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

1 Tbit/s/λ, 560 km three-dimensional quantum noise stream cipher transmission using multi-carrier method

Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

Published Sep 16, 2026• 0 citations
Publisher

Abstract

With the use of a 40 Gbit/s quantum noise stream cipher (QNSC) transmitter and receiver, we succeed in the first secure optical transmission exceeding 1 Tbit/s/λ over 560 km by combining 29 optical carriers generated from a single light source. In addition to amplitude and phase encryption, time-domain masking is newly introduced to further enhance the security of the random sequence used for encryption. This three-dimensional QNSC scheme employs irregular mapping of the QAM constellation, together with symbol order shuffling in the time domain. As a result of the time-domain shuffling, the BER at an eavesdropper reaches 0.5 for each bit within a symbol, even when the irregular mapping is decrypted.

DOI
10.1364/opticaopen.33806035

Related papers

1 Tbit/s/λ, 560 km three-dimensional quantum noise stream cipher transmission using multi-carrier method

Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka +1 more

With the use of a 40 Gbit/s quantum noise stream cipher (QNSC) transmitter and receiver, we succeed in the first secure optical transmission exceeding 1 Tbit/s/λ over 560 km by combining 29 optical carriers generated from a single light source. In addition to amplitude and phase encryption, time-domain masking is newly introduced to further enhance the security of the random sequence used for encryption. This three-dimensional QNSC scheme employs irregular mapping of the QAM constellation, together with symbol order shuffling in the time domain. As a result of the time-domain shuffling, the BER at an eavesdropper reaches 0.5 for each bit within a symbol, even when the irregular mapping is decrypted.

•Sep 16, 2026•0 citations

Single-channel 40 Gbit/s digital coherent QAM quantum noise stream cipher transmission over 480 km

Masato Yoshida, Toshihiko Hirooka, Keisuke Kasai +1 more

We demonstrate the first 40 Gbit/s single-channel polarization-multiplexed, 5 Gsymbol/s, 16 QAM quantum noise stream cipher (QNSC) transmission over 480 km by incorporating ASE quantum noise from EDFAs as well as the quantum shot noise of the coherent state with multiple photons for the random masking of data. By using a multi-bit encoded scheme and digital coherent transmission techniques, secure optical communication with a record data capacity and transmission distance has been successfully realized. In this system, the signal level received by Eve is hidden by both the amplitude and the phase noise. The highest number of masked signals, 7.5 x 10(4), was achieved by using a QAM scheme with FEC, which makes it possible to reduce the output power from the transmitter while maintaining an error free condition for Bob. We have newly measured the noise distribution around I and Q encrypted data and shown experimentally with a data size of as large as 2(25) that the noise has a Gaussian distribution with no correlations. This distribution is suitable for the random masking of data.

Optics Express•Jan 8, 2016•51 citations

10 Tbit/s QAM Quantum Noise Stream Cipher Coherent Transmission Over 160 Km

Masato Yoshida, Takashi Kan, Keisuke Kasai +2 more

We describe in detail our recent demonstration of a 10 Tbit/s secure physical layer transmission that we achieved by using digital coherent QAM quantum noise stream cipher (QNSC) and injection-locked WDM techniques. We used an FPGA-based transmitter and receiver to demonstrate a 165 channel polarization-multiplexed WDM 5 Gbaud 128 QAM/QNSC (70 Gbit/s) on-line transmission over 160 km with a spectral efficiency of 6 bit/s/Hz. In the present system, the original 128 QAM data were encrypted in a 1024 × 1024 QAM format using basis information. The encrypted signal was then masked by a large ASE noise, which reduced the detection “success” probability for an eavesdropper to 0.13% for each symbol. Furthermore, the multiplicity of the original QAM data and the seed keys used to generate the basis information were arbitrarily changed with time, which makes the decryption much more difficult.

Journal of Lightwave Technology•Aug 14, 2020•42 citations

QAM quantum stream cipher using digital coherent optical transmission

Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka +1 more

A Quantum Stream Cipher (QSC) using Quadrature Amplitude Modulation (QAM) is presented to greatly increase the secure degree compared with ASK or PSK/QSC. We propose encoding multi-bit data in one symbol with a multi-bit basis state, resulting in QAM/QSC, which employs amplitude and phase encryption of the light beam simultaneously. A 16 QAM/QSC experiment at 10 Gbit/s was successfully carried out over 160 km using a digital coherent optical transmission technique, where 16 QAM data were encrypted in a constellation with 32 × 32~4096 × 4096 symbols. We show experimentally that the Number of Masked Signals (NMS) in the quantum noise Γ(QAM) for QAM/QSC becomes a square multiple larger than Γ(ASK) for ASK/QSC. Γ(QAM) exceeds 10,000. This result indicates that the QSC technique is more robust against eavesdroppers than ASK or PSK/QSC.

Optics Express•Feb 13, 2014•88 citations

QAM quantum noise stream cipher using digital coherent optical transmission

Masato Yoshida, Toshihiko Hirooka, Keisuke Kasai +1 more

We present a high-security digital-coherent transmission scheme with a QAM-based two-dimensional quantum-noise stream cipher employing amplitude and phase encryption simultaneously and multi-bit encoding with a multi-bit basis state. 40 Gbit/s-480 km and real-time adaptive 20~60 Gbit/s-320 km secure transmissions are demonstrated.

Asilomar Conference on Signals, Systems and Computers (ACSSC)•Nov 1, 2015•6 citations

10 Tbit/s QAM Quantum Noise Stream Cipher Coherent Transmission over 160 km

Masato Yoshida, Takashi Kan, Keisuke Kasai +2 more

We present the first 10 Tbit/s secure physical layer transmission over 160 km with a spectral efficiency of 6 bit/s/Hz by using digital coherent QAM quantum noise stream cipher (QNSC) and injection-locked WDM techniques.

Optical Fiber Communication Conference•Jan 1, 2020•7 citations
With the use of a 40 Gbit/s quantum noise stream cipher (QNSC) transmitter and receiver, we succeed in the first secure optical transmission exceeding 1 Tbit/s/λ over 560 km by combining 29 optical carriers generated from a single light source. In addition to amplitude and phase encryption, time-domain masking is newly introduced to further enhance the security of the random sequence used for encryption. This three-dimensional QNSC scheme employs irregular mapping of the QAM constellation, together with symbol order shuffling in the time domain. As a result of the time-domain shuffling, the BER at an eavesdropper reaches 0.5 for each bit within a symbol, even when the irregular mapping is decrypted.
With the use of a 40 Gbit/s quantum noise stream cipher (QNSC) transmitter and receiver, we succeed in the first secure optical transmission exceeding 1 Tbit/s/λ over 560 km by combining 29 optical carriers generated from a single light source. In addition to amplitude and phase encryption, time-domain masking is newly introduced to further enhance the security of the random sequence used for encryption. This three-dimensional QNSC scheme employs irregular mapping of the QAM constellation, together with symbol order shuffling in the time domain. As a result of the time-domain shuffling, the BER at an eavesdropper reaches 0.5 for each bit within a symbol, even when the irregular mapping is decrypted.
We demonstrate the first 40 Gbit/s single-channel polarization-multiplexed, 5 Gsymbol/s, 16 QAM quantum noise stream cipher (QNSC) transmission over 480 km by incorporating ASE quantum noise from EDFAs as well as the quantum shot noise of the coherent state with multiple photons for the random masking of data. By using a multi-bit encoded scheme and digital coherent transmission techniques, secure optical communication with a record data capacity and transmission distance has been successfully realized. In this system, the signal level received by Eve is hidden by both the amplitude and the phase noise. The highest number of masked signals, 7.5 x 10(4), was achieved by using a QAM scheme with FEC, which makes it possible to reduce the output power from the transmitter while maintaining an error free condition for Bob. We have newly measured the noise distribution around I and Q encrypted data and shown experimentally with a data size of as large as 2(25) that the noise has a Gaussian distribution with no correlations. This distribution is suitable for the random masking of data.
We describe in detail our recent demonstration of a 10 Tbit/s secure physical layer transmission that we achieved by using digital coherent QAM quantum noise stream cipher (QNSC) and injection-locked WDM techniques. We used an FPGA-based transmitter and receiver to demonstrate a 165 channel polarization-multiplexed WDM 5 Gbaud 128 QAM/QNSC (70 Gbit/s) on-line transmission over 160 km with a spectral efficiency of 6 bit/s/Hz. In the present system, the original 128 QAM data were encrypted in a 1024 × 1024 QAM format using basis information. The encrypted signal was then masked by a large ASE noise, which reduced the detection “success” probability for an eavesdropper to 0.13% for each symbol. Furthermore, the multiplicity of the original QAM data and the seed keys used to generate the basis information were arbitrarily changed with time, which makes the decryption much more difficult.
A Quantum Stream Cipher (QSC) using Quadrature Amplitude Modulation (QAM) is presented to greatly increase the secure degree compared with ASK or PSK/QSC. We propose encoding multi-bit data in one symbol with a multi-bit basis state, resulting in QAM/QSC, which employs amplitude and phase encryption of the light beam simultaneously. A 16 QAM/QSC experiment at 10 Gbit/s was successfully carried out over 160 km using a digital coherent optical transmission technique, where 16 QAM data were encrypted in a constellation with 32 × 32~4096 × 4096 symbols. We show experimentally that the Number of Masked Signals (NMS) in the quantum noise Γ(QAM) for QAM/QSC becomes a square multiple larger than Γ(ASK) for ASK/QSC. Γ(QAM) exceeds 10,000. This result indicates that the QSC technique is more robust against eavesdroppers than ASK or PSK/QSC.