[Paper Review] Review Article: Quantum Nanophotonics in Diamond

Tim Schröder, Sara Mouradian+7 more|arXiv (Cornell University)|Mar 17, 2016

Diamond and Carbon-based Materials Research192 references3 citations

TL;DR

This review synthesizes recent advances in diamond-based quantum nanophotonics, focusing on nanofabrication techniques that enhance light collection and enable strong light-matter coupling via photonic structures like waveguides, solid immersion lenses, and optical cavities. Key contributions include deterministic defect-center integration, high-Q nanocavities, and hybrid systems enabling scalable, high-fidelity quantum networks with long spin coherence and near-lifetime-limited emission linewidths.

ABSTRACT

The past decade has seen great advances in developing color centers in diamond for sensing, quantum information processing, and tests of quantum foundations. Increasingly, the success of these applications as well as fundamental investigations of light-matter interaction depend on improved control of optical interactions with color centers -- from better fluorescence collection to efficient and precise coupling with confined single optical modes. Wide ranging research efforts have been undertaken to address these demands through advanced nanofabrication of diamond. This review will cover recent advances in diamond nano- and microphotonic structures for efficient light collection, color center to nanocavity coupling, hybrid integration of diamond devices with other material systems, and the wide range of fabrication methods that have enabled these complex photonic diamond systems.

Motivation & Objective

• Address the challenge of low photon collection efficiency and weak light-matter coupling in diamond color centers for quantum applications.
• Overcome stochastic defect creation by developing deterministic, scalable fabrication methods for high-quality quantum nodes.
• Enable high-fidelity quantum information processing and sensing through improved control of optical and spin properties in nanophotonic diamond structures.
• Integrate diamond photonic devices with other materials (e.g., superconducting detectors) to enhance detection efficiency and system scalability.
• Advance the design of hybrid and all-diamond photonic architectures for routing, interaction, and detection of single photons in quantum networks.

Proposed method

• Employ advanced nanofabrication techniques including focused ion beam milling, electron beam lithography, and angular/isotropic etching to pattern polycrystalline and single-crystal diamond.
• Implement transferrable silicon mask lithography and reactive ion etching to achieve high-aspect-ratio, high-quality diamond nanostructures.
• Use delta-doping and ion implantation to control the spatial and spectral placement of color centers during diamond growth.
• Engineer photonic cavities—such as whispering-gallery-mode and photonic crystal cavities—using thin-film and bulk diamond to achieve high Q-factors and small mode volumes.
• Integrate diamond devices with superconducting nanowire single-photon detectors (SNSPDs) on diamond substrates to achieve >66% detection efficiency at 1550 nm.
• Apply deterministic coupling techniques to align defect dipole moments with optical modes, enabling high-fidelity, on-demand single-photon emission.

Experimental results

Research questions

• RQ1 How can nanofabrication techniques be optimized to achieve high-quality, high-Q diamond photonic structures with minimal defect-induced decoherence?
• RQ2 What fabrication strategies enable deterministic placement and coupling of color centers to nanocavities for scalable quantum networks?
• RQ3 To what extent can hybrid integration with superconducting detectors and waveguides improve single-photon detection efficiency and timing resolution?
• RQ4 How do surface defects and lattice damage from dry etching degrade spin coherence and emission linewidths, and how can they be mitigated?
• RQ5 What is the potential for tuning defect transition frequencies and cavity resonances to achieve resonant coupling without sacrificing Q-factor or coherence?

Key findings

• High-quality diamond photonic structures with Q-factors exceeding 10^5 have been achieved in thin-film and bulk diamond, enabling strong light-matter interaction.
• Superconducting nanowire single-photon detectors (SNSPDs) on diamond substrates achieved 66% detection efficiency at 1550 nm with 190 ps timing resolution.
• Deterministic coupling of nitrogen-vacancy centers to photonic cavities enabled near-lifetime-limited emission linewidths, approaching the fundamental limit despite a current degradation factor of ~30.
• Waveguide and solid immersion lens structures increased photon collection efficiency by up to 10× compared to bulk diamond, enhancing single-photon source brightness.
• Hybrid integration of diamond waveguides with niobium nitride (NbN) SNSPDs on polycrystalline diamond achieved low dark count rates and high detection efficiency.
• Controlled ion implantation and delta-doping enabled precise spatial and spectral placement of color centers, reducing stochasticity in quantum node fabrication.