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Dr Nicholas Chancellor's Outputs (28)

Domain wall encoding of discrete variables for quantum annealing and QAOA (2019)
Journal Article
Chancellor, N. (2019). Domain wall encoding of discrete variables for quantum annealing and QAOA. Quantum Science and Technology, 4(4), Article 045004. https://doi.org/10.1088/2058-9565/ab33c2

In this paper I propose a new method of encoding discrete variables into Ising model qubits for quantum optimization. The new method is based on the physics of domain walls in one dimensional Ising spin chains. I find that these encodings and the enc... Read More about Domain wall encoding of discrete variables for quantum annealing and QAOA.

Protecting quantum memories using coherent parity check codes (2018)
Journal Article
Roffe, J., Headley, D., Chancellor, N., Horsman, D., & Kendon, V. (2018). Protecting quantum memories using coherent parity check codes. Quantum Science and Technology, 3(3), Article 035010. https://doi.org/10.1088/2058-9565/aac64e

Coherent parity check (CPC) codes are a new framework for the construction of quantum error correction codes that encode multiple qubits per logical block. CPC codes have a canonical structure involving successive rounds of bit and phase parity check... Read More about Protecting quantum memories using coherent parity check codes.

Circuit design for multi-body interactions in superconducting quantum annealing systems with applications to a scalable architecture (2017)
Journal Article
Chancellor, N., Zohren, S., & Warburton, P. (2017). Circuit design for multi-body interactions in superconducting quantum annealing systems with applications to a scalable architecture. npj Quantum Information, 3(1), Article 21. https://doi.org/10.1038/s41534-017-0022-6

Quantum annealing provides a way of solving optimization problems by encoding them as Ising spin models which are implemented using physical qubits. The solution of the optimization problem then corresponds to the ground state of the system. Quantum... Read More about Circuit design for multi-body interactions in superconducting quantum annealing systems with applications to a scalable architecture.

Modernizing quantum annealing using local searches (2017)
Journal Article
Chancellor, N. (2017). Modernizing quantum annealing using local searches. New Journal of Physics, 19(2), Article 023024. https://doi.org/10.1088/1367-2630/aa59c4

I describe how real quantum annealers may be used to perform local (in state space) searches around specified states, rather than the global searches traditionally implemented in the quantum annealing algorithm (QAA). Such protocols will have numerou... Read More about Modernizing quantum annealing using local searches.

Quantum walk transport properties on graphene structures (2016)
Journal Article
Bougroura, H., Aissaoui, H., Chancellor, N., & Kendon, V. (2016). Quantum walk transport properties on graphene structures. Physical Review A, 94(6), Article 062331. https://doi.org/10.1103/physreva.94.062331

We present numerical studies of quantum walks on C 60 and related graphene structures to investigate their transport properties. Also known as a honeycomb lattice, the lattice formed by carbon atoms in the graphene phase can be rolled up to form nano... Read More about Quantum walk transport properties on graphene structures.

A Direct Mapping of Max k-SAT and High Order Parity Checks to a Chimera Graph (2016)
Journal Article
Chancellor, N., Zohren, S., Warburton, P., Benjamin, S., & Roberts, S. (2016). A Direct Mapping of Max k-SAT and High Order Parity Checks to a Chimera Graph. Scientific Reports, 6, Article 37107. https://doi.org/10.1038/srep37107

We demonstrate a direct mapping of max k-SAT problems (and weighted max k-SAT) to a Chimera graph, which is the non-planar hardware graph of the devices built by D-Wave Systems Inc. We further show that this mapping can be used to map a similar class... Read More about A Direct Mapping of Max k-SAT and High Order Parity Checks to a Chimera Graph.

Maximum-entropy inference with a programmable annealer (2016)
Journal Article
Chancellor, N., Szoke, S., Vinci, W., Aeppli, G., & Warburton, P. (2016). Maximum-entropy inference with a programmable annealer. Scientific Reports, 6(1), Article 22318. https://doi.org/10.1038/srep22318

Optimisation problems typically involve finding the ground state (i.e. the minimum energy configuration) of a cost function with respect to many variables. If the variables are corrupted by noise then this maximises the likelihood that the solution i... Read More about Maximum-entropy inference with a programmable annealer.