Superconducting nanowire single-photon detection system and demonstration in quantum key distribution

Abstract

We developed a superconducting nanowire single-photon detection (SNSPD) system based on Gifford-McMahon cryocooler for quantum communication applications. Environmental factors which may influence the system performance are intensively studied. Those factors include temperature fluctuations, the ambient magnetic field and the background radiation. By optimizing the bias circuit, the stability of SNSPD system to electrical noise and disturbance was effectively enhanced, thus making it more suitable for field application. A 4-channel SNSPD system with quantum efficiency higher than 4% at the dark count rate of 10 Hz for =1550 nm is integrated and applied into a quantum key distribution (QKD) experiment. QKD was successfully carried out over 100 km optical fiber with the final secure key rate of 1.6 kbps and the quantum bit error rate of less than 2%. Quantum communication is a new-generation technology based on the theory of quantum mechanics, which may provide absolute security for future communication [1]. It is a hot topic in science and technology of quantum control and now in its critical stage from the theoretical research to practical applications. Quantum key distribution (QKD) is the kernel of the quantum communication. The implementation of QKD relies on several technologies, including single-photon source, encrypting/decrypting, key storage/transmission and singlephoton detection. QKD in fiber over 100 km had been reported [2]. However, further improvement is limited by the available single-photon detection technique. Traditional semiconducting single-photon detectors (SPD) (such as APD: avalanche photodiode, PMT: photomultiplier tube) cannot fulfill the requirement of long haul quantum communication due to the high dark count rate (R DC ).Superconducting nanowire single-photon detector/detection (SNSPD) is a novel single-photon detection technology, which uses a nanowire folded into a meander structure fabricated on superconducting ultrathin films. When a photon hits the nanowire, it may produce a transient voltage pulse, which forms the basis of the detection mechanism of SNSPD. This concept was first proposed by Kadin et al. in 1996 [3] and demonstrated by Gol'tsman et al. in 2001 using SNSPD made of an ultra-thin NbN film [4]. SNSPD

Statistical analysis of the temporal single-photon response of superconducting nanowire single photon detection

“…The superconducting nanowire single-photon detector (SNSPD) is a promising technology for near-infrared single photon detection, owing to its high system detection efficiency (DE), low dark count rate (DCR), low timing jitter, and high counting rate. [1][2][3][4][5] Many SNSPD-based applications have been demonstrated, such as quantum key distribution (QKD), [6][7][8][9] deep space laser communications, [10] and time-of-fight laser ranging and imaging. [11] Counting rate is an important parameter of SNSPDs for many of the applications mentioned above.…”