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

Engineering and Modelling Integrated Nonlinear Quantum Photonics

Tim Weiss

Published Jun 12, 2026• 0 citations
Publisher

Abstract

Nonlinear photonics studies situations in which light passing through a material can be used to create, reshape, or convert other light in ways that are not possible in ordinary optical systems. In recent years, this has become especially important for quantum photonics, where carefully prepared states of light are used as resources for emerging technologies such as secure communication, ultra-precise measurement, and new forms of information processing. A major challenge, however, is that these effects are delicate, difficult to control, and highly sensitive to the imperfections that arise when trying to build practical devices on a chip. This thesis examines how such nonlinear quantum-optical processes can be both engineered more deliberately and modelled more realistically, with the broader goal of helping move quantum photonic technology from proof-of-principle laboratory demonstrations toward robust and scalable implementation. To do this, the thesis first places nonlinear quantum photonics in a broader technological context and explains the main physical ideas needed to understand how quantum states of light are generated, transformed, and measured. It then develops this picture through a set of concrete examples. These include a method for generating quantum light on a chip while avoiding one of the field’s standard fabrication steps, a proposed chip-scale device that could help connect otherwise incompatible quantum systems by changing the colour and spectral width of light, and a modelling framework that links quantum theory directly to realistic fabricated waveguides, including common imperfections such as loss, non-uniformity, and writing errors. The thesis also reviews a wider class of design methods in which the nonlinear properties of a material are deliberately patterned in order to tailor the light produced. Taken together, the central message is that progress in quantum photonics will depend not only on discovering new effects, but on learning how to design, fabricate, and model these devices in ways that make them practical outside idealized laboratory conditions.

DOI
10.25439/rmt.34140780

Related papers

Nonlinear Single-photon Generation for Photonic Quantum Technology

Matthew J. Collins

Single photons are the smallest indivisible quanta of light, canonically described by quantum mechanics. By carefully controlling the interaction of single photons, exquisite non-classical phenomena can be observed. Mature photonic chip technology has recently emerged as an ideal platform for quantum information processing using single photons. However, generating single photons efficiently on-chip remains a fundamental challenge. One solution is to harness the intrinsic nonlinearity available in certain photonic materials for nonlinear photon generation directly in on-chip waveguides themselves. This work examines nonlinear photon generation in two key material platforms. The first is chalcogenide glass. Chalcogenide, while highly nonlinear, is amorphous and thus has broadband Raman noise. In this study the Raman noise is characterised at the single-photon level to find an intrinsic minima, which is then targeted for low-noise photon generation using an engineered waveguide. The second platform is silicon. As silicon is complementary metal-oxide-semiconductor (CMOS) fabrication compatible, it is congruent with mass production. Thus, in this study, photon-pair generation is first shown in a compact photonic crystal, before combining two monolithic sources using active multiplexing. This thesis presents significant progress towards a key goal of the field – on- demand photon generation in a fully integrated photonic quantum processor.

•Oct 1, 2014•0 citations

Quantum nonlinear parametric interaction in realistic waveguides: a comprehensive study

Tim F. Weiss, Akram Youssry, Alberto Peruzzo

Abstract Nonlinear sources of quantum light are foundational to a majority of optical quantum technologies and are actively advancing toward real-world deployment. Achieving this goal requires fabrication capabilities to be scaled to industrial standards, necessitating precise modeling tools that can both guide device design within realistic fabrication constraints and enable accurate post-fabrication characterization. In this paper, building on existing work, we introduce a modeling framework that explicitly integrates the engineering tools used for designing classical properties of integrated waveguides with quantum mechanical theory describing the underlying nonlinear interactions. We analyze the validity and limitations of approximations relevant to this framework and apply it to comprehensively study how typical fabrication errors and deviations from nominal design—common in practical waveguide manufacturing—affect the nonlinear optical response. Our findings highlight, in particular, a critical sensitivity of the framework to group-velocity dispersion, the potentially highly disruptive role of geometric inhomogeneities in the waveguide, and an upper bound on uncorrelated squeezed-state generation arising from asymmetric group-velocity matching conditions.

arXiv:2506.20184•Quantum Science and Technology•Mar 31, 2026•0 citations

On-chip generation and characterization of quantum light

James Titchener

Technologies based on quantum mechanics promise to revolutionize the collection, processing and communication of information. However, due to the fragility of quantum coherence, complex quantum states can only exist in highly isolated and stable environments. One suitable environment is that of a quantum photonic chip. Quantum integrated photonics seeks to generate, process and detect complex quantum states inside a photonic chip. This thesis presents theory and experimental verification of novel approaches for the integration of various functionalities into quantum photonic chips in a scalable way. As such, this thesis encompasses a broad area of physics including quantum optics and nonlinear photonics. The results presented in this thesis have applications in the areas of quantum enhanced measurement, communication and information processing. In particular we develop the theory and experimentally demonstrate flexible on-chip sources of spatially entangled photons, the state of which can be reconfigured alloptically. We show how such techniques could enable the realization of simple cluster state quantum computing algorithms using spatially encoded two-photon states. Furthermore, we suggest new and practical approaches for the efficient characterization of mass produced nonlinear quantum photonic chips. Finally we develop and experimentally demonstrate a scalable method for the full quantum state tomography of multi-photon states on-chip. Importantly this technique only requires a linearly increasing number of single photon detectors relative to the number of photons in the state being characterized, and is also highly compatible with on-chip single photon detectors.

•Jan 1, 2017•0 citations

Scalable Quantum Light Sources in Silicon Photonic Circuits

Cale M. Gentry

Chip-scale integrated photonic circuits provide an attractive platform for the implementation of many quantum photonic technologies ranging from precise metrology to secure communication and quantum computation. In particular, silicon photonic platforms support micron-scale nonlinear optical sources of non-classical light which can be mass manufactured using the robust fabrication processes pioneered by the CMOS microelectronics industry. Integration of these quantum photonic sources with high-performance classical photonic devices on the same chip is required for truly scalable quantum information technologies. Integrated nonlinear resonators are investigated as sources of quantum mechanically correlated photon pair sources. An all-order dispersion engineering method is presented as a robust design synthesis for micoring sources. In addition, a novel concept of coupled mode dispersion compensation is proposed and demonstrated, providing significantly improved performance characteristics of resonant four-wave mixing sources. Next a photon pair source is demonstrated in a commercial CMOS microelectronics process opening the door to future integration of quantum photonics with electronic logic and control circuits. Classical nonlinear optical measurements of stimulated four-wave mixing are used for the first time to accurately predict the quantum correlations from the same device operating in the photon pair regime. Next the first demonstration of fully on-chip pump rejection is demonstrated with over 95 dB pump extinction improving the figures of merit from previous demonstrations by multiple orders of magnitude, including losses, detected pair rates and size. Finally, proposals for introducing novel degrees of freedom provided by an integrated platform are presented for further improving the performance of both photon pair and classical nonlinear optical sources.

•Jan 1, 2018•1 citation

Quantum enhanced precision measurement and information processing with integrated photonics

Nicholas L. Thomas-Peter

Photons have proven to be an effective test-bed for the fundamental concepts and elements of quantum-enhanced technologies. As systems become increasingly complex, however, practical considerations make the traditional approach of bulk optics and free-space propagation progressively more difficult. The major obstacles are the physical space necessary to realise and operate such a complex system, its stability, and maintaining low losses. In order to address these issues, quantum optical technologies can take a cue from their classical counterparts and look towards an integrated architecture to provide miniaturisation, greatly enhanced stability, less alignment, and low loss interfaces between different system components. In this thesis the feasibility of chip-based waveguides as a platform for metrology and information processing will be explored. In Part I, the necessary criteria for a metrology system to out-perform its classical counterpart will be investigated. It will be found that loss is a major barrier to this aim and, critically, that it is unlikely to have been achieved to date by any experiment which consumes resources of a fixed photon number. The issue of loss will be addressed by developing a scalable heralded source of a class of entangled photonic states which are both robust to losses and practically feasible to prepare. A novel tomographic technique will be developed to characterize these states and it will be explicitly demonstrated how it is possible to beat some bounds on classical performance without being able to out-perform a comparable classical system. Finally, a proof of principle demonstration of a waveguide-based interferometer with an integrated phase-shifter will be undertaken. It will be shown that the device preserves quantum interference, making it suitable for use in quantum-enhanced metrology applications. In Part II, integrated optics in the context of information processing will be discussed. First, a novel characterization technique will be developed which enables the behaviour of complex circuits to be predicted. The technique is independent of loss in the device being characterized. A method of simulating these circuits will be outlined that takes advantage of the computational speed-up available from parallelisation and sparse matrix operations. A key increase in complexity for integrated photonic systems will be demonstrated by showing quantum interference of three photons from two separate sources in eight spatial modes. The resulting interference has a visibility which beats all possible classical interference visibilities for similar circuits. Finally, a fully integrated waveguide-coupled photon-number-resolving detector will be developed and demonstrated. This proof of concept demonstration will show good resolution of different photon number events. The device will be modelled and routes to high efficiency operation will be explored.

•Jan 1, 2012•2 citations

Chip-scale nonlinear photonics for quantum light generation

Galan Moody, Lin Chang, Trevor J. Steiner +1 more

Nonclassical states of light are an essential resource for many emerging quantum technologies and applications ranging from information processing, encrypted communications, and networking to sensing, metrology, and imaging. Nonlinear optical processes in solid-state materials are widely used for generating quantum light, including single photons, entangled-photon pairs, and quadrature-squeezed states. Recent advances in nonlinear photonics have enabled the functionality of benchtop nonlinear instruments to be scaled down to a single chip without sacrificing efficiency or degrading the key performance metrics. The dramatic improvement in the size, weight, power, cost, and stability enabled by photonic integrated circuits has been essential for enabling the chip-scale generation, manipulation, and detection of quantum light at a steadily increasing degree of complexity and scale. Within the last decade, the authors have seen the progression from few-component photonic circuits operating on two photons to arrays of 18 identical heralded single-photon sources and reconfigurable devices operating with more than 650 components for multidimensional entanglement and arbitrary two-photon quantum gates. In this review, the authors summarize the history and recent key technological developments of chip-scale nonlinear quantum light generation based on integrated nonlinear photonics, recent advances in heterogeneous integrated methods, and approaches for system-level integration and demonstrated applications.

AVS Quantum Science•Oct 14, 2020•117 citations
Nonlinear photonics studies situations in which light passing through a material can be used to create, reshape, or convert other light in ways that are not possible in ordinary optical systems. In recent years, this has become especially important for quantum photonics, where carefully prepared states of light are used as resources for emerging technologies such as secure communication, ultra-precise measurement, and new forms of information processing. A major challenge, however, is that these effects are delicate, difficult to control, and highly sensitive to the imperfections that arise when trying to build practical devices on a chip. This thesis examines how such nonlinear quantum-optical processes can be both engineered more deliberately and modelled more realistically, with the broader goal of helping move quantum photonic technology from proof-of-principle laboratory demonstrations toward robust and scalable implementation. To do this, the thesis first places nonlinear quantum photonics in a broader technological context and explains the main physical ideas needed to understand how quantum states of light are generated, transformed, and measured. It then develops this picture through a set of concrete examples. These include a method for generating quantum light on a chip while avoiding one of the field’s standard fabrication steps, a proposed chip-scale device that could help connect otherwise incompatible quantum systems by changing the colour and spectral width of light, and a modelling framework that links quantum theory directly to realistic fabricated waveguides, including common imperfections such as loss, non-uniformity, and writing errors. The thesis also reviews a wider class of design methods in which the nonlinear properties of a material are deliberately patterned in order to tailor the light produced. Taken together, the central message is that progress in quantum photonics will depend not only on discovering new effects, but on learning how to design, fabricate, and model these devices in ways that make them practical outside idealized laboratory conditions.
Single photons are the smallest indivisible quanta of light, canonically described by quantum mechanics. By carefully controlling the interaction of single photons, exquisite non-classical phenomena can be observed. Mature photonic chip technology has recently emerged as an ideal platform for quantum information processing using single photons. However, generating single photons efficiently on-chip remains a fundamental challenge. One solution is to harness the intrinsic nonlinearity available in certain photonic materials for nonlinear photon generation directly in on-chip waveguides themselves. This work examines nonlinear photon generation in two key material platforms. The first is chalcogenide glass. Chalcogenide, while highly nonlinear, is amorphous and thus has broadband Raman noise. In this study the Raman noise is characterised at the single-photon level to find an intrinsic minima, which is then targeted for low-noise photon generation using an engineered waveguide. The second platform is silicon. As silicon is complementary metal-oxide-semiconductor (CMOS) fabrication compatible, it is congruent with mass production. Thus, in this study, photon-pair generation is first shown in a compact photonic crystal, before combining two monolithic sources using active multiplexing. This thesis presents significant progress towards a key goal of the field – on- demand photon generation in a fully integrated photonic quantum processor.
Abstract Nonlinear sources of quantum light are foundational to a majority of optical quantum technologies and are actively advancing toward real-world deployment. Achieving this goal requires fabrication capabilities to be scaled to industrial standards, necessitating precise modeling tools that can both guide device design within realistic fabrication constraints and enable accurate post-fabrication characterization. In this paper, building on existing work, we introduce a modeling framework that explicitly integrates the engineering tools used for designing classical properties of integrated waveguides with quantum mechanical theory describing the underlying nonlinear interactions. We analyze the validity and limitations of approximations relevant to this framework and apply it to comprehensively study how typical fabrication errors and deviations from nominal design—common in practical waveguide manufacturing—affect the nonlinear optical response. Our findings highlight, in particular, a critical sensitivity of the framework to group-velocity dispersion, the potentially highly disruptive role of geometric inhomogeneities in the waveguide, and an upper bound on uncorrelated squeezed-state generation arising from asymmetric group-velocity matching conditions.
Technologies based on quantum mechanics promise to revolutionize the collection, processing and communication of information. However, due to the fragility of quantum coherence, complex quantum states can only exist in highly isolated and stable environments. One suitable environment is that of a quantum photonic chip. Quantum integrated photonics seeks to generate, process and detect complex quantum states inside a photonic chip. This thesis presents theory and experimental verification of novel approaches for the integration of various functionalities into quantum photonic chips in a scalable way. As such, this thesis encompasses a broad area of physics including quantum optics and nonlinear photonics. The results presented in this thesis have applications in the areas of quantum enhanced measurement, communication and information processing. In particular we develop the theory and experimentally demonstrate flexible on-chip sources of spatially entangled photons, the state of which can be reconfigured alloptically. We show how such techniques could enable the realization of simple cluster state quantum computing algorithms using spatially encoded two-photon states. Furthermore, we suggest new and practical approaches for the efficient characterization of mass produced nonlinear quantum photonic chips. Finally we develop and experimentally demonstrate a scalable method for the full quantum state tomography of multi-photon states on-chip. Importantly this technique only requires a linearly increasing number of single photon detectors relative to the number of photons in the state being characterized, and is also highly compatible with on-chip single photon detectors.
Chip-scale integrated photonic circuits provide an attractive platform for the implementation of many quantum photonic technologies ranging from precise metrology to secure communication and quantum computation. In particular, silicon photonic platforms support micron-scale nonlinear optical sources of non-classical light which can be mass manufactured using the robust fabrication processes pioneered by the CMOS microelectronics industry. Integration of these quantum photonic sources with high-performance classical photonic devices on the same chip is required for truly scalable quantum information technologies. Integrated nonlinear resonators are investigated as sources of quantum mechanically correlated photon pair sources. An all-order dispersion engineering method is presented as a robust design synthesis for micoring sources. In addition, a novel concept of coupled mode dispersion compensation is proposed and demonstrated, providing significantly improved performance characteristics of resonant four-wave mixing sources. Next a photon pair source is demonstrated in a commercial CMOS microelectronics process opening the door to future integration of quantum photonics with electronic logic and control circuits. Classical nonlinear optical measurements of stimulated four-wave mixing are used for the first time to accurately predict the quantum correlations from the same device operating in the photon pair regime. Next the first demonstration of fully on-chip pump rejection is demonstrated with over 95 dB pump extinction improving the figures of merit from previous demonstrations by multiple orders of magnitude, including losses, detected pair rates and size. Finally, proposals for introducing novel degrees of freedom provided by an integrated platform are presented for further improving the performance of both photon pair and classical nonlinear optical sources.
Photons have proven to be an effective test-bed for the fundamental concepts and elements of quantum-enhanced technologies. As systems become increasingly complex, however, practical considerations make the traditional approach of bulk optics and free-space propagation progressively more difficult. The major obstacles are the physical space necessary to realise and operate such a complex system, its stability, and maintaining low losses. In order to address these issues, quantum optical technologies can take a cue from their classical counterparts and look towards an integrated architecture to provide miniaturisation, greatly enhanced stability, less alignment, and low loss interfaces between different system components. In this thesis the feasibility of chip-based waveguides as a platform for metrology and information processing will be explored. In Part I, the necessary criteria for a metrology system to out-perform its classical counterpart will be investigated. It will be found that loss is a major barrier to this aim and, critically, that it is unlikely to have been achieved to date by any experiment which consumes resources of a fixed photon number. The issue of loss will be addressed by developing a scalable heralded source of a class of entangled photonic states which are both robust to losses and practically feasible to prepare. A novel tomographic technique will be developed to characterize these states and it will be explicitly demonstrated how it is possible to beat some bounds on classical performance without being able to out-perform a comparable classical system. Finally, a proof of principle demonstration of a waveguide-based interferometer with an integrated phase-shifter will be undertaken. It will be shown that the device preserves quantum interference, making it suitable for use in quantum-enhanced metrology applications. In Part II, integrated optics in the context of information processing will be discussed. First, a novel characterization technique will be developed which enables the behaviour of complex circuits to be predicted. The technique is independent of loss in the device being characterized. A method of simulating these circuits will be outlined that takes advantage of the computational speed-up available from parallelisation and sparse matrix operations. A key increase in complexity for integrated photonic systems will be demonstrated by showing quantum interference of three photons from two separate sources in eight spatial modes. The resulting interference has a visibility which beats all possible classical interference visibilities for similar circuits. Finally, a fully integrated waveguide-coupled photon-number-resolving detector will be developed and demonstrated. This proof of concept demonstration will show good resolution of different photon number events. The device will be modelled and routes to high efficiency operation will be explored.
Nonclassical states of light are an essential resource for many emerging quantum technologies and applications ranging from information processing, encrypted communications, and networking to sensing, metrology, and imaging. Nonlinear optical processes in solid-state materials are widely used for generating quantum light, including single photons, entangled-photon pairs, and quadrature-squeezed states. Recent advances in nonlinear photonics have enabled the functionality of benchtop nonlinear instruments to be scaled down to a single chip without sacrificing efficiency or degrading the key performance metrics. The dramatic improvement in the size, weight, power, cost, and stability enabled by photonic integrated circuits has been essential for enabling the chip-scale generation, manipulation, and detection of quantum light at a steadily increasing degree of complexity and scale. Within the last decade, the authors have seen the progression from few-component photonic circuits operating on two photons to arrays of 18 identical heralded single-photon sources and reconfigurable devices operating with more than 650 components for multidimensional entanglement and arbitrary two-photon quantum gates. In this review, the authors summarize the history and recent key technological developments of chip-scale nonlinear quantum light generation based on integrated nonlinear photonics, recent advances in heterogeneous integrated methods, and approaches for system-level integration and demonstrated applications.