Session D28: Photonic Quantum Computing

Fusion based photonic quantum computing

All components of a photonic quantum computer can be built in a tier-1 foundry, and packaged in the same back-end-of-line processes used to build laptops and cellphones. Thus with photons we can realistically stare down the sorts of numbers (~1 million qubits) which capture the size of machine required to do useful quantum computation.  However the specific type of entanglement we need between different photons can only be created probabilistically, and is difficult to create in the presence of loss. In this talk I will overview an architecture Fusion Based Quantum Computing (FBQC) that sits somewhere between the extremes of matter (circuit) based and one-way (cluster state) quantum computing. It requires the production of only fixed size entangled states regardless of the size of computation being performed, and these states can have high probability of loss (or failure to be produced at all). This allows us to attempt creation of the desired entangled states multiple times in parallel, and then to select out successful events. It also allows for the extensive use of high quality fixed optical delays (e.g fiber) to amplify the effects of small amounts of entanglement by multiple orders of magnitude.    

Scaling photonic systems for quantum information processing

Photonic quantum simulations and computations requires an efficient scaling of photonic quantum systems, which comprise many controllable modes and input states with many photons. However, the implementation of such systems including many operations with high control still poses a considerable challenge. Here we present our approaches for the experimental implementation of future multi-dimensional photonic quantum systems.   

Blueprint for a Scalable Photonic Fault-Tolerant Quantum Computer

We present Xanadu's proposal for a scalable and fault-tolerant photonic quantum computer. Central to our architecture are Gottesman-Kitaev-Preskill bosonic qubits and squeezed states of light, stitched together into a qubit cluster state with one time and two spatial dimensions. This proposal for generating and manipulating a 3D resource state for fault-tolerant, measurement-based quantum computation combines state-of-the-art procedures for the preparation of bosonic qubits with the strengths of continuous-variable quantum computation performed using easy-to-generate squeezed states. Moreover, the architecture is based on modular, easy-to-network integrated photonic chips, opening the door to scalable fabrication and operation, which may in turn allow photonics to leap-frog other platforms on the path to a quantum computer with millions of qubits. In addition to overviewing the architecture from Xanadu's blueprint, we discuss subsequent work - including improvements to the stitching component - that significantly facilitate the creation of a useful quantum computer.   

Continuous Variables Measurement-based Photonic Quantum Computing

Quantum computing can be realized with numerous different hardware platforms and using different computational protocols. One highly promising strategy to foster scalability is to use a photonic platform combined with a measurement-induced quantum processing protocol where the computational gates are realized through optical measurements on a multi-partite entangled state. In this talk I will discuss our progress towards the construction of a universal and fault-tolerant measurement-based optical quantum computer.