Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1002.3240 · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

2.23 GHz gating InGaAs/InP single-photon avalanche diode for quantum key distribution

Jun Zhang, Patrick Eraerds, Nino Walenta, Claudio Barreiro, Rob Thew, Hugo Zbinden

Published Apr 20, 2010• 68 citations
arXivHTMLPDF

Abstract

We implement an InGaAs/InP single-photon avalanche diode (SPAD) for single-photon detection with the fastest gating frequency reported so far, of 2.23GHz, which approaches the limit given by the bandwidth of the SPAD - 2.5 GHz. We propose a useful way to characterize the afterpulsing distribution for rapid gating that allows for easy comparison with conventional gating regimes. We compare the performance of this rapid gating scheme with free-running detector and superconducting single-photon detector (SSPD) for the coherent one-way quantum key distribution (QKD) protocol. The rapid gating system is well suited for both high-rate and long-distance QKD applications, in which Mbps key rates can be achieved for distances less than 40km with 50 ns deadtime and the maximum distance is limited to ~190km with 5 μs deadtime. These results illustrate that the afterpulsing is no longer a limiting factor for QKD.

DOI
10.1117/12.862118

Related papers

2.5 GHz Gated InGaAs/InP Single-Photon Avalanche Diode with 44 ps Time Jitter

De‐Yong He, Shuang Wang, Jia-Lin Chen +6 more

Gated single-photon avalanche diodes (SPADs) are practical solutions for quantum key distribution (QKD) applications. However, the gating frequency is limited by time jitter and afterpulse probability when SPADs operate at a frequency higher than 2 GHz. We find that filter distortion and variation of signal amplitude are the dominant mechanisms for time jitter in high-frequency scenarios, and design a specific low-pass filter (LPF) and a zero crossing discriminator to reduce the time jitter effectively. Specifically, the LPF extracts avalanche signals and forms accurate zero crossing points by its impulse response, and the zero crossing discriminator correctly discriminates avalanche signals to achieve low time jitter. When the SPAD is operated at a gating frequency of 2.5 GHz with a detection efficiency of 21%, the time jitter and afterpulse probability are 44 ps and 1.4%, respectively. Our results pave the way to practical QKD systems at higher clock rates.

Advanced Devices & Instrumentation•Jan 1, 2023•22 citations

Fully integrated InGaAs/InP single-photon detector module with gigahertz sine wave gating

Xiao-Lei Liang, Jian-Hong Liu, Quan Wang +6 more

InGaAs/InP single-photon avalanche diodes (SPADs) working in the regime of GHz clock rates are crucial components for the high-speed quantum key distribution (QKD). We have developed for the first time a compact, stable, and user-friendly tabletop InGaAs/InP single-photon detector system operating at a 1.25 GHz gate rate that fully integrates functions for controlling and optimizing SPAD performance. We characterize the key parameters of the detector system and test the long-term stability of the system for continuous operation of 75 h. The detector system can substantially enhance QKD performance and our present work paves the way for practical high-speed QKD applications.

arXiv:1208.0127•Review of Scientific Instruments•Aug 1, 2012•39 citations

Afterpulsing reduction in InGaAs/InP SPADs with a compact, high-speed quenching circuit

Fabio Signorelli, Enrico Conca, Fabio Telesca +2 more

InGaAs/InP Single-Photon Avalanche Diodes (SPADs) are widely employed in quantum optics applications, particularly in Quantum Key Distribution (QKD), due to their high sensitivity in the near-infrared range. In QKD, low noise and high timing resolution are essential to ensure secure and high-rate key exchange. One of the main limitations of InGaAs/InP SPADs is afterpulsing, which degrades the quantum bit error rate (QBER), limits the maximum count rate, and can compromise both the security and throughput of QKD systems. Reducing afterpulsing is thus crucial for enabling high-speed, reliable quantum communication. We present a newly developed gating and quenching circuit that significantly reduces afterpulsing. The circuit is located entirely outside the detector package, maintaining compatibility with any InGaAs/InP SPAD, and supports both gated and free-running operation. Unlike integrated ASIC-based solutions, which offer low parasitics but are often limited by process constraints (e.g., low maximum voltages), our approach uses high-speed discrete components, allowing high excess bias operation and design flexibility. While discrete designs are typically more prone to parasitics, our compact layout effectively mitigates these effects and preserves signal integrity. Experimental results show a strong afterpulsing reduction compared to our current commercial module. Additionally, the measured SPAD current highlights that the avalanche is completely quenched in less than a nanosecond after sensing. Eventually, the small footprint of the design paves the way for a new generation of compact, low-afterpulsing InGaAs/InP SPAD modules suitable for high-performance quantum optics applications.

Photonic Instrumentation Engineering•Mar 4, 2026•0 citations

Single-photon detectors for practical quantum cryptography

Alberto Tosi, Franco Zappa, S. Cova

The implementation and commercialization of quantum cryptography technologies have to face some challenges related to the development of single-photon detectors operating at 1550 nm. The main requirements are: i) high detection efficiency; ii) low noise; iii) high count rate; iv) low timing jitter. Different technologies are currently available for single-photon detection at 1550 nm, but semiconductor devices (like Single-Photon Avalanche Diode, SPAD) offer a photon detection efficiency that is inherently higher than any photocathode employed in vacuum tube detectors. Additionally InGaAs/InP SPADs can detect single photons at 1550 nm with low noise when moderately cooled by means of thermo-electric coolers. Consequently, InGaAs/InP SPAD can be the enabling technology of practical quantum key distribution (QKD) systems, provided that the maximum count rate is increased above 1 Mcps. The main limit is the afterpulsing effect that usually sets too long (< 10 μs) a hold-off time after each avalanche ignition. We present the developments achieved in InGaAs/InP SPAD device design, fabrication technology and front-end electronics, aimed at decreasing the afterpulsing effect, while not impairing photon detection efficiency and timing jitter. The new InGaAs/InP SPADs provide count rates higher than 1 Mcps and temporal response with 60 ps Full-Width at Half Maximum and very short (30 ps time constant) tail. The front-end electronics includes a wide-band pulse generator able to gate the SPAD up to 133 MHz repetition rate. Eventually, a fast avalanche-quenching scheme minimizes quenching time to less than 1 ns, thus effectively reducing afterpulsing by decreasing the total charge flowing through the junction.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Nov 19, 2012•14 citations

High-rate quantum key distribution over 100 km using ultra-low-noise, 2-GHz sinusoidally gated InGaAs/InP avalanche photodiodes

Naoto Namekata, Hiroki Takesue, Toshimori Honjo +2 more

We have demonstrated quantum key distribution (QKD) over 100 km using single-photon detectors based on InGaAs/InP avalanche photodiodes (APDs). We implemented the differential phase shift QKD (DPS-QKD) protocol with electrically cooled and 2-GHz sinusoidally gated APDs. The single-photon detector has a dark count probability of 2.8 × 10(-8) (55 counts per second) with a detection efficiency of 6 %, which enabled us to achieve 24 kbit/s secure key rate over 100 km of optical fiber. The DPS-QKD system offers better performances in a practical way than those achieved using superconducting single-photon detectors. Moreover, the distance that secure keys against the general individual attacks can be distributed has been extended to 160 km.

Optics Express•May 16, 2011•84 citations

SPAD electronics for high-speed quantum communications

Joshua C. Bienfang, Alessandro Restelli, Alan L. Migdall

We discuss high-speed electronics that support the use of single-photon avalanche diodes (SPADs) in gigahertz singlephoton communications systems. For InGaAs/InP SPADs, recent work has demonstrated reduced afterpulsing and count rates approaching 500 MHz can be achieved with gigahertz periodic-gating techniques designed to minimize the total avalanche charge to less than 100 fC. We investigate afterpulsing in this regime and establish a connection to observations using more conventional techniques. For Si SPADs, we report the benefits of improved timing electronics that enhance the temporal resolution of Si SPADs used in a free-space quantum key distribution (QKD) system operating in the GHz regime. We establish that the effects of count-rate fluctuations induced by daytime turbulent scintillation are significantly reduced, benefitting the performance of the QKD system.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Dec 7, 2010•2 citations
We implement an InGaAs/InP single-photon avalanche diode (SPAD) for single-photon detection with the fastest gating frequency reported so far, of 2.23GHz, which approaches the limit given by the bandwidth of the SPAD - 2.5 GHz. We propose a useful way to characterize the afterpulsing distribution for rapid gating that allows for easy comparison with conventional gating regimes. We compare the performance of this rapid gating scheme with free-running detector and superconducting single-photon detector (SSPD) for the coherent one-way quantum key distribution (QKD) protocol. The rapid gating system is well suited for both high-rate and long-distance QKD applications, in which Mbps key rates can be achieved for distances less than 40km with 50 ns deadtime and the maximum distance is limited to ~190km with 5 μs deadtime. These results illustrate that the afterpulsing is no longer a limiting factor for QKD.
Gated single-photon avalanche diodes (SPADs) are practical solutions for quantum key distribution (QKD) applications. However, the gating frequency is limited by time jitter and afterpulse probability when SPADs operate at a frequency higher than 2 GHz. We find that filter distortion and variation of signal amplitude are the dominant mechanisms for time jitter in high-frequency scenarios, and design a specific low-pass filter (LPF) and a zero crossing discriminator to reduce the time jitter effectively. Specifically, the LPF extracts avalanche signals and forms accurate zero crossing points by its impulse response, and the zero crossing discriminator correctly discriminates avalanche signals to achieve low time jitter. When the SPAD is operated at a gating frequency of 2.5 GHz with a detection efficiency of 21%, the time jitter and afterpulse probability are 44 ps and 1.4%, respectively. Our results pave the way to practical QKD systems at higher clock rates.
InGaAs/InP single-photon avalanche diodes (SPADs) working in the regime of GHz clock rates are crucial components for the high-speed quantum key distribution (QKD). We have developed for the first time a compact, stable, and user-friendly tabletop InGaAs/InP single-photon detector system operating at a 1.25 GHz gate rate that fully integrates functions for controlling and optimizing SPAD performance. We characterize the key parameters of the detector system and test the long-term stability of the system for continuous operation of 75 h. The detector system can substantially enhance QKD performance and our present work paves the way for practical high-speed QKD applications.
InGaAs/InP Single-Photon Avalanche Diodes (SPADs) are widely employed in quantum optics applications, particularly in Quantum Key Distribution (QKD), due to their high sensitivity in the near-infrared range. In QKD, low noise and high timing resolution are essential to ensure secure and high-rate key exchange. One of the main limitations of InGaAs/InP SPADs is afterpulsing, which degrades the quantum bit error rate (QBER), limits the maximum count rate, and can compromise both the security and throughput of QKD systems. Reducing afterpulsing is thus crucial for enabling high-speed, reliable quantum communication. We present a newly developed gating and quenching circuit that significantly reduces afterpulsing. The circuit is located entirely outside the detector package, maintaining compatibility with any InGaAs/InP SPAD, and supports both gated and free-running operation. Unlike integrated ASIC-based solutions, which offer low parasitics but are often limited by process constraints (e.g., low maximum voltages), our approach uses high-speed discrete components, allowing high excess bias operation and design flexibility. While discrete designs are typically more prone to parasitics, our compact layout effectively mitigates these effects and preserves signal integrity. Experimental results show a strong afterpulsing reduction compared to our current commercial module. Additionally, the measured SPAD current highlights that the avalanche is completely quenched in less than a nanosecond after sensing. Eventually, the small footprint of the design paves the way for a new generation of compact, low-afterpulsing InGaAs/InP SPAD modules suitable for high-performance quantum optics applications.
The implementation and commercialization of quantum cryptography technologies have to face some challenges related to the development of single-photon detectors operating at 1550 nm. The main requirements are: i) high detection efficiency; ii) low noise; iii) high count rate; iv) low timing jitter. Different technologies are currently available for single-photon detection at 1550 nm, but semiconductor devices (like Single-Photon Avalanche Diode, SPAD) offer a photon detection efficiency that is inherently higher than any photocathode employed in vacuum tube detectors. Additionally InGaAs/InP SPADs can detect single photons at 1550 nm with low noise when moderately cooled by means of thermo-electric coolers. Consequently, InGaAs/InP SPAD can be the enabling technology of practical quantum key distribution (QKD) systems, provided that the maximum count rate is increased above 1 Mcps. The main limit is the afterpulsing effect that usually sets too long (< 10 μs) a hold-off time after each avalanche ignition. We present the developments achieved in InGaAs/InP SPAD device design, fabrication technology and front-end electronics, aimed at decreasing the afterpulsing effect, while not impairing photon detection efficiency and timing jitter. The new InGaAs/InP SPADs provide count rates higher than 1 Mcps and temporal response with 60 ps Full-Width at Half Maximum and very short (30 ps time constant) tail. The front-end electronics includes a wide-band pulse generator able to gate the SPAD up to 133 MHz repetition rate. Eventually, a fast avalanche-quenching scheme minimizes quenching time to less than 1 ns, thus effectively reducing afterpulsing by decreasing the total charge flowing through the junction.
We have demonstrated quantum key distribution (QKD) over 100 km using single-photon detectors based on InGaAs/InP avalanche photodiodes (APDs). We implemented the differential phase shift QKD (DPS-QKD) protocol with electrically cooled and 2-GHz sinusoidally gated APDs. The single-photon detector has a dark count probability of 2.8 × 10(-8) (55 counts per second) with a detection efficiency of 6 %, which enabled us to achieve 24 kbit/s secure key rate over 100 km of optical fiber. The DPS-QKD system offers better performances in a practical way than those achieved using superconducting single-photon detectors. Moreover, the distance that secure keys against the general individual attacks can be distributed has been extended to 160 km.
We discuss high-speed electronics that support the use of single-photon avalanche diodes (SPADs) in gigahertz singlephoton communications systems. For InGaAs/InP SPADs, recent work has demonstrated reduced afterpulsing and count rates approaching 500 MHz can be achieved with gigahertz periodic-gating techniques designed to minimize the total avalanche charge to less than 100 fC. We investigate afterpulsing in this regime and establish a connection to observations using more conventional techniques. For Si SPADs, we report the benefits of improved timing electronics that enhance the temporal resolution of Si SPADs used in a free-space quantum key distribution (QKD) system operating in the GHz regime. We establish that the effects of count-rate fluctuations induced by daytime turbulent scintillation are significantly reduced, benefitting the performance of the QKD system.