View source for Superconducting nanowire single-photon detector

{{Short description|Type of single-photon detector}}
[[File:NIST SEM Image of Superconducting Nanowire Single Photon Detector.jpg|thumb|alt=Scanning electron micrograph of a superconducting nanowire single-photon detector.|False-color [[scanning electron micrograph]] of a superconducting nanowire single-photon detector (SNSPD). Image credit: [[NIST]].]]
[[File:Superconducting nanowire single-photon detector in the DARPA Quantum Network (BBN) - June 2005 - P1010035.jpg|thumb|right|Superconducting nanowire single-photon detector in the DARPA Quantum Network laboratory at BBN, June 2005]]

The '''superconducting nanowire single-photon detector''' ('''SNSPD or SSPD''') is a type of [[light|optical]] and [[near-infrared]] single-[[photon]] [[Photon-counting detector|detector]] based on a [[biasing|current-biased]] [[superconductivity|superconducting]] [[nanowire]].<ref>{{cite journal | doi=10.1088/0953-2048/25/6/063001 | title=Superconducting nanowire single-photon detectors: Physics and applications | year=2012 | last1=Natarajan | first1=Chandra M. | last2=Tanner | first2=Michael G. | last3=Hadfield | first3=Robert H. | journal=Superconductor Science and Technology | volume=25 | issue=6 | page=063001 | arxiv=1204.5560 | bibcode=2012SuScT..25f3001N | s2cid=4893642 }}</ref> It was first developed by scientists at [[Moscow State Pedagogical University]] and at the [[University of Rochester]] in 2001.<ref>{{cite journal | doi=10.1016/S0921-4534(00)01637-3 | title=Quantum detection by current carrying superconducting film | year=2001 | last1=Semenov | first1=Alex D. | last2=Gol'Tsman | first2=Gregory N. | last3=Korneev | first3=Alexander A. | journal=Physica C: Superconductivity | volume=351 | issue=4 | pages=349–356 | bibcode=2001PhyC..351..349S }}</ref><ref>{{cite journal | doi=10.1063/1.1388868 | title=Picosecond superconducting single-photon optical detector | year=2001 | last1=Gol'Tsman | first1=G. N. | last2=Okunev | first2=O. | last3=Chulkova | first3=G. | last4=Lipatov | first4=A. | last5=Semenov | first5=A. | last6=Smirnov | first6=K. | last7=Voronov | first7=B. | last8=Dzardanov | first8=A. | last9=Williams | first9=C. | last10=Sobolewski | first10=Roman | journal=Applied Physics Letters | volume=79 | issue=6 | pages=705–707 | bibcode=2001ApPhL..79..705G }}</ref> The first fully operational prototype was demonstrated in 2005 by the [[National Institute of Standards and Technology]] (Boulder), and [[BBN Technologies]] as part of the [[DARPA Quantum Network]].<ref>Chip Elliott, "The DARPA quantum network", Quantum physics of nature. Theory, experiment and interpretation. in collaboration with 6th European QIPC workshop, Austria, 2005.</ref><ref>Martin A. Jaspan, Jonathan L. Habif, Robert H. Hadfield, Sae Woo Nam, "Heralding of telecommunication photon pairs with a superconducting single photon detector", ''Applied Physics Letters'' 89(3):031112-031112-3, July 2006.</ref><ref>BBN Technologies, "DARPA Quantum Network Testbed", Final Technical Report, 2007.</ref><ref>{{Cite journal|last1=Hadfield|first1=Robert H.|last2=Habif|first2=Jonathan L.|last3=Schlafer|first3=John|last4=Schwall|first4=Robert E.|last5=Nam|first5=Sae Woo|date=2006-12-11|title=Quantum key distribution at 1550nm with twin superconducting single-photon detectors|url=https://aip.scitation.org/doi/abs/10.1063/1.2405870|journal=Applied Physics Letters|volume=89|issue=24|pages=241129|doi=10.1063/1.2405870|bibcode=2006ApPhL..89x1129H|issn=0003-6951}}</ref>

As of 2023, a superconducting [[Niobium nanowire|nanowire]] single-photon detector is the fastest single-photon detector (SPD) for [[photon counting]].<ref>
Francesco Marsili.
[https://www.nist.gov/pml/div686/manufacturing/high-efficiency-single-photon-detector.cfm "High Efficiency in the Fastest Single-Photon Detector System"]. 2013.</ref><ref>{{Cite journal |last=Hadfield |first=Robert H. |date=December 2009 |title=Single-photon detectors for optical quantum information applications |journal=Nature Photonics |language=En |volume=3 |issue=12 |pages=696–705 |doi=10.1038/nphoton.2009.230 |issn=1749-4885 |bibcode=2009NaPho...3..696H}}</ref><ref>{{Cite journal|last1=Esmaeil Zadeh|first1=Iman|last2=Chang|first2=J.|last3=Los|first3=Johannes W. N.|last4=Gyger|first4=Samuel|last5=Elshaari|first5=Ali W.|last6=Steinhauer|first6=Stephan|last7=Dorenbos|first7=Sander N.|last8=Zwiller|first8=Val|date=2021-05-10|title=Superconducting nanowire single-photon detectors: A perspective on evolution, state-of-the-art, future developments, and applications|journal=Applied Physics Letters|volume=118|issue=19|pages=190502|doi=10.1063/5.0045990|bibcode=2021ApPhL.118s0502E|s2cid=236573004|issn=0003-6951|doi-access=free}}</ref>
It is a key enabling technology for [[quantum optics]] and optical [[Quantum technology|quantum technologies]]. SNSPDs are available with very high detection efficiency, very low dark count rate and very low timing jitter, compared to other types of single-photon detectors. SNSPDs are covered by [[International Electrotechnical Commission]] (IEC) international standards.<ref>{{Cite web |title=IEC 61788-22-3:2022 {{!}} IEC Webstore |url=https://webstore.iec.ch/publication/63471#:~:text=IEC%2061788-22-3:2022%20is%20applicable%20to%20the,and%20operating%20temperature%20(T). |access-date=2023-04-29 |website=webstore.iec.ch}}</ref> As of 2023, commercial SNSPD devices are available in multichannel systems in a price range of 100,000 euros.

It was recently discovered that superconducting wires as wide as 1.5 µm can detect single infra-red photons.<ref>Luskin et al. (2023). “Large active-area superconducting microwire detector array with single-photon sensitivity in the near-infrared”, Appl. Phys. Lett. 122, 243506. https://doi.org/10.1063/5.0150282</ref><ref>G.-Z. Xu et al. (2023). “Millimeter-scale active area superconducting microstrip single-photon detector fabricated by ultraviolet photolithography,” Optics Express, vol. 31, pp. 16348-16360.</ref> This is important because optical lithography rather than electron lithography can be used in their construction. This reduces the cost for applications that require large photodetector areas. One application is in dark matter detection experiments, where the target is a scintillating GaAs crystal. GaAs suitably doped with silicon and boron is a luminous cryogenic scintillator that has no apparent afterglow and is available commercially in the form of large, high-quality crystals.<ref>Derenzo, S.; Bourret, E.; Hanrahan, S.; Bizarri, G. (2018). "Cryogenic scintillation properties of n-type GaAs for the direct detection of MeV/c<sup>2</sup> dark matter". Journal of Applied Physics. 123 (11): 114501. arXiv:1802.09171. Bibcode:2018JAP...123k4501D. doi:10.1063/1.5018343. S2CID 56118568</ref><ref>Vasiukov, S.; Chiossi, F.; Braggio, C.; Carugno, G.; Moretti, F.; Bourret, E.; Derenzo, S. (2019). "GaAs as a Bright Cryogenic Scintillator for the Detection of Low-Energy Electron Recoils from MeV/c<sup>2</sup> Dark Matter". IEEE Transactions on Nuclear Science. 66 (11): 2333–2337. Bibcode:2019ITNS...66.2333V. doi:10.1109/TNS.2019.2946725. S2CID 208208697</ref><ref>Derenzo, S.; Bourret, E.; Frank-Rotsch, C.; Hanrahan, S.; Garcia-Sciveres, M. (2021). "How silicon and boron dopants govern the cryogenic scintillation properties of n-type GaAs". Nuclear Instruments and Methods in Physics Research Section A. 989: 164957. arXiv:2012.07550. Bibcode:2021NIMPA.98964957D. doi:10.1016/j.nima.2020.164957. S2CID 229158562</ref>

== Principle of operation ==
The SNSPD consists of a thin (≈ 5&nbsp;nm) and narrow (≈ 100&nbsp;nm) [[superconductivity|superconducting]] [[Niobium nanowire|nanowire]]. The length is typically hundreds of [[micrometre|micrometers]], and the nanowire is patterned in a compact meander geometry to create a square or circular pixel with high detection efficiency. The nanowire is cooled well below its superconducting critical temperature and biased with a DC [[electric current|current]] that is close to but less than the superconducting critical current of the nanowire. A [[photon]] incident on the nanowire breaks [[Cooper pairs]] and reduces the local critical current below that of the bias current. This results in the formation of a localized non-superconducting region, or hotspot, with finite [[electrical resistance]]. This resistance is typically larger than the 50&nbsp;ohm input [[nominal impedance|impedance]] of the readout amplifier, and hence most of the bias current is shunted to the amplifier. This produces a measurable voltage pulse that is approximately equal to the bias current multiplied by 50&nbsp;ohms. With most of the bias current flowing through the amplifier, the non-superconducting region cools and returns to the superconducting state. The time for the current to return to the nanowire is typically set by the inductive time constant of the nanowire, equal to the [[kinetic inductance]] of the nanowire divided by the impedance of the readout circuit.<ref>{{cite journal | doi=10.1063/1.2183810 | title=Kinetic-inductance-limited reset time of superconducting nanowire photon counters | year=2006 | last1=Kerman | first1=Andrew J. | last2=Dauler | first2=Eric A. | last3=Keicher | first3=William E. | last4=Yang | first4=Joel K. W. | last5=Berggren | first5=Karl K. | last6=Gol'Tsman | first6=G. | last7=Voronov | first7=B. | journal=Applied Physics Letters | volume=88 | issue=11 | page=111116 | arxiv=physics/0510238 | bibcode=2006ApPhL..88k1116K | s2cid=53373647 }}</ref> Proper self-resetting of the device requires that this inductive time constant be slower than the intrinsic cooling time of the nanowire hotspot.<ref>{{cite journal | doi=10.1063/1.3498809 | title=Reset dynamics and latching in niobium superconducting nanowire single-photon detectors | year=2010 | last1=Annunziata | first1=Anthony J. | last2=Quaranta | first2=Orlando | last3=Santavicca | first3=Daniel F. | last4=Casaburi | first4=Alessandro | last5=Frunzio | first5=Luigi | last6=Ejrnaes | first6=Mikkel | last7=Rooks | first7=Michael J. | last8=Cristiano | first8=Roberto | last9=Pagano | first9=Sergio | last10=Frydman | first10=Aviad | last11=Prober | first11=Daniel E. | journal=Journal of Applied Physics | volume=108 | issue=8 | pages=084507–084507–7 | arxiv=1008.0895 | bibcode=2010JAP...108h4507A | s2cid=13941277 }}</ref>

While the SNSPD does not match the intrinsic energy or photon-number resolution of the superconducting [[transition edge sensor]], the SNSPD is significantly faster than conventional transition edge sensors and operates at higher temperatures. A degree of photon-number resolution can be achieved in SNSPD arrays,<ref>{{Cite journal|last1=Divochiy|first1=Aleksander|last2=Marsili|first2=Francesco|last3=Bitauld|first3=David|last4=Gaggero|first4=Alessandro|last5=Leoni|first5=Roberto|last6=Mattioli|first6=Francesco|last7=Korneev|first7=Alexander|last8=Seleznev|first8=Vitaliy|last9=Kaurova|first9=Nataliya|last10=Minaeva|first10=Olga|last11=Gol'tsman|first11=Gregory|date=May 2008|title=Superconducting nanowire photon-number-resolving detector at telecommunication wavelengths|url=https://www.nature.com/articles/nphoton.2008.51|journal=Nature Photonics|language=en|volume=2|issue=5|pages=302–306|doi=10.1038/nphoton.2008.51|issn=1749-4893}}</ref> through time-binning<ref>{{Cite journal|last1=Natarajan|first1=Chandra M.|last2=Zhang|first2=Lijian|last3=Coldenstrodt-Ronge|first3=Hendrik|last4=Donati|first4=Gaia|last5=Dorenbos|first5=Sander N.|last6=Zwiller|first6=Val|last7=Walmsley|first7=Ian A.|last8=Hadfield|first8=Robert H.|date=2013-01-14|title=Quantum detector tomography of a time-multiplexed superconducting nanowire single-photon detector at telecom wavelengths|url=https://www.osapublishing.org/oe/abstract.cfm?uri=oe-21-1-893|journal=Optics Express|language=EN|volume=21|issue=1|pages=893–902|doi=10.1364/OE.21.000893|pmid=23388983|bibcode=2013OExpr..21..893N|issn=1094-4087|doi-access=free}}</ref> or advanced readout schemes.<ref>{{Cite journal|last1=Zhu|first1=Di|last2=Colangelo|first2=Marco|last3=Chen|first3=Changchen|last4=Korzh|first4=Boris A.|last5=Wong|first5=Franco N. C.|last6=Shaw|first6=Matthew D.|last7=Berggren|first7=Karl K.|date=2020-05-13|title=Resolving Photon Numbers Using a Superconducting Nanowire with Impedance-Matching Taper|url=https://doi.org/10.1021/acs.nanolett.0c00985|journal=Nano Letters|volume=20|issue=5|pages=3858–3863|doi=10.1021/acs.nanolett.0c00985|pmid=32271591|arxiv=1911.09485|bibcode=2020NanoL..20.3858Z|s2cid=215726323|issn=1530-6984}}</ref>  Most SNSPDs are made of [[Sputter deposition|sputtered]] [[niobium nitride]] (NbN), which offers a relatively high superconducting critical temperature (≈ 10&nbsp;[[Kelvin|K]]) which enables SNSPD operation in the temperature range 1 K to 4 K (compatible with liquid helium or modern closed-cycle [[cryocooler]]s).  The intrinsic thermal time constants of NbN are short, giving very fast cooling time after photon absorption (<100 picoseconds).<ref>{{cite journal | doi=10.1016/0921-4526(94)91007-3 | title=Electron-phonon interaction in disordered NBN films | year=1994 | last1=Gousev | first1=Yu.P. | last2=Semenov | first2=A.D. | last3=Gol'Tsman | first3=G.N. | last4=Sergeev | first4=A.V. | last5=Gershenzon | first5=E.M. | journal=Physica B: Condensed Matter | volume=194-196 | pages=1355–1356 | bibcode=1994PhyB..194.1355G }}</ref>

The absorption in the superconducting nanowire can be boosted by a variety of strategies: integration with an [[optical cavity]],<ref>{{Cite journal|last1=Rosfjord|first1=Kristine M.|last2=Yang|first2=Joel K. W.|last3=Dauler|first3=Eric A.|last4=Kerman|first4=Andrew J.|last5=Anant|first5=Vikas|last6=Voronov|first6=Boris M.|last7=Gol'tsman|first7=Gregory N.|last8=Berggren|first8=Karl K.|date=2006-01-23|title=Nanowire Single-photon detector with an integrated optical cavity and anti-reflection coating|url=https://www.osapublishing.org/oe/abstract.cfm?uri=oe-14-2-527|journal=Optics Express|language=EN|volume=14|issue=2|pages=527–534|doi=10.1364/OPEX.14.000527|pmid=19503367|bibcode=2006OExpr..14..527R|issn=1094-4087|doi-access=free}}</ref> integration with a [[Photonic integrated circuit|photonic waveguide]]<ref>{{Cite journal|last1=Pernice|first1=W. H. P.|last2=Schuck|first2=C.|last3=Minaeva|first3=O.|last4=Li|first4=M.|last5=Goltsman|first5=G. N.|last6=Sergienko|first6=A. V.|last7=Tang|first7=H. X.|date=2012-12-27|title=High-speed and high-efficiency travelling wave single-photon detectors embedded in nanophotonic circuits|journal=Nature Communications|language=en|volume=3|issue=1|pages=1325|doi=10.1038/ncomms2307|pmid=23271658|pmc=3535416|arxiv=1108.5299|bibcode=2012NatCo...3.1325P|issn=2041-1723}}</ref> or addition of [[Plasmonics|nanoantenna]] structures.<ref>{{Cite journal|last1=Heath|first1=Robert M.|last2=Tanner|first2=Michael G.|last3=Drysdale|first3=Timothy D.|last4=Miki|first4=Shigehito|last5=Giannini|first5=Vincenzo|last6=Maier|first6=Stefan A.|last7=Hadfield|first7=Robert H.|date=2015-02-11|title=Nanoantenna Enhancement for Telecom-Wavelength Superconducting Single Photon Detectors|url=https://doi.org/10.1021/nl503055a|journal=Nano Letters|volume=15|issue=2|pages=819–822|doi=10.1021/nl503055a|pmid=25575021|arxiv=1501.03333|bibcode=2015NanoL..15..819H|s2cid=16305859|issn=1530-6984}}</ref>  SNSPD cavity devices in NbN, NbTiN, WSi & MoSi have demonstrated fibre-coupled device detection efficiencies greater than 98% at 1550&nbsp;nm wavelength<ref>{{Cite journal|last1=Reddy|first1=Dileep V.|last2=Nerem|first2=Robert R.|last3=Nam|first3=Sae Woo|last4=Mirin|first4=Richard P.|last5=Verma|first5=Varun B.|date=2020-12-20|title=Superconducting nanowire single-photon detectors with 98% system detection efficiency at 1550 nm|url=https://www.osapublishing.org/optica/abstract.cfm?uri=optica-7-12-1649|journal=Optica|language=EN|volume=7|issue=12|pages=1649–1653|doi=10.1364/OPTICA.400751|bibcode=2020Optic...7.1649R|issn=2334-2536|doi-access=free}}</ref> with count rates in the tens of MHz.<ref>{{cite journal |author1=Peng Hu |display-authors=etal |title=Detecting single infrared photons toward optimal system detection efficiency |journal=Optics Express |volume=28 |pages=36884–36891 |number=24 |year=2020 |doi=10.1364/OE.410025 |pmid=33379772 |arxiv=2009.14690 |bibcode=2020OExpr..2836884H |doi-access= free}}</ref>
The detection efficiencies are optimized for a specific wavelength range in each detector. They vary widely, however, due to highly localized regions of the nanowires where the effective cross-sectional area for superconducting current is reduced.<ref>{{cite journal |author1=Andrew J Kerman|author-link= Andrew J. Kerman|author2= Eric A Dauler|author3= Joel KW Yang|author4= Kristine M Rosfjord|author5= Vikas Anant|author6= Karl K Berggren|author7= Gregory N Gol'tsman|author8= Boris M Voronov|title=Constriction-limited detection efficiency of superconducting nanowire single-photon detectors|journal= Applied Physics Letters|volume=90|issue = 10|pages = 101110|year=2007|doi=10.1063/1.2696926|arxiv = physics/0611260|bibcode= 2007ApPhL..90j1110K|s2cid= 118985342}}</ref>
SNSPD devices have also demonstrated exceptionally low [[jitter]] – the uncertainty in the photon arrival time – as low as 3 picoseconds at visible wavelengths.<ref>{{Cite journal|last1=Korzh|first1=Boris|last2=Zhao|first2=Qing-Yuan|last3=Allmaras|first3=Jason P.|last4=Frasca|first4=Simone|last5=Autry|first5=Travis M.|last6=Bersin|first6=Eric A.|last7=Beyer|first7=Andrew D.|last8=Briggs|first8=Ryan M.|last9=Bumble|first9=Bruce|last10=Colangelo|first10=Marco|last11=Crouch|first11=Garrison M.|date=April 2020|title=Demonstration of sub-3 ps temporal resolution with a superconducting nanowire single-photon detector|url=https://www.nature.com/articles/s41566-020-0589-x|journal=Nature Photonics|language=en|volume=14|issue=4|pages=250–255|doi=10.1038/s41566-020-0589-x|arxiv=1804.06839 |bibcode=2020NaPho..14..250K|s2cid=216455902|issn=1749-4893}}</ref><ref>{{Cite journal|last=Hadfield|first=Robert H.|date=April 2020|title=Superfast photon counting|url=https://www.nature.com/articles/s41566-020-0614-0|journal=Nature Photonics|language=en|volume=14|issue=4|pages=201–202|doi=10.1038/s41566-020-0614-0|bibcode=2020NaPho..14..201H|s2cid=216178290|issn=1749-4893}}</ref>  Timing jitter increases as photon energy drops and has been verified out to 3.5 micrometres wavelength.<ref>{{Cite journal |last1=Taylor |first1=Gregor G. |last2=MacKenzie |first2=Ewan N. |last3=Korzh |first3=Boris |last4=Morozov |first4=Dmitry V. |last5=Bumble |first5=Bruce |last6=Beyer |first6=Andrew D. |last7=Allmaras |first7=Jason P. |last8=Shaw |first8=Matthew D. |last9=Hadfield |first9=Robert H. |date=2022-11-21 |title=Mid-infrared timing jitter of superconducting nanowire single-photon detectors |journal=Applied Physics Letters |volume=121 |issue=21 |pages=214001 |doi=10.1063/5.0128129 |issn=0003-6951|doi-access=free }}</ref>  Timing jitter is an extremely important property for time-correlated single-photon counting (TCSPC)<ref>{{Cite book|last=Becker|first=Wolfgang|date=2005|title=Advanced Time-Correlated Single Photon Counting Techniques|url=https://link.springer.com/book/10.1007/3-540-28882-1|series=Springer Series in Chemical Physics|volume=81|language=en-gb|doi=10.1007/3-540-28882-1|isbn=978-3-540-26047-9|issn=0172-6218}}</ref> applications.  Furthermore, SNSPDs have extremely low rates of dark counts, i.e. the occurrence of voltage pulses in the absence of a detected photon.<ref>{{cite journal | doi=10.1109/TASC.2005.849914 | title=Origin of Dark Counts in Nanostructured NBN Single-Photon Detectors | year=2005 | last1=Kitaygorsky | first1=J. | last2=Zhang | first2=J. | last3=Verevkin | first3=A. | last4=Sergeev | first4=A. | last5=Korneev | first5=A. | last6=Matvienko | first6=V. | last7=Kouminov | first7=P. | last8=Smirnov | first8=K. | last9=Voronov | first9=B. | last10=Gol'Tsman | first10=G. | last11=Sobolewski | first11=R. | journal=IEEE Transactions on Applied Superconductivity | volume=15 | issue=2 | pages=545–548 | bibcode=2005ITAS...15..545K | s2cid=10285736 }}</ref> In addition, the deadtime (time interval following a detection event during which the detector is not sensitive) is on the order of a few nanoseconds, this short deadtime translates into very high saturation count rates and enables antibunching measurements with a single detector.<ref>{{cite journal | doi=10.1103/PhysRevA.86.053814 | title=Measuring the quantum nature of light with a single source and a single detector | year=2012 | last1=Steudle | first1=Gesine A. | last2=Schietinger | first2=Stefan | last3=Höckel | first3=David | last4=Dorenbos | first4=Sander N. | last5=Zadeh | first5=Iman E. | last6=Zwiller | first6=Valery | last7=Benson | first7=Oliver | journal=Physical Review A | volume=86 | issue=5 | page=053814 | arxiv=1107.1353 | bibcode=2012PhRvA..86e3814S | s2cid=119287808 }}</ref>

For the detection of longer wavelength photons, however, the detection efficiency of standard SNSPDs decreases significantly.<ref>{{cite journal | doi=10.1109/TASC.2005.849923 | title=Quantum Efficiency and Noise Equivalent Power of Nanostructured, NBN, Single-Photon Detectors in the Wavelength Range from Visible to Infrared | year=2005 | last1=Korneev | first1=A. | last2=Matvienko | first2=V. | last3=Minaeva | first3=O. | last4=Milostnaya | first4=I. | last5=Rubtsova | first5=I. | last6=Chulkova | first6=G. | last7=Smirnov | first7=K. | last8=Voronov | first8=V. | last9=Gol'Tsman | first9=G. | last10=Slysz | first10=W. | last11=Pearlman | first11=A. | last12=Verevkin | first12=A. | last13=Sobolewski | first13=R. | journal=IEEE Transactions on Applied Superconductivity | volume=15 | issue=2 | pages=571–574 | bibcode=2005ITAS...15..571K | s2cid=20606230 }}</ref> Recent efforts to improve the detection efficiency at [[near-infrared]] and [[mid-infrared]] wavelengths include studies of narrower (20&nbsp;nm and 30&nbsp;nm wide) NbN nanowires<ref>{{cite journal | doi=10.1021/nl2005143 | title=Single-Photon Detectors Based on Ultranarrow Superconducting Nanowires | year=2011 | last1=Marsili | first1=Francesco | last2=Najafi | first2=Faraz | last3=Dauler | first3=Eric | last4=Bellei | first4=Francesco | last5=Hu | first5=Xiaolong | last6=Csete | first6=Maria | last7=Molnar | first7=Richard J. | last8=Berggren | first8=Karl K. | journal=Nano Letters | volume=11 | issue=5 | pages=2048–2053 | pmid=21456546 | arxiv=1012.4149 | bibcode=2011NanoL..11.2048M | s2cid=7796191 }}</ref> as well as extensive studies of alternative superconducting materials<ref>{{Cite journal|last1=Holzman|first1=Itamar|last2=Ivry|first2=Yachin|date=2019|title=Superconducting Nanowires for Single-Photon Detection: Progress, Challenges, and Opportunities|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/qute.201800058|journal=Advanced Quantum Technologies|language=en|volume=2|issue=3–4|pages=1800058|doi=10.1002/qute.201800058|arxiv=1807.09060|s2cid=119427730|issn=2511-9044}}</ref> with lower superconducting critical temperatures than NbN ([[tungsten silicide]],<ref>{{cite journal | doi=10.1063/1.3600793 | title=Superconducting a-WxSi1−x nanowire single-photon detector with saturated internal quantum efficiency from visible to 1850 nm | year=2011 | last1=Baek | first1=Burm | last2=Lita | first2=Adriana E. | last3=Verma | first3=Varun | last4=Nam | first4=Sae Woo | journal=Applied Physics Letters | volume=98 | issue=25 | page=251105 | bibcode=2011ApPhL..98y1105B }}</ref> niobium silicide,<ref>{{cite journal | doi=10.1063/1.3599712 | title=Low gap superconducting single photon detectors for infrared sensitivity | year=2011 | last1=Dorenbos | first1=S. N. | last2=Forn-Díaz | first2=P. | last3=Fuse | first3=T. | last4=Verbruggen | first4=A. H. | last5=Zijlstra | first5=T. | last6=Klapwijk | first6=T. M. | last7=Zwiller | first7=V. | journal=Applied Physics Letters | volume=98 | issue=25 | page=251102 | bibcode=2011ApPhL..98y1102D }}</ref> molybdenum silicide<ref>{{Cite journal|last1=Li|first1=Jian|last2=Kirkwood|first2=Robert A.|last3=Baker|first3=Luke J.|last4=Bosworth|first4=David|last5=Erotokritou|first5=Kleanthis|last6=Banerjee|first6=Archan|last7=Heath|first7=Robert M.|last8=Natarajan|first8=Chandra M.|last9=Barber|first9=Zoe H.|date=2016-06-27|title=Nano-optical single-photon response mapping of waveguide integrated molybdenum silicide (MoSi) superconducting nanowires|journal=Optics Express|language=EN|volume=24|issue=13|pages=13931–13938|doi=10.1364/OE.24.013931|pmid=27410555|issn=1094-4087|bibcode=2016OExpr..2413931L|hdl=1983/502e0a88-986b-4e79-8905-2bbd3bd75afd|url=https://research-information.bris.ac.uk/portal/en/publications/nanooptical-singlephoton-response-mapping-of-waveguide-integrated-molybdenum-silicide-mosi-superconducting-nanowires(502e0a88-986b-4e79-8905-2bbd3bd75afd).html|doi-access=free|hdl-access=free}}</ref> and [[tantalum nitride]]<ref>{{Cite journal|last1=Engel|first1=A.|last2=Aeschbacher|first2=A.|last3=Inderbitzin|first3=K.|last4=Schilling|first4=A.|last5=Il'in|first5=K.|last6=Hofherr|first6=M.|last7=Siegel|first7=M.|last8=Semenov|first8=A.|last9=Hübers|first9=H.-W.|date=2012-02-06|title=Tantalum nitride superconducting single-photon detectors with low cut-off energy|url=https://aip.scitation.org/doi/full/10.1063/1.3684243|journal=Applied Physics Letters|volume=100|issue=6|pages=062601|doi=10.1063/1.3684243|arxiv=1110.4576|bibcode=2012ApPhL.100f2601E|s2cid=118674991|issn=0003-6951}}</ref>).  Single photon sensitivity up to 10 micrometer wavelength has recently been demonstrated in a tungsten silicide SNSPD.<ref>{{Cite journal|last1=Verma|first1=V. B.|last2=Korzh|first2=B.|last3=Walter|first3=A. B.|last4=Lita|first4=A. E.|last5=Briggs|first5=R. M.|last6=Colangelo|first6=M.|last7=Zhai|first7=Y.|last8=Wollman|first8=E. E.|last9=Beyer|first9=A. D.|last10=Allmaras|first10=J. P.|last11=Vora|first11=H.|date=2021-05-01|title=Single-photon detection in the mid-infrared up to 10 μm wavelength using tungsten silicide superconducting nanowire detectors|journal=APL Photonics|volume=6|issue=5|pages=056101|doi=10.1063/5.0048049|pmid=37621960 |pmc=10448953 |arxiv=2012.09979|bibcode=2021APLP....6e6101V|s2cid=229331770}}</ref>  Alternative thin film deposition techniques such as [[atomic layer deposition]] are of interest for extending the spectral range and scalability of SNSPDs to large areas.<ref>{{Cite journal|last1=Taylor|first1=Gregor G.|last2=Morozov|first2=Dmitry V.|last3=Lennon|first3=Ciaran T.|last4=Barry|first4=Peter S.|last5=Sheagren|first5=Calder|last6=Hadfield|first6=Robert H.|date=2021-05-10|title=Infrared single-photon sensitivity in atomic layer deposited superconducting nanowires|journal=Applied Physics Letters|volume=118|issue=19|pages=191106|doi=10.1063/5.0048799|bibcode=2021ApPhL.118s1106T|issn=0003-6951|doi-access=free}}</ref>  [[High-temperature superconductivity|High temperature superconductors]] have been investigated for SNSPDs<ref>{{Cite journal|date=2015-02-15|title=High-temperature superconducting nanowires for photon detection|url=https://www.sciencedirect.com/science/article/abs/pii/S092145341400358X|journal=Physica C: Superconductivity and Its Applications|language=en|volume=509|pages=16–21|doi=10.1016/j.physc.2014.09.017|issn=0921-4534|last1=Arpaia|first1=R.|last2=Ejrnaes|first2=M.|last3=Parlato|first3=L.|last4=Tafuri|first4=F.|last5=Cristiano|first5=R.|last6=Golubev|first6=D.|last7=Sobolewski|first7=Roman|last8=Bauch|first8=T.|last9=Lombardi|first9=F.|last10=Pepe|first10=G.P.}}</ref><ref>{{Cite journal|date=2023-10-10|title=Scalable nanofabrication of high-quality YBCO nanowires for single-photon detectors|url=https://link.aps.org/doi/10.1103/PhysRevApplied.20.044025|journal=Physical Review Applied|language=en|volume=2O|pages=044025|doi=10.1103/PhysRevApplied.20.044025|last1=Amari|first1=P.|last2=Kozlov|first2=S.|last3=Recoba-Pawlowski|first3=E.|last4=Velluire-Pellat|first4=Z.|last5=Jouan|first5=A.|last6=Couedo|first6=F.|last7=Ulysse|first7=C.|last8=Briatico|first8=J.|last9=Roditchev|first9=D.|last10=Bergeal|first10=N.|last11=Lesueur|first11=J.|last12=Feuillet-Palma|first12=C.|s2cid=263840977 }}</ref> with some encouraging recent reports.<ref>{{Cite journal |last1=Merino |first1=Rafael Luque |last2=Seifert |first2=Paul |last3=Retamal |first3=José Durán |last4=Mech |first4=Roop K |last5=Taniguchi |first5=Takashi |last6=Watanabe |first6=Kenji |last7=Kadowaki |first7=Kazuo |last8=Hadfield |first8=Robert H |last9=Efetov |first9=Dmitri K |date=2023-04-01 |title=Two-dimensional cuprate nanodetector with single telecom photon sensitivity at T = 20 K |journal=2D Materials |volume=10 |issue=2 |pages=021001 |doi=10.1088/2053-1583/acb4a8 |bibcode=2023TDM....10b1001M |s2cid=256166805 |issn=2053-1583|doi-access=free |hdl=10261/337040 |hdl-access=free }}</ref><ref>{{cite journal |last1=Charaev |first1=I. |last2=Bandurin |first2=D. A. |last3=Bollinger |first3=A. T. |last4=Phinney |first4=I. Y. |last5=Drozdov |first5=I. |last6=Colangelo |first6=M. |last7=Butters |first7=B. A. |last8=Taniguchi |first8=T. |last9=Watanabe |first9=K. |last10=He |first10=X. |last11=Božović |first11=I. |last12=Jarillo-Herrero |first12=P. |last13=Berggren |first13=K. K. |date=2023 |title=Single-photon detection using high-temperature superconductors |journal=Nature Nanotechnology |volume=18 |issue=4 |pages=343–349 |doi=10.1038/s41565-023-01325-2 |pmid=36941357 |arxiv=2208.05674 |bibcode=2023NatNa..18..343C |s2cid=251493161 }}</ref>  SNSPDs have been created from [[magnesium diboride]] with some single photon sensitivity in the visible and near infrared.<ref>{{Cite journal|last1=Shibata|first1=H.|last2=Takesue|first2=H.|last3=Honjo|first3=T.|last4=Akazaki|first4=T.|last5=Tokura|first5=Y.|date=2010-11-22|title=Single-photon detection using magnesium diboride superconducting nanowires|url=https://aip.scitation.org/doi/full/10.1063/1.3518723|journal=Applied Physics Letters|volume=97|issue=21|pages=212504|doi=10.1063/1.3518723|bibcode=2010ApPhL..97u2504S|issn=0003-6951}}</ref><ref>{{Cite journal|title=Low kinetic inductance superconducting MgB2 nanowires with a 130 ps relaxation time for single-photon detection applications|url=https://iopscience.iop.org/article/10.1088/1361-6668/abdeda/meta|journal=Superconductor Science and Technology|year=2021|language=en|doi=10.1088/1361-6668/abdeda| issn=0953-2048 |arxiv=1911.01480|last1=Cherednichenko|first1=Sergey|last2=Acharya|first2=Narendra|last3=Novoselov|first3=Evgenii|last4=Drakinskiy|first4=Vladimir|volume=34|issue=4|page=044001|bibcode=2021SuScT..34d4001C|s2cid=234305489}}</ref>

There is considerable interest and effort in scaling up SNSPDs to large multipixel arrays and cameras.<ref>{{Cite journal|last1=Steinhauer|first1=Stephan|last2=Gyger|first2=Samuel|last3=Zwiller|first3=Val|date=2021-03-08|title=Progress on large-scale superconducting nanowire single-photon detectors|journal=Applied Physics Letters|volume=118|issue=10|pages=100501|doi=10.1063/5.0044057|bibcode=2021ApPhL.118j0501S|issn=0003-6951|doi-access=free}}</ref><ref>{{Cite journal|last1=Doerner|first1=S.|last2=Kuzmin|first2=A.|last3=Wuensch|first3=S.|last4=Charaev|first4=I.|last5=Boes|first5=F.|last6=Zwick|first6=T.|last7=Siegel|first7=M.|date=2017-07-17|title=Frequency-multiplexed bias and readout of a 16-pixel superconducting nanowire single-photon detector array|url=https://aip.scitation.org/doi/full/10.1063/1.4993779|journal=Applied Physics Letters|volume=111|issue=3|pages=032603|doi=10.1063/1.4993779|arxiv=1705.05345|bibcode=2017ApPhL.111c2603D|s2cid=119328620|issn=0003-6951}}</ref>  A kilopixel SNSPD array has recently been reported.<ref>{{Cite journal|last1=Wollman|first1=Emma E.|last2=Verma|first2=Varun B.|last3=Verma|first3=Varun B.|last4=Lita|first4=Adriana E.|last5=Farr|first5=William H.|last6=Shaw|first6=Matthew D.|last7=Mirin|first7=Richard P.|last8=Nam|first8=Sae Woo|date=2019-11-25|title=Kilopixel array of superconducting nanowire single-photon detectors|url=https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-24-35279|journal=Optics Express|language=EN|volume=27|issue=24|pages=35279–35289|doi=10.1364/OE.27.035279|pmid=31878700|arxiv=1908.10520|bibcode=2019OExpr..2735279W|s2cid=201651262|issn=1094-4087}}</ref>  A key challenge is readout,<ref>{{Cite journal|last=McCaughan|first=Adam N|date=2018-04-01|title=Readout architectures for superconducting nanowire single photon detectors|journal=Superconductor Science and Technology|volume=31|issue=4|pages=040501|doi=10.1088/1361-6668/aaa1b3|issn=0953-2048|pmc=6459399|pmid=30983702|bibcode=2018SuScT..31d0501M}}</ref> which can be addressed via multiplexing<ref>{{Cite journal|last1=Allman|first1=M. S.|last2=Verma|first2=V. B.|last3=Stevens|first3=M.|last4=Gerrits|first4=T.|last5=Horansky|first5=R. D.|last6=Lita|first6=A. E.|last7=Marsili|first7=F.|last8=Beyer|first8=A.|last9=Shaw|first9=M. D.|last10=Kumor|first10=D.|last11=Mirin|first11=R.|date=2015-05-11|title=A near-infrared 64-pixel superconducting nanowire single photon detector array with integrated multiplexed readout|url=https://aip.scitation.org/doi/full/10.1063/1.4921318|journal=Applied Physics Letters|volume=106|issue=19|pages=192601|doi=10.1063/1.4921318|arxiv=1504.02812|bibcode=2015ApPhL.106s2601A|s2cid=119263216|issn=0003-6951}}</ref><ref>{{Cite journal|last1=Doerner|first1=S.|last2=Kuzmin|first2=A.|last3=Wuensch|first3=S.|last4=Charaev|first4=I.|last5=Boes|first5=F.|last6=Zwick|first6=T.|last7=Siegel|first7=M.|date=2017-07-17|title=Frequency-multiplexed bias and readout of a 16-pixel superconducting nanowire single-photon detector array|url=https://aip.scitation.org/doi/full/10.1063/1.4993779|journal=Applied Physics Letters|volume=111|issue=3|pages=032603|doi=10.1063/1.4993779|arxiv=1705.05345|bibcode=2017ApPhL.111c2603D|s2cid=119328620|issn=0003-6951}}</ref> or digital readout using superconducting [[Superconducting computing|single flux quantum]] logic.<ref>{{Cite journal|last1=Miyajima|first1=Shigeyuki|last2=Yabuno|first2=Masahiro|last3=Miki|first3=Shigehito|last4=Yamashita|first4=Taro|last5=Terai|first5=Hirotaka|date=2018-10-29|title=High-time-resolved 64-channel single-flux quantum-based address encoder integrated with a multi-pixel superconducting nanowire single-photon detector|url=https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-22-29045|journal=Optics Express|language=EN|volume=26|issue=22|pages=29045–29054|doi=10.1364/OE.26.029045|pmid=30470072|bibcode=2018OExpr..2629045M|issn=1094-4087|doi-access=free}}</ref>

==Applications==
Many of the initial application demonstrations of SNSPDs have been in the area of [[quantum information]],<ref>{{Cite book|date=2016|editor-last=Hadfield|editor-first=Robert H.|editor2-last=Johansson|editor2-first=Göran|title=Superconducting Devices in Quantum Optics|url=https://link.springer.com/book/10.1007/978-3-319-24091-6|journal=Quantum Science and Technology|language=en-gb|doi=10.1007/978-3-319-24091-6|bibcode=2016sdqo.book.....H |isbn=978-3-319-24089-3|issn=2364-9054}}</ref> such as [[quantum key distribution]]<ref>H. Takesue ''et al.'', "Quantum key distribution over a 40-dB channel loss using superconducting single-photon detectors," ''Nature Photonics'' '''1''', 343 (2007), {{doi|10.1038/nphoton.2007.75}}, [https://arxiv.org/abs/0706.0397 arXiv:0706.0397]</ref> and optical [[quantum computing]].<ref>{{Cite journal|last1=Zhong|first1=Han-Sen|last2=Wang|first2=Hui|last3=Deng|first3=Yu-Hao|last4=Chen|first4=Ming-Cheng|last5=Peng|first5=Li-Chao|last6=Luo|first6=Yi-Han|last7=Qin|first7=Jian|last8=Wu|first8=Dian|last9=Ding|first9=Xing|last10=Hu|first10=Yi|last11=Hu|first11=Peng|date=2020-12-18|title=Quantum computational advantage using photons|url=https://www.science.org/doi/10.1126/science.abe8770|journal=Science|language=en|volume=370|issue=6523|pages=1460–1463|doi=10.1126/science.abe8770|issn=0036-8075|pmid=33273064|arxiv=2012.01625|bibcode=2020Sci...370.1460Z|s2cid=227254333}}</ref><ref>{{Citation|title=Silicon Photonic Quantum Computing - PsiQuantum at 2021 APS March Meeting|url=https://www.youtube.com/watch?v=WQRmSOKgMPA|language=en|access-date=2021-05-16}}</ref> Other current and emerging applications include imaging of infrared photoemission for defect analysis in [[CMOS]] circuitry,<ref>{{cite journal | doi=10.1016/S0026-2714(00)00137-2 | title=PICA: Backside failure analysis of CMOS circuits using Picosecond Imaging Circuit Analysis | year=2000 | last1=Mc Manus | first1=M.K. | last2=Kash | first2=J.A. | last3=Steen | first3=S.E. | last4=Polonsky | first4=S. | last5=Tsang | first5=J.C. | last6=Knebel | first6=D.R. | last7=Huott | first7=W. | journal=Microelectronics Reliability | volume=40 | issue=8–10 | pages=1353–1358 }}</ref> [[Single-photon source|single photon emitter characterization]],<ref>{{Cite journal|last1=Hadfield|first1=Robert H.|last2=Stevens|first2=Martin J.|last3=Gruber|first3=Steven S.|last4=Miller|first4=Aaron J.|last5=Schwall|first5=Robert E.|last6=Mirin|first6=Richard P.|last7=Nam|first7=Sae Woo|date=2005-12-26|title=Single photon source characterization with a superconducting single photon detector|url=https://www.osapublishing.org/oe/abstract.cfm?uri=oe-13-26-10846|journal=Optics Express|language=EN|volume=13|issue=26|pages=10846–10853|doi=10.1364/OPEX.13.010846|pmid=19503303|arxiv=quant-ph/0511030|bibcode=2005OExpr..1310846H|s2cid=11428224|issn=1094-4087}}</ref> [[LIDAR]],<ref>{{cite journal | doi=10.1364/OE.21.008904 | title=Kilometer-range, high resolution depth imaging via 1560 nm wavelength single-photon detection | year=2013 | last1=McCarthy | first1=Aongus | last2=Krichel | first2=Nils J. | last3=Gemmell | first3=Nathan R. | last4=Ren | first4=Ximing | last5=Tanner | first5=Michael G. | last6=Dorenbos | first6=Sander N. | last7=Zwiller | first7=Val | last8=Hadfield | first8=Robert H. | last9=Buller | first9=Gerald S. | journal=Optics Express | volume=21 | issue=7 | pages=8904–8915 | pmid=23571981 | bibcode=2013OExpr..21.8904M | doi-access=free }}</ref><ref>{{Cite journal|last1=Taylor|first1=Gregor G.|last2=Morozov|first2=Dmitry|last3=Gemmell|first3=Nathan R.|last4=Erotokritou|first4=Kleanthis|last5=Miki|first5=Shigehito|last6=Miki|first6=Shigehito|last7=Terai|first7=Hirotaka|last8=Hadfield|first8=Robert H.|date=2019-12-23|title=Photon counting LIDAR at 2.3μm wavelength with superconducting nanowires|url=https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-26-38147|journal=Optics Express|language=EN|volume=27|issue=26|pages=38147–38158|doi=10.1364/OE.27.038147|pmid=31878586|s2cid=209489291|issn=1094-4087|doi-access=free}}</ref><ref>{{Cite journal |url=https://opg.optica.org/optica/viewmedia.cfm?uri=optica-10-9-1124&html=true |access-date=2023-08-29 |journal=Optica |doi=10.1364/optica.488853 | title=Single-photon detection for long-range imaging and sensing | date=2023 | last1=Hadfield | first1=Robert H. | last2=Leach | first2=Jonathan | last3=Fleming | first3=Fiona | last4=Paul | first4=Douglas J. | last5=Tan | first5=Chee Hing | last6=Ng | first6=Jo Shien | last7=Henderson | first7=Robert K. | last8=Buller | first8=Gerald S. | volume=10 | issue=9 | page=1124 | doi-access=free | hdl=20.500.11820/4d60bb02-3c2c-4f86-a737-f985cb8613d8 | hdl-access=free }}</ref> on-chip [[quantum optics]],<ref>{{cite journal | arxiv=1408.2275 | doi=10.1021/acs.nanolett.5b01444 | title=On-Chip Generation, Routing, and Detection of Resonance Fluorescence | year=2015 | last1=Reithmaier | first1=G. | last2=Kaniber | first2=M. | last3=Flassig | first3=F. | last4=Lichtmannecker | first4=S. | last5=Müller | first5=K. | last6=Andrejew | first6=A. | last7=Vučković | first7=J. | last8=Gross | first8=R. | last9=Finley | first9=J. J. | journal=Nano Letters | volume=15 | issue=8 | pages=5208–5213 | pmid=26102603 | bibcode=2015NanoL..15.5208R | s2cid=15612865 }}</ref><ref>{{Cite journal|last1=Silverstone|first1=J. W.|last2=Bonneau|first2=D.|last3=Ohira|first3=K.|last4=Suzuki|first4=N.|last5=Yoshida|first5=H.|last6=Iizuka|first6=N.|last7=Ezaki|first7=M.|last8=Natarajan|first8=C. M.|last9=Tanner|first9=M. G.|last10=Hadfield|first10=R. H.|last11=Zwiller|first11=V.|date=February 2014|title=On-chip quantum interference between silicon photon-pair sources|url=https://www.nature.com/articles/nphoton.2013.339|journal=Nature Photonics|language=en|volume=8|issue=2|pages=104–108|doi=10.1038/nphoton.2013.339|arxiv=1304.1490|bibcode=2014NaPho...8..104S|s2cid=21739609|issn=1749-4893}}</ref> optical [[neuromorphic computing]],<ref>{{Cite journal|last1=Shainline|first1=Jeffrey M.|last2=Buckley|first2=Sonia M.|last3=McCaughan|first3=Adam N.|last4=Chiles|first4=Jeffrey T.|last5=Jafari Salim|first5=Amir|last6=Castellanos-Beltran|first6=Manuel|last7=Donnelly|first7=Christine A.|last8=Schneider|first8=Michael L.|last9=Mirin|first9=Richard P.|last10=Nam|first10=Sae Woo|date=2019-07-25|title=Superconducting optoelectronic loop neurons|journal=Journal of Applied Physics|volume=126|issue=4|pages=044902|doi=10.1063/1.5096403|bibcode=2019JAP...126d4902S|issn=0021-8979|doi-access=free}}</ref><ref>{{Cite journal |last1=Casaburi |first1=Alessandro |last2=Hadfield |first2=Robert H. |date=October 2022 |title=Superconducting circuits that mimic the brain |url=https://www.nature.com/articles/s41928-022-00855-2 |journal=Nature Electronics |language=en |volume=5 |issue=10 |pages=627–628 |doi=10.1038/s41928-022-00855-2 |s2cid=253002403 |issn=2520-1131}}</ref> [[Fiber-optic sensor|fibre optic temperature sensing]],<ref>{{Cite journal |last1=Tanner |first1=Michael G. |last2=Dyer |first2=Shellee D. |last3=Baek |first3=Burm |last4=Hadfield |first4=Robert H. |last5=Woo Nam |first5=Sae |date=2011-11-14 |title=High-resolution single-mode fiber-optic distributed Raman sensor for absolute temperature measurement using superconducting nanowire single-photon detectors |journal=Applied Physics Letters |language=en |volume=99 |issue=20 |page=201110 |doi=10.1063/1.3656702 |issn=0003-6951|bibcode=2011ApPhL..99t1110T }}</ref> [[Optical time-domain reflectometer|optical time domain reflectometry]],<ref>{{Cite web|date=2020-10-28|title=News {{!}} Successful rocket test with ID Quantique photon counting OTDR|url=https://www.idquantique.com/successful-final-test-firing-of-the-p120c-solid-rocket-motor-ariane-6-in-kourou/|access-date=2021-05-16|website=ID Quantique|language=en-GB}}</ref> readout for [[Trapped ion quantum computer|ion trap]] qubits,<ref>{{Cite journal|last1=Todaro|first1=S. L.|last2=Verma|first2=V. B.|last3=McCormick|first3=K. C.|last4=Allcock|first4=D. T. C.|last5=Mirin|first5=R. P.|last6=Wineland|first6=D. J.|last7=Nam|first7=S. W.|last8=Wilson|first8=A. C.|last9=Leibfried|first9=D.|last10=Slichter|first10=D. H.|date=2021-01-06|title=State Readout of a Trapped Ion Qubit Using a Trap-Integrated Superconducting Photon Detector|url=https://link.aps.org/doi/10.1103/PhysRevLett.126.010501|journal=Physical Review Letters|volume=126|issue=1|pages=010501|doi=10.1103/PhysRevLett.126.010501|pmid=33480763|arxiv=2008.00065|bibcode=2021PhRvL.126a0501T|s2cid=220936640}}</ref> quantum plasmonics,<ref>{{cite journal | doi=10.1021/nl903761t | title=On-Chip Single Plasmon Detection | year=2010 | last1=Heeres | first1=Reinier W. | last2=Dorenbos | first2=Sander N. | last3=Koene | first3=Benny | last4=Solomon | first4=Glenn S. | last5=Kouwenhoven | first5=Leo P. | last6=Zwiller | first6=Valery | journal=Nano Letters | volume=10 | issue=2 | pages=661–664 | pmid=20041700 | arxiv=1001.2723 | bibcode=2010NanoL..10..661H | s2cid=20962227 }}</ref><ref>{{cite journal | doi=10.1038/nnano.2013.150 | title=Quantum interference in plasmonic circuits | year=2013 | last1=Heeres | first1=Reinier W. | last2=Kouwenhoven | first2=Leo P. | last3=Zwiller | first3=Valery | journal=Nature Nanotechnology | volume=8 | issue=10 | pages=719–722 | pmid=23934097 | arxiv=1309.6942 | bibcode=2013NatNa...8..719H | s2cid=18196878 }}</ref> single electron detection,<ref>{{cite journal | doi=10.1063/1.3506692 | title=A high efficiency superconducting nanowire single electron detector | year=2010 | last1=Rosticher | first1=M. | last2=Ladan | first2=F. R. | last3=Maneval | first3=J. P. | last4=Dorenbos | first4=S. N. | last5=Zijlstra | first5=T. | last6=Klapwijk | first6=T. M. | last7=Zwiller | first7=V. | last8=Lupaşcu | first8=A. | last9=Nogues | first9=G. | journal=Applied Physics Letters | volume=97 | issue=18 | page=183106 | bibcode=2010ApPhL..97r3106R | s2cid=123559525 | url=https://hal.archives-ouvertes.fr/hal-00533120/file/1.3506692.pdf }}</ref> single α and β particle detection,<ref>{{cite journal | doi=10.1063/1.4740074 | title=Efficient single particle detection with a superconducting nanowire | year=2012 | last1=Azzouz | first1=Hatim | last2=Dorenbos | first2=Sander N. | last3=De Vries | first3=Daniel | last4=Ureña | first4=Esteban Bermúdez | last5=Zwiller | first5=Valery | journal=AIP Advances | volume=2 | issue=3 | page=032124 | bibcode=2012AIPA....2c2124A | doi-access=free }}</ref> [[singlet oxygen]] luminescence detection,<ref>{{cite journal | doi=10.1364/OE.21.005005 | title=Singlet oxygen luminescence detection with a fiber-coupled superconducting nanowire single-photon detector | year=2013 | last1=Gemmell | first1=Nathan R. | last2=McCarthy | first2=Aongus | last3=Liu | first3=Baochang | last4=Tanner | first4=Michael G. | last5=Dorenbos | first5=Sander D. | last6=Zwiller | first6=Valery | last7=Patterson | first7=Michael S. | last8=Buller | first8=Gerald S. | last9=Wilson | first9=Brian C. | last10=Hadfield | first10=Robert H. | journal=Optics Express | volume=21 | issue=4 | pages=5005–5013 | pmid=23482033 | arxiv=1302.6371 | bibcode=2013OExpr..21.5005G | s2cid=33116480 }}</ref> [[Deep Space Optical Communications|deep space optical communication]],<ref>{{cite book | doi=10.1117/12.543010 | chapter=Overview of high-rate deep-space laser communications options | title=Free-Space Laser Communication Technologies XVI | year=2004 | editor-last1=Mecherle | editor-first1=G. S | last1=Boroson | first1=Don M. | last2=Bondurant | first2=Roy S. | last3=Scozzafava | first3=Joseph J. | volume=5338 | page=37 | s2cid=122154440 | editor-first2=Cynthia Y | editor-first3=John S | editor-last2=Young |editor2-link=Cynthia Y. Young| editor-last3=Stryjewski }}</ref><ref>{{Cite journal|last=Deutsch|first=Leslie J.|date=September 2020|title=Towards deep space optical communications|url=https://www.nature.com/articles/s41550-020-1193-1|journal=Nature Astronomy|language=en|volume=4|issue=9|pages=907|doi=10.1038/s41550-020-1193-1|bibcode=2020NatAs...4..907D|s2cid=225206152|issn=2397-3366}}</ref> [[dark matter]] searches<ref>{{Cite journal|last1=Hochberg|first1=Yonit|last2=Charaev|first2=Ilya|last3=Nam|first3=Sae-Woo|last4=Verma|first4=Varun|last5=Colangelo|first5=Marco|last6=Berggren|first6=Karl K.|date=2019-10-10|title=Detecting Sub-GeV Dark Matter with Superconducting Nanowires|url=https://link.aps.org/doi/10.1103/PhysRevLett.123.151802|journal=Physical Review Letters|volume=123|issue=15|pages=151802|doi=10.1103/PhysRevLett.123.151802|pmid=31702301|arxiv=1903.05101|bibcode=2019PhRvL.123o1802H|s2cid=84840364}}</ref> and [[exoplanet]] detection.<ref>{{Cite journal|last1=Wollman|first1=Emma E.|last2=Verma|first2=Varun B.|last3=Walter|first3=Alexander B.|last4=Chiles|first4=Jeff|last5=Korzh|first5=Boris|last6=Allmaras|first6=Jason P.|last7=Zhai|first7=Yao|last8=Lita|first8=Adriana E.|last9=McCaughan|first9=Adam N.|last10=Schmidt|first10=Ekkehart|last11=Frasca|first11=Simone|date=January 2021|title=Recent advances in superconducting nanowire single-photon detector technology for exoplanet transit spectroscopy in the mid-infrared|journal=Journal of Astronomical Telescopes, Instruments, and Systems|volume=7|issue=1|pages=011004|doi=10.1117/1.JATIS.7.1.011004|bibcode=2021JATIS...7a1004W|s2cid=232484010|issn=2329-4124|doi-access=free}}</ref>  A number of companies worldwide are successfully commercializing complete single-photon detection systems based on superconducting nanowires, including [https://singlequantum.com/ Single Quantum], [http://photonspot.com/ Photon Spot], [https://www.scontel.ru/ Scontel], [https://www.quantumopus.com/web/ Quantum Opus], [[ID Quantique]], [https://www.cnphotec.com PhoTec] and [http://www.pixelphotonics.com/ Pixel Photonics].  Wider adoption of SNSPD technology is closely linked to advances in [[cryocooler]]s for 4 K and below, and SNSPDs have recently been demonstrated in miniaturized systems.<ref>{{Cite journal|last=Gemmell|first=N. R.|date=September 2017|title=A miniaturized 4 K platform for superconducting infrared photon counting detectors |journal=Superconductor Science and Technology |volume=30 |issue=11|page=11LT01 |doi=10.1088/1361-6668/aa8ac7 |bibcode=2017SuScT..30kLT01G|doi-access=free}}</ref><ref>{{Cite journal |last1=Cooper |first1=Bernard E |last2=Hadfield |first2=Robert H |date=2022-06-28 |title=Viewpoint: Compact cryogenics for superconducting photon detectors |journal=Superconductor Science and Technology |language=en |volume=35 |issue=8 |pages=080501 |doi=10.1088/1361-6668/ac76e9 |bibcode=2022SuScT..35h0501C |s2cid=249534834 |issn=0953-2048|doi-access=free }}</ref>

==References==
{{Reflist|30em}}

<!--- Categories --->
[[Category:Particle detectors]]
[[Category:Photodetectors]]
[[Category:Radiometry]]
[[Category:Sensors]]
[[Category:Superconducting detectors]]
[[Category:Quantum optics]]
[[Category:Superconductivity]]
[[Category:Optoelectronics]]
[[Category:Photonics]]
[[Category:Optical metrology]]
[[Category:Engineering]]
[[Category:Single-photon detectors]]