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A Low-Power, Inductorless Wideband Cryogenic Amplifier For Supercondcting Nanowire Single Photon Detector
摘要： This paper presents a low-power, inductorless wideband cryogenic amplifier for superconducting nanowire single photon detector (SNSPD). To achieve wide bandwidth, low power consumption and small chip area, a modified Cherry-Hooper amplifier topology is used. With good input and output match, at 4.2 K temperature the measurement results show that the amplifier achieves 23-dB gain with a flat gain response, a 3-dB bandwidth (BW) of over 3.4 GHz, which covers frequencies as low as 130 kHz. Fabricated in a 0.13-μm silicon germanium (SiGe) BiCMOS technology, the amplifier core occupies a silicon area of only 0.075 mm2 and consumes a power of only 4 mW.
关键词： low power,Cryogenic amplifier,wideband,Superconducting Nanowire Single Photon Detectors,SNSPD
更新于2025-09-23 15:23:52
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Minimal Timing Jitter in Superconducting Nanowire Single-Photon Petectors
摘要： Using a two-temperature model coupled with the modified time-dependent Ginzburg-Landau equation, we calculate the delay time τd in the appearance of a growing normal domain in the current-biased superconducting strip after absorption of the single photon. We demonstrate that τd depends on the place in the strip where the photon is absorbed and monotonically decreases with an increasing current. We argue that the variation of τd (timing jitter), connected either with position-dependent response or Fano fluctuations, could be as small as the lowest relaxation time of the superconducting order parameter, approximately ?/kBTc (Tc is the critical temperature of the superconductor), when the current approaches the depairing current.
关键词： position-dependent response,timing jitter,superconducting nanowire single-photon detectors,delay time,Fano fluctuations
更新于2025-09-23 15:23:52
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Superior properties in room-temperature colloidal-dot quantum emitters revealed by ultralow-dark-count detections of temporally-purified single photons
摘要： The realization of high-quality quantum emitters that can operate at room temperature is important for accelerating the application of quantum technologies, such as quantum communication, quantum information processing, and quantum metrology. In this work, we study the photon-antibunching properties on room-temperature emission from individual colloidal quantum dots (CQDs) using superconducting-nanowire single-photon detectors and temporal filtering of the photoluminescence decay curve. We find that high single-photon purities and high photon-generation rates can be simultaneously achieved by removing the signals originating from the sequential two-photon emission of biexcitons created by multiple excitation pulses. We successfully demonstrate that the ultrahigh performance of the room-temperature single-photon sources showing g(2)(0) ? 10?2 can be confirmed by the ultralow-dark-count detection of the temporally purified single photons. These findings provide strong evidence for the attractiveness of CQDs as candidates for high-quality room-temperature quantum light sources.
关键词： single-photon sources,room-temperature,superconducting-nanowire single-photon detectors,quantum emitters,colloidal quantum dots,temporal filtering
更新于2025-09-11 14:15:04
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Suppressing Dark Counts of Multimode-Fiber-Coupled Superconducting Nanowire Single-Photon Detector
摘要： Large active-area superconducting nanowire single-photon detectors (SNSPDs) coupled with multimode fibers (MMFs) can provide high light-gathering capacity, which is essential for free-space detection applications in photon-starved regimes. However, MMF-coupled SNSPDs often suffer from large system dark count rates (DCRsys) over kHz due to blackbody radiation of the MMF at room temperature. Such large DCRsys would significantly degrade signal-to-noise ratio (SNR) of the receiving system. This paper reports an MMF-coupled large-active-area SNSPD system with low DCRsys by using a homemade cryogenic MMF filter bench. The filter bench, which consists of lenses and optical filters, can provide a high transmittance of about 80% at the central wavelength of the passband (1550 ± 12.5 nm) and a wide blocking range from 500 nm to over 6000 nm at 40 K. With using the filter bench, the DCRsys of an MMF-coupled 9-pixel SNSPD array with an active area of 50 μm in diameter is greatly suppressed by 23 dB with 1 dB loss of system detection efficiency (SDE). The detector demonstrates an SDE of 51% at a DCRsys of 100 Hz for 1550 nm photons. Thus, SNR of the detector is enhanced by about 160 times and the noise equivalent power is improved to 3×10?19 W/Hz1/2.
关键词： cryogenic MMF filter bench,multimode fibers (MMFs),Superconducting nanowire single-photon detectors (SNSPDs),dark count rates (DCRsys),signal-to-noise ratio (SNR)
更新于2025-09-11 14:15:04