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Superconductive MiR phOton Counter

Periodic Reporting for period 1 - ShaMROCk (Superconductive MiR phOton Counter)

Reporting period: 2018-06-01 to 2020-05-31

The developments of novel technologies as well as the advancements in science knowledge have frequently been led by improvements in measurement capacity. Single photon detectors (SPDs) compose one of the most attractive devices due to the ability of registering light at its fundamental level. This is an extremely demanding challenge since the energy of a single photon in the near-infrared range is in the order of 10^(-19)J and therefore SPDs have to be exceptionally sensible in order to produce an electronic signal upon the arrival of one photon.
Even though competitive SPD technologies are available for the visible and in the near-infrared range, the mid-infrared (MIR) spectral region lacks in a performant analogue. A detector able to register individual photons in this wavelength range (2.5-25μm) would be extremely desirable for many areas of technology and science, from analysis in industry to advanced research applications. In the MIR spectral range reside vibrational modes of several molecules as well as fundamental absorption bands of gases, intersubband transitions in quantum wells and specific fingerprints of chemical species. A detector sensible at single photon level would greatly boost the field of vibrational and MIR spectroscopy.
By taking advantage of superconducting nanowire SPDs (SNSPDs), the goal of ShaMROCk is to realize an efficient, fast and accurate SPD operating in the MIR with a minimum number of dark counts. This tantalizing perspective can be reached by merging SNSPD technology with Silicon Carbide (SiC) photonics. Due to the presence of quantum emitters, the development of SNSPDs on top SiC photonic components is additionally important as this material is emerging as scalable platform for quantum information processing with photons.
Toward the realization of an efficient MiR SPD, several technological progress had to be first achieved and validated in the telecom wavelength range. The work carried out during the project comprises a series of technological endeavours involving both SiC photonics and the integration of SNSPDs with photonic structures. Several results were achieved ranging from the development of SiC photonic crystal cavities for enhanced light-matter interaction to the integration of efficient readout scheme of SNSPDs fabricated on top of confined waveguides. Thanks to an extensive process optimization, we were able to realize for the first time efficient single photon detectors atop of SiC photonic structures. The results, published in high impact-factor journal (Optica, Opex and ACS Phot.), were also presented in both broad audience conferences (CLEO and ICTON) and in specific ones (Single Photon Workshop and Low Temperature Detector).
The fabrication of high-efficiency SNSPD on top of SiC photonic structures is a fundamental step toward a monolithic integrated quantum-optic processor where single photons could be generated from integrated colour centers, interact in a reconfigurable linear-optic circuit and be detected from integrated SPDs, all within the same chip. We expect that further process optimization of the superconducting material deposition on top of SiC will result in exceptional performances of the SNSPDs, enabling the operation in the MIR range.