Fiber source of entangled photons with giant tunable frequency separation

• Applicants: Professorin Maria Chekhova, Ph.D.; Professor Dr. Nicolas Joly
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 433761978

• Final Report Year: 2025

Final Report Abstract

Nonclassical states of light play a crucial role in quantum technologies, particularly in quantum communication, computation, imaging, sensing, and spectroscopy. Among them, entangled photon pairs (biphotons) are highly sought after, enabling heralded single-photon generation and novel techniques like imaging and spectroscopy with undetected photons. This approach, based on induced coherence, allows one to probe materials at a specific frequency by analyzing an entangled photon at a vastly different frequency. This could give access to challenging spectral regions, such as ultraviolet (UV) or mid-infrared (MIR). The generation of biphotons must meet stringent requirements, including tunability in frequency and mode structure. Additionally, large spectral separations within photon pairs enhance applications in imaging and spectroscopy. In the past, we had demonstrated the possibility to generate tunable correlated twin beams using hollow-core photonic crystal fibres filled with argon gas. By pumping in the anomalous dispersion, the modulational instability regime was accessed. The use of monatomic gas circumvents Raman scattering, which usually degrades the quality of the sources. In this project, we aimed at producing entangled photon pairs with extreme frequency separation, covering the UV and IR ranges, using gas-filled hollow-core fibre, but operating in the normal dispersion range, where sidebands are very far from the pump wavelength. To avoid issues with group velocity dispersion, we required a mode-locked laser that delivers ps-long pulses. To validate our approach, we planned to conduct induced coherence experiments.

Publications

• Fiber-based biphoton source with ultrabroad frequency tunability. Optics Letters, 46(16), 4033.
  Lopez-Huidobro, Santiago; Lippl, Markus; Joly, Nicolas Y. & Chekhova, Maria V.
  
• Tunable fiber source of entangled UV-C and infrared photons. Optics Letters, 48(13), 3423.
  Lopez-Huidobro, Santiago; Noureddin, Mohammad; Chekhova, Maria V. & Joly, Nicolas Y.
  
• “Tunable Fiber Source of Entangled Ultraviolet and Infrared Photons,” FF1L.4, 2023 Conference on Lasers and Electro-Optics (CLEO), San Jose, CA, USA, pp. 1-2.
  S. Lopez-Huidobro, M. V. Chekhova & N. Y. Joly