Titanium Superconducting Photon-Number-Resolving Detector

Fukuda, Daiji; Fujii, Go; Nozaki, Takayuki; Amemiya, K.; Yoshizawa, Akio; Tsuchida, Hidemi; Fujino, H.; Ishii, Hiroyuki; Itatani, Taro; Inoue, Shuichiro; Zama, Tatsuya

doi:10.1109/tasc.2010.2089953

Cited by 26 publications

(18 citation statements)

References 20 publications

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“…We have considered an additional analysis to estimate the detection efficiency [10] of a 20 µm × 20 µm device (Fig. 5).…”

Section: Tes Properties and Resultsmentioning

confidence: 99%

“…Thanks to a calibrated measurement of the source, we know the number of emitted photons per pulse μ e = 31. Considering a response distribution of an ideal detector and the photon number statistic of the used incident light source, the photon distribution is [10] P n (η) = (ημ e ) n n! e −ημ e (1) where n is the number of photon state and η is the overall detection efficiency of the device.…”

Section: Tes Properties and Resultsmentioning

confidence: 99%

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Ti/Au TES to Discriminate Single Photons

2012

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“…We have considered an additional analysis to estimate the detection efficiency [10] of a 20 µm × 20 µm device (Fig. 5).…”

Section: Tes Properties and Resultsmentioning

confidence: 99%

Section: Tes Properties and Resultsmentioning

confidence: 99%

Ti/Au TES to Discriminate Single Photons

2012

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“…16,17 Figure 2 shows wavelength dependence of dcr black (λ,T) at various temperatures, calculated using eq.…”

Section: Superconducting Single-photon Detectors (Sspds Ormentioning

confidence: 99%

Superconducting Nanowire Single-Photon Detector with Ultralow Dark Count Rate Using Cold Optical Filters

Shibata

Shimizu

Takesue

et al. 2013

Appl. Phys. Express

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We report the fabrication of a superconducting nanowire single-photon detector (SSPD or SNSPD) with an ultralow dark count rate. By introducing optical band-pass filters at the input of the SSPD and cooling the filters at 3 K, the dark count rate is reduced to less than 1/100 at low bias. An SSPD with 0.1 cps dark count rate and 5.6% system detection efficiency at 1550 nm wavelength is obtained. We show that a quantum key distribution (QKD) over 300 km of fiber is possible based on a numerical calculation assuming a differential phase shift QKD protocol implemented with our SSPDs.Superconducting single-photon detectors (SSPDs or SNSPDs) based on ultrathin superconducting nanowires are now widely used as high-performance single-photon detectors in many fields such as quantum information and quantum optics. 1-3 SSPDs offer a wide detection wavelength range from ultraviolet to infrared, a high detection efficiency (η) of more than 10%, a low dark count rate (DCR) of 10 to 1000 cps, and a small timing jitter (Δt) of less than 100 ps. There have been many efforts to further improve their performance. In particular, many studies have been attempted to increase system η, and recently, a very high system η of 93% has been reported using amorphous WSi. [4][5][6] Besides η, the DCR is also an important factor determining the performance of single-photon detectors. The figure of merit of a single-photon detector is usually represented as η/(DCRΔt). 7,8 In the figure of merit, decreasing DCR has the same weight as that of increasing η.The importance of low DCR is also evident in long-distance quantum key distribution (QKD) experiments. 9 In QKD, the quantum bit error rate (QBER) increases as the length of the fiber increases. A secure key cannot be obtained from the sifted key when QBER exceeds a certain level, which limits the QKD distance.Since the QBER is usually governed by the DCR of the detector, a single-photon detector with low DCR is essential for long-distance QKD. Actually, to achieve the QKD distance of 260 km, the longest reported so far, SSPDs were operated in a very low-bias region to strongly reduce DCR (DCR = 1 cps, η = 3%). 10 To further increase the distance of QKD, an SSPD with lower DCR is necessary.In this letter, we describe the fabrication of an SSPD with a dark count rate below 1 cps.The fabrication process of the device is as follows. 11,12 NbN thin films of 3.5 nm thickness were synthesized at 350°C on a MgO (100) substrate by reactive DC magnetron sputtering. The meander pattern of NbN was fabricated by the standard e-beam process using a negative resist and C 2 F 5 dry etching. The size of the meander is 10 × 10 μm2 with a line and space width of 80 nm. Then, the cavity structure was formed on the meander using the standard photolithography process to enhance the detection efficiency. The cavity was

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“…In some cases, a trade-off can be made between η threshold -and hence detection efficiency-and this background count rate [32,14]. For example, if electrical pulses resulting from dark counts (or background counts arising from detected background blackbody radiation) have a comparable but somewhat smaller amplitude than signal pulses, then a threshold in the external electronics may be adjusted to reduce the background count rate.…”

Section: Detection Efficiencymentioning

confidence: 99%

Photon Statistics, Measurements, and Measurements Tools

Stevens

2013

Experimental Methods in the Physical Sciences

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Titanium Superconducting Photon-Number-Resolving Detector

Cited by 26 publications

References 20 publications

Ti/Au TES to Discriminate Single Photons

Ti/Au TES to Discriminate Single Photons

Superconducting Nanowire Single-Photon Detector with Ultralow Dark Count Rate Using Cold Optical Filters

Photon Statistics, Measurements, and Measurements Tools

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