Unlocking the potential of Quantum LDPC Codes for low-overhead fault-tolerance
Lead Research Organisation:
Royal Holloway University of London
Department Name: Mathematics
Abstract
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People |
ORCID iD |
| Alastair Kay (Principal Investigator) | |
| Ivan Rungger (Co-Investigator) |
| Description | We have been studying a particular class of error correcting code known as the "balanced product code", which has excellent properties in terms of the density of information storage and ability to correct errors. We have shown that this code can be modified in such a way to permit transversal gates (the main aim of this award) to be applied to the quantum data stored in the code, making these codes much more useful from a computing perspective. The general insights should be applicable to a wide range of other codes. We continue to investigate the impact of the modified construction on the storage density and, especially, the tolerance of errors. |
| Exploitation Route | This result is a first of its kind, as there is a widely held belief that what we have tried to do is not possible. This should prompt further studies into these codes with the aim of improving the parameters and making computation a much more realistic prospect. In the medium term, this work should contribute to an argument for quantum computing companies reviewing quantum Low Density Parity Check codes for placement on their roadmaps. |
| Sectors | Digital/Communication/Information Technologies (including Software) |
| Description | Influence into international standardization activities on quantum computing benchmarks |
| Geographic Reach | Multiple continents/international |
| Policy Influence Type | Participation in a guidance/advisory committee |
| Description | Collaboration with NPL and UCL |
| Organisation | National Physical Laboratory |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Royal Holloway and UCL designed minimal QLDPC codes for low qubit number to systematically benchmark practical error correction performance with NPL's noise models and on quantum computing hardware through the NQCC's Quantum Computing Access Programme, for which a joint proposal was written. RHUL and UCL provided quantum error correction and specifically QLDPC code expertise into NPL's standardization activities for benchmarks of quantum computers by advising on requirements for running QLDPC codes in practice. |
| Collaborator Contribution | UCL contributes to the QLDPC code design. NPL provides the noise model for various quantum computing hardware platforms, and the restrictions that the QLDPC code has to satisfy for each platform, such as available connectivities, quantum operations and their expected fidelities, numbers of qubits. The input from Royal Holloway and UCL on quantum error correction and requirements for QLDPC codes were taken into account by NPL when formulating the state of the art and open research questions for benchmarks in the article "A Review and Collection of Metrics and Benchmarks for Quantum Computers: definitions, methodologies and software" (https://arxiv.org/abs/2502.06717), which NPL/NQCC/Quantum Software Lab and a number of Universities wrote, and which guides NPL's input into international standardization activities on benchmarking. |
| Impact | Requirements for metrics and benchmarks for quantum computers in the review article mentioned above. |
| Start Year | 2024 |
| Description | Collaboration with NPL and UCL |
| Organisation | University College London |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Royal Holloway and UCL designed minimal QLDPC codes for low qubit number to systematically benchmark practical error correction performance with NPL's noise models and on quantum computing hardware through the NQCC's Quantum Computing Access Programme, for which a joint proposal was written. RHUL and UCL provided quantum error correction and specifically QLDPC code expertise into NPL's standardization activities for benchmarks of quantum computers by advising on requirements for running QLDPC codes in practice. |
| Collaborator Contribution | UCL contributes to the QLDPC code design. NPL provides the noise model for various quantum computing hardware platforms, and the restrictions that the QLDPC code has to satisfy for each platform, such as available connectivities, quantum operations and their expected fidelities, numbers of qubits. The input from Royal Holloway and UCL on quantum error correction and requirements for QLDPC codes were taken into account by NPL when formulating the state of the art and open research questions for benchmarks in the article "A Review and Collection of Metrics and Benchmarks for Quantum Computers: definitions, methodologies and software" (https://arxiv.org/abs/2502.06717), which NPL/NQCC/Quantum Software Lab and a number of Universities wrote, and which guides NPL's input into international standardization activities on benchmarking. |
| Impact | Requirements for metrics and benchmarks for quantum computers in the review article mentioned above. |
| Start Year | 2024 |
| Description | Collabroation with Dan Browne's Group, University College London |
| Organisation | University College London |
| Department | Department of Physics & Astronomy |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | This grant is jointly run between my group at Royal Holloway and Dan Browne's group at UCL, but is generating a collaboration which is further reaching. The grant has already supported the hiring of one post-doc at each institution. Myself, Ivang Rungger, my post-doc, and one PhD student (not supported on the grant) have provided expertise and intellectual input. My post-doc is coordinating a monthly journal club meet-up between the two groups. |
| Collaborator Contribution | The partners at UCL have also contributed expertise and intellectual input, both from those hired on the grant, and from more widely within Dan Browne's research group. UCL has also provided facilities to allow for collaborative, in person, meetings. |
| Impact | none yet |
| Start Year | 2023 |