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:2501.18704 · Physical Review Letters

Uniting Quantum Processing Nodes of Cavity-Coupled Ions with Rare-Earth Quantum Repeaters Using Single-Photon Pulse Shaping Based on Atomic Frequency Comb

Pierre Cussenot, B. Grivet, Leo Feldmann, Sören Wengerowsky, B. P. Lanyon, Tracy E. Northup, Hugues de Riedmatten, Anders Søndberg Sørensen, Nicolas Sangouard

Published Nov 10, 2025• 7 citations
arXivHTMLPDF

Abstract

We present an architecture for remotely connecting cavity-coupled trapped ions via a quantum repeater based on rare-earth-doped crystals. The main challenge for its realization lies in interfacing these two physical platforms, which produce photons with a typical temporal mismatch of one or two orders of magnitude. To address this, we propose an efficient protocol that enables custom temporal reshaping of single-photon pulses while preserving purity. Our approach is to modify a commonly used memory protocol, called atomic frequency comb, for systems exhibiting inhomogeneous broadening like rare-earth-doped crystals. Pertaining to a growing interest in hybrid quantum information systems designed to exploit the distinct advantages of diverse physical components, our results offer a viable solution for uniting quantum processing nodes with a quantum repeater backbone.

DOI
10.1103/hvsx-cx2d

Related papers

Solid state source of non-classical multimode photon pairs with controllable delay

Kutlu Kutluer, Margherita Mazzera, Hugues de Riedmatten

The process of storing information carried by single photons demands strong light-matter interaction. While interfacing single photon sources with quantum memories is still challenging, a possible short-cut by combining source and memory in the same ensemble was proposed by Duan, Lukin, Cirac, and Zoller (DLCZ) [1]. It is already a quite common protocol in cold atomic ensemble QMs, however it is very demanding to realize in solid state systems. Here we demonstrate for the first time a DLCZ-type memory with a rare-earth ion-doped crystal (REIC) with photon counting, directly applicable to the well-known quantum repeater schemes which works with QMs. We find second order cross correlation values up to 21±4 and violate Cauchy-Schwarz equality by R = 44 ± 20. Although the original DLCZ protocol does not support temporal multi-modality, we store 11 temporal modes thanks to a modified scheme in which we combine the DLCZ and the Atomic Frequency Comb protocols. Generating and storing non-classical multiplexed photon pairs with a single scheme in a REIC paves the way of making scalable, solid-state quantum repeater architectures.

Quantum Information and Measurement (QIM)•Jan 1, 2017•0 citations

Solid state source of non-classical multimode photon pairs with controllable delay

Kutlu Kutluer, Margherita Mazzera, Hugues de Riedmatten

The process of storing information carried by single photons demands strong light-matter interaction. While interfacing single photon sources with quantum memories is still challenging, a possible short-cut by combining source and memory in the same ensemble was proposed by Duan, Lukin, Cirac, and Zoller (DLCZ) [1]. It is already a quite common protocol in cold atomic ensemble QMs, however it is very demanding to realize in solid state systems. Here we demonstrate for the first time a DLCZ-type memory with a rare-earth ion-doped crystal (REIC) with photon counting, directly applicable to the well-known quantum repeater schemes which works with QMs. We find second order cross correlation values up to 21±4 and violate Cauchy-Schwarz equality by R = 44 ± 20. Although the original DLCZ protocol does not support temporal multi-modality, we store 11 temporal modes thanks to a modified scheme in which we combine the DLCZ and the Atomic Frequency Comb protocols. Generating and storing non-classical multiplexed photon pairs with a single scheme in a REIC paves the way of making scalable, solid-state quantum repeater architectures.

Conference on Lasers and Electro-Optics•Jan 1, 2017•0 citations

Towards an efficient nanophotonic platform integrating quantum memories and single qubits based on rare-earth ions

Tian Zhong, Jonathan M. Kindem, John G. Bartholomew +4 more

The integration of rare-earth ions in an on-chip photonic platform would enable quantum repeaters and scalable quantum networks. While ensemble-based quantum memories have been routinely realized, implementing single rare-earth ion qubit remains an outstanding challenge due to its weak photoluminescence. Here we demonstrate a nanophotonic platform consisting of yttrium vanadate (YVO) photonic crystal nanobeam resonators coupled to a spectrally dilute ensemble of Nd ions. The cavity acts as a memory when prepared with spectral hole burning, meanwhile it permits addressing of single ions when high-resolution spectroscopy is employed. For quantum memory, atomic frequency comb (AFC) protocol was implemented in a 50 ppm Nd:YVO nanocavity cooled to 480 mk. The high-fidelity quantum storage of time-bin qubits is demonstrated with a 80% efficient WSi superconducting nanowire single photon detector (SNSPD). The small mode volume of the cavity results in a peak atomic spectral density of <10 ions per homogeneous linewidth, suitable for probing single ions when detuned from the center of the inhomogeneous distribution. The high-cooperativity coupling of a single ion yields a strong signature (20%) in the cavity reection spectrum, which could be detected by our efficient SNSPD. We estimate a signal-to-noise ratio exceeding 10 for addressing a single Nd ion with its 879.7nm transition. This, combines with the AFC memory, constitutes a promising platform for preparation, storage and detection of rare-earth qubits on the same ship.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Feb 20, 2017•0 citations

On-chip quantum storage in a rare-earth-doped photonic nanocavity

Tian Zhong, Jonathan M. Kindem, Jake Rochman +4 more

Rare-earth-ion doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical and microwave photons. Here we describe our progress towards a nanophotonic quantum memory based on a rare-earth (Neodymium) doped yttrium orthosilicate (YSO) photonic crystal resonator. The Purcell-enhanced coupling of the 883 nm transitions of Neodymium (Nd3+) ions to the nano-resonator results in increased optical depth, which could in principle facilitate highly efficient photon storage via cavity impedance matching. The atomic frequency comb (AFC) memory protocol can be implemented in the Nd:YSO nano-resonator by efficient optical pumping into the long-lived Zeeman state. Coherent optical signals can be stored and retrieved from the AFC memory. We currently measure a storage efficiency on par with a bulk crystal Nd:YSO memory that is millimeters long. Our results will enable multiplexed on-chip quantum storage and thus quantum repeater devices using rare-earth-ions.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Mar 16, 2016•5 citations

Broadband photonic quantum interface based on a cavity-protected rare-earth ensemble

Tian Zhong, Jonathan M. Kindem, Jake Rochman +1 more

Rare-earth ions doped in crystals are renowned for their excellent coherence properties and large inhomogeneous broadening, which make them ideal for quantum interfaces with broadband photons. These properties have made them one of the leading technologies in quantum optical memories and a promising candidate for optical-to-microwave conversion. To take advantage of the full bandwidth of the rare-earth ensemble, one must overcome the decoherence of a broadband collective excitation due to inhomogeneous broadening. To this end, techniques based on controllable rephasing, such as atomic frequency comb (AFC) or controlled reversible inhomogeneous broadening (CRIB) memories, have been developed with great success. Recently, an alternative method was proposed to suppress the decoherence of an inhomogeneous ensemble via strong coupling to a cavity, a phenomenon called cavity protection. This technique has been demonstrated in the microwave domain with an NV spin ensemble, but has not been demonstrated in the optical domain. Here, we demonstrate cavity protection in the optical domain at the single photon level using an ensemble of rare earths ions coupled to a nanophotonic resonator. The reduction in decoherence due to the cavity-protection effect enables transfer of ultrafast (~50 GHz) frequency qubits into the collective ion excitation and retrieval with 98.7% fidelity. Building on these results to transfer these excitations to long-lived spin states would enable broadband, on-demand quantum memories. Furthermore, this works compliments the work done coupling rare-earths to superconducting resonators in the microwave regime with potential for applications in optical-to-microwave transducers.

•Jun 2, 2017•0 citations

Multimode solid-state quantum memory

Tian-Shu Yang, Zong‐Quan Zhou, Chuan‐Feng Li +1 more

The faithful storage and coherent manipulation of single photon state in a matter-system are crucial for linear-optical quantum computation, long-distance quantum communication, and quantum networking.To reach useful data rate in a large-scale quantum network, highly multimode quantum memories are required to build a multiplexed quantum repeater.Rare-earth-ion doped crystal (REIC) is very promising material as a candidate for multimode quantum storage due to the wide inhomogeneous broadening and long optical coherence time.In this article, we review the recent advances in multimode quantum memories based on REICs.First, we briefly introduce the properties of REIC and the atomic frequency comb protocol based on REIC.Next, we review the achievements of multimode quantum memories based on REIC in recent years, including frequency, temporal and spatial multimode storage.Afterwards, we review our experimental work on multiplexed storage based on a multiple degree-of-freedom quantum memory.Finally, we introduce the quantum mode converter and real-time arbitrary manipulations based on the multiple degree-of-freedom quantum memory. The combination of storage and real-time manipulation in a device should enable the construction of a versatility quantum repeater.This review highlights that multimode quantum memories based on REIC can be found to possess some practical applications in developing the optical quantum information processing in the near future.

Acta Physica Sinica•Jan 1, 2019•2 citations
We present an architecture for remotely connecting cavity-coupled trapped ions via a quantum repeater based on rare-earth-doped crystals. The main challenge for its realization lies in interfacing these two physical platforms, which produce photons with a typical temporal mismatch of one or two orders of magnitude. To address this, we propose an efficient protocol that enables custom temporal reshaping of single-photon pulses while preserving purity. Our approach is to modify a commonly used memory protocol, called atomic frequency comb, for systems exhibiting inhomogeneous broadening like rare-earth-doped crystals. Pertaining to a growing interest in hybrid quantum information systems designed to exploit the distinct advantages of diverse physical components, our results offer a viable solution for uniting quantum processing nodes with a quantum repeater backbone.
The process of storing information carried by single photons demands strong light-matter interaction. While interfacing single photon sources with quantum memories is still challenging, a possible short-cut by combining source and memory in the same ensemble was proposed by Duan, Lukin, Cirac, and Zoller (DLCZ) [1]. It is already a quite common protocol in cold atomic ensemble QMs, however it is very demanding to realize in solid state systems. Here we demonstrate for the first time a DLCZ-type memory with a rare-earth ion-doped crystal (REIC) with photon counting, directly applicable to the well-known quantum repeater schemes which works with QMs. We find second order cross correlation values up to 21±4 and violate Cauchy-Schwarz equality by R = 44 ± 20. Although the original DLCZ protocol does not support temporal multi-modality, we store 11 temporal modes thanks to a modified scheme in which we combine the DLCZ and the Atomic Frequency Comb protocols. Generating and storing non-classical multiplexed photon pairs with a single scheme in a REIC paves the way of making scalable, solid-state quantum repeater architectures.
The process of storing information carried by single photons demands strong light-matter interaction. While interfacing single photon sources with quantum memories is still challenging, a possible short-cut by combining source and memory in the same ensemble was proposed by Duan, Lukin, Cirac, and Zoller (DLCZ) [1]. It is already a quite common protocol in cold atomic ensemble QMs, however it is very demanding to realize in solid state systems. Here we demonstrate for the first time a DLCZ-type memory with a rare-earth ion-doped crystal (REIC) with photon counting, directly applicable to the well-known quantum repeater schemes which works with QMs. We find second order cross correlation values up to 21±4 and violate Cauchy-Schwarz equality by R = 44 ± 20. Although the original DLCZ protocol does not support temporal multi-modality, we store 11 temporal modes thanks to a modified scheme in which we combine the DLCZ and the Atomic Frequency Comb protocols. Generating and storing non-classical multiplexed photon pairs with a single scheme in a REIC paves the way of making scalable, solid-state quantum repeater architectures.
The integration of rare-earth ions in an on-chip photonic platform would enable quantum repeaters and scalable quantum networks. While ensemble-based quantum memories have been routinely realized, implementing single rare-earth ion qubit remains an outstanding challenge due to its weak photoluminescence. Here we demonstrate a nanophotonic platform consisting of yttrium vanadate (YVO) photonic crystal nanobeam resonators coupled to a spectrally dilute ensemble of Nd ions. The cavity acts as a memory when prepared with spectral hole burning, meanwhile it permits addressing of single ions when high-resolution spectroscopy is employed. For quantum memory, atomic frequency comb (AFC) protocol was implemented in a 50 ppm Nd:YVO nanocavity cooled to 480 mk. The high-fidelity quantum storage of time-bin qubits is demonstrated with a 80% efficient WSi superconducting nanowire single photon detector (SNSPD). The small mode volume of the cavity results in a peak atomic spectral density of <10 ions per homogeneous linewidth, suitable for probing single ions when detuned from the center of the inhomogeneous distribution. The high-cooperativity coupling of a single ion yields a strong signature (20%) in the cavity reection spectrum, which could be detected by our efficient SNSPD. We estimate a signal-to-noise ratio exceeding 10 for addressing a single Nd ion with its 879.7nm transition. This, combines with the AFC memory, constitutes a promising platform for preparation, storage and detection of rare-earth qubits on the same ship.
Rare-earth-ion doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical and microwave photons. Here we describe our progress towards a nanophotonic quantum memory based on a rare-earth (Neodymium) doped yttrium orthosilicate (YSO) photonic crystal resonator. The Purcell-enhanced coupling of the 883 nm transitions of Neodymium (Nd3+) ions to the nano-resonator results in increased optical depth, which could in principle facilitate highly efficient photon storage via cavity impedance matching. The atomic frequency comb (AFC) memory protocol can be implemented in the Nd:YSO nano-resonator by efficient optical pumping into the long-lived Zeeman state. Coherent optical signals can be stored and retrieved from the AFC memory. We currently measure a storage efficiency on par with a bulk crystal Nd:YSO memory that is millimeters long. Our results will enable multiplexed on-chip quantum storage and thus quantum repeater devices using rare-earth-ions.
Rare-earth ions doped in crystals are renowned for their excellent coherence properties and large inhomogeneous broadening, which make them ideal for quantum interfaces with broadband photons. These properties have made them one of the leading technologies in quantum optical memories and a promising candidate for optical-to-microwave conversion. To take advantage of the full bandwidth of the rare-earth ensemble, one must overcome the decoherence of a broadband collective excitation due to inhomogeneous broadening. To this end, techniques based on controllable rephasing, such as atomic frequency comb (AFC) or controlled reversible inhomogeneous broadening (CRIB) memories, have been developed with great success. Recently, an alternative method was proposed to suppress the decoherence of an inhomogeneous ensemble via strong coupling to a cavity, a phenomenon called cavity protection. This technique has been demonstrated in the microwave domain with an NV spin ensemble, but has not been demonstrated in the optical domain. Here, we demonstrate cavity protection in the optical domain at the single photon level using an ensemble of rare earths ions coupled to a nanophotonic resonator. The reduction in decoherence due to the cavity-protection effect enables transfer of ultrafast (~50 GHz) frequency qubits into the collective ion excitation and retrieval with 98.7% fidelity. Building on these results to transfer these excitations to long-lived spin states would enable broadband, on-demand quantum memories. Furthermore, this works compliments the work done coupling rare-earths to superconducting resonators in the microwave regime with potential for applications in optical-to-microwave transducers.
The faithful storage and coherent manipulation of single photon state in a matter-system are crucial for linear-optical quantum computation, long-distance quantum communication, and quantum networking.To reach useful data rate in a large-scale quantum network, highly multimode quantum memories are required to build a multiplexed quantum repeater.Rare-earth-ion doped crystal (REIC) is very promising material as a candidate for multimode quantum storage due to the wide inhomogeneous broadening and long optical coherence time.In this article, we review the recent advances in multimode quantum memories based on REICs.First, we briefly introduce the properties of REIC and the atomic frequency comb protocol based on REIC.Next, we review the achievements of multimode quantum memories based on REIC in recent years, including frequency, temporal and spatial multimode storage.Afterwards, we review our experimental work on multiplexed storage based on a multiple degree-of-freedom quantum memory.Finally, we introduce the quantum mode converter and real-time arbitrary manipulations based on the multiple degree-of-freedom quantum memory. The combination of storage and real-time manipulation in a device should enable the construction of a versatility quantum repeater.This review highlights that multimode quantum memories based on REIC can be found to possess some practical applications in developing the optical quantum information processing in the near future.