Building blocks for spin-photon quantum computation with semiconductor quantum dot devices

Overview & Synopsis

Semiconductor quantum dots have emerged as a promising platform for quantum computation as they are able to generate single photons on demand with high rate and excellent indistinguishability. In addition, by hosting a single charge, they provide an efficient spin-photon interface that combines the strengths of matter-based qubits and photonic qubits. This spin-photon interface can be harnessed to deterministically generate entangled states known as cluster states, which are crucial resources for quantum computing architectures such as measurement-based quantum computation.Efficiently generating these entangled spin-photon states with many particles and high fidelity remains an outstanding challenge, requiring a high degree of control over the confined spin. In this PhD work, we address these challenges and demonstrate the generation of large cluster states comprising up to nine photons. In addition, we introduce and use optical spin rotations to implement full control over the spin, enabling the generation of caterpillar graph states. This technique also allows us to implement dynamical decoupling sequences to mitigate the effects of the hyperfine interaction between the resident spin and the nuclear spin bath, significantly increasing the spin coherence time.Finally, we introduce a fully hybrid architecture called SPOQC (spin-optical quantum computation) that exploits the properties of photonic qubits to interconnect stationary spin qubits and enable fault-tolerant quantum computation. We additionally demonstrate a first proof-of-principle implementation of a two-qubit gate that is critical to this architecture.