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Single-crystal diamond possesses exceptional physical and optical properties, rendering it an ideal platform for integrated quantum optics. The direct integration of broadband-sensitive and high-performance single-photon detectors on diamond holds significant implications for the realization of integrated diamond quantum optical circuits. In this study, we polished the diamond surface with RMS (root mean square) below 0.6 nm suitable for the deposition and patterning of NbN thin films through ion beam etching. Subsequently, we fabricated superconducting nanowire single-photon detectors directly on the polished diamond substrates and characterized for their electrical and optical properties. The NbN-SNSPD exhibited a high critical current density (2 MA cm−2), a saturated quantum efficiency (QE) below 2.5 K, and a maximum value of QE up to 88% at 4 K. These findings offer a promising solution for fully integrated quantum optical chips on single-crystal diamond substrates. [ABSTRACT FROM AUTHOR]

A large-area single-photon detector with a high maximum count rate (MCR) is expected by LiDAR application for a large dynamic range and high coupling efficiency. Superconducting nanowire single-photon detectors (SNSPDs) are very competitive for high quantum efficiency at near infrared wavelengths. However, it is a great challenge to balance the efficiency, area, and MCR of SNSPDs due to the long superconducting nanowire architecture. In this article, we design a large-area SNSPD with a high MCR for LiDAR applications. The SNSPD has four independent channels, and each of them is composed of four parallel nanowires. The photosensitive area has a diameter of 60 μm and can be coupled with a 200-μm multimode fiber through a lens. At the same time, we analyze the origin of the detector latching under high count rates and propose a discharge acceleration circuit to alleviate it. In the experiment, an MCR of 147 Mcps is achieved in this SNSPD. The product of area and MCR for each channel of this SNSPD is twice higher than previously reported results. We highlight that this work is of great significance for the application of SNSPD in LiDAR. [ABSTRACT FROM AUTHOR]

Although many multiplexed arrays of a superconducting nanowire single-photon detector (SNSPD) have been reported, it is still a major challenge to develop pixel-level readout arrays with high efficiency, parallel detection, and fast processing for real-time imaging. Here, we report a SNSPD array with inductor-shaping pulses for approaching the pixel-level readout. Optimized inductors are introduced to shape the output pulses of each pixel, and the response pulses of all pixels are synthesized in a series-connected structure. Then, the on/off states of all pixels can be encoded to the widths, amplitudes, and areas of the output pulses by the single-channel readout. This proposal is verified by a 4-pixel SNSPD array and a 16-pixel SNSPD array. It shows that the array not only inherits the features of the single-pixel SNSPD, such as photosensitive area, filling factor, quantum efficiency, and dark count rate, but also implements parallel operation of all pixels, which is always confused in traditional multiplexed SNSPD arrays. At the same time, the single-channel readout simplifies the system, and the serial digital signal converted from the shaped pulse enabled an easy and fast readout process, paving the way for high performance and real-time imaging. [ABSTRACT FROM AUTHOR]

This document is an erratum for an article titled "Superconducting nanowire single-photon detectors with saturated quantum efficiency at 1550 nm on single-crystal diamond substrates" published in Applied Physics Letters. The authors have identified two errors in the original article: an incorrect AFM scanning image in Figure 1 and a marked incorrect size in Figure 4(b). The corrected figures are provided in the erratum. The errors do not affect any other results, discussions, or conclusions in the original article. [Extracted from the article]

In this Letter, we report on a device with which to resolve photon numbers and positions simultaneously, using single-channel readout from superconducting nanowire single-photon detectors (SNSPDs). The nanowires in the SNSPDs are connected in series with parallel resistors for producing response pulses with different amplitudes, whose values obey a distribution of 1:2:4:,..,2n-1. In single-photon detection, a saturated counting rate is obtained at a low dark count rate (<10 cps). Furthermore, we observed 16 output modes corresponding one-to-one with 16 states (15 photon responses + 1 state without photons) in multiphoton mode. This structure not only inherits the advantages of high quantum efficiency and low dark count rate of traditional SNSPD, but also realizes the resolution of photon position and number simultaneously without complicated optical system. Thus, this proposal offers a promising platform for realizing scalable and practical quantum information chips. [ABSTRACT FROM AUTHOR]

Linear photon-number resolution is the key to quantum tomography. However, it is difficult to realize ideal linear photon-number resolution through multi-pixel technology because of the lack of detectors with both an ultrahigh quantum efficiency and infinite pixel number. In this letter, a photon-number-resolving detector approaching linear resolution is demonstrated. The detector is composed of 16 niobium nitride nanowires (4 × 4 on the chip) driven by independent readouts. The parallel readout enables all pixels to register incident photons independently and efficiently. The experimental results indicate that the amplitudes of the output pulse signals after being combined are linearly proportional to the number of detected photons, and the maximum number of resolved photons reaches 16. The mean photon-number distribution μ = 0.5, 2.2, 3.5, and 5.5 in a laser pulse approximates an ideal Poisson distribution, which indicates that this detector approaches linear resolution. Moreover, the spatial distribution of light can be illustrated by the array device, and the result is consistent with the theoretical prediction. [ABSTRACT FROM AUTHOR]