10077765H3Lo-QP: High-voltage High-IO High-transmission Low-temperature Quantum PhotonicsClosedCollaborative R&DInnovate UKIntegrated optical circuits are a cutting edge method of trapping and guiding light in millimetre sized chips that will be used to power the next generation of information and communication technologies. Optical chips are already ubiquitous in data centres that power the internet and enable an ever more interconnected digital society. Quantum technologies using single particles of light - photons - facilitate secure communications, enhanced environmental sensors, and ultra-fast computers. Since information is carried on individual photons, losing them represents an irretrievable loss of information. Switches that retain as much of the light as possible are a fundamental building block for all of these applications. Photons interact weakly and are mostly undisturbed by the environment at room temperature. The detectors used to measure photons, however, must be operated cryogenically. The next generation of scalable quantum photonics must solve the challenge of operating the optical chips, and switching light in the same environment as the detectors. The largest scale quantum information experiments to date have used switches that operate by creating a large temperature change in the material. These switches, however, cannot be operated en masse at cryogenic temperatures due to limited cooling power in cryostats. This roadblock can be overcome by using a different switch where an electric field is applied across the switch and facilitating active control with minimal heat dissipation. The H3Lo-QP (High-IO High-transmission High-voltage Low-temperature Quantum Photonics) project will address important challenges of designing, fabricating, post-processing, and developing the system-level architecture for cryogenically operating a large number of low heat-dissipation integrated photonics switches necessary for the next generation of optical quantum technologies. We will investigate the feasibility of two types of switches by post-processing silicon chips made using mass-manufacturing techniques, and by developing fabrication techniques to deliver optical switches in a cutting edge integrated photonics platform: thin-film lithium niobate. The architecture for the control electronics will be developed, enabling a large number of device switches to be rapidly reconfigured. We will package fabricated optical chips using special techniques where a polymer optical wire directly connects the silicon/lithium niobate chips to optical fibres used to transmit light in and out of the cryogenic environment. Finally, we will demonstrate a large-scale device operating at cryogenic temperatures using the electro-optic switches developed in this project. This work will ensure that photonic quantum technologies will flourish and with far reaching impacts across science, academia, industry, and society.