Grant: Research Tools and Instruments - Category 1 (<$150,000)

Entanglement, in quantum mechanics, describes situations where different quantum systems become to tightly intertwined that each loses their own identity. The famous physicist Erwin Schroedinger remarked in 1935 that entanglement is ""... the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of thought"". The rapidly growing field of quantum information science is based on the realization that entanglement is not only the characteristic trait of quantum mechanics, but can be harnessed for truly disruptive new technologies in communication and computation. Pairs of optical photons, the fundamental particles of light, can be entangled through the process of down-conversion, where a blue photon breaks into two red photons. A longstanding open problem in quantum optics was to find a process that could break one photon into three to produce entangled photon triplets. We recently made a crucial step towards this open problem by demonstrating the first direct source of photon triplets from a cascade of two down-conversion processes. These results have been published in the prestigious science journal Nature; we must now move quickly to avoid being eclipsed by international competitors and keep this research in Canada. Demonstrating the entanglement of photon triplets will be the next major breakthrough. To achieve this, we require photon triplet sources with dramatically improved production rates and signal to noise. This can only be realized with major advancements in the first stage of down-conversion and is the basis for this RTI application. The requested equipment consists of a narrowband diode laser to pump the whole process, highly-efficient fibre-coupled PPKTP waveguides, diagnostics, electronics and feedback control for stablizing interferometers, optics, and optomechanics. This equipment, to be used by undergraduate, MSc, PhD, and post-doctoral fellows, will enable development of both energy-time and polarization-entangled photon triplets.