Scaleable integration of electronic and Photonic integrated circuits for quantum optics in silicon

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The majority of this PhD will be undertaken with Josh in The Big Photon group looking at scalable integration of electronic and photonic integrated circuits for quantum optics in silicon. Another project will be undertaken with Jorge looking at frequency multiplexed control of phase modulators in order to reduce wiring requirements into the cryostat and onto the chip. These projects fall under the same banner of scalability in silicon photonics with both supervisors eager to collaborate.Photonic integrated circuits (PICs) represent a promising platform for classical and quantum information processing. Information can be encoded into different properties of the light confined to waveguides lithographically fabricated on the PICs. Manipulation of the light, and thus the encoded information, is typically achieved using beam splitters and phase modulators. Reck et al. showed that any NxNunitary operation can be expressed as some linear combination of 2x2 unitary operations achieved using simple Mach-Zehnder Interferometers. These Reck schemes, and other large-scale manipulation of quantum states on chip, will require>1000 phase modulators thus be requiring a number of electrical control wires of the same order. To reduce this wiring bottleneck multiplexing techniques can be used to allow for the control of multiple phase modulators from a single, or few, control wires. Designing the phase modulators to be frequency dependent would allow for all modulators to be controlled froma single control wire with the phase modulating voltages superimposed. This scheme would allow for simultaneous and independent control of all modulators. This scheme is of particular importance for photonic systems operating at cryogenic temperatures where the cooling system imposes strict limitations on the number of control wires available. Many quantum optic schemes in silicon photonics are non-deterministic and require the use of feed-forward signals to correctly route heralded events. Single-photons in silicon photonics are generated through parametric processes that are non-deterministic, requiring the heralding of the idler photon through detection of the signal photon. Additionally, in order to reduce the chances of undesired multi-photon generation events the pump power is reduced, further reducing the likelihood of photon-pair production. In order to achieve pseudo-deterministic production of heralded single-photons multiple sources are multiplexed together such that a successful single-photon generation even at one source can be switched to the output. When completely integrated on chip, the short time available for switching the single-photon requires highly integrated and fast electronics. Design of this electronics architecture and the way in which it is integrated in a scalable manner requires additional research.