© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

Chinese Physics B

Generation of polarization-entangled photon pairs in higher-order spatial mode using a mode-maintaining few-mode fiber

Sheng-Jie Zhu, Liang Cui, Xiao-Ying Li

Published May 20, 2026• 0 citations

Abstract

Abstract The spatial degree of freedom has enabled a wide range of applications in quantum information processing (QIP), such as increasing the capacity of quantum channels and realizing novel QIP protocols. In such applications, generating and manipulating quantum states in different spatial modes is one of the primary tasks. In this paper, by utilizing a telecom-band panda-type mode-maintaining few-mode fiber (MM-FMF) with a Sagnac loop configuration, we generate polarization-entangled photon pairs in higher-order spatial modes, namely the LP 11 modes, via intermodal spontaneous four-wave mixing process. The polarization- and spatial-mode-maintaining capabilities of the MM-FMF, combined with the automatic phase-stabilization of the Sagnac loop, provide a robust architecture for entanglement generation. We verify the polarization entanglement by two-photon interference measurements, yielding raw visibilities exceeding 76%. The visibilities are mainly limited by spontaneous Raman scattering noise, which could be reduced by cooling the fiber. The photon pairs directly emerging from MM-FMF are in a well-defined spatial mode, which greatly facilitates further manipulation and transmission of the entanglement. Our work demonstrates that the MM-FMF is a robust platform for developing devices and protocols exploiting the spatial degree of freedom in QIP applications.

DOI: 10.1088/1674-1056/ae7064

Related papers

Generation and transformation of spatial mode entanglement by using a mode-maintaining few-mode fiber

Shengjie Zhu, Liang Cui, Jian Guo +3 more

The spatial degree of freedom (DOF) has significant applications in the emerging high-dimensional quantum information processing. Using a mode-maintaining few-mode fiber (FMF) and a dual-Sagnac-loop configuration, we generate polarization-entangled photon pairs and transform the entanglement into spatial DOF. We obtain Bell states encoded in the linearly polarized (LP) and orbital angular momentum (OAM) mode bases, respectively. The entangled photons from the FMF are in well-defined spatial modes, providing great advantages for the entanglement generation, manipulation, and transmission. The measured fidelities of the obtained entangled states are more than 97%. Our generation-and-transformation protocol can also be adopted on other integrated waveguide platforms to develop robust and miniaturized sources of spatial entanglement.

Optics Letters•Mar 9, 2026•1 citation

Polarization-entangled photon pairs in the visible spectral band using intermodal spontaneous four-wave mixing

Ju Han Lee, Kyungtaek Lee, Junha Jung

Abstract The theoretical and experimental investigation results of the generation of the polarization-entangled photon pairs operating at visible wavelengths are reported. The generation of polarization-entangled photon pairs was based on intermodal spontaneous four-wave mixing (IM-SFWM) using standard step-index few-mode fiber. It was shown theoretically that several combinations of IM-SFWM processes could occur depending on spatial modes of a pump beam. A polarization-entangled photon pair source based on Sagnac loop incorporating a segment of few-mode fiber were then experimentally created. A two-photon interference fringe visibility of our implemented photon pair source were 91.7% and 88.8% in H/V bases and D/A bases, respectively. A quantum state tomography was also conducted to reconstruct the density matrix of the generated state with a fidelity to a maximum entangled state of 93.1%.

•Mar 29, 2022•0 citations

Optical fiber polarization-entangled photon pair source using intermodal spontaneous four-wave mixing in the visible spectral band

K Lee, Jae‐Sun Jung, J H Lee

Abstract The theoretical and experimental investigation results of the generation of the polarization-entangled photon pairs operating at visible wavelengths are reported. The generation of polarization-entangled photon pairs was based on intermodal spontaneous four-wave mixing (IM-SFWM) using standard step-index few-mode fiber. It was shown theoretically that several combinations of IM-SFWM processes could occur depending on spatial modes of a pump beam. A polarization-entangled photon pair source based on Sagnac loop incorporating a segment of few-mode fiber were then experimentally created. A two-photon interference fringe visibility of our implemented photon pair source were 91.7% and 88.8% in H/V bases and D/A bases, respectively. A quantum state tomography was also conducted to reconstruct the density matrix of the generated state with a fidelity to a maximum entangled state of 93.1%.

Laser Physics Letters•Dec 13, 2022•4 citations

Generation of polarization entangled photon pairs by using polarization- and transverse-mode maintaining few-mode fiber

Shengjie Zhu, Liang Cui, Xiaoying Li

Polarization entangled signal and idler photons in the higher-order LP11a and LP11b modes, respectively, are generated via inter-spatial-mode spontaneous four-wave mixing in a 17-m-long mode maintaining few-mode fiber with a panda type elliptical core.

•Jan 1, 2025•0 citations

Fiber-based frequency-degenerate polarization entangled photon pair sources for information encoding

Feng Zhu, Wei Zhang, Yidong Huang

In this paper, a generation scheme of telecom band frequency-degenerate polarization entangled photon pairs is proposed and demonstrated experimentally. It is based on the vector spontaneous four wave mixing (SFWM) process in a Sagnac fiber loop, in which two frequency-degenerate and polarization orthogonal biphoton states have equal probabilities for generating along the clockwise and counter-clockwise directions. The quantum interference between them at the 50:50 fiber coupler of the fiber loop separates the two frequency-degenerate photons in a pair, leading to the generation of polarization entanglement. The raw fringe visibilities of the two-photon interferences under two non-orthogonal polarization bases are 91% and 90%, respectively. Information can be encoded on the generated photon pairs using the polarization entangled Bell states, which requires the frequency-degenerate property. It is demonstrated by a simplified Bell state measurement with a fringe visibility of 83%.

Optics Express•Oct 25, 2016•17 citations

Fiber-based frequency-degenerate polarization-entanglement photon pair sources for information encoding

Feng Zhu, Wei Zhang, Yidong Huang

We propose and experimentally demonstrate a generation scheme of telecom-band fiber-based frequency-degenerate polarization-entanglement photon pair source. Basing on the vector spontaneous four wave mixing process in a Sagnac fiber loop along the clockwise and counter-clockwise directions, two frequency-degenerate and polarization orthogonal biphoton states generate and then lead to the polarization entanglement states by the interference at the beamsplitter. The raw fringe visibilities of the two-photon interferences are 97% and 92%, respectively. Information can be encoded on the generated photon pairs using the polarization entangled Bell states. It is demonstrated by a simplified Bell state measurement with a fringe visibility of 83%.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Nov 3, 2016•0 citations

Abstract The spatial degree of freedom has enabled a wide range of applications in quantum information processing (QIP), such as increasing the capacity of quantum channels and realizing novel QIP protocols. In such applications, generating and manipulating quantum states in different spatial modes is one of the primary tasks. In this paper, by utilizing a telecom-band panda-type mode-maintaining few-mode fiber (MM-FMF) with a Sagnac loop configuration, we generate polarization-entangled photon pairs in higher-order spatial modes, namely the LP 11 modes, via intermodal spontaneous four-wave mixing process. The polarization- and spatial-mode-maintaining capabilities of the MM-FMF, combined with the automatic phase-stabilization of the Sagnac loop, provide a robust architecture for entanglement generation. We verify the polarization entanglement by two-photon interference measurements, yielding raw visibilities exceeding 76%. The visibilities are mainly limited by spontaneous Raman scattering noise, which could be reduced by cooling the fiber. The photon pairs directly emerging from MM-FMF are in a well-defined spatial mode, which greatly facilitates further manipulation and transmission of the entanglement. Our work demonstrates that the MM-FMF is a robust platform for developing devices and protocols exploiting the spatial degree of freedom in QIP applications.

The spatial degree of freedom (DOF) has significant applications in the emerging high-dimensional quantum information processing. Using a mode-maintaining few-mode fiber (FMF) and a dual-Sagnac-loop configuration, we generate polarization-entangled photon pairs and transform the entanglement into spatial DOF. We obtain Bell states encoded in the linearly polarized (LP) and orbital angular momentum (OAM) mode bases, respectively. The entangled photons from the FMF are in well-defined spatial modes, providing great advantages for the entanglement generation, manipulation, and transmission. The measured fidelities of the obtained entangled states are more than 97%. Our generation-and-transformation protocol can also be adopted on other integrated waveguide platforms to develop robust and miniaturized sources of spatial entanglement.

Abstract The theoretical and experimental investigation results of the generation of the polarization-entangled photon pairs operating at visible wavelengths are reported. The generation of polarization-entangled photon pairs was based on intermodal spontaneous four-wave mixing (IM-SFWM) using standard step-index few-mode fiber. It was shown theoretically that several combinations of IM-SFWM processes could occur depending on spatial modes of a pump beam. A polarization-entangled photon pair source based on Sagnac loop incorporating a segment of few-mode fiber were then experimentally created. A two-photon interference fringe visibility of our implemented photon pair source were 91.7% and 88.8% in H/V bases and D/A bases, respectively. A quantum state tomography was also conducted to reconstruct the density matrix of the generated state with a fidelity to a maximum entangled state of 93.1%.

Abstract The theoretical and experimental investigation results of the generation of the polarization-entangled photon pairs operating at visible wavelengths are reported. The generation of polarization-entangled photon pairs was based on intermodal spontaneous four-wave mixing (IM-SFWM) using standard step-index few-mode fiber. It was shown theoretically that several combinations of IM-SFWM processes could occur depending on spatial modes of a pump beam. A polarization-entangled photon pair source based on Sagnac loop incorporating a segment of few-mode fiber were then experimentally created. A two-photon interference fringe visibility of our implemented photon pair source were 91.7% and 88.8% in H/V bases and D/A bases, respectively. A quantum state tomography was also conducted to reconstruct the density matrix of the generated state with a fidelity to a maximum entangled state of 93.1%.

In this paper, a generation scheme of telecom band frequency-degenerate polarization entangled photon pairs is proposed and demonstrated experimentally. It is based on the vector spontaneous four wave mixing (SFWM) process in a Sagnac fiber loop, in which two frequency-degenerate and polarization orthogonal biphoton states have equal probabilities for generating along the clockwise and counter-clockwise directions. The quantum interference between them at the 50:50 fiber coupler of the fiber loop separates the two frequency-degenerate photons in a pair, leading to the generation of polarization entanglement. The raw fringe visibilities of the two-photon interferences under two non-orthogonal polarization bases are 91% and 90%, respectively. Information can be encoded on the generated photon pairs using the polarization entangled Bell states, which requires the frequency-degenerate property. It is demonstrated by a simplified Bell state measurement with a fringe visibility of 83%.

We propose and experimentally demonstrate a generation scheme of telecom-band fiber-based frequency-degenerate polarization-entanglement photon pair source. Basing on the vector spontaneous four wave mixing process in a Sagnac fiber loop along the clockwise and counter-clockwise directions, two frequency-degenerate and polarization orthogonal biphoton states generate and then lead to the polarization entanglement states by the interference at the beamsplitter. The raw fringe visibilities of the two-photon interferences are 97% and 92%, respectively. Information can be encoded on the generated photon pairs using the polarization entangled Bell states. It is demonstrated by a simplified Bell state measurement with a fringe visibility of 83%.