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

Optical Quantum Memory and Signal Processing Using a Rare-earth-ion-doped Waveguide

Neil E. Sinclair

Published Jan 1, 2016• 0 citations
Publisher

Abstract

Advanced applications of quantum information science, such as long-distance quantum communication based on quantum repeaters, require photons to be interfaced with different devices. These devices, such as single photon detectors, quantum memories, quantum signal processors, and linear optical elements, may be integrated on a single chip to enable efficient, robust and scalable implementations. With aim of constructing a quantum repeater, and towards realizing integrated optical quantum memories and signal processors in general, we experimentally develop quantum light-matter interfaces using a cryogenically-cooled rare-earth-ion-doped waveguide, namely thulium-doped lithium niobate (Tm3+:LiNbO3). As the basis for our work, we describe a quantum repeater architecture that uses spectral multiplexing and quantum memories that operate with a fixed storage time. Our repeater architecture promises efficient operation, is compatible with the properties of cryogenically-cooled rare-earth-ion-doped crystals, and simplifies the demands of quantum memories compared to other architectures. To demonstrate the feasibility of our repeater design, we utilize our light-matter interface as a quantum memory to perform several experimental demonstrations. These include high-fidelity storage and retrieval of 26 spectrally-multiplexed quantum bits encoded into single-photon-level laser pulses, high-fidelity storage and retrieval of single and entangled photons derived from a photon-pair source, and high-visibility two-photon interference between weak laser pulses that are stored in one or two, separate, quantum memories. The unique properties of our light-matter interface allow us to demonstrate additional protocols that further highlight its promise for integrated quantum signal processing. By combining our Tm3+:LiNbO3 waveguide with a LiNbO3 waveguide phase modulator, we demonstrate operations such as sequencing, filtering, interference, and compression of laser pulses attenuated to the single-photon level. In another experiment, we measure the cross-phase modulation between strong pulses, by which we demonstrate photon-photon interactions that point towards non-destructive measurements of quantum bits. Since the performance of all aforementioned protocols, and future light-matter applications, hinge on the basic spectroscopic properties of our waveguide, we measure these properties at temperatures as low as 800 millikelvin. Our findings, discussed over several attached publications, usher the development of integrated quantum memories and processors for multi-component optical quantum information applications such as repeaters and networks.

DOI
10.11575/prism/27205

Related papers

Single-photon storage in laser written waveguides fabricated in rare-earth-doped solids (Conference Presentation)

Giacomo Corrielli, Alessandro Seri, Dario Lago-Rivera +4 more

Efficient and long-lived multimode quantum memories are crucial devices in the development of quantum technolgies. The reversible mapping of quantum states of light in rare earth doped crystals represents one of the most promising routes towards the realization of this goal. Such systems are also compatible with the miniaturization of quantum memories in integrated optics platforms, which offer unique features in terms of experimental scalability and enhanced light-matter interaction. Here, we fabricate single mode channel waveguides for 606 nm light in a praseodymium-doped yttrium orthosilicate crystal (Pr3+:Y2SiO5), that, thanks to its excellent coherence properties, is a widely studied material for light storage experiments. Waveguides are inscribed by femtosecond laser writing, adopting the so-called Type I configuration, where the core is directly obtained at the irradiated area. Remarkably, fabricating this kind of waveguides in crystals is a difficult task, as it requires to operate in a very narrow processing parameters window, if existing. We then use these waveguides for performing the storage and retrieval of single photons, implementing the atomic frequency comb protocol. We achieve a storage time of 5,5 µs, which is almost 2 orders of magnitude longer than previous realizations of quantum light storage in a waveguide. In addition, we investigate the potential information multiplexing capabilities of our system by performing the quantum storage of single photons delocalized over 14 different spectral modes. Our results show that laser written waveguides in rare earth-doped solid state systems are very promising for the development of efficient and long-lived multimode quantum memories.

Advances in Photonics of Quantum Computing, Memory, and Communication•Mar 4, 2019•0 citations

Broadband Waveguide Quantum Memory for Quantum Communication

Erhan Sağlamyürek

Quantum communication founds on the possibility to encode quantum states into photons and allows, for instance, the provable secure distribution of encryption keys. Despite a lot of progress during the past two decades, quantum communication still faces a distance barrier, which can be overcome by quantum repeaters whose currently most challenging ingredient is a memory for quantum states of light. In addition to robustness and ease of use, the requirements for such a quantum memory include high fidelity quantum state storage and the preservation of entanglement, sufficiently long storage time with on-demand recall, high efficiency, large bandwidth, and high multimode capacity. Six years ago, some of these properties had already been demonstrated using atomic vapor. However, practical solid-state memories were virtually unexplored in view of quantum state storage. The main goal of this thesis was to realize a solid-state quantum memory for light with emphasis on meeting requirements for long distance quantum communication. First, we identified a potential material candidate, a thulium doped lithium niobate waveguide, and conducted spectroscopic investigations to assess its suitability for quantum state storage using a photon-echo type approach. Next, we demonstrated that our storage device is suitable for high fidelity quantum state storage and for the storage of photonic entanglement, and that its large spectral multimode capacity allows for on-demand selective recall in conjunction with standard spectral filters and frequency shifters. In addition, by performing two-photon interference experiments and Bell-State measurements, we found that our memory preserves not only quantum information, but, more generally, the entire photonic wave function, which further confirms its suitability for quantum repeaters as well as for linear optics quantum computers. Finally, we showed that our integrated device also allows for general temporal and spectral manipulation of individual quantum optical pulses, which paves the way towards on-chip quantum optical processors. While more work remains to be done, in particular to improve memory efficiency and storage time, the large number of achievements, together with known ways to overcome the remaining obstacles, makes us confident that a quantum memory suitable for quantum repeaters will soon be built.

•Jan 1, 2013•1 citation

Rare-earth quantum memories for single photons and entanglement

Imam Usmani

The ability of storing and retrieving quantum states of light is an important experimental challenge in quantum information science. A powerful quantum memory for light is required in a quantum repeater, which would allow long distance (>500km) quantum communications. To be implemented in such application, the quantum memory must allow on-demand readout, with high fidelity and efficiency, and a long storage time. Additionally a multimode capacity (for temporal or spatial modes) would allow multiplexing. Our approaches focus on rare-earth doped crystals, i.e. solid state quantum memory. I present, in this work, our contributions for a solid-state quantum storage, with good performances in every criteria. In particular, I present the preservation of quantum entanglement during the storage, which paves the way for the implementation of quantum memories in quantum repeaters.

•Jan 1, 2013•0 citations

An Integrated Photonic Platform For Quantum Information Processing

Subhojit Dutta

Quantum photonics provides a powerful toolbox with vast applications ranging from quantum simulation, photonic information processing, all optical universal quantum computation, secure quantum internet as well as quantum enhanced sensing. Many of these applications require the integration of several complex optical elements and material systems which pose a challenge to scalability. It is essential to integrate linear and non-linear photonics on a chip to tackle this issue leading to more compact, high bandwidth devices. In this thesis we demonstrate a pathway to achieving several components in the quantum photonic toolbox on the same integrated photonic platform. We focus particularly on two of the more nontrivial components, a single photon source and an integrated quantum light-matter interface. We address the problem of a scalable, chip integrated, fast single photon source, by using atomically thin layers of 2D materials interfaced with plasmonic waveguides. We further embark on the challenge of creating a new material system by integrating rare earth ions with the emerging commercial platform of thin film lithium niobate on insulator. Rare earth ions have found widespread use in classical and quantum information processing. However, these are traditionally doped in bulk crystals which hinder their scalability. We demonstrate an integrated photonic interface for rare earth ions in thin film lithium niobate that preserves the optical and coherence properties of the ions. This combination of rare earth ions with the chip-scale active interface of thin film lithium niobate opens a plethora of opportunities for compact optoelectronic devices. As an immediate application we demonstrate an integrated optical quantum memory with a rare earth atomic ensemble in the thin film. The new light matter interface in thin film lithium niobate acts as a key enabler in an already rich optical platform representing a significant advancement in the field of integrated quantum photonics.

•Jan 1, 2021•0 citations

Proposal and proof-of-principle demonstration of non-destructive detection of photonic qubits using a Tm:LiNbO3 waveguide

Neil E. Sinclair, Khabat Heshami, Chetan Deshmukh +3 more

Abstract Non-destructive detection of photonic qubits is an enabling technology for quantum information processing and quantum communication. For practical applications, such as quantum repeaters and networks, it is desirable to implement such detection in a way that allows some form of multiplexing as well as easy integration with other components such as solid-state quantum memories. Here, we propose an approach to non-destructive photonic qubit detection that promises to have all the mentioned features. Mediated by an impurity-doped crystal, a signal photon in an arbitrary time-bin qubit state modulates the phase of an intense probe pulse that is stored during the interaction. Using a thulium-doped waveguide in LiNbO3, we perform a proof-of-principle experiment with macroscopic signal pulses, demonstrating the expected cross-phase modulation as well as the ability to preserve the coherence between temporal modes. Our findings open the path to a new key component of quantum photonics based on rare-earth-ion-doped crystals.

arXiv:1510.01164•Nature Communications•Nov 17, 2016•31 citations

Crystalline waveguides for highly efficient integrated quantum memories

Mickael Chan, Alban Ferrier, A. Talneau +3 more

This paper presents progress in developing crystalline waveguides to enable efficient and integrated quantum memories for long-distance quantum communications. The primary objective is to overcome low light-matter interaction strength encountered in rare-earth ion (REI) doped crystals, particularly Yttrium Orthosilicate (YSO), which limits optical storage efficiencies. Compared to other strategies toward photonic integration, our novel approach utilizes traditional lithography and dry-etching techniques to retain the beneficial properties of bulk crystals while allowing for design flexibility. Bonding, lapping, polishing, and dry-etching processes were optimized to fabricate the suitable YSO waveguide geometry demonstrated by simulations. This research paves the way toward fully integrated quantum repeaters. It also contributes toward integration for other REI-doped crystals-based quantum technologies such as quantum computing, single photon generation, RF spectral analysis, and microwave-to-optical quantum transduction.

Quantum Computing, Communication, and Simulation•Mar 19, 2025•0 citations
Advanced applications of quantum information science, such as long-distance quantum communication based on quantum repeaters, require photons to be interfaced with different devices. These devices, such as single photon detectors, quantum memories, quantum signal processors, and linear optical elements, may be integrated on a single chip to enable efficient, robust and scalable implementations. With aim of constructing a quantum repeater, and towards realizing integrated optical quantum memories and signal processors in general, we experimentally develop quantum light-matter interfaces using a cryogenically-cooled rare-earth-ion-doped waveguide, namely thulium-doped lithium niobate (Tm3+:LiNbO3). As the basis for our work, we describe a quantum repeater architecture that uses spectral multiplexing and quantum memories that operate with a fixed storage time. Our repeater architecture promises efficient operation, is compatible with the properties of cryogenically-cooled rare-earth-ion-doped crystals, and simplifies the demands of quantum memories compared to other architectures. To demonstrate the feasibility of our repeater design, we utilize our light-matter interface as a quantum memory to perform several experimental demonstrations. These include high-fidelity storage and retrieval of 26 spectrally-multiplexed quantum bits encoded into single-photon-level laser pulses, high-fidelity storage and retrieval of single and entangled photons derived from a photon-pair source, and high-visibility two-photon interference between weak laser pulses that are stored in one or two, separate, quantum memories. The unique properties of our light-matter interface allow us to demonstrate additional protocols that further highlight its promise for integrated quantum signal processing. By combining our Tm3+:LiNbO3 waveguide with a LiNbO3 waveguide phase modulator, we demonstrate operations such as sequencing, filtering, interference, and compression of laser pulses attenuated to the single-photon level. In another experiment, we measure the cross-phase modulation between strong pulses, by which we demonstrate photon-photon interactions that point towards non-destructive measurements of quantum bits. Since the performance of all aforementioned protocols, and future light-matter applications, hinge on the basic spectroscopic properties of our waveguide, we measure these properties at temperatures as low as 800 millikelvin. Our findings, discussed over several attached publications, usher the development of integrated quantum memories and processors for multi-component optical quantum information applications such as repeaters and networks.
Efficient and long-lived multimode quantum memories are crucial devices in the development of quantum technolgies. The reversible mapping of quantum states of light in rare earth doped crystals represents one of the most promising routes towards the realization of this goal. Such systems are also compatible with the miniaturization of quantum memories in integrated optics platforms, which offer unique features in terms of experimental scalability and enhanced light-matter interaction. Here, we fabricate single mode channel waveguides for 606 nm light in a praseodymium-doped yttrium orthosilicate crystal (Pr3+:Y2SiO5), that, thanks to its excellent coherence properties, is a widely studied material for light storage experiments. Waveguides are inscribed by femtosecond laser writing, adopting the so-called Type I configuration, where the core is directly obtained at the irradiated area. Remarkably, fabricating this kind of waveguides in crystals is a difficult task, as it requires to operate in a very narrow processing parameters window, if existing. We then use these waveguides for performing the storage and retrieval of single photons, implementing the atomic frequency comb protocol. We achieve a storage time of 5,5 µs, which is almost 2 orders of magnitude longer than previous realizations of quantum light storage in a waveguide. In addition, we investigate the potential information multiplexing capabilities of our system by performing the quantum storage of single photons delocalized over 14 different spectral modes. Our results show that laser written waveguides in rare earth-doped solid state systems are very promising for the development of efficient and long-lived multimode quantum memories.
Quantum communication founds on the possibility to encode quantum states into photons and allows, for instance, the provable secure distribution of encryption keys. Despite a lot of progress during the past two decades, quantum communication still faces a distance barrier, which can be overcome by quantum repeaters whose currently most challenging ingredient is a memory for quantum states of light. In addition to robustness and ease of use, the requirements for such a quantum memory include high fidelity quantum state storage and the preservation of entanglement, sufficiently long storage time with on-demand recall, high efficiency, large bandwidth, and high multimode capacity. Six years ago, some of these properties had already been demonstrated using atomic vapor. However, practical solid-state memories were virtually unexplored in view of quantum state storage. The main goal of this thesis was to realize a solid-state quantum memory for light with emphasis on meeting requirements for long distance quantum communication. First, we identified a potential material candidate, a thulium doped lithium niobate waveguide, and conducted spectroscopic investigations to assess its suitability for quantum state storage using a photon-echo type approach. Next, we demonstrated that our storage device is suitable for high fidelity quantum state storage and for the storage of photonic entanglement, and that its large spectral multimode capacity allows for on-demand selective recall in conjunction with standard spectral filters and frequency shifters. In addition, by performing two-photon interference experiments and Bell-State measurements, we found that our memory preserves not only quantum information, but, more generally, the entire photonic wave function, which further confirms its suitability for quantum repeaters as well as for linear optics quantum computers. Finally, we showed that our integrated device also allows for general temporal and spectral manipulation of individual quantum optical pulses, which paves the way towards on-chip quantum optical processors. While more work remains to be done, in particular to improve memory efficiency and storage time, the large number of achievements, together with known ways to overcome the remaining obstacles, makes us confident that a quantum memory suitable for quantum repeaters will soon be built.
The ability of storing and retrieving quantum states of light is an important experimental challenge in quantum information science. A powerful quantum memory for light is required in a quantum repeater, which would allow long distance (>500km) quantum communications. To be implemented in such application, the quantum memory must allow on-demand readout, with high fidelity and efficiency, and a long storage time. Additionally a multimode capacity (for temporal or spatial modes) would allow multiplexing. Our approaches focus on rare-earth doped crystals, i.e. solid state quantum memory. I present, in this work, our contributions for a solid-state quantum storage, with good performances in every criteria. In particular, I present the preservation of quantum entanglement during the storage, which paves the way for the implementation of quantum memories in quantum repeaters.
Quantum photonics provides a powerful toolbox with vast applications ranging from quantum simulation, photonic information processing, all optical universal quantum computation, secure quantum internet as well as quantum enhanced sensing. Many of these applications require the integration of several complex optical elements and material systems which pose a challenge to scalability. It is essential to integrate linear and non-linear photonics on a chip to tackle this issue leading to more compact, high bandwidth devices. In this thesis we demonstrate a pathway to achieving several components in the quantum photonic toolbox on the same integrated photonic platform. We focus particularly on two of the more nontrivial components, a single photon source and an integrated quantum light-matter interface. We address the problem of a scalable, chip integrated, fast single photon source, by using atomically thin layers of 2D materials interfaced with plasmonic waveguides. We further embark on the challenge of creating a new material system by integrating rare earth ions with the emerging commercial platform of thin film lithium niobate on insulator. Rare earth ions have found widespread use in classical and quantum information processing. However, these are traditionally doped in bulk crystals which hinder their scalability. We demonstrate an integrated photonic interface for rare earth ions in thin film lithium niobate that preserves the optical and coherence properties of the ions. This combination of rare earth ions with the chip-scale active interface of thin film lithium niobate opens a plethora of opportunities for compact optoelectronic devices. As an immediate application we demonstrate an integrated optical quantum memory with a rare earth atomic ensemble in the thin film. The new light matter interface in thin film lithium niobate acts as a key enabler in an already rich optical platform representing a significant advancement in the field of integrated quantum photonics.
Abstract Non-destructive detection of photonic qubits is an enabling technology for quantum information processing and quantum communication. For practical applications, such as quantum repeaters and networks, it is desirable to implement such detection in a way that allows some form of multiplexing as well as easy integration with other components such as solid-state quantum memories. Here, we propose an approach to non-destructive photonic qubit detection that promises to have all the mentioned features. Mediated by an impurity-doped crystal, a signal photon in an arbitrary time-bin qubit state modulates the phase of an intense probe pulse that is stored during the interaction. Using a thulium-doped waveguide in LiNbO3, we perform a proof-of-principle experiment with macroscopic signal pulses, demonstrating the expected cross-phase modulation as well as the ability to preserve the coherence between temporal modes. Our findings open the path to a new key component of quantum photonics based on rare-earth-ion-doped crystals.
This paper presents progress in developing crystalline waveguides to enable efficient and integrated quantum memories for long-distance quantum communications. The primary objective is to overcome low light-matter interaction strength encountered in rare-earth ion (REI) doped crystals, particularly Yttrium Orthosilicate (YSO), which limits optical storage efficiencies. Compared to other strategies toward photonic integration, our novel approach utilizes traditional lithography and dry-etching techniques to retain the beneficial properties of bulk crystals while allowing for design flexibility. Bonding, lapping, polishing, and dry-etching processes were optimized to fabricate the suitable YSO waveguide geometry demonstrated by simulations. This research paves the way toward fully integrated quantum repeaters. It also contributes toward integration for other REI-doped crystals-based quantum technologies such as quantum computing, single photon generation, RF spectral analysis, and microwave-to-optical quantum transduction.