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Adam Grace

Adam Grace

M.A.Sc. Candidate

Quantum Nanophotonics Lab

Physics, Engineering Physics & Astronomy

adam.grace@queensu.ca

Adam joined the Quantum Nanophotonics Lab in 2021, where he has been using machine learning to reduce the effects of environmental noise on quantum dots. He is also a member of Shastri Lab, which develops neuromorphic photonic circuits for various computing and control tasks. His interests include quantum computing & communication, deep learning, and alternative computing approaches. In his free time, he enjoys playing hockey, rock climbing, and exploring Kingston's many restaurants.

 

A QD chirally-coupled to a waveguide with its forward direction to the right, βR ≫ βL, imparts a phase shift Δφ on coherently-scattered photons but not to those with which it interacts incoherently (due to fast dephasing). If βR < 1, then some photons are either reflected or scattered out of the waveguide.

Abstract: Quantum photonic integrated circuits, composed of linear-optical elements, offer an efficient way for encoding and processing quantum information on-chip. At their core, these circuits rely on reconfigurable phase shifters, typically constructed from classical components such as thermo- or electro-optical materials, while quantum solid-state emitters such as quantum dots are limited to acting as single-photon sources. Here, we demonstrate the potential of quantum dots as reconfigurable phase shifters. We use numerical models based on established literature parameters to show that circuits utilizing these emitters enable high-fidelity operation and are scalable. Despite the inherent imperfections associated with quantum dots, such as imperfect coupling, dephasing, or spectral diffusion, we show that circuits based on these emitters may be optimized such that these do not significantly impact the unitary infidelity. Specifically, they do not increase the infidelity by more than 0.001 in circuits with up to 10 modes, compared to those affected only by standard nanophotonic losses and routing errors. For example, we achieve fidelities of 0.9998 in quantum-dot-based circuits enacting controlled-phase and – not gates without any redundancies. These findings demonstrate the feasibility of quantum emitter-driven quantum information processing and pave the way for cryogenically-compatible, fast, and low-loss reconfigurable quantum photonic circuits.