In the field of quantum technologies, the superconducting nanowire single photon detector (SNSPD) is nowadays well recognized as a key enabling device. SNSPDs combine high detection efficiency in the visible and near IR spectral ranges, timing jitter as low as 10 ps, low dark count rate (<100 s−1) and cut-off frequency above 100 MHz. These features make it particularly attractive e.g. for fundamental quantum optics experiments and quantum communications.
Plug-and-play SNSPDs with fibered optical access, as shown in Figure 1, are based on a meander nanowire defined by patterning an ultrathin (<10 nm) superconducting film. The device is designed so that absorption of a single photon is enough to brake locally the superconducting order, and to induce a measurable change of the wire’s resistance. Until recently, such devices displayed two main limitations: (1) their efficiency did not exceed ~40% due to the limited optical absorption of the thin film; and (2) their response was strongly polarization-sensitive, due to the optical anisotropy of the nanowire. I will present two different approaches which enable to get very high (>90% [1]) and polarization-insensitive [2,3] detection efficiency. We consider designs based on the integration of the nanowire within an optical microcavity (compatible with the plug-and-play configuration) or on top of an optical waveguide (preferred approach for integration in photonic circuits). I will finally discuss novel application prospects of such detectors, with emphasis on photon-number resolution.
Figure 1.
(a) Top-view scanning electron micrographs of the NbN superconducting nanowire used as active core in SNSPDs; (b) SNSPD device mounted on a print circuit board with fibered optical access.
References
- Redaelli, L.; Bulgarini, G.; Dobrovolskiy, S.; Dorenbos, S.N.; Zwiller, V.; Monroy, E.; Gérard, J.M. Design of broadband high-efficiency superconducting-nanowire single photon detectors. Supercond. Sci. Technol. 2016, 29. [Google Scholar] [CrossRef]
- Redaelli, L.; Zwiller, V.; Monroy, E.; Gérard, J.M. Design of polarization-insensitive superconducting nanowire single photon detectors with high-index dielectrics. Supercond. Sci. Technol. 2017, 30, 035005. [Google Scholar] [CrossRef]
- Mukhtarova, A.; Redaelli, L.; Hazra, D.; Machhadani, H.; Lequien, S.; Hofheinz, M.; Thomassin, J.L.; Gustavo, F.; Zichi, J.; Zwiller, V.; et al. Polarization-Insensitive Fiber-Coupled Superconducting-Nanowire Single Photon Detector Using a High-Index Dielectric Capping Layer. Opt. Express 2018, 26, 17697–17704. [Google Scholar] [CrossRef] [PubMed]
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).