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Size Effects and Excess Noise in Superconducting Nanowire Single-Photon Detectors

Sidorova, Mariia and Raupach, Sebastian and Semenov, Alexey (2023) Size Effects and Excess Noise in Superconducting Nanowire Single-Photon Detectors. 2023 IEEE 13th International Conference Nanomaterials: Applications & Properties, 2023-09-10 - 2023-09-15, Bratislava, Slowakei.

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Superconducting Nanowire Single-Photon Detectors (SNSPDs) offer unique performance such as extended spectral sensitivity (from visible to near-infrared range), low dark count rate (1 dark count per hour), and high timing resolution (a few picoseconds) making them highly desirable for applications in quantum computing, quantum communication, and quantum/classical light detection. However, new sophisticated applications such as deep-space communication or direct detection of dark matter particles require even more stringent performance criteria from the SNSPD technology. Among others, they require extremely low, if any, dark count levels and broad spectral sensitivity up to the middle infrared range. We identify new strategies for improving the overall performance of these devices from a material science perspective by investigating size effects and excess noise in superconducting nanowires. The photon detection mechanism in a current-carrying superconducting nanowire is relatively simple. An absorbed photon with energy largely exceeding the superconducting gap locally breaks superconductivity that eventually drives the nanowire into the resistive state which is experimentally registered as a photon count. The dynamics of this process is governed by phonons and electron systems and thermal coupling to the substrate. The miniaturization of device sizes in superconducting nanoelectronics, and particularly in SNSPDs, which are conventionally made of 5 nm-thick and 100 nm-wide superconducting nanowires, leads to modification of their thermal properties at low temperatures. The reciprocal film thickness limits the phonon wave vectors perpendicular to the film plane, significantly altering the phonon spectrum and the heat capacitance of phonons. Our extensive studies of superconducting NbTiN films [1, 2] with polycrystalline granular morphology revealed the impact of mean grain size on the phonon heat capacitance. Such size effect can be used to tune the cut-off in the spectral sensitivity of SNSPDs via engineering the phonon properties. In SNSPDs, besides stochastic dark counts caused by thermal fluctuations [3], there are conditional dark counts, or afterpulsing [4], as a kind of excess noise that presents a significant challenge in improving device performance. We observed that the probability of an afterpulse in an SNSPD made of amorphous MoSi depends on the mean number of photons per light pulse, including values much less than one. Our proposed phenomenological model explains our findings by introducing slowly relaxing afterpulsing centers, which we believe may be two-level systems in amorphous materials. While two-level systems are well-known sources of decoherence and losses in superconducting qubits and resonators, their impact on SNSPD performance is yet to be explored. Therefore, understanding the microscopic details and material science aspects may play a dominant role in further improving the performance of superconducting devices.

Item URL in elib:https://elib.dlr.de/199641/
Document Type:Conference or Workshop Item (Speech)
Title:Size Effects and Excess Noise in Superconducting Nanowire Single-Photon Detectors
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Raupach, SebastianPTB BraunschweigUNSPECIFIEDUNSPECIFIED
Date:15 September 2023
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Keywords:superconducting nanowire detectors, granular films, afterpulsing
Event Title:2023 IEEE 13th International Conference Nanomaterials: Applications & Properties
Event Location:Bratislava, Slowakei
Event Type:international Conference
Event Start Date:10 September 2023
Event End Date:15 September 2023
Organizer:Institute of Electrical Engineering, Slovak Academy of Science
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space System Technology
DLR - Research area:Raumfahrt
DLR - Program:R SY - Space System Technology
DLR - Research theme (Project):R - Detectors for optical instruments
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Optical Sensor Systems > Terahertz and Laser Spectroscopy
Deposited By: Semenov, Prof.Dr. Alexey
Deposited On:24 Nov 2023 09:12
Last Modified:24 Apr 2024 21:00

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