Shortly after their inception,superconducting nanowire single-photon detectors(SNSPDs)became the leading quantum light detection technology.With the capability of detecting single-photons with near-unity efficiency,high time resolution,low dark count rate,and fast recovery time,SNSPDs outperform conventional single-pho-ton detection techniques.However,detecting lower energy single photons(＜0.8 eV)with high efficiency and low timing jitter has remained a challenge.To achieve unity internal efficiency at mid-infrared wavelengths,previous works used amorphous superconducting materials with low energy gaps at the expense of reduced time resolution(close to a nanosecond),and by operating them in complex milliKelvin(mK)dilution refrigerators.In this work,we provide an alternative approach with SNSPDs fabricated from 5 to 9.5 nm thick NbTiN superconducting films and devices operated in conventional Gifford-McMahon cryocoolers.By optimizing the superconducting film deposition process,film thickness,and nanowire design,our fiber-coupled devices achieved＞70％system de-tection efficiency(SDE)at 2 μm and sub-15 ps timing jitter.Furthermore,detectors from the same batch dem-onstrated unity internal detection efficiency at 3 μm and 80％internal efficiency at 4 μm,paving the road for an efficient mid-infrared single-photon detection technology with unparalleled time resolution and without mK cooling requirements.We also systematically studied the dark count rates(DCRs)of our detectors coupled to different types of mid-infrared optical fibers and blackbody radiation filters.This offers insight into the trade-off between bandwidth and DCRs for mid-infrared SNSPDs.To conclude,this paper significantly extends the working wavelength range for SNSPDs made from polycrystalline NbTiN to 1.5-4 μm,and we expect quantum optics experiments and applications in the mid-infrared range to benefit from this far-reaching technology.

JIN CHANG;JOHANNES W.N.LOS;RONAN GOURGUES;STEPHAN STEINHAUER;S.N.DORENBOS;SILVANIA F.PEREIRA;H.PAUL URBACH;VAL ZWILLER;IMAN ESMAEIL ZADEH

Optics Research Group,ImPhys Department,Faculty of Applied Sciences,Delft University of Technology,Delft 2628 CJ,The Netherlands;Single Quantum B.V,Delft 2628 CJ,The Netherlands;KTH Royal Institute of Technology,Department of Applied Physics,Albanova University Centre,106 91 Stockholm,Sweden

光子学研究（英文）

[1]JIN CHANG;JOHANNES W.N.LOS;RONAN GOURGUES;STEPHAN STEINHAUER;S.N.DORENBOS;SILVANIA F.PEREIRA;H.PAUL URBACH;VAL ZWILLER;IMAN ESMAEIL ZADEH-.Efficient mid-infrared single-photon detection using superconducting NbTiN nanowires with high time resolution in a Gifford-McMahon cryocooler)[J].光子学研究（英文）,2022(04):1063-1070

NbTiN,Gifford,McMahon,cryocooler,SNSPDs,milliKelvin,cryocoolers,DCRs

Efficient,mid,infrared,single,detection,using,superconducting,nanowires,high,resolution,Shortly,after,their,inception,detectors,became,leading,quantum,light,technology,With,capability,detecting,photons,near,unity,efficiency,dark,count,fast,recovery,outperform,conventional,techniques,However,lower,energy,eV,timing,jitter,has,remained,challenge,To,internal,wavelengths,previous,works,used,amorphous,materials,gaps,expense,reduced,close,nanosecond,by,operating,them,complex,mK,dilution,refrigerators,In,this,provide,alternative,approach,fabricated,from,films,devices,operated,By,optimizing,deposition,process,thickness,design,our,coupled,achieved,SDE,sub,Furthermore,same,batch,dem,onstrated,paving,road,efficient,unparalleled,without,cooling,requirements,We,also,systematically,studied,rates,different,types,optical,fibers,blackbody,radiation,filters,This,offers,insight,into,trade,between,bandwidth,conclude,paper,significantly,extends,working,range,made,polycrystalline,expect,optics,experiments,applications,benefit,far,reaching

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