Resources for Integrated Quantum Sensing in the Mid-infrared

Arianna Elefante, Stefano Dello Russo, Fabrizio Sgobba +4 more

The generation of single photons in the mid-infrared spectral region is attracting the interest of scientific and technological research, motivated by the potential improvements that many important and emerging applications, such as quantum sensing, metrology and communication, could benefit from. This review reports the progress in short and mid-infrared single photon generation, focusing on probabilistic sources based on the two non-linear processes of spontaneous parametric downconversion (SPDC) and four wave mixing (FWM). On one hand, numerical simulations of mid-infrared SPDC are described as a powerful tool to assist and guide the experimental realization, along with the implementation and engineering of novel non-linear materials. On the other hand, the advantages offered by FWM in silicon waveguides in terms of integration, miniaturization and manufacturability are presented, providing an optimal technology for integrated quantum applications.

Boris Kantsepolsky, Itzhak Aviv, Ruti Gafni +2 more

Parth S. Patel, Darshan B. Desai

Matteo Sanna, Davide Rizzotti, Stefano Signorini +1 more

In this work, we investigate the application of intermodal spontaneous four wave mixing (SFWM) to ghost spectroscopy in the mid-infrared (MIR) spectral region. This technique is of great interest for MIR sensing, being able to overcome the limitations faced by MIR detectors in terms of background noise and dark counts. Through intermodal SFWM in a Silicon-On-Insulator (SOI) waveguide, two temporally correlated photons are generated: using a standard C-band pump, the idler photon is in the near-infrared (NIR) and the signal photon is in the MIR. The integrated source, with a coincidence to accidental ratio (CAR) of 114 ± 4, is used to demonstrate that, in situations of environmental noise, ghost spectroscopy yields advantages with respect to the traditional absorption spectroscopy. The time-energy entanglement of the photon pairs is used to enhance the visibility of the measurement against noisy background conditions and to increase the spectral resolution in the MIR by spectral filtering the NIR photons. Modeling and experimental data support these improvements.

Ana R. Bastos, Emmanuel Zambrini Cruzeiro, M. Niehus +1 more

Gregor G. Taylor, D. Morozov, Robert H. Hadfield

Single-photon counting has become an essential tool in quantum optics experiments, as well as remote sensing and life science applications. However conventional technologies such as single-photon avalanche diodes, as well as the availability of standard telecom optical components, has limited much of this work to the near infrared/telecom wavelength range. Superconducting nanowire single photon detectors (SNSPDs) have emerged in recent years as the gold standard in photon counting applications due to their low dark count rates, fast timing resolution and high efficiency [1]. SNSPDs have also demonstrated photon counting efficiency out to much greater wavelengths which enables us to explore new experimental possibilities in the mid-infrared [2]. In this work we design and fabricate mid-infrared SNSPDs and deploy them in a variety of photon counting experiments [3,4]. The devices are based on a NbTiN superconducting film integrated into an optical cavity to enhance absorption in the mid-infrared. We characterise these devices using an optical parametric oscillator, tuneable between 1.5 m and 4.2 m. We then deploy these in a proof-of-principle tabletop light detection and ranging (LIDAR) experiment at 2.3 m. LIDAR in the mid-infrared is attractive due to spectral regions of low atmospheric absorption and reduced solar background photon flux, when compared to telecom wavelengths. We also present results from a photon-pair source operating at 2 m. This is a key resource for extending quantum optics and quantum secure communications to the mid infrared domain. Pairs are generated using a custom lithium niobate crystal and detected using SNSPDs. We demonstrate two-photon interference and polarisation entanglement of the photon pairs at 2 m. This work opens the pathway to future development of quantum optics and quantum technologies in the mid-infrared spectral region. References [1] Gol’tsman et al Applied Physics Letters 79 705 (2001) [2] Marisli et al Nano Letters 12 (9) 4799 (2012) [3] G. G. Taylor et al Optics Express 26 (27) 38147 (2018) [4] S. Prabhakar et al Science Advances 6 (13) eaay5195 (2019)