Stable, high-performance operation of a fiber-coupled superconducting nanowire avalanche photon detector

Miki, Shigehito; Yabuno, Masahiro; Yamashita, Taro; Terai, Hirotaka

doi:10.1364/oe.25.006796

Cited by 76 publications

(46 citation statements)

References 29 publications

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“…We developed SNSPDs with two-parallel-nanowire serial-connected configuration [25], which cover an active area of 16 µm in diameter. The SNSPD's recovery time is mainly limited by its kinetic inductance [26].…”

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confidence: 99%

Experimental Twin-Field Quantum Key Distribution through Sending or Not Sending

et al. 2019

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Channel loss seems to be the most severe limitation on the practical application of long distance quantum key distribution. The idea of twin-field quantum key distribution can improve the key rate from the linear scale of channel loss in the traditional decoy-state method to the square root scale of the channel transmittance. However, the technical demanding is rather tough because it requests single photon level interference of two remote independent lasers. Here, we adopt the technology developed in the frequency and time transfer to lock two independent lasers' wavelengths and utilize additional phase reference light to estimate and compensate the fiber fluctuation. Further with a single photon detector with high detection rate, we demonstrate twin field quantum key distribution through the sending-or-not-sending protocol with realistic phase drift over 300 km optical fiber spools. We calculate the secure key rates with finite size effect. The secure key rate at 300 km (1.96 × 10 −6 ) is higher than that of the repeaterless secret key capacity (8.64 × 10 −7 ).Introduction.-Although quantum key distribution (QKD) can in principle offer secure private communication [1][2][3][4][5][6][7], there are still some technical limitations on practical long distance quantum communication. Perhaps the most severe of these is channel loss, given that quantum signals cannot be amplified. Much efforts have been made towards QKD over longer-distance. Theoretically, the decoy-state method [8][9][10] can improve the key rate of coherent-state based QKD from scaling quadratically to linearly with the channel transmittance, as what behaves of a perfect single-photon source. This method can defeat the photon-number-splitting attack to the imperfect source and the coherent state is used as if only the single-photon pulses were used for key distillation, and hence it can reach a key rate in the linear scale of channel loss, as the perfect single-photon source does. Remarkable theoretical progress was made toward achieving practical, secure QKD over longer distance with the proposal of twin-field QKD [11], which improves the key rate scaling to follow the square root of the channel transmittance. It shows that, the coherent-state source can actually be an advantage over the single-photon source because the post-selection of phase coherence of the twin fields from Alice and Bob can potentially lead to secure QKD with the encoding state of single-photon and vacuum, and their linear super-positions.This method has the potential to achieve a key rate that scales with the square root of channel transmittance, and can by far break the known distance limit of existing protocols in practical QKD [12][13][14][15][16][17][18][19][20]. The theoretical secure key rate can be even higher than the repeaterless secret key capacities, known as the Takeoka-Guha-Wilde (TGW) bound [19] and the Pirandola-Laurenza-Ottaviani-Bianchi (PLOB) bound [20]. However, considerable work still remains to make this a reality.First, there is the theoretical challenge ...

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confidence: 99%

Experimental Twin-Field Quantum Key Distribution through Sending or Not Sending

et al. 2019

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“…The telecom photon from the QFC passes through a polarization analyzer followed by an etalon with a bandwidth of 690 MHz and a pair of fiber Bragg gratings with a total bandwidth of ~0.9 GHz. Finally, the telecom photon is detected by a superconducting single photon detector (SSPD) denoted by D ast with a quantum efficiency of ~60% 49 .…”

Section: Resultsmentioning

confidence: 99%

Polarization insensitive frequency conversion for an atom-photon entanglement distribution via a telecom network

Ikuta¹,

Kobayashi²,

Kawakami³

et al. 2018

Nat Commun

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Long-lifetime quantum storages accessible to the telecom photonic infrastructure are essential to long-distance quantum communication. Atomic quantum storages have achieved subsecond storage time corresponding to 1000 km transmission time for a telecom photon through a quantum repeater algorithm. However, the telecom photon cannot be directly interfaced to typical atomic storages. Solid-state quantum frequency conversions fill this wavelength gap. Here we report on the experimental demonstration of a polarization-insensitive solid-state quantum frequency conversion to a telecom photon from a short-wavelength photon entangled with an atomic ensemble. Atom–photon entanglement has been generated with a Rb atomic ensemble and the photon has been translated to telecom range while retaining the entanglement by our nonlinear-crystal-based frequency converter in a Sagnac interferometer.

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“…In particular, a manuscript reported by Zhang et al [11] shows an important result of achievement of~90% SDE at a wavelength of 1550 nm by applying sophisticated technologies. Although the results showed a narrower saturated region in the bias-current dependencies than that of WSi-SNSPD operating at 120 mK, wider saturated bias-current dependency has been demonstrated in NbTiN-SNSPD by applying the avalanche switching architecture [16]. It should be noted that MoSi-SNSPD has also demonstrated a high SDE of~80%, and therefore, can also serve as a prospective candidate [13].…”

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confidence: 81%

Quest towards ultimate performance in superconducting nanowire single photon detectors

Miki

2017

Sci. China Phys. Mech. Astron.

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Citation:S. Miki, Quest towards ultimate performance in superconducting nanowire single photon detectors, Sci. China-Phys. Mech. Astron. 61, 020331 (2018), https://doi.org/10.1007/s11433-017- In 2007, superconducting nanowire single photon detectors (SSPD or SNSPD) [1] made an outstanding impact in the field of quantum information technology by demonstrating quantum key distribution (QKD) over a 200-km optical fiber with a 42-dB optical loss using a practical SNSPD system [2]. This successful demonstration was realized thanks to its extremely low dark count rate (DCR) of a few Hz and short timing jitter of 60 ps, while the system detection efficiency (SDE) showed a poor value of 0.7% at a wavelength of 1550 nm. Afterwards, significant efforts have been devoted to the improvement of SDE in practical systems, and remarkable advancements have been continually achieved in the past decade. The SDE of SNSPD is primarily determined by the product of three factors: optical coupling efficiency (η oc ), absorption efficiency (η abs ), and intrinsic detection efficiency (η int ). Therefore, the advancements to increase each factor cumulatively resulted in the improvement of SDE.In the initial stage of the SNSPD research, the nanowire device consists only of an NbN superconducting nanowire on the substrate. In this case, the nanowire cannot absorb the incident photons efficiently, because the thickness of the superconducting nanowire is only few nanometers. To achieve high η abs , Rosfjord et al. [3] demonstrated an integrated λ/4 optical-cavity structure on the superconducting nanowire, and this approach could be successfully adapted in practically available devices with relatively large sensitive area [4,5]. The optical cavity design has evolved through various ap-*Corresponding author (email: s-miki@nict.go.jp) proaches aimed at obtaining higher η abs : double-side cavity for back side illumination [6,7], optimized optical cavity for front side illumination [8], and cavity with distribution Bragg reflector (DBR) [9][10][11]. It is to be noted that such interesting approaches also made additional attempts to obtain the flexible wavelength spectrum by employing nonperiodic DBR [12], and to reduce the polarization sensitivity by optimizing the optical cavity design [13].Considerable attention has also been focused on obtaining an η int that is as high as possible. Among various approaches aimed at increasing η int , exploration of the optimal superconducting material is one of the most interesting topic. SNSPD with various superconducting materials have demonstrated excellent SDEs exceeding 80% at a wavelength of 1550 nm. For example, SNSPD with amorphous WSi nanowire showed the highest SDE of 93% thus far, with widely saturated bias current dependencies at an operation temperature of 120 mK [8]. However, an operation temperature of 120 mK is not favorable from a practical point of view, because a relatively large and complicated cryocooler system such as an adiabatic demagnetization (ADR) cryocooler or a 3 He cryocooler...

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Stable, high-performance operation of a fiber-coupled superconducting nanowire avalanche photon detector

Cited by 76 publications

References 29 publications

Experimental Twin-Field Quantum Key Distribution through Sending or Not Sending

Experimental Twin-Field Quantum Key Distribution through Sending or Not Sending

Polarization insensitive frequency conversion for an atom-photon entanglement distribution via a telecom network

Quest towards ultimate performance in superconducting nanowire single photon detectors

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