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

Investigation on the electromagnetic radiated emissions of a single-photon avalanche diode

John J. Pantoja, Alfonso Tello Castillo, Dimitris E. Anagnostou, James Kirrane, Mark Stonehouse, A. Koehler-Sidki, Michele Natrella, Ross J. Donaldson

Published Nov 30, 2023• 1 citation
Publisher

Abstract

The security provided by Quantum Key Distribution (QKD) can be strongly compromised by interception of the raw and sifted key through side channels, such as the practical characteristics of electronic components used in the transmitter and receiver modules. Some out-of-band electromagnetic attacks have already been identified and tested in components used in QKD, such as quantum random number generators. In this presentation, we explore out-of-band electromagnetic attacks of other components used in a quantum receiver, such as Single Photon Avalanche Diodes (SPADs), and the time-correlated single-photon counting module. We measured the electromagnetic (EM) radiated emissions of the components to quantify the emanation levels and evaluate the vulnerability that this QKD side channel may present. The test was conducted in an anechoic chamber up to 1 GHz, at 3 m distance, and rotating the SPAD to provide radiation from four azimuth angles. Results show that measurable radiated pulses are generated by the SPAD in this frequency range due to dark count pulses and due to incoming Single-Photon level pulses. Dark counts of few kHz and Single-Photon level counts of hundreds of kHz were considered in the tests. EM radiation frequency bands with main emissions and electric field strengths are identified for both operation conditions.

DOI
10.1117/12.2689901

Related papers

Electromagnetic side-channel attack risk assessment on a practical quantum-key-distribution receiver based on multi-class classification

John J. Pantoja, Víctor Bucheli, Ross J. Donaldson

Abstract While quantum key distribution (QKD) is a theoretically secure way of growing quantum-safe encryption keys, many practical implementations are challenged due to various open attack vectors, resulting in many variations of QKD protocols. Side channels are one such vector that allows a passive or active eavesdropper to obtain QKD information leaked through practical devices. This paper assesses the feasibility and implications of extracting the raw secret key from far-field radiated emissions from the single-photon avalanche diodes used in a BB84 QKD quad-detector receiver. Enhancement of the attack was also demonstrated through the use of deep-learning model to distinguish radiated emissions due to the four polarized encoding states. To evaluate the severity of such side-channel attack, multi-class classification based on raw-data and pre-processed data is implemented and assessed. Results show that classifiers based on both raw-data and pre-processed features can discern variations of the electromagnetic emissions caused by specific orientations of the detectors within the receiver with an accuracy higher than 90%. This research proposes machine learning models as a technique to assess EM information leakage risk of QKD and highlights the feasibility of side-channel attacks in the far-field region, further emphasizing the need to utilise mechanisms to avoid electromagnetic radiation information leaks and measurement-device-independent QKD protocols.

EPJ Quantum Technology•Nov 18, 2024•11 citations

Electromagnetic Side-Channel Vulnerability in QKD Equipment

Mikio Fujiwara, Katsumi Fujii, Fumie Ono +2 more

Actual quantum key distribution network nodes may be vulnerable to side-channel attacks such as electromagnetic leakage. In this study, we measured electromagnetic emissions from a prototype quantum key distribution device implementing a time-bin decoy-state BB84 protocol with Y and Z bases. We measured the electromagnetic spectra and waveforms at distances of 0 m and 3 m from the transmitter and receiver inside an anechoic chamber. The results showed that the transmitter was the primary source of electromagnetic leakage, and distinct differences were observed between the quantum states generated at the third harmonic of the 1241.6 MHz clock.

quant-pharXiv:2610.01609•IEEE Access•Oct 2, 2026•0 citations

Spurious Pulse Detection in Fibre-Optic Channels Using Measurement-Device-Independent Quantum Key Distribution with Single-Photon Avalanche Photodiodes

J. Suneetha, Smita Darandale

Abstract The safe exchange of cryptographic keys is made possible by Quantum Key Distribution (QKD), which makes use of the basic ideas of quantum physics. Quantum Bit Error Rate (QBER), key generation rate, and transmission distance are important performance measures in QKD systems. Nevertheless, undesired noise sources that impair system performance, such dark counts and afterpulses, restrict traditional QKD implementations. The Measurement-Device-Independent QKD (MDI-QKD) protocol and Single Photon Avalanche Diodes (SPADs) for single-photon detection are combined in this research to create an improved QKD model. All detector-side-channel weaknesses are naturally eliminated by the MDI-QKD protocol, while SPADs' excellent sensitivity and temporal precision allow for precise noise source detection and characterisation, including dark count and afterpulse rates. When compared to conventional QKD systems, the suggested method performs better when assessed using QBER. According to experimental findings, including SPADs into the MDI-QKD architecture greatly improves the security and effectiveness of quantum communication systems by detecting detector-induced errors.

•Mar 12, 2026•0 citations

Radiofrequency emanations of a single-photon detector

John J. Pantoja, Alfonso Tello Castillo, Dimitris E. Anagnostou +5 more

Quantum key distribution (QKD) offers the possibility of information theoretic secure key establishment. However, non-ideal behaviour of some components used in practical implementations causes security risks and loopholes that need to be addressed. Previously identified loopholes have resulted in changes to hardware and the invention of new QKD protocols. In this document, we report an investigation into the eavesdropping risk due to out-of-band radiofrequency emanations produced by a QKD receiver. We present experimental results that show a QKD receiver may produce significant pulsed-like emissions that can be detected by a passive eavesdropper antenna to identify clicks in single-photon detectors.

IET conference proceedings.•Dec 18, 2023•2 citations

Controlled Laser Damage of Single-Photon Avalanche Photodiodes

Audun Nystad Bugge

Quantum cryptography has been developed from being a theoretical proposal to having real world applications, with companies developing and selling quantum key distribution (QKD) instruments commercially. Although laws of quantum physics guarantee perfect security in the key distribution protocol, several vulnerabilities in the practical implementations have been described and demonstrated. In some of these attacks the eavesdropper has been able to acquire the entire secret key without being detected by the two communicating parties. This thesis describes an experimental setup for automatically characterizing and damaging single photon avalanche photodiodes using a high power laser to damage the diode with the intention to find new weaknesses in QKD systems. Hopefully, the discovery of loopholes will stimulate the researchers and commercial manufacturers to fix their implementations, leading to more secure systems. For a silicon avalanche photodiode (APD) in a passive-quenching circuit, a number of interesting results have been found. It has been shown that we are able to change many of the APDs key characteristics by applying strong illumination. We have been able to reduce the dark count rate of several APDs by up to 80% in a predictable way by strong laser illumination, an effect which is believed to be caused by localized annealing. This is an interesting result not only in the field of quantum cryptography, but perhaps also for improving the manufacturing process of different semiconductor components. Other parameters that have been found to change in interesting ways are the dark current and the breakdown voltage. It has been demonstrated that these changes may compromise the security of QKD systems.

77•Jan 1, 2012•0 citations

Quantum Simulation of SPAD in the Space Radiation Environment

Durgesh Tinker, Kavita Lalwani

Single-Photon Avalanche Diodes (SPADs) are critical components of emerging quantum communication networks that detect single photons. They are placed in satellites for long-distance communication and are susceptible to radiation-induced displacement damage in space. This degrades SPAD performance parameters, including reduced efficiency, increased thermal dark counts, damage to the Si crystal, and increased afterpulsing rate. This paper simulates SPAD in a space radiation environment by introducing a quantum simulation framework, modeling the SPAD detector as a three-level quantum system, ground state ($|g\rangle$), excited state ($|e\rangle$) and a trap state ($|t\rangle$). Furthermore, to model the photon as a quantum system, second quantization and Fock-space truncation are used. The interaction between the photon-SPAD closed system is simulated using the Jaynes-Cummings model, and the open-system dynamics is governed by the Lindblad master equation and Qiskit's gate-based noise channels. The key characteristics, such as the efficiency, timing jitter, thermal dark counts, and afterpulsing \& radiation effects, are obtained using quantum simulation of SPAD. This approach differs significantly from conventional TCAD simulations, which rely on semiclassical approximations that do not capture the discrete quantum statistics of single-photon interactions and the dynamics of trap states.

quant-pharXiv:2608.00040•Jul 24, 2026•0 citations
The security provided by Quantum Key Distribution (QKD) can be strongly compromised by interception of the raw and sifted key through side channels, such as the practical characteristics of electronic components used in the transmitter and receiver modules. Some out-of-band electromagnetic attacks have already been identified and tested in components used in QKD, such as quantum random number generators. In this presentation, we explore out-of-band electromagnetic attacks of other components used in a quantum receiver, such as Single Photon Avalanche Diodes (SPADs), and the time-correlated single-photon counting module. We measured the electromagnetic (EM) radiated emissions of the components to quantify the emanation levels and evaluate the vulnerability that this QKD side channel may present. The test was conducted in an anechoic chamber up to 1 GHz, at 3 m distance, and rotating the SPAD to provide radiation from four azimuth angles. Results show that measurable radiated pulses are generated by the SPAD in this frequency range due to dark count pulses and due to incoming Single-Photon level pulses. Dark counts of few kHz and Single-Photon level counts of hundreds of kHz were considered in the tests. EM radiation frequency bands with main emissions and electric field strengths are identified for both operation conditions.
Abstract While quantum key distribution (QKD) is a theoretically secure way of growing quantum-safe encryption keys, many practical implementations are challenged due to various open attack vectors, resulting in many variations of QKD protocols. Side channels are one such vector that allows a passive or active eavesdropper to obtain QKD information leaked through practical devices. This paper assesses the feasibility and implications of extracting the raw secret key from far-field radiated emissions from the single-photon avalanche diodes used in a BB84 QKD quad-detector receiver. Enhancement of the attack was also demonstrated through the use of deep-learning model to distinguish radiated emissions due to the four polarized encoding states. To evaluate the severity of such side-channel attack, multi-class classification based on raw-data and pre-processed data is implemented and assessed. Results show that classifiers based on both raw-data and pre-processed features can discern variations of the electromagnetic emissions caused by specific orientations of the detectors within the receiver with an accuracy higher than 90%. This research proposes machine learning models as a technique to assess EM information leakage risk of QKD and highlights the feasibility of side-channel attacks in the far-field region, further emphasizing the need to utilise mechanisms to avoid electromagnetic radiation information leaks and measurement-device-independent QKD protocols.
Actual quantum key distribution network nodes may be vulnerable to side-channel attacks such as electromagnetic leakage. In this study, we measured electromagnetic emissions from a prototype quantum key distribution device implementing a time-bin decoy-state BB84 protocol with Y and Z bases. We measured the electromagnetic spectra and waveforms at distances of 0 m and 3 m from the transmitter and receiver inside an anechoic chamber. The results showed that the transmitter was the primary source of electromagnetic leakage, and distinct differences were observed between the quantum states generated at the third harmonic of the 1241.6 MHz clock.
Abstract The safe exchange of cryptographic keys is made possible by Quantum Key Distribution (QKD), which makes use of the basic ideas of quantum physics. Quantum Bit Error Rate (QBER), key generation rate, and transmission distance are important performance measures in QKD systems. Nevertheless, undesired noise sources that impair system performance, such dark counts and afterpulses, restrict traditional QKD implementations. The Measurement-Device-Independent QKD (MDI-QKD) protocol and Single Photon Avalanche Diodes (SPADs) for single-photon detection are combined in this research to create an improved QKD model. All detector-side-channel weaknesses are naturally eliminated by the MDI-QKD protocol, while SPADs' excellent sensitivity and temporal precision allow for precise noise source detection and characterisation, including dark count and afterpulse rates. When compared to conventional QKD systems, the suggested method performs better when assessed using QBER. According to experimental findings, including SPADs into the MDI-QKD architecture greatly improves the security and effectiveness of quantum communication systems by detecting detector-induced errors.
Quantum key distribution (QKD) offers the possibility of information theoretic secure key establishment. However, non-ideal behaviour of some components used in practical implementations causes security risks and loopholes that need to be addressed. Previously identified loopholes have resulted in changes to hardware and the invention of new QKD protocols. In this document, we report an investigation into the eavesdropping risk due to out-of-band radiofrequency emanations produced by a QKD receiver. We present experimental results that show a QKD receiver may produce significant pulsed-like emissions that can be detected by a passive eavesdropper antenna to identify clicks in single-photon detectors.
Quantum cryptography has been developed from being a theoretical proposal to having real world applications, with companies developing and selling quantum key distribution (QKD) instruments commercially. Although laws of quantum physics guarantee perfect security in the key distribution protocol, several vulnerabilities in the practical implementations have been described and demonstrated. In some of these attacks the eavesdropper has been able to acquire the entire secret key without being detected by the two communicating parties. This thesis describes an experimental setup for automatically characterizing and damaging single photon avalanche photodiodes using a high power laser to damage the diode with the intention to find new weaknesses in QKD systems. Hopefully, the discovery of loopholes will stimulate the researchers and commercial manufacturers to fix their implementations, leading to more secure systems. For a silicon avalanche photodiode (APD) in a passive-quenching circuit, a number of interesting results have been found. It has been shown that we are able to change many of the APDs key characteristics by applying strong illumination. We have been able to reduce the dark count rate of several APDs by up to 80% in a predictable way by strong laser illumination, an effect which is believed to be caused by localized annealing. This is an interesting result not only in the field of quantum cryptography, but perhaps also for improving the manufacturing process of different semiconductor components. Other parameters that have been found to change in interesting ways are the dark current and the breakdown voltage. It has been demonstrated that these changes may compromise the security of QKD systems.
Single-Photon Avalanche Diodes (SPADs) are critical components of emerging quantum communication networks that detect single photons. They are placed in satellites for long-distance communication and are susceptible to radiation-induced displacement damage in space. This degrades SPAD performance parameters, including reduced efficiency, increased thermal dark counts, damage to the Si crystal, and increased afterpulsing rate. This paper simulates SPAD in a space radiation environment by introducing a quantum simulation framework, modeling the SPAD detector as a three-level quantum system, ground state (∣g⟩|g\rangle∣g⟩), excited state (∣e⟩|e\rangle∣e⟩) and a trap state (∣t⟩|t\rangle∣t⟩). Furthermore, to model the photon as a quantum system, second quantization and Fock-space truncation are used. The interaction between the photon-SPAD closed system is simulated using the Jaynes-Cummings model, and the open-system dynamics is governed by the Lindblad master equation and Qiskit's gate-based noise channels. The key characteristics, such as the efficiency, timing jitter, thermal dark counts, and afterpulsing \& radiation effects, are obtained using quantum simulation of SPAD. This approach differs significantly from conventional TCAD simulations, which rely on semiclassical approximations that do not capture the discrete quantum statistics of single-photon interactions and the dynamics of trap states.