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

Optica

Direct and efficient verification of entanglement between two multimode–multiphoton systems

Takayuki Kiyohara, Naoki Yamashiro, Ryo Okamoto, Hirotaka Araki, Jun-Yi Wu, Holger Friedrich Hofmann, Shigeki Takeuchi

Published Sep 30, 2020• 7 citations
Publisher

Abstract

Linear-optic photonic networks with multiple single-photon inputs are attracting attention due to their great potential for quantum computation, quantum communication, and quantum sensing. They are also essential for verifying quantum advantages via boson sampling schemes. The quantum coherence of generated multimode–multiphoton states is crucial for various applications. However, the coherence is invisible in the normally obtained photon number distributions, which strictly limits the efficiency of entanglement verification between multimode–multiphoton systems since the required resources for quantum state tomography increase exponentially as the number of photons/modes increases. In this paper, we report the experimental demonstration of direct and efficient verification of entanglement between two multimode–multiphoton systems (one photon in three modes and two photons in three modes) using just two sets of classical correlation tables with and without a discrete Fourier transformation of the optical modes, clearly demonstrating a dramatic reduction in the resources required for entanglement verification. Our experimental demonstration paves the way to understanding the coherence and entanglement of multi-partite systems, not only for photons but for other quantum resources with high-dimensional degrees of freedom.

DOI
10.1364/optica.397943

Related papers

Efficient generation and evaluation of single photons propagating in the multiple optical modes

Shigeki Takeuchi, Takayuki Kiyohara, Ryo Okamoto

In this talk, we report the experimental demonstration of direct and efficient verification of entanglement between two multimode-multiphoton systems (one photon in three modes and two photons in three modes) using just two sets of classical correlation tables with and without a discrete Fourier transformation of the optical modes, clearly demonstrating a dramatic reduction in the resources required for entanglement verification. We will also report a novel method to produce a multi-photon parallel state efficiently with reducing excess photon components using multiple heralding single photon sources and N x N active optical switch.

Quantum Computing, Communication, and Simulation•Mar 9, 2022•0 citations

Efficient analysis of entangled photons and single photons

Shigeki Takeuchi

Efficient analysis of the quantum states of photons are essential for photonic quantum technologies. In the first part, we report the experimental demonstration of direct and efficient verification of entanglement between two multimode-multiphoton systems (one photon in three modes and two photons in three modes) using just two sets of classical correlation tables with and without a discrete Fourier transformation of the optical modes, clearly demonstrating a dramatic reduction in the resources required for entanglement verification. In the second part, we report our experimental demonstration of adaptive quantum state estimation for quantum states of photons changing in time.

Quantum Communications and Quantum Imaging•Jul 30, 2021•0 citations

Generation and evaluation of entanglement between two multi-photon systems using single photon sources and linear optics

Jun-Yi Wu, Holger Friedrich Hofmann

Single photon sources can be used to generate and control highly non-classical states of light. Here, we consider the possibility of generating bi-partite entanglement between two separate multi-photon states by splitting the input modes of the single photon sources into a mode distributed to $A$ and a mode distributed to $B$. If multiple photons are combined at $A$ and at $B$, the large variety of photon patterns observed after linear optics transformations of the local multi-mode systems can be used to characterize the non-classical correlation of this entangled state. However, the transformation between different photon number states in linear optics is a complicated problem, and further analysis is needed to understand the possible applications of this scalable quantum system. To obtain maximal complementarity between two measurements, we consider the unbiased interference of all input modes represented by a discrete Fourier transform of the multi-mode field. We identify characteristic patterns that can be used to identify non-classical correlations between the two multi-photon systems at $A$ and $B$ and derive a quantitative criterion for entanglement verification. Our results indicate that the large scale quantum operations can be achieved by a comparatively simple quantum network interfering the outputs of multiple single photons, where the size of the system mainly depends on the number of available single photon sources.

•Sep 8, 2016•0 citations

Photon number statistics of entanglement generated by multiple single photon sources

Jun-Yi Wu, Holger Friedrich Hofmann

Multiphoton interference results in a wide variety of non-classical photon number statistics, including characteristic signatures of entanglement between two or more sets of optical modes. Here, we consider the photon number statistics observed after applying discrete Fourier transformations (DFTs) to bipartite entangled states generated using single photon sources and beam splitters. It is shown that the output photon number states of DFTs are eigenstates of a translational mode shifting operator in the input. The complex eigenvalues of the mode shift can be identified by a phase number K obtained from the output photon distribution. For each output distribution, the possible input states are limited to mode shift eigenstates with the same K-value. Using this mode shift rule, we can identify the quantum coherence between different photon number distributions in the input with experimentally observable K-values in the output of the DFT. In the case of multi-photon entanglement obtained by post-selection and beam splitting single photons, this coherence is non-local, resulting in correlated pairs of K-values that always sum up to zero. We can therefore observe both the correlations between the input photon number distributions and a complementary correlation between the output photon numbers of two DFTs to obtain a reliable characterization of the entanglement between the two multi-mode multi-photon systems. Importantly, the K-value allows a classification of large sets of possible photon number distributions, resulting in a significant simplification of the experimental evaluation of the multi-photon output statistics and opening up the road towards more efficient applications of non-classical multi-photon states

Quantum Communications and Quantum Imaging•Aug 30, 2017•0 citations

Evaluation of bipartite entanglement between two optical multi-mode systems using mode translation symmetry

Jun-Yi Wu, Holger Friedrich Hofmann

Optical multi-mode systems provide large scale Hilbert spaces that can be accessed and controlled using single photon sources, linear optics and photon detection. Here, we consider the bipartite entanglement generated by coherently distributing M photons in M modes to two separate locations, where linear optics and photon detection is used to verify the non-classical correlations between the two M -mode systems. We show that the entangled state is symmetric under mode shift operations performed in the two systems and use this symmetry to derive correlations between photon number distributions detected after a discrete Fourier transform (DFT) of the modes. The experimentally observable correlations can be explained by a simple and intuitive rule that relates the sum of the output mode indices to the eigenvalue of the input state under the mode shift operation. Since the photon number operators after the DFT do not commute with the initial photon number operators, entanglement is necessary to achieve strong correlations in both the initial mode photon numbers and the photon numbers observed after the DFT. We can therefore derive entanglement witnesses based on the experimentally observable correlations in both photon number distributions, providing a practical criterion for the evaluation of large scale entanglement in optical multi-mode systems. Our method thus demonstrates how non-classical signatures in large scale optical quantum circuits can be accessed experimentally by choosing an appropriate combination of modes in which to detect the photon number distributions that characterize the quantum coherences of the state.

arXiv:1609.02239•New Journal of Physics•Aug 22, 2017•8 citations

Realization of photon correlations beyond the linear optics limit

Geobae Park, Issei Matsumoto, Takayuki Kiyohara +3 more

Linear optical transformations of multiple single-photon inputs are fundamental for the development of photonic quantum technologies. Various nonclassical correlations can already be observed directly in states generated using only single-photon inputs and linear optics transformations. However, some quantum correlations require additional operations, and states that exhibit such correlations are classified as non-Fock states. Here, we demonstrate the generation of a two-photon three-mode non-Fock state that exhibits conditional quantum coherences that can only be achieved by non-Fock states. We determine the fidelity of the non-Fock state based on experimentally observed conditional visibilities that characterize the state and compare the result to the fidelity bounds for different classes of Fock and non-Fock states. Our experimental verification of the non-Fock character of the state provides insights into the technological requirements needed to achieve nonclassical correlations in multiphoton quantum optics.

Science Advances•Dec 22, 2023•8 citations
Linear-optic photonic networks with multiple single-photon inputs are attracting attention due to their great potential for quantum computation, quantum communication, and quantum sensing. They are also essential for verifying quantum advantages via boson sampling schemes. The quantum coherence of generated multimode–multiphoton states is crucial for various applications. However, the coherence is invisible in the normally obtained photon number distributions, which strictly limits the efficiency of entanglement verification between multimode–multiphoton systems since the required resources for quantum state tomography increase exponentially as the number of photons/modes increases. In this paper, we report the experimental demonstration of direct and efficient verification of entanglement between two multimode–multiphoton systems (one photon in three modes and two photons in three modes) using just two sets of classical correlation tables with and without a discrete Fourier transformation of the optical modes, clearly demonstrating a dramatic reduction in the resources required for entanglement verification. Our experimental demonstration paves the way to understanding the coherence and entanglement of multi-partite systems, not only for photons but for other quantum resources with high-dimensional degrees of freedom.
In this talk, we report the experimental demonstration of direct and efficient verification of entanglement between two multimode-multiphoton systems (one photon in three modes and two photons in three modes) using just two sets of classical correlation tables with and without a discrete Fourier transformation of the optical modes, clearly demonstrating a dramatic reduction in the resources required for entanglement verification. We will also report a novel method to produce a multi-photon parallel state efficiently with reducing excess photon components using multiple heralding single photon sources and N x N active optical switch.
Efficient analysis of the quantum states of photons are essential for photonic quantum technologies. In the first part, we report the experimental demonstration of direct and efficient verification of entanglement between two multimode-multiphoton systems (one photon in three modes and two photons in three modes) using just two sets of classical correlation tables with and without a discrete Fourier transformation of the optical modes, clearly demonstrating a dramatic reduction in the resources required for entanglement verification. In the second part, we report our experimental demonstration of adaptive quantum state estimation for quantum states of photons changing in time.
Single photon sources can be used to generate and control highly non-classical states of light. Here, we consider the possibility of generating bi-partite entanglement between two separate multi-photon states by splitting the input modes of the single photon sources into a mode distributed to AAA and a mode distributed to BBB. If multiple photons are combined at AAA and at BBB, the large variety of photon patterns observed after linear optics transformations of the local multi-mode systems can be used to characterize the non-classical correlation of this entangled state. However, the transformation between different photon number states in linear optics is a complicated problem, and further analysis is needed to understand the possible applications of this scalable quantum system. To obtain maximal complementarity between two measurements, we consider the unbiased interference of all input modes represented by a discrete Fourier transform of the multi-mode field. We identify characteristic patterns that can be used to identify non-classical correlations between the two multi-photon systems at AAA and BBB and derive a quantitative criterion for entanglement verification. Our results indicate that the large scale quantum operations can be achieved by a comparatively simple quantum network interfering the outputs of multiple single photons, where the size of the system mainly depends on the number of available single photon sources.
Multiphoton interference results in a wide variety of non-classical photon number statistics, including characteristic signatures of entanglement between two or more sets of optical modes. Here, we consider the photon number statistics observed after applying discrete Fourier transformations (DFTs) to bipartite entangled states generated using single photon sources and beam splitters. It is shown that the output photon number states of DFTs are eigenstates of a translational mode shifting operator in the input. The complex eigenvalues of the mode shift can be identified by a phase number K obtained from the output photon distribution. For each output distribution, the possible input states are limited to mode shift eigenstates with the same K-value. Using this mode shift rule, we can identify the quantum coherence between different photon number distributions in the input with experimentally observable K-values in the output of the DFT. In the case of multi-photon entanglement obtained by post-selection and beam splitting single photons, this coherence is non-local, resulting in correlated pairs of K-values that always sum up to zero. We can therefore observe both the correlations between the input photon number distributions and a complementary correlation between the output photon numbers of two DFTs to obtain a reliable characterization of the entanglement between the two multi-mode multi-photon systems. Importantly, the K-value allows a classification of large sets of possible photon number distributions, resulting in a significant simplification of the experimental evaluation of the multi-photon output statistics and opening up the road towards more efficient applications of non-classical multi-photon states
Optical multi-mode systems provide large scale Hilbert spaces that can be accessed and controlled using single photon sources, linear optics and photon detection. Here, we consider the bipartite entanglement generated by coherently distributing M photons in M modes to two separate locations, where linear optics and photon detection is used to verify the non-classical correlations between the two M -mode systems. We show that the entangled state is symmetric under mode shift operations performed in the two systems and use this symmetry to derive correlations between photon number distributions detected after a discrete Fourier transform (DFT) of the modes. The experimentally observable correlations can be explained by a simple and intuitive rule that relates the sum of the output mode indices to the eigenvalue of the input state under the mode shift operation. Since the photon number operators after the DFT do not commute with the initial photon number operators, entanglement is necessary to achieve strong correlations in both the initial mode photon numbers and the photon numbers observed after the DFT. We can therefore derive entanglement witnesses based on the experimentally observable correlations in both photon number distributions, providing a practical criterion for the evaluation of large scale entanglement in optical multi-mode systems. Our method thus demonstrates how non-classical signatures in large scale optical quantum circuits can be accessed experimentally by choosing an appropriate combination of modes in which to detect the photon number distributions that characterize the quantum coherences of the state.
Linear optical transformations of multiple single-photon inputs are fundamental for the development of photonic quantum technologies. Various nonclassical correlations can already be observed directly in states generated using only single-photon inputs and linear optics transformations. However, some quantum correlations require additional operations, and states that exhibit such correlations are classified as non-Fock states. Here, we demonstrate the generation of a two-photon three-mode non-Fock state that exhibits conditional quantum coherences that can only be achieved by non-Fock states. We determine the fidelity of the non-Fock state based on experimentally observed conditional visibilities that characterize the state and compare the result to the fidelity bounds for different classes of Fock and non-Fock states. Our experimental verification of the non-Fock character of the state provides insights into the technological requirements needed to achieve nonclassical correlations in multiphoton quantum optics.