© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

IEEE Future Networks World Forum (FNWF)

Imperfect unambiguous state discrimination: practical case study for future networks

Anshul Singhal, Shahram Dehdashti, Janis Nötzel

Published Oct 15, 2024• 0 citations

Abstract

We thoroughly investigate the amplitude and phase fluctuations affect the performance of USD. We provide a comprehensive analysis insights into the limitations of USD in practical scenarios, making the findings relevant for real-world applications. By introducing a set of positive operator value measurements, we suggest a USD measurement for discriminating between to coherent states with the same amplitude and different phases. The model develops by setting orthogonal states, i.e., a superposition of the potential outputs, to discriminate two phases. However, as during the preparation of this signal from the laser beam, unavoidable errors occur which transform the output coherent signals into imperfect input signals. This imperfection can be modeled as fluctuation errors i.e., amplitude and phase fluctuations. We apply this model by considering the noise and study the impact of both the states on the USD measurement. This results in an error in the measurement making "perfect" USD to "imperfect" USD. We further stimulate and analyse the impact of both the errors and found out that the proposed method works for a certain window of intensity of light. It doesn’t provide us with desired results for lower amplitudes of light while for higher amplitudes the error in the measurement becomes too large making the measurement meaningless. This have implications on low-energy transmitters and practical implementations of USD, thereby, we address a significant gap in the literature regarding the applicability of quantum state discrimination methods in future quantum communication systems.

DOI: 10.1109/fnwf63303.2024.11028795

Related papers

Unambiguous discrimination of coherent states

Jasminder S. Sidhu, Michael S. Bullock, Saikat Guha +1 more

Coherent states of the quantum electromagnetic field, the quantum description of ideal laser light, are a prime candidate as information carriers for optical communications. A large body of literature exists on quantum-limited parameter estimation and discrimination for coherent states. However, very little is known about practical realizations of receivers for unambiguous state discrimination (USD) of coherent states. Here we fill this gap and establish a theory of unambiguous discrimination of coherent states, with receivers that are allowed to employ: passive multimode linear optics, phase-space displacements, un-excited auxiliary input modes, and on-off photon detection. Our results indicate that these currently-available optical components are near optimal for unambiguous discrimination of multiple coherent states in a constellation.

•Aug 31, 2021•0 citations

Unambiguous discrimination of binary coherent states

Alex X. Liu, Siyao Wang, Yinsong Xu +4 more

Considering quantum detection, there are two different ways to make a measurement on signals set. One is minimum error discrimination and another is unambiguous states discrimination. In this work, we study the unambiguous state discrimination of coherent states. The quantum measurement model investigated is based on binary signals. All necessary positive-operator valued measurements are established to implement the quantum measurements in non-ambiguity way. The conclusive probability and inconclusive probability for the unambiguous discrimination of both on-off keying and binary-phase-shifting keying modulations are derived rigorously to show the measurement performance of proposed detection method theoretically.

International Journal of Computational Science and Engineering•Jan 1, 2020•0 citations

Linear optics and photodetection achieve near-optimal unambiguous coherent state discrimination

Jasminder S. Sidhu, Michael S. Bullock, Saikat Guha +1 more

Coherent states of the quantum electromagnetic field, the quantum description of ideal laser light, are prime candidates as information carriers for optical communications. A large body of literature exists on their quantum-limited estimation and discrimination. However, very little is known about the practical realizations of receivers for unambiguous state discrimination (USD) of coherent states. Here we fill this gap and outline a theory of USD with receivers that are allowed to employ: passive multimode linear optics, phase-space displacements, auxiliary vacuum modes, and on-off photon detection. Our results indicate that, in some regimes, these currently-available optical components are typically sufficient to achieve near-optimal unambiguous discrimination of multiple, multimode coherent states.

arXiv:2109.00008•Quantum•May 31, 2023•19 citations

Contextuality of quantum non-demolition measurement via state discrimination

Min Namkung, Ilhwan Kim, Hyang-Tag Lim

Quantum non-demolition measurements facilitate various quantum technologies, including quantum communication. Notably, their operational structure can be replicated by a classical model--referred to as a noncontextual model--making it crucial to identify which features prevents such models from reproducing the corresponding quantum measurements. In this work, we theoretically demonstrate contextual features inherent in the structure of quantum non-demolition measurements. These features not only reveal the nonclassicality of unambiguous state discrimination, but also extend to sequential unambiguous discrimination and probabilistic quantum cloning, both of which involve post-measurement states. Moreover, our analysis extends to noisy scenarios, highlighting its potential relevance for practical implementations. We believe that our results broaden the scope of observing nonclassicality in quantum systems and ultimately contribute to the advancement of various quantum technologies.

quant-pharXiv:2603.27917•Mar 31, 2026•0 citations

Unambiguous discrimination of binary coherent states

Wenbin Yu, Zijia Xiong, Shanshan Rong +4 more

Considering quantum detection, there are two different ways to make a measurement on signals set. One is minimum error discrimination and another is unambiguous states discrimination. In this work, we study the unambiguous state discrimination of coherent states. The quantum measurement model investigated is based on binary signals. All necessary positive-operator valued measurements are established to implement the quantum measurements in non-ambiguity way. The conclusive probability and inconclusive probability for the unambiguous discrimination of both on-off keying and binary-phase-shifting keying modulations are derived rigorously to show the measurement performance of proposed detection method theoretically.

International Journal of Computational Science and Engineering•Jan 1, 2020•1 citation

Security of quantum key distribution with a laser reference coherent state, resistant to loss in the communication channel

S. N. Molotkov, T. A. Potapova

The problem of quantum key distribution security in channels with large losses is still open. Quasi-single-photon sources of quantum states with losses in the quantum communication channel open up the possibility of attacking with unambiguous state discrimination (USD) measurements, resulting in a loss of privacy. In this letter, the problem is solved by counting the classic reference pulses. Conservation of the number of counts of intense coherent pulses makes it impossible to conduct USD measurements. Moreover, the losses in the communication channel are considered to be unknown in advance and are subject to change throughout the series parcels. Unlike other protocols, differential phase shift (Inoue et al 2002 Phys. Rev. Lett. 89 037902, Inoue et al 2003 Phys. Rev. A 68 022317, Takesue et al 2007 Nat. Photon. 1 343, Wen et al 2009 Phys. Rev. Lett. 103 170503) and coherent one way (Stucki et al 2005 Appl. Phys. Lett. 87 194108, Branciard et al 2005 Appl. Phys. Lett. 87 194108, Branciard et al 2008 New J. Phys. 10 013031, Stucki et al 2008 Opt. Express 17 13326), the simplicity of the protocol makes it possible to carry out a complete analysis of its security.

Laser Physics Letters•Apr 23, 2015•6 citations

We thoroughly investigate the amplitude and phase fluctuations affect the performance of USD. We provide a comprehensive analysis insights into the limitations of USD in practical scenarios, making the findings relevant for real-world applications. By introducing a set of positive operator value measurements, we suggest a USD measurement for discriminating between to coherent states with the same amplitude and different phases. The model develops by setting orthogonal states, i.e., a superposition of the potential outputs, to discriminate two phases. However, as during the preparation of this signal from the laser beam, unavoidable errors occur which transform the output coherent signals into imperfect input signals. This imperfection can be modeled as fluctuation errors i.e., amplitude and phase fluctuations. We apply this model by considering the noise and study the impact of both the states on the USD measurement. This results in an error in the measurement making "perfect" USD to "imperfect" USD. We further stimulate and analyse the impact of both the errors and found out that the proposed method works for a certain window of intensity of light. It doesn’t provide us with desired results for lower amplitudes of light while for higher amplitudes the error in the measurement becomes too large making the measurement meaningless. This have implications on low-energy transmitters and practical implementations of USD, thereby, we address a significant gap in the literature regarding the applicability of quantum state discrimination methods in future quantum communication systems.

Coherent states of the quantum electromagnetic field, the quantum description of ideal laser light, are a prime candidate as information carriers for optical communications. A large body of literature exists on quantum-limited parameter estimation and discrimination for coherent states. However, very little is known about practical realizations of receivers for unambiguous state discrimination (USD) of coherent states. Here we fill this gap and establish a theory of unambiguous discrimination of coherent states, with receivers that are allowed to employ: passive multimode linear optics, phase-space displacements, un-excited auxiliary input modes, and on-off photon detection. Our results indicate that these currently-available optical components are near optimal for unambiguous discrimination of multiple coherent states in a constellation.

Considering quantum detection, there are two different ways to make a measurement on signals set. One is minimum error discrimination and another is unambiguous states discrimination. In this work, we study the unambiguous state discrimination of coherent states. The quantum measurement model investigated is based on binary signals. All necessary positive-operator valued measurements are established to implement the quantum measurements in non-ambiguity way. The conclusive probability and inconclusive probability for the unambiguous discrimination of both on-off keying and binary-phase-shifting keying modulations are derived rigorously to show the measurement performance of proposed detection method theoretically.

Coherent states of the quantum electromagnetic field, the quantum description of ideal laser light, are prime candidates as information carriers for optical communications. A large body of literature exists on their quantum-limited estimation and discrimination. However, very little is known about the practical realizations of receivers for unambiguous state discrimination (USD) of coherent states. Here we fill this gap and outline a theory of USD with receivers that are allowed to employ: passive multimode linear optics, phase-space displacements, auxiliary vacuum modes, and on-off photon detection. Our results indicate that, in some regimes, these currently-available optical components are typically sufficient to achieve near-optimal unambiguous discrimination of multiple, multimode coherent states.

Quantum non-demolition measurements facilitate various quantum technologies, including quantum communication. Notably, their operational structure can be replicated by a classical model--referred to as a noncontextual model--making it crucial to identify which features prevents such models from reproducing the corresponding quantum measurements. In this work, we theoretically demonstrate contextual features inherent in the structure of quantum non-demolition measurements. These features not only reveal the nonclassicality of unambiguous state discrimination, but also extend to sequential unambiguous discrimination and probabilistic quantum cloning, both of which involve post-measurement states. Moreover, our analysis extends to noisy scenarios, highlighting its potential relevance for practical implementations. We believe that our results broaden the scope of observing nonclassicality in quantum systems and ultimately contribute to the advancement of various quantum technologies.

Considering quantum detection, there are two different ways to make a measurement on signals set. One is minimum error discrimination and another is unambiguous states discrimination. In this work, we study the unambiguous state discrimination of coherent states. The quantum measurement model investigated is based on binary signals. All necessary positive-operator valued measurements are established to implement the quantum measurements in non-ambiguity way. The conclusive probability and inconclusive probability for the unambiguous discrimination of both on-off keying and binary-phase-shifting keying modulations are derived rigorously to show the measurement performance of proposed detection method theoretically.

The problem of quantum key distribution security in channels with large losses is still open. Quasi-single-photon sources of quantum states with losses in the quantum communication channel open up the possibility of attacking with unambiguous state discrimination (USD) measurements, resulting in a loss of privacy. In this letter, the problem is solved by counting the classic reference pulses. Conservation of the number of counts of intense coherent pulses makes it impossible to conduct USD measurements. Moreover, the losses in the communication channel are considered to be unknown in advance and are subject to change throughout the series parcels. Unlike other protocols, differential phase shift (Inoue et al 2002 Phys. Rev. Lett. 89 037902, Inoue et al 2003 Phys. Rev. A 68 022317, Takesue et al 2007 Nat. Photon. 1 343, Wen et al 2009 Phys. Rev. Lett. 103 170503) and coherent one way (Stucki et al 2005 Appl. Phys. Lett. 87 194108, Branciard et al 2005 Appl. Phys. Lett. 87 194108, Branciard et al 2008 New J. Phys. 10 013031, Stucki et al 2008 Opt. Express 17 13326), the simplicity of the protocol makes it possible to carry out a complete analysis of its security.