PaperlayerView exact revision on arXiv

Source-linked AI summary

Recent advances on integrated quantum communications

Adeline Orieux, Eleni Diamanti

arXiv:1606.07346v1quant-ph

TL;DR

Large-scale quantum communications require integrated technologies, but practical chip-based systems must combine diverse components and platforms while addressing loss and probabilistic operation. This review surveys integrated photonic platforms, communication components, and system-level implementations, including QKD, and reports promising prototype systems alongside remaining limitations.

  • Problem

    Scaling quantum information systems and developing practical on-chip quantum communications require integrated technologies, but the field faces challenges across multiple components, platforms, and system operations.

  • Method

    The review evaluates integration platforms and surveys integrated sources, optical elements, memories, detectors, and system designs for quantum communications.

  • Results

    Chip-based QKD and quantum teleportation systems have reached promising prototypical stages, while integrated experiments have demonstrated compact entangled-state generation and entanglement distribution.

  • Takeaways & Limitations

    Reduced payload in integrated quantum communication systems could support applications including mobile QKD networks and satellite deployment.

  • Takeaways & Limitations

    The review is not exhaustive, and current integrated communication experiments generally lack appreciable distance because losses remain a bottleneck.

Abstract

from arXiv · show

In recent years, the use of integrated technologies for applications in the field of quantum information processing and communications has made great progress. The resulting devices feature valuable characteristics such as scalability, reproducibility, low cost and interconnectivity, and have the potential to revolutionize our computation and communication practices in the future, much in the way that electronic integrated circuits have drastically transformed our information processing capacities since the last century. Among the multiple applications of integrated quantum technologies, this review will focus on typical components of quantum communication systems and on overall integrated system operation characteristics. We are interested in particular in the use of photonic integration platforms for developing devices necessary in quantum communications, including sources, detectors and both passive and active optical elements. We also illustrate the challenges associated with performing quantum communications on chip, by using the case study of quantum key distribution - the most advanced application of quantum information science. We conclude with promising perspectives in this field.

1. Introduction

Integrated quantum technologies are presented as necessary for scaling quantum information systems, while integrated photonics offers a promising route for chip-based quantum communications. The review surveys communication components and systems, emphasizing on-chip QKD and remaining challenges.

  • Scaling quantum information systems will necessitate integrated technologies, analogous to the role of integrated circuits in modern communications.
  • Photons are suitable on-chip information carriers because of their long coherence time, weak environmental interaction, and high speed.
  • The review covers integrated platforms, nonclassical-light generation, optical manipulation, storage, detection, and system-level quantum communication applications.
  • Quantum key distribution receives particular attention as the most advanced application used to illustrate on-chip communication challenges.
  • The review is not exhaustive and aims to present the current state of the art alongside major tasks still to be addressed.

2. Integration platforms for quantum communications

Quantum communication integration uses multiple photonic platforms, each offering different capabilities and constraints. Because no platform combines all desired properties, future devices are expected to use hybrid integration technologies.

  • Platform suitability is judged by manufacturing compatibility, nonlinear and electro-optic functionality, single-photon detection, encoding support, and network adaptability.
  • Silicon-based platforms offer CMOS-compatible, reproducible fabrication, compact high-index waveguides, and strong confinement that benefits nonlinear effects.
  • III-V semiconductors support laser emission and fast optoelectronic operation through direct-bandgap materials such as InP, GaAs, and GaN.
  • Lithium niobate and KTP provide strong second-order nonlinearities and electro-optic properties for down-conversion, frequency conversion, and modulation, but their larger size limits scalability.
  • Glass-waveguide platforms provide low propagation loss, strong fiber mode matching, rapid fabrication, and complex linear circuits, but cannot support nonlinear or electro-optic functions.
  • No single platform provides every desired characteristic, motivating hybrid technologies that combine the strengths of different platforms.

3. Integrated quantum communication devices

Integrated quantum communication devices increasingly combine sources, manipulators, wavelength converters, memories, and detectors, but each platform imposes different performance and integration constraints. Demonstrated systems show high-quality photonic states and reconfigurable processing, while probabilistic emission, coupling losses, and the lack of telecom-compatible memories remain important limitations.

  • 3.1. Generation: Integrated sources generate heralded single photons, entangled pairs, NOON states, and multi-photon states using SPDC, SFWM, and related nonlinear processes.Correlated photon pairs support both heralded single-photon generation and two-photon entanglement, while recent experiments have demonstrated heralded multi-photon states and photon triplets.
  • 3.1. Generation: Silicon sources have demonstrated 89% raw visibility, Bell parameters up to 2.69, over 96% two-photon-interference visibility, and more than 91% Bell-state fidelity.These compact devices exploit tight bending radii and strong mode confinement, but SFWM requires high-extinction notch filtering because pump and generated wavelengths are close.
  • 3.1. Generation: AlGaAs and PPLN/PPKTP platforms provide complementary capabilities, including CAR above 100, Bell parameters around 2.6–2.82, NOON-state fidelity above 84%, and 60% heralding efficiency.PPLN/PPKTP sources are described as established, while AlGaAs phase-matching techniques provide narrowband, broadband, and electrically pumped devices.
  • 3.2. Manipulation: Photon manipulation uses integrated linear-optical circuits, with demonstrations spanning reconfigurable interferometers, Boson Sampling over 13 modes, and single-photon W states over 16 spatial modes.Dual-rail encoding dominates because its building blocks are easier to integrate than polarization-based counterparts, although glass circuits also manipulate polarization and hyper-entangled photons.
  • 3.2. Manipulation: Single-photon wavelength conversion from 910 nm to 600 nm achieved over 70% internal efficiency while maintaining a similar signal-to-noise ratio.Such conversion can connect telecom photons with detectors or quantum memories operating in other wavelength ranges.
  • 3.3. Storage: Quantum memories could extend communication distance, synchronize probabilistic photonic processes, and improve scalability, but no integrated memory directly compatible with optical telecom networks had yet been demonstrated.Promising integrated memories had stored red-frequency photons using thulium-doped LiNbO3 and praseodymium-doped Y2SiO5 waveguides.

4. Integrated quantum communication systems

Integrated quantum communication systems are advancing from partially integrated demonstrations toward chip-based platforms for QKD, entanglement distribution, and scalable network operation. Practical deployment remains constrained by detector integration, optical losses, synchronization, and the need to combine heterogeneous technologies.

  • Quantum key distribution: Fully chip-based QKD systems are needed for long-distance secure communications, server-server key sharing, and enhanced integration with communication networks.Partially integrated client-server demonstrations provide proof of principle, but their application scope remains limited.
  • Quantum key distribution: Integrated QKD demonstrations combine platforms and functions, including InP transmitters with tunable lasers and modulators, SiON receivers with interferometers, and silicon photonics for CV-QKD.The reported DV and distributed-phase-reference system achieved GHz operation, while the CV chip included modulation and shot-noise-limited homodyne detection with Ge photodiodes.
  • Entanglement distribution and quantum teleportation: Intrinsic channel losses impose network structures because point-to-point quantum communication becomes impractical over sufficiently long links.Entanglement distribution is identified as a foundation for quantum teleportation and quantum repeaters, which extend communication range.
  • Entanglement distribution and quantum teleportation: Entanglement distribution between separate fiber-connected photonic chips demonstrates a network-oriented path toward flexible and interconnected quantum communication systems.The experiment used silicon photonics with path and polarization encodings and certified entanglement through a Bell-test violation.
  • System challenges: Losses within chips and at fiber couplings remain a bottleneck, as existing integrated experiments generally lack appreciable distance between communicating parties.Reducing losses at every stage is presented as essential for improving performance and enabling practical on-chip quantum communication.
  • System challenges: Practical networks also require fast-electronics integration for synchronization and multiplexing techniques to increase bandwidth.These requirements extend system design beyond the photonic components themselves to the surrounding network environment.

5. Conclusions and outlook

Integrated quantum communications has advanced across both component technologies and network-level operation, but further engineering and infrastructure work is needed for scalable systems. The field may also enable mobile, satellite, and foundational-physics applications while opening new directions in silicon photonics.

  • 5. Conclusions and outlook: Recent advances address both the main components of integrated quantum communication systems and the system-level challenges of operating in networks.The review frames these advances as progress that also generates further challenges.
  • 5. Conclusions and outlook: Improving source heralding efficiency and developing integrated frequency converters, quantum memories, detectors, and photon counters remain key component priorities.Hybrid integration solutions may be needed to advance these functions.
  • 5. Conclusions and outlook: Reduced payloads could support mobile QKD networks and satellite deployment, while further loss reduction and multiplexing are needed for advanced on-chip protocols.The review identifies device-independent and measurement-device-independent QKD, multipartite communications, teleportation, and repeater links as target applications.
  • 5. Conclusions and outlook: Integrated systems may make loophole-free Bell tests and long-distance quantum communications in space more accessible for probing nonlocality, contextuality, and the quantum/classical interface.The review connects these applications to tests of fundamental physics in previously inaccessible regimes.
  • 5. Conclusions and outlook: Practical industrial deployment requires higher-capacity foundry infrastructure, use of deployed fibers and satellites, and continued certification and standardization work.The review also notes that QKD-driven silicon modulator requirements can open new possibilities in silicon photonics.
Loading 1606.07346v1…