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

arXiv:2604.02081 · Physical Review A

Photonic qubit encoding interconversion for heterogeneous quantum networking

Vedansh Nehra, Richard J. Birrittella, Christopher C. Tison, Benjamin K. Malia, Zachary S. Smith, Dylan Heberle, Nicholas J. Barton, Amos Matthew Smith, Andrew Brownell, Michael L. Fanto, James Schneeloch, Erin Sheridan, David Hucul

quant-phSubmitted Apr 2, 2026• Announced Apr 3, 2026• 0 citations
arXivHTMLPDF

Abstract

Quantum information processing, communication, and sensing networks are being developed with various qubit platforms that use different encoding schemes. Connecting quantum network nodes to distribute entanglement requires matching photon qubit basis encoding. In this work, we implement an interconversion protocol which converts photon qubit encoding from the polarization basis to the time-bin basis, transmits the photons through a transport fiber with large fluctuations in polarization, and converts back to polarization encoding for ease of measurement. This interconversion scheme faithfully transmits a polarization Bell state across the transport fiber by converting sources of infidelity to changes in transmission rate. These results illustrate a practical approach for interfacing distinct qubit platforms to enable modular and flexible operation in heterogeneous quantum networks.

Related papers

Telecom-compatible polarization-to-time-bin conversion of atom-photon entanglement for heterogeneous quantum networks

Christian Haen, Julian Groß-Funk, Max Bergerhoff +5 more

A key enabling feature of future quantum networks is interoperability between platforms that operate at different wavelengths and with different qubit encodings. We demonstrate an interface that converts atom-photon entanglement from polarization encoding at an atomic wavelength to time-bin encoding in the telecom C-band. Atom-entangled photons at 854 nm are generated from a single $^{40}$Ca$^+$ ion. After quantum frequency conversion to 1550 nm, the photonic polarization qubit is converted into a time-bin qubit using a fiber-based Mach--Zehnder-like encoder. Full quantum tomography of the final state verifies that the process preserves entanglement with 96.3(4.2)% fidelity. Together with the independent work of Ferrari et al. [arXiv:2607.07805 (2026)], this is the first demonstration of polarization-to-time-bin conversion of photons entangled with a single atomic quantum memory. The telecom-compatible interface enables robust qubit transmission over optical fibers and provides a key building block for heterogeneous quantum networking architectures.

quant-pharXiv:2607.29609•Aug 3, 2026•0 citations

Robust Ion-Photon Entanglement via Polarization-to-Time-Bin Conversion

Ana Luiza Ferrari, Denton Wu, Mika A. Zalewski +1 more

Time-bin photonic qubits are well-suited for quantum network applications due to their robustness to polarization instability in fiber links and potential for heterogeneous networks. In this work, we implement the first entanglement-preserving polarization-to-time-bin conversion of a photon qubit in an entangled state with a matter qubit, together with the independent work of Haen \textit{et al.} \cite{haen2026telecom}. Photons initially generated with polarization encoding are converted to the time-bin basis through a polarization-discriminating asymmetric Mach--Zehnder interferometer. The photonic qubits are generated via the $1092$~nm transition of a $^{88}$Sr$^{+}$ ion. We measure state fidelity bounds of $0.906 \pm 0.011 \le \mathcal{F} \le 0.934\pm 0.011$, with conversion error $< 0.028$, and find this fidelity shows no statistically significant reduction under depolarizing noise, even at full depolarization strength.

quant-pharXiv:2607.07805•Jul 10, 2026•0 citations

Time-bin-to-polarization conversion of ultrafast photonic qubits

Connor Kupchak, Philip J. Bustard, Khabat Heshami +4 more

The encoding of quantum information in photonic time-bin qubits is apt for long-distance quantum communication schemes. In practice, due to technical constraints such as detector response time, or the speed with which copolarized time-bins can be switched, other encodings, e.g., polarization, are often preferred for operations like state detection. Here, we present the conversion of qubits between polarization and time-bin encodings by using a method that is based on an ultrafast optical Kerr shutter and attain efficiencies of 97% and an average fidelity of $0.827\ifmmode\pm\else\textpm\fi{}0.003$ with shutter speeds near 1 ps. Our demonstration delineates an essential requirement for the development of hybrid and high-rate optical quantum networks.

arXiv:1708.07145•Physical Review A•Nov 6, 2017•34 citations

Encoding converters for quantum communication networks

Huaxing Xu, Shaohua Wang, Yaqi Song +2 more

Abstract Quantum communication networks, such as quantum key distribution (QKD) networks, typically employ the measurement-resend mechanism between two users using quantum communication devices based on different quantum encoding types. To achieve direct communication between the devices with different quantum encoding types, in this paper, we propose encoding conversion schemes between the polarization bases (rectilinear, diagonal and circular bases) and the time-bin phase bases (two phase bases and time-bin basis) and design the quantum encoding converters. The theoretical analysis of the encoding conversion schemes is given in detail, and the basis correspondence of encoding conversion and the property of bit flip are revealed. The conversion relationship between polarization bases and time-bin phase bases can be easily selected by controlling a phase shifter. Since no optical switches are used in our scheme, the converter can be operated with high speed. The converters can also be modularized, which may be utilized to realize miniaturization in the future.

Chinese Physics B•Apr 17, 2025•1 citation

Connecting heterogeneous quantum networks by hybrid entanglement swapping

Giovanni Guccione, Tom Darras, Hanna Le Jeannic +4 more

Recent advances in quantum technologies are rapidly stimulating the building of quantum networks. With the parallel development of multiple physical platforms and different types of encodings, a challenge for present and future networks is to uphold a heterogeneous structure for full functionality and therefore support modular systems that are not necessarily compatible with one another. Central to this endeavor is the capability to distribute and interconnect optical entangled states relying on different discrete and continuous quantum variables. Here, we report an entanglement swapping protocol connecting such entangled states. We generate single-photon entanglement and hybrid entanglement between particle- and wave-like optical qubits and then demonstrate the heralded creation of hybrid entanglement at a distance by using a specific Bell-state measurement. This ability opens up the prospect of connecting heterogeneous nodes of a network, with the promise of increased integration and novel functionalities.

arXiv:2003.11041•Science Advances•May 29, 2020•96 citations

Network converter of photonic qubits between phase-frequency and polarization encodings

K. S. Melnik, Mansur M. Minnegaliev, Sergey A. Moiseev

Abstract The conversion of photonic qubits between different physical encodings is a necessary condition for the creation of hybrid quantum networks. We propose and demonstrate a network scheme for a photonic qubit state converter from phase-frequency to polarization encoding, implemented in a Sagnac loop topology over a distance of 25 km. The obtained results of photonic qubit conversion with a fidelity of ( 0.99 ± 0.01 ) open up the possibility of creating photonic qubit converters that are more resistant to external noise and can be integrated into a subcarrier wave quantum communication network with independent detection.

Laser Physics Letters•Jul 1, 2026•0 citations
Quantum information processing, communication, and sensing networks are being developed with various qubit platforms that use different encoding schemes. Connecting quantum network nodes to distribute entanglement requires matching photon qubit basis encoding. In this work, we implement an interconversion protocol which converts photon qubit encoding from the polarization basis to the time-bin basis, transmits the photons through a transport fiber with large fluctuations in polarization, and converts back to polarization encoding for ease of measurement. This interconversion scheme faithfully transmits a polarization Bell state across the transport fiber by converting sources of infidelity to changes in transmission rate. These results illustrate a practical approach for interfacing distinct qubit platforms to enable modular and flexible operation in heterogeneous quantum networks.
A key enabling feature of future quantum networks is interoperability between platforms that operate at different wavelengths and with different qubit encodings. We demonstrate an interface that converts atom-photon entanglement from polarization encoding at an atomic wavelength to time-bin encoding in the telecom C-band. Atom-entangled photons at 854 nm are generated from a single 40^{40}40Ca+^++ ion. After quantum frequency conversion to 1550 nm, the photonic polarization qubit is converted into a time-bin qubit using a fiber-based Mach--Zehnder-like encoder. Full quantum tomography of the final state verifies that the process preserves entanglement with 96.3(4.2)% fidelity. Together with the independent work of Ferrari et al. [arXiv:2607.07805 (2026)], this is the first demonstration of polarization-to-time-bin conversion of photons entangled with a single atomic quantum memory. The telecom-compatible interface enables robust qubit transmission over optical fibers and provides a key building block for heterogeneous quantum networking architectures.
Time-bin photonic qubits are well-suited for quantum network applications due to their robustness to polarization instability in fiber links and potential for heterogeneous networks. In this work, we implement the first entanglement-preserving polarization-to-time-bin conversion of a photon qubit in an entangled state with a matter qubit, together with the independent work of Haen \textit{et al.} \cite{haen2026telecom}. Photons initially generated with polarization encoding are converted to the time-bin basis through a polarization-discriminating asymmetric Mach--Zehnder interferometer. The photonic qubits are generated via the 109210921092~nm transition of a 88^{88}88Sr+^{+}+ ion. We measure state fidelity bounds of 0.906±0.011≤F≤0.934±0.0110.906 \pm 0.011 \le \mathcal{F} \le 0.934\pm 0.0110.906±0.011≤F≤0.934±0.011, with conversion error <0.028< 0.028<0.028, and find this fidelity shows no statistically significant reduction under depolarizing noise, even at full depolarization strength.
The encoding of quantum information in photonic time-bin qubits is apt for long-distance quantum communication schemes. In practice, due to technical constraints such as detector response time, or the speed with which copolarized time-bins can be switched, other encodings, e.g., polarization, are often preferred for operations like state detection. Here, we present the conversion of qubits between polarization and time-bin encodings by using a method that is based on an ultrafast optical Kerr shutter and attain efficiencies of 97% and an average fidelity of $0.827\ifmmode\pm\else\textpm\fi{}0.003$ with shutter speeds near 1 ps. Our demonstration delineates an essential requirement for the development of hybrid and high-rate optical quantum networks.
Abstract Quantum communication networks, such as quantum key distribution (QKD) networks, typically employ the measurement-resend mechanism between two users using quantum communication devices based on different quantum encoding types. To achieve direct communication between the devices with different quantum encoding types, in this paper, we propose encoding conversion schemes between the polarization bases (rectilinear, diagonal and circular bases) and the time-bin phase bases (two phase bases and time-bin basis) and design the quantum encoding converters. The theoretical analysis of the encoding conversion schemes is given in detail, and the basis correspondence of encoding conversion and the property of bit flip are revealed. The conversion relationship between polarization bases and time-bin phase bases can be easily selected by controlling a phase shifter. Since no optical switches are used in our scheme, the converter can be operated with high speed. The converters can also be modularized, which may be utilized to realize miniaturization in the future.
Recent advances in quantum technologies are rapidly stimulating the building of quantum networks. With the parallel development of multiple physical platforms and different types of encodings, a challenge for present and future networks is to uphold a heterogeneous structure for full functionality and therefore support modular systems that are not necessarily compatible with one another. Central to this endeavor is the capability to distribute and interconnect optical entangled states relying on different discrete and continuous quantum variables. Here, we report an entanglement swapping protocol connecting such entangled states. We generate single-photon entanglement and hybrid entanglement between particle- and wave-like optical qubits and then demonstrate the heralded creation of hybrid entanglement at a distance by using a specific Bell-state measurement. This ability opens up the prospect of connecting heterogeneous nodes of a network, with the promise of increased integration and novel functionalities.
Abstract The conversion of photonic qubits between different physical encodings is a necessary condition for the creation of hybrid quantum networks. We propose and demonstrate a network scheme for a photonic qubit state converter from phase-frequency to polarization encoding, implemented in a Sagnac loop topology over a distance of 25 km. The obtained results of photonic qubit conversion with a fidelity of ( 0.99 ± 0.01 ) open up the possibility of creating photonic qubit converters that are more resistant to external noise and can be integrated into a subcarrier wave quantum communication network with independent detection.