Master Thesis Defence by Iñigo Lara Izcue

Towards percolation-based quantum computing with a photonic machine gun

Measurement-based quantum computing is an alternative point of view to execute quantum computations in which a highly entangled resource state, called cluster state, is grown at first, and then the computation is simulated by disentangling such state through single-qubit measurements. This approach suites perfectly optical systems, as these can provide many entangled qubits encoded in photons. However the creation of such highly-entangled resources in a scalable way is difficult.
One way to solvent this challenge is to use a percolation approach, in which spanning 3D clusters states states are grown by probabilistically fusing together smaller clusters. These small clusters are created by the emission of a Quantum Dot, referred to as the photonic machine-gun. If the fusion operations operate above the percolation threshold, entanglement percolates, and a universal resource for fault-tolerant quantum computing can be achieved.
This thesis studies and analyses entanglement percolation over a cubic lattice. It is determined that the protocol proposed can tolerate up to 8% photon loss, is ballistic an heralded. The protocol analyzed generates a cluster state encoded into the spin QD quits, which means that the grown entangled state is stored in the solid-state QDs until the mesurement-based computation is ready to start, therefore avoiding the need for quantum memories. Finally, an abstract blueprint of what a percolation-based quantum computer might look like is shown.
In short, this thesis serves as a natural path towards implementing fusion-based quantum computing with the photonic machine gun system.