Photon Triplets in Optical Fibres [MPL]

Carla Brunner, Minjae Hong

We are investigating the direct generation of photon triplets, the quantum analog of third-harmonic generation. This process, never observed before in the optical domain, is being explored using sub-micron tapered fibres embedded in gas cells to finely tune dispersion and nonlinear properties [1,2].

[1] J. Hammer et al., Phys. Rev. Res. 2, 012079(R) (2020)
[2] C. Brunner and N.J. Joly, arXiv:2410.13531 (2024)

Frequency Conversion Using Raman-Active Gases [MPL]

Markus Lippl

Instead of avoiding Raman interactions, we exploit them to shift one photon of an entangled pair to a different wavelength while preserving quantum correlations. Using di-hydrogen, we achieved over 70% conversion efficiency (Fig. 1), opening new paths for quantum state manipulation and telecom-compatible quantum networks [1].
This technique is under active development with partners at Ikerbasque (Spain), ENS-Paris (France), and MIT (USA).

Fig. 1 : (a) Concept of the Frequency shifter using hollow-core PCF filling with molecular gas, (b) Excitation of a coherent wave by beating of the pump and the Stokes signal (b) without pumping, there is no phase relation between the oscillating molecules. (c) Frequency versus wave vector diagrams at 70 bar of H2 filling a 60 μm core diameter SR-PCF. The arrows represent the coherence waves (solid) and the corresponding single-photon transitions (dashed), which perfectly match at ~70 bar and are otherwise highly dephased. The yellow circle indicates the zero-dispersion wavelength. Adapt. from [1].

[1] R. Tyumenev et al., Science, 376, 621 (2022)

Rydberg physics at room temperature

Daniel Häupl
in collaboration with the group of Robert Löw at the 5. Institute of physics in Stuttgart

This project aims to combine atomic physics with fibre optics. By trapping light inside hollow-core photonic crystal fibres we aim to enhance the interaction between atoms and light. One application is to generate THz radiation, where the increased interaction length will result in higher emission rates compared to free space.

Another aim is to make the setup even more integrated, to allow for a much more versatile and easier-to-use tool.

>> Lab Tour

[1] G. Epple, et al., Nat. Comm., 5, 4132 (2014)
[2] G. Epple, et al., Opt. Lett., 42, 3271 (2017)
[3] D. Häupl et al., New Journal of Physics, 24, 113017 (2022)
[4] D. Häupl et al., New Journal of Physics, 27, 033003 (2025)

Contact

Research Group Nicolas Joly

Professor for Photonics
Friedrich-Alexander-Universität Erlangen-Nürnberg

and

Max Planck Institute for the Science of Light
Staudtstr. 2
91058 Erlangen, Germany

nicolas.joly@mpl.mpg.de
nicolas.joly@fau.de

Data Collection