We use a superconducting single-photon detector with less than 40Hz dark count rate to measure spontaneous emission lifetimes of quantum wells emitting light at wavelengths of 935 and 1245nm. The timing jitter of the measurement system—which includes the detector and all other electronic and optical components—is 68±3ps. We demonstrate how the infrared sensitivity and Gaussian temporal response function of this superconducting detector present clear advantages over conventional detector technologies.
We use a superconducting single-photon detector with less than 40Hz dark count rate to measure spontaneous emission lifetimes of quantum wells emitting light at wavelengths of 935 and 1245nm. The timing jitter of the measurement system—which includes the detector and all other electronic and optical components—is 68±3ps. We demonstrate how the infrared sensitivity and Gaussian temporal response function of this superconducting detector present clear advantages over conventional detector technologies.
We report use of a niobium nitride superconducting single-photon detector in a time-correlated single-photon counting experiment. The detector has a timing jitter of 68 ± 3 ps full width at half maximum with a Gaussian temporal profile. The detector's dark count rate and detection efficiency can be tuned by adjusting the bias current applied to the device. Typical values include a detection efficiency of ~1-2% and a dark count rate below 100 Hz. We use this detector to measure time-resolved photoluminescence at wavelengths up to 1650 nm, well beyond the range of conventional silicon detectors. We also use this superconducting detector to measure the emission of a quantum dot single-photon source.
We report the observation of photon antibunching from a single, self-assembled InGaAs quantum dot (QD) at temperatures up to 135 K. The second-order intensity correlation,g(2)(0), is less than 0.260$\pm0.024fortemperaturesupto100K.At120K,g^{(2)}(0)increasestoabout0.471,whichisslightlylessthanthesecond−orderintensitycorrelationexpectedfromtwoindependentsingleemitters.Inaddition,wecharacterizetheperformanceofasuperconductingsinglephotondetector(SSPD)basedonananopatternedniobiumnitridewirethatexhibits68\pm3−pstimingjitterandlessthan100−Hzdarkcountratewithadetectionefficiency(DE)ofupto2\mumandtheGaussiantemporalresponseofthissuperconductingdetectorpresentclearadvantagesovertheconventionaldetectortechnologies.WealsousethisdetectortocharacterizetheemissionfromasingleInGaAsQDembeddedinamicropillarcavity,measuringaspontaneousemissionlifetimeof370psandag^{(2)}(0)of0.24\pm$0.03.
Superconducting single photon detectors (SSPD) based on nanopatterned niobium nitride wires offer single photon counting at fast rates, low jitter, and low dark counts, from visible wavelengths well into the infrared. We demonstrate the first use of an SSPD, packaged in a commercial cryocooler, for single photon source characterization. The source is an optically pumped, microcavity-coupled InGaAs quantum dot, emitting single photons at 902 nm. The SSPD replaces the second silicon Avalanche Photodiode (APD) in a Hanbury-Brown Twiss interferometer measurement of the source second-order correlation function, g(2)( ?). The detection efficiency of the superconducting detector system is >2 % (coupling losses included). The SSPD system electronics jitter is 170 ps, versus 550 ps for the APD unit, allowing the source spontaneous emission lifetime to be measured with improved resolution.
We have developed a new class of superconducting single-photon detectors (SSPDs) for ultrafast counting of infrared (IR) photons for secure quantum communications. The devices are operated on the quantum detection mechanism, based on the photon-induced hotspot formation and subsequent appearance of a transient resistive barrier across an ultrathin and submicron-wide superconducting stripe. The detectors are fabricated from 3.5-nm-thick NbN films and they operate at 4.2 K inside a closed-cycle refrigerator or liquid helium cryostat. Various continuous and pulsed laser sources have been used in our experiments, enabling us to determine the detector experimental quantum efficiency (QE) in the photon-counting mode, response time, time jitter, and dark counts. Our 3.5-nm-thick SSPDs reached QE above 15% for visible light photons and 5% at 1.3 - 1.5 μm infrared range. The measured real-time counting rate was above 2 GHz and was limited by the read-out electronics (intrinsic response time is <30 ps). The measured jitter was <18 ps, and the dark counting rate was <0.01 per second. The measured noise equivalent power (NEP) is 2 x 10-18 W/Hz1/2 at λ = 1.3 μm. In near-infrared range, in terms of the counting rate, jitter, dark counts, and overall sensitivity, the NbN SSPDs significantly outperform their semiconductor counterparts. An ultrafast quantum cryptography communication technology based on SSPDs is proposed and discussed.
We present a new class of single-photon devices for counting of both visible and infrared photons. Our superconducting single-photon detectors (SSPDs) are characterized by the intrinsic quantum efficiency (QE) reaching up to 100%, above 10 GHz counting rate, and negligible dark counts. The detection mechanism is based on the photon-induced hotspot formation and subsequent appearance of a transient resistive barrier across an ultrathin and submicron-wide superconducting stripe. The devices are fabricated from 3.5-nm-thick NbN films and operate at 4.2 K, well below the NbN superconducting transition temperature. Various continuous and pulsed laser sources in the wavelength range from 0.4 μm up to >3 μm were implemented in our experiments, enabling us to determine the detector QE in the photon-counting mode, response time, and jitter. For our best 3.5-nm-thick, 10×10 μm2-area devices, QE was found to reach almost 100% for any wavelength shorter than about 800 nm. For longer-wavelength (infrared) radiation, QE decreased exponentially with the photon wavelength increase. Time-resolved measurements of our SSPDs showed that the system-limited detector response pulse width was below 150 ps. The system jitter was measured to be 35 ps. In terms of the counting rate, jitter, and dark counts, the NbN SSPDs significantly outperform their semiconductor counterparts. Already identifeid and implemented applications of our devices range from noninvasive testing of semiconductor VLSI circuits to free-space quantum communications and quantum cryptography.
Single photon detection technology is a frontier in the field of photon detection. As a newly developed technique, superconductor single photon detector (SSPD) has many attractive advantages such as wide response bandwidth, low noise, and fast speed. In this paper, we experimentally demonstrate a high performance SSPD with large system efficiency and low dark count rate at infrared wavelengths. The devices structure, fabrication process and system performance are presented in details. For our SSPD, we achieve a system efficiency of 60% at 1550 nm with a dark count rate of 100 cps. The time jitter and the maximum repetition rate are also measured to be 46 ps and 50 MHz respectively.