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

National Conference on Communications

Decoy-pulse protocol for frequency-coded quantum key distribution

Sudeshna Bhattacharya, K. Pradeep Kumar

Published Feb 1, 2012• 0 citations
Publisher

Abstract

We propose a decoy-pulse protocol for frequency-coded implementation of B92 quantum key distribution protocol. A direct extension of decoy-pulse method to frequency-coding scheme results in security loss as an eavesdropper can distinguish between signal and decoy pulses by measuring the carrier photon number without affecting other statistics. We overcome this problem by optimizing the ratio of carrier photon number of decoy-to-signal pulse to be as close to unity as possible. In our method the switching between signal and decoy pulses is achieved by changing the amplitude of RF signal as opposed to modulating the intensity of optical signal thus reducing system cost. Our simulation results show a key generation rate of 1.5×10-4/pulse for link lengths up to 70 km. Finally, we discuss the optimum value of average photon number of signal pulse for a given key rate while also optimizing the carrier ratio.

DOI
10.1109/ncc.2012.6176805

Related papers

Decoy-state method for subcarrier-multiplexed frequency-coded quantum key distribution

Sudeshna Bhattacharya, Pradeep Kumar Krishnamurthy

We propose a decoy-state method to increase key generation rate of frequency-coded (FC) implementation of B92 quantum key distribution (QKD) protocol. Direct application of decoy-state method to FC-QKD results in a security loophole. We overcome this loophole by optimizing the ratio of decoy-to-signal carrier photon number to unity. Simulation results for a single-channel FC-QKD show 16 kbits of raw key length at a transmission distance of 70 km. We then extend the decoy-state method to subcarrier-multiplexed FC-QKD. We show that key generation rate and secure link length improves by a factor of 5 and 40 km, respectively, compared to single-carrier with decoy-state method.

Journal of the Optical Society of America B•Mar 5, 2013•2 citations

Quantum key distribution with distinguishable decoy states

Anqi Huang, Shi‐Hai Sun, Zhihong Liu +1 more

The decoy-state protocol has been considered to be one of the most important methods to protect the security of quantum key distribution (QKD) with a weak coherent source. Here we test two experimental approaches to generating the decoy states with different intensities: modulation of the pump current of a semiconductor laser diode, and external modulation by an optical intensity modulator. The former approach shows a side channel in the time domain that allows an attacker to distinguish s signal state from a decoy state, breaking a basic assumption in the protocol. We model a photon-number-splitting attack based on our experimental data, and show that it compromises the system's security. Then, based on the work of Tamaki et al. [New J. Phys. 18, 065008 (2016)], we obtain two analytical formulas to estimate the yield and error rate of single-photon pulses when the signal and decoy states are distinguishable. The distinguishability reduces the secure key rate below that of a perfect decoy-state protocol. To mitigate this reduction, we propose to calibrate the transmittance of the receiver (Bob's) unit. We apply our method to three QKD systems and estimate their secure key rates.

arXiv:1711.00597•Physical Review A•Jul 27, 2018•95 citations

Optical modulation schemes for frequency-coded quantum key distribution

Pradeep K Kumar

We discuss possible modulation schemes to implement BB84 and B92 quantum key distribution protocols using frequency-coding method. We derive time evolution of quantum states of light in a Mach-Zehnder interferometer based optical intensity modulator. We then show that phase modulator-phase modulator (PM-PM) combination can be used to implement the B92 protocol and intensity modulator-intensity modulator (IM-IM) combination can be used to implement the BB84 protocol. However, the combinations-PM-IM or IM-PM-cannot be used to implement BB84 and B92 protocols using frequency-coding method. Finally, we discuss the security of frequency-coded implementation of B92 protocol.

National Conference on Communications•Jan 1, 2010•7 citations

Phase-Matching Quantum Key Distribution Without Intensity Modulation

Shan-Feng Shao, Xiaoyu Cao, Yuan-Mei Xie +5 more

Quantum key distribution provides a promising solution for sharing secure keys between two distant parties with unconditional security. Nevertheless, quantum key distribution is still severely threatened by the imperfections of devices. In particular, the classical pulse correlation threatens security when sending decoy states. To address this problem and simplify experimental requirements, we propose a phase-matching quantum key distribution protocol without intensity modulation. Instead of using decoy states, we propose an alternative method to estimate the theoretical upper bound on the phase error rate contributed by even-photon-number components. Simulation results show that the transmission distance of our protocol could reach 305 km in telecommunication fiber. Furthermore, we perform a proof-of-principle experiment to demonstrate the feasibility of our protocol, and the key rate reaches 22.5 bit/s under a 45-dB channel loss. Addressing the security loophole of pulse intensity correlation and replacing continuous random phase with a six- or eight-slice random phase, our protocol provides a promising solution for constructing quantum networks.

arXiv:2303.11585•Physical Review Applied•Aug 18, 2023•5 citations

Quantum Key Distribution Using Decoy State Protocol

Sellami Ali, Suhairi Saharudin, Mohamed Ridza Wahiddin

Problem statement: Quantum key distribution provides unconditional security guaranteed by the fundamental laws of quantum physics. Unfortunately, for real-life experimental set-ups, which mainly based on faint laser pulses, the occasional production of multi-photons and channel loss make it possible for sophisticated eavesdroppers to launch various subtle eavesdropping attacks including the Photon Number Splitting (PNS) attack. The decoy state protocols recently proposed to beat PNS attack and to improve dramatically distance and secure key generation rate of Quantum Key Distribution (QKD). Approach: Objective of this study was experimental implementation of weak decoy + vacuum states QKD for increasing the performance of QKD system. To show conceptually how simple it was to apply the weak decoy + vacuum state idea to a commercial QKD system, we chosen ID-3000 commercial quantum key distribution system manufactured by id quantique. To implement the weak decoy + vacuum state protocol, we had to add some new optical and electronics components to id quantique and to attenuate each signal to the intensity of either signal state or weak decoy or vacuum state randomly. Results: In our implementation, the attenuation will be done by placing a VOA (variable optical attenuator) in Alice’s side. Specifically, our QKD system required the polarizations of 2 pulses from the same signal to be orthogonal. Therefore the VOA must be polarization independent so as to attenuate the two pulses equally. The VOA utilized in experiment to attenuate signals dynamically was Intensity Modulator (IM). We had implemented weak + vacuum protocol on a modified commercial QKD system over a 25 km of telecom fibers with an unconditionally secure key rate of 6.2931×10-4 per pulse. Conclusion: By making simple modifications to a commercial quantum key distribution system, we could achieve much better performance with substantially higher key generation rate and longer distance than QKD system without decoy state.

American Journal of Engineering and Applied Sciences•Apr 1, 2009•7 citations

Quantum Key Distribution with High Loss: Toward Global Secure Communication

Won-Young Hwang

We propose a decoy-pulse method to overcome the photon-number-splitting attack for Bennett-Brassard 1984 quantum key distribution protocol in the presence of high loss: A legitimate user intentionally and randomly replaces signal pulses by multiphoton pulses (decoy pulses). Then they check the loss of the decoy pulses. If the loss of the decoy pulses is abnormally less than that of signal pulses, the whole protocol is aborted. Otherwise, to continue the protocol, they estimate the loss of signal multiphoton pulses based on that of decoy pulses. This estimation can be done with an assumption that the two losses have similar values. We justify that assumption.

arXiv:quant-ph/0211153•Physical Review Letters•Aug 1, 2003•1,809 citations
We propose a decoy-pulse protocol for frequency-coded implementation of B92 quantum key distribution protocol. A direct extension of decoy-pulse method to frequency-coding scheme results in security loss as an eavesdropper can distinguish between signal and decoy pulses by measuring the carrier photon number without affecting other statistics. We overcome this problem by optimizing the ratio of carrier photon number of decoy-to-signal pulse to be as close to unity as possible. In our method the switching between signal and decoy pulses is achieved by changing the amplitude of RF signal as opposed to modulating the intensity of optical signal thus reducing system cost. Our simulation results show a key generation rate of 1.5×10-4/pulse for link lengths up to 70 km. Finally, we discuss the optimum value of average photon number of signal pulse for a given key rate while also optimizing the carrier ratio.
We propose a decoy-state method to increase key generation rate of frequency-coded (FC) implementation of B92 quantum key distribution (QKD) protocol. Direct application of decoy-state method to FC-QKD results in a security loophole. We overcome this loophole by optimizing the ratio of decoy-to-signal carrier photon number to unity. Simulation results for a single-channel FC-QKD show 16 kbits of raw key length at a transmission distance of 70 km. We then extend the decoy-state method to subcarrier-multiplexed FC-QKD. We show that key generation rate and secure link length improves by a factor of 5 and 40 km, respectively, compared to single-carrier with decoy-state method.
The decoy-state protocol has been considered to be one of the most important methods to protect the security of quantum key distribution (QKD) with a weak coherent source. Here we test two experimental approaches to generating the decoy states with different intensities: modulation of the pump current of a semiconductor laser diode, and external modulation by an optical intensity modulator. The former approach shows a side channel in the time domain that allows an attacker to distinguish s signal state from a decoy state, breaking a basic assumption in the protocol. We model a photon-number-splitting attack based on our experimental data, and show that it compromises the system's security. Then, based on the work of Tamaki et al. [New J. Phys. 18, 065008 (2016)], we obtain two analytical formulas to estimate the yield and error rate of single-photon pulses when the signal and decoy states are distinguishable. The distinguishability reduces the secure key rate below that of a perfect decoy-state protocol. To mitigate this reduction, we propose to calibrate the transmittance of the receiver (Bob's) unit. We apply our method to three QKD systems and estimate their secure key rates.
We discuss possible modulation schemes to implement BB84 and B92 quantum key distribution protocols using frequency-coding method. We derive time evolution of quantum states of light in a Mach-Zehnder interferometer based optical intensity modulator. We then show that phase modulator-phase modulator (PM-PM) combination can be used to implement the B92 protocol and intensity modulator-intensity modulator (IM-IM) combination can be used to implement the BB84 protocol. However, the combinations-PM-IM or IM-PM-cannot be used to implement BB84 and B92 protocols using frequency-coding method. Finally, we discuss the security of frequency-coded implementation of B92 protocol.
Quantum key distribution provides a promising solution for sharing secure keys between two distant parties with unconditional security. Nevertheless, quantum key distribution is still severely threatened by the imperfections of devices. In particular, the classical pulse correlation threatens security when sending decoy states. To address this problem and simplify experimental requirements, we propose a phase-matching quantum key distribution protocol without intensity modulation. Instead of using decoy states, we propose an alternative method to estimate the theoretical upper bound on the phase error rate contributed by even-photon-number components. Simulation results show that the transmission distance of our protocol could reach 305 km in telecommunication fiber. Furthermore, we perform a proof-of-principle experiment to demonstrate the feasibility of our protocol, and the key rate reaches 22.5 bit/s under a 45-dB channel loss. Addressing the security loophole of pulse intensity correlation and replacing continuous random phase with a six- or eight-slice random phase, our protocol provides a promising solution for constructing quantum networks.
Problem statement: Quantum key distribution provides unconditional security guaranteed by the fundamental laws of quantum physics. Unfortunately, for real-life experimental set-ups, which mainly based on faint laser pulses, the occasional production of multi-photons and channel loss make it possible for sophisticated eavesdroppers to launch various subtle eavesdropping attacks including the Photon Number Splitting (PNS) attack. The decoy state protocols recently proposed to beat PNS attack and to improve dramatically distance and secure key generation rate of Quantum Key Distribution (QKD). Approach: Objective of this study was experimental implementation of weak decoy + vacuum states QKD for increasing the performance of QKD system. To show conceptually how simple it was to apply the weak decoy + vacuum state idea to a commercial QKD system, we chosen ID-3000 commercial quantum key distribution system manufactured by id quantique. To implement the weak decoy + vacuum state protocol, we had to add some new optical and electronics components to id quantique and to attenuate each signal to the intensity of either signal state or weak decoy or vacuum state randomly. Results: In our implementation, the attenuation will be done by placing a VOA (variable optical attenuator) in Alice’s side. Specifically, our QKD system required the polarizations of 2 pulses from the same signal to be orthogonal. Therefore the VOA must be polarization independent so as to attenuate the two pulses equally. The VOA utilized in experiment to attenuate signals dynamically was Intensity Modulator (IM). We had implemented weak + vacuum protocol on a modified commercial QKD system over a 25 km of telecom fibers with an unconditionally secure key rate of 6.2931×10-4 per pulse. Conclusion: By making simple modifications to a commercial quantum key distribution system, we could achieve much better performance with substantially higher key generation rate and longer distance than QKD system without decoy state.
We propose a decoy-pulse method to overcome the photon-number-splitting attack for Bennett-Brassard 1984 quantum key distribution protocol in the presence of high loss: A legitimate user intentionally and randomly replaces signal pulses by multiphoton pulses (decoy pulses). Then they check the loss of the decoy pulses. If the loss of the decoy pulses is abnormally less than that of signal pulses, the whole protocol is aborted. Otherwise, to continue the protocol, they estimate the loss of signal multiphoton pulses based on that of decoy pulses. This estimation can be done with an assumption that the two losses have similar values. We justify that assumption.