Dr Nicholas Chancellor's Outputs (28)

Quantum optimization with linear Ising penalty functions for customer data science (2024)
Journal Article
Mirkarimi, P., Shukla, I., Hoyle, D. C., Williams, R., & Chancellor, N. (2024). Quantum optimization with linear Ising penalty functions for customer data science. Physical Review Research, 6(4), Article 043241. https://doi.org/10.1103/physrevresearch.6.043241

Constrained combinatorial optimization problems, which are ubiquitous in industry, can be solved by quantum algorithms such as quantum annealing (QA) and the quantum approximate optimization algorithm (QAOA). In these quantum algorithms, constraints... Read More about Quantum optimization with linear Ising penalty functions for customer data science.

Experimental demonstration of improved quantum optimization with linear Ising penalties (2024)
Journal Article
Mirkarimi, P., Hoyle, D. C., Williams, R., & Chancellor, N. (2024). Experimental demonstration of improved quantum optimization with linear Ising penalties. New Journal of Physics, 26(10), Article 103005. https://doi.org/10.1088/1367-2630/ad7e4a

The standard approach to encoding constraints in quantum optimization is the quadratic penalty method. Quadratic penalties introduce additional couplings and energy scales, which can be detrimental to the performance of a quantum optimizer. In quantu... Read More about Experimental demonstration of improved quantum optimization with linear Ising penalties.

Cycle discrete-time quantum walks on a noisy quantum computer (2024)
Journal Article
Wadhia, V., Chancellor, N., & Kendon, V. (2024). Cycle discrete-time quantum walks on a noisy quantum computer. The European Physical Journal D, 78(3), Article 29. https://doi.org/10.1140/epjd/s10053-023-00795-2

The rapid development of quantum computing has led to increasing interest in quantum algorithms for a variety of different applications. Quantum walks have also experienced a surge in interest due to their potential use in quantum algorithms. Using t... Read More about Cycle discrete-time quantum walks on a noisy quantum computer.

A thermodynamic approach to optimization in complex quantum systems (2024)
Journal Article
Imparato, A., Chancellor, N., & De Chiara, G. (2024). A thermodynamic approach to optimization in complex quantum systems. Quantum Science and Technology, 9(2), Article 025011. https://doi.org/10.1088/2058-9565/ad26b3

We consider the problem of finding the energy minimum of a complex quantum Hamiltonian by employing a non-Markovian bath prepared in a low energy state. The energy minimization problem is thus turned into a thermodynamic cooling protocol in which we... Read More about A thermodynamic approach to optimization in complex quantum systems.

Graphical structures for design and verification of quantum error correction (2023)
Journal Article
Chancellor, N., Kissinger, A., Zohren, S., Roffe, J., & Horsman, D. (2023). Graphical structures for design and verification of quantum error correction. Quantum Science and Technology, 8(4), Article 045028. https://doi.org/10.1088/2058-9565/acf157

We introduce a high-level graphical framework for designing and analysing quantum error correcting codes, centred on what we term the coherent parity check (CPC). The graphical formulation is based on the diagrammatic tools of the ZX-calculus of quan... Read More about Graphical structures for design and verification of quantum error correction.

Using copies can improve precision in continuous-time quantum computing (2023)
Journal Article
Bennett, J., Callison, A., O’Leary, T., West, M., Chancellor, N., & Kendon, V. (2023). Using copies can improve precision in continuous-time quantum computing. Quantum Science and Technology, 8(3), Article 035031. https://doi.org/10.1088/2058-9565/acdcb5

In the quantum optimisation setting, we build on a scheme introduced by Young et al (2013 Phys. Rev. A 88 062314), where physical qubits in multiple copies of a problem encoded into an Ising spin Hamiltonian are linked together to increase the logica... Read More about Using copies can improve precision in continuous-time quantum computing.

Comparing the hardness of MAX 2-SAT problem instances for quantum and classical algorithms (2023)
Journal Article
Mirkarimi, P., Callison, A., Light, L., Chancellor, N., & Kendon, V. (2023). Comparing the hardness of MAX 2-SAT problem instances for quantum and classical algorithms. Physical Review Research, 5(2), https://doi.org/10.1103/physrevresearch.5.023151

An algorithm for a particular problem may find some instances of the problem easier and others harder to solve, even for a fixed input size. We numerically analyze the relative hardness of MAX 2-SAT problem instances for various continuous-time quant... Read More about Comparing the hardness of MAX 2-SAT problem instances for quantum and classical algorithms.

NP-hard but no longer hard to solve? Using quantum computing to tackle optimization problems (2023)
Journal Article
Au-Yeung, R., Chancellor, N., & Halffmann, P. (2023). NP-hard but no longer hard to solve? Using quantum computing to tackle optimization problems. Quantum Science and Technology, 2, Article 1128576. https://doi.org/10.3389/frqst.2023.1128576

In the last decade, public and industrial research funding has moved quantum computing from the early promises of Shor’s algorithm through experiments to the era of noisy intermediate scale quantum devices (NISQ) for solving real-world problems. It i... Read More about NP-hard but no longer hard to solve? Using quantum computing to tackle optimization problems.

Controller-Based Energy-Aware Wireless Sensor Network Routing Using Quantum Algorithms (2022)
Journal Article
Chen, J., Date, P., Chancellor, N., Atiquzzaman, M., & Sreenan, C. (2022). Controller-Based Energy-Aware Wireless Sensor Network Routing Using Quantum Algorithms. IEEE Transactions on Quantum Engineering, 3, https://doi.org/10.1109/tqe.2022.3217297

Energy-efficient routing in wireless sensor networks has attracted attention from researchers in both academia and industry, most recently motivated by the opportunity to use software-defined network-inspired approaches. These problems are NP-hard, w... Read More about Controller-Based Energy-Aware Wireless Sensor Network Routing Using Quantum Algorithms.

Modernizing quantum annealing II: genetic algorithms with the inference primitive formalism (2022)
Journal Article
Chancellor, N. (2023). Modernizing quantum annealing II: genetic algorithms with the inference primitive formalism. Natural Computing, 22, 737–752. https://doi.org/10.1007/s11047-022-09905-2

Quantum annealing, a method of computing where optimization and machine learning problems are mapped to physically implemented energy landscapes subject to quantum fluctuations, allows for these fluctuations to be used to assist in finding the soluti... Read More about Modernizing quantum annealing II: genetic algorithms with the inference primitive formalism.

Hybrid quantum-classical algorithms in the noisy intermediate-scale quantum era and beyond (2022)
Journal Article
Callison, A., & Chancellor, N. (2022). Hybrid quantum-classical algorithms in the noisy intermediate-scale quantum era and beyond. Physical Review A, 106(1), Article 010101. https://doi.org/10.1103/physreva.106.010101

Hybrid quantum-classical algorithms are central to much of the current research in quantum computing, particularly when considering the noisy intermediate-scale quantum (NISQ) era, with a number of experimental demonstrations having already been perf... Read More about Hybrid quantum-classical algorithms in the noisy intermediate-scale quantum era and beyond.

Error measurements for a quantum annealer using the one-dimensional Ising model with twisted boundaries (2022)
Journal Article
Chancellor, N., Crowley, P. J., Durić, T., Vinci, W., Amin, M. H., Green, A. G., Warburton, P. A., & Aeppli, G. (2022). Error measurements for a quantum annealer using the one-dimensional Ising model with twisted boundaries. npj Quantum Information, 8(1), Article 73. https://doi.org/10.1038/s41534-022-00580-w

A finite length ferromagnetic chain with opposite spin polarization imposed at its two ends is one of the simplest frustrated spin models. In the clean classical limit the domain wall inserted on account of the boundary conditions resides with equal... Read More about Error measurements for a quantum annealer using the one-dimensional Ising model with twisted boundaries.

AKLT-States as ZX-Diagrams: Diagrammatic Reasoning for Quantum States (2022)
Journal Article
East, R. D., van de Wetering, J., Chancellor, N., & Grushin, A. G. (2022). AKLT-States as ZX-Diagrams: Diagrammatic Reasoning for Quantum States. PRX Quantum, 3(1), https://doi.org/10.1103/prxquantum.3.010302

From Feynman diagrams to tensor networks, diagrammatic representations of computations in quantum mechanics have catalyzed progress in physics. These diagrams represent the underlying mathematical operations and aid physical interpretation, but canno... Read More about AKLT-States as ZX-Diagrams: Diagrammatic Reasoning for Quantum States.

Experimental test of search range in quantum annealing (2021)
Journal Article
Chancellor, N., & Kendon, V. (2021). Experimental test of search range in quantum annealing. Physical Review A, 104(1), Article 012604. https://doi.org/10.1103/physreva.104.012604

We construct an Ising Hamiltonian with an engineered energy landscape such that it has a local energy minimum which is near the true global minimum solution and further away from a false minimum. Using a technique established in previous experiments,... Read More about Experimental test of search range in quantum annealing.

The challenge and opportunities of quantum literacy for future education and transdisciplinary problem-solving (2021)
Journal Article
Nita, L., Mazzoli Smith, L., Chancellor, N., & Cramman, H. (2023). The challenge and opportunities of quantum literacy for future education and transdisciplinary problem-solving. Research in Science and Technological Education, 41(2), 564-580. https://doi.org/10.1080/02635143.2021.1920905

Background Knowledge of quantum computing is arguably inaccessible to many, with knowledge of the complex mathematics involving a particular barrier to entry, creating difficulty in terms of teaching and inclusive learning for those without a high le... Read More about The challenge and opportunities of quantum literacy for future education and transdisciplinary problem-solving.

Energetic Perspective on Rapid Quenches in Quantum Annealing (2021)
Journal Article
Callison, A., Festenstein, M., Chen, J., Nita, L., Kendon, V., & Chancellor, N. (2021). Energetic Perspective on Rapid Quenches in Quantum Annealing. PRX Quantum, 2(1), Article 010338. https://doi.org/10.1103/prxquantum.2.010338

There are well-developed theoretical tools to analyze how quantum dynamics can solve computational problems by varying Hamiltonian parameters slowly, near the adiabatic limit. On the other hand, there are relatively few tools to understand the opposi... Read More about Energetic Perspective on Rapid Quenches in Quantum Annealing.

Quantum computing for quantum tunneling (2021)
Journal Article
Abel, S., Chancellor, N., & Spannowsky, M. (2021). Quantum computing for quantum tunneling. Physical Review D, 103(1), Article 016008. https://doi.org/10.1103/physrevd.103.016008

We demonstrate how quantum field theory problems can be practically encoded by using a discretization of the field theory problem into a general Ising model, with the continuous field values being encoded into Ising spin chains. To illustrate the met... Read More about Quantum computing for quantum tunneling.

Fluctuation-guided search in quantum annealing (2020)
Journal Article
Chancellor, N. (2020). Fluctuation-guided search in quantum annealing. Physical Review A, 102(6), Article 062606. https://doi.org/10.1103/physreva.102.062606

Quantum annealing has great promise in leveraging quantum mechanics to solve combinatorial optimization problems. However, to realize this promise to its fullest extent we must appropriately leverage the underlying physics. In this spirit, we examine... Read More about Fluctuation-guided search in quantum annealing.

Practical designs for permutation-symmetric problem Hamiltonians on hypercubes (2019)
Journal Article
Dodds, A. B., Kendon, V., Adams, C. S., & Chancellor, N. (2019). Practical designs for permutation-symmetric problem Hamiltonians on hypercubes. Physical Review A, 100(3), Article 032320. https://doi.org/10.1103/physreva.100.032320

We present a method to experimentally realize large-scale permutation-symmetric Hamiltonians for continuous-time quantum protocols such as quantum walks and adiabatic quantum computation. In particular, the method can be used to perform an encoded co... Read More about Practical designs for permutation-symmetric problem Hamiltonians on hypercubes.

Quantum Codes from Classical Graphical Models (2019)
Journal Article
Roffe, J., Zohren, S., Horsman, D., & Chancellor, N. (2020). Quantum Codes from Classical Graphical Models. IEEE Transactions on Information Theory, 66(1), 130-146. https://doi.org/10.1109/tit.2019.2938751

We introduce a new graphical framework for designing quantum error correction codes based on classical principles. A key feature of this graphical language, over previous approaches, is that it is closely related to that of factor graphs or graphical... Read More about Quantum Codes from Classical Graphical Models.