Arrays of on-chip microcavities for quantum applications

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In the not-too-distant future, devices that exploit quantum mechanics will enable computing, communications, and sensing systems whose capabilities greatly exceed those of our current technologies.  One promising vision is the creation of a quantum network, or 'quantum internet'. In such a network, light is used to transmit quantum state information over potentially large distances (typically using low-loss fiber optics), and atoms or solid-state materials are used (at network nodes) to process and store this quantum information. One particular challenge for quantum technology development is that the interaction between light and matter is inherently weak. Placing atoms or solid-state materials between two mirrors (a so-called optical cavity) strongly increases the efficiency of light-matter interactions, especially as the cavity is scaled to microscopic dimensions. Practical engineering solutions are needed for embedding nano-scale solid-state materials into micro-scale optical cavities, and for building systems that comprise large numbers of such cavities. Typically, these systems must also be integrated with electrical circuitry. A world-wide research effort towards this goal is ongoing, but it remains as a significant, unsolved technological challenge. The proposed work is an engineering development effort, and springs from our established and unique capability to fabricate arrays of high-quality, microscopic and `open-access' optical cavities on a single chip. These `open-access' cavities are essentially a pair of ultra-high-reflectance mirrors separated by an empty space, which creates the potential to confine light and arbitrary material objects within the same microscopic volume. The monolithic (single chip) nature of our process is unique compared to most of the alternative technologies that are under study.  Furthermore, we have shown that these cavities have great potential for controlling and tailoring the emission of light for an embedded emitter, and that they are well-suited for coupling this light to and from an external fiber optic network. Building on this, we propose a long-term vision to implement chips combining arrays of micro-cavities, techniques for precisely locating light emitters and mechanical resonators within these cavities, and on-chip electrical wiring for tuning and controlling the emission and absorption of light and as an interface for microwave signals. This could lead to a practical and scalable implementation of critically needed quantum building blocks, such as controllable sources of single light particles (single photon emitters) and devices for converting quantum information between optical and microwave frequencies (quantum transducers). The work promises to place Canada at the forefront of widely sought technologies, and to enhance Canada's already strong standing in the field of quantum information sciences.