Publications
Publications are listed newest first. Find me on Google Scholar for citation information.
W. E. Salazar, G. Saxena, J. S. Baker, L. C. Kwek, and T. H. Kyaw, Stabilizer Statistical Mechanics: A Framework for Efficient Quantification and Classification of Magic States, arXiv preprint arXiv:2608.14798 (2026).
Summary: We develop a statistical-mechanical framework for quantum magic based on an efficiently estimable stabilizer partition function and stabilizer work, which continuously connects stabilizer 2-Rényi entropy with stabilizer nullity.
Summary: We develop a statistical-mechanical framework for quantum magic based on an efficiently estimable stabilizer partition function and stabilizer work, which continuously connects stabilizer 2-Rényi entropy with stabilizer nullity.
J. S. Baker, G. Saxena, and T. H. Kyaw, Efficient Quantum Circuits for Coherent Conversion Between General First- and Second-Quantized Many-Body Representations, arXiv preprint arXiv:2606.25029 (2026).
Summary: We introduce polynomial-complexity quantum circuits that coherently convert fixed-particle many-body states between first- and second-quantized representations while resolving exchange symmetry for bosons, fermions, and parastatistical sectors.
Summary: We introduce polynomial-complexity quantum circuits that coherently convert fixed-particle many-body states between first- and second-quantized representations while resolving exchange symmetry for bosons, fermions, and parastatistical sectors.
P. Díez-Valle, G. Saxena, J. S. Baker, J.-H. Lee, and T. H. Kyaw, Physics-inspired extrapolation for efficient error mitigation and hardware certification, Quantum Science and Technology 11(2), 025032, arXiv:2505.07977 (2026).
Summary: We develop Physics-Inspired Extrapolation, a low-overhead and low-variance error-mitigation protocol whose fitted slope also quantifies hardware noise through max-relative entropy, and demonstrate it on 84-qubit IBM quantum dynamics.
Summary: We develop Physics-Inspired Extrapolation, a low-overhead and low-variance error-mitigation protocol whose fitted slope also quantifies hardware noise through max-relative entropy, and demonstrate it on 84-qubit IBM quantum dynamics.
P. A. M. Casares, Y. Zhou, U. Azad, S. Fomichev, J. S. Baker, C. Ling, D. Banerjee, A. Delgado, and J. M. Arrazola, Quantum algorithms to identify optically detected magnetic resonance-active defects for quantum sensing applications, Physical Review A 113, 052454 (2026).
Summary: We propose two quantum algorithms that screen spin defects for optically detected magnetic resonance activity without directly calculating costly intersystem-crossing rates, with resource estimates for the negatively charged boron vacancy in hexagonal boron nitride.
Summary: We propose two quantum algorithms that screen spin defects for optically detected magnetic resonance activity without directly calculating costly intersystem-crossing rates, with resource estimates for the negatively charged boron vacancy in hexagonal boron nitride.
D. G. A. Cabral, B. Allen, F. Pavošević, S. Hammes-Schiffer, P. Díez-Valle, J. S. Baker, G. Saxena, T. H. Kyaw, and V. S. Batista, Error-Mitigation Enabled Multicomponent Quantum Simulations beyond the Born–Oppenheimer Approximation, Journal of Chemical Theory and Computation 22(4), 1760–1769, arXiv:2511.11941 (2026).
Summary: We introduce a multicomponent unitary coupled-cluster framework and demonstrate the first error-mitigated correlated simulations of coupled electronic and nuclear quantum effects on IBM Heron hardware with ground-state energies within chemical accuracy.
Summary: We introduce a multicomponent unitary coupled-cluster framework and demonstrate the first error-mitigated correlated simulations of coupled electronic and nuclear quantum effects on IBM Heron hardware with ground-state energies within chemical accuracy.
J. Naranjo, T. H. Kyaw, G. Saxena, K. Ferreira, and J. S. Baker, Designing quantum technologies with a quantum computer, arXiv preprint arXiv:2601.22091 (2026).
Summary: We develop a quantum-computer-aided framework for simulating and optimizing solid-state spin technologies, combining efficient encodings and Krylov fast-forwarding to model realistic long-time dynamics of the nitrogen-vacancy center in diamond.
Summary: We develop a quantum-computer-aided framework for simulating and optimizing solid-state spin technologies, combining efficient encodings and Krylov fast-forwarding to model realistic long-time dynamics of the nitrogen-vacancy center in diamond.
J. S. Baker, H. Horowitz, S. K. Radha, S. Fernandes, C. Jones, N. Noorani, V. Skavysh, P. Lamontagne, and B. C. Sanders, Quantum Variational Rewinding for Time Series Anomaly Detection, Proceedings of the AAAI Symposium Series 7(1), 330–338, arXiv:2210.16438 (2025).
Summary: We train parameterized quantum time-devolution operators to detect anomalies in cryptocurrency time series and show on IBM superconducting hardware that error mitigation reduces anomaly-score errors by as much as 14% on average.
Summary: We train parameterized quantum time-devolution operators to detect anomalies in cryptocurrency time series and show on IBM superconducting hardware that error mitigation reduces anomaly-score errors by as much as 14% on average.
J. S. Baker, G. Saxena, and T. H. Kyaw, Universal initial state preparation for first quantized quantum simulations, arXiv preprint arXiv:2510.07278 (2025).
Summary: We present an efficient universal method for mapping polynomial-size superpositions of occupation-number configurations into first-quantized states for fermions, bosons, and Green’s paraparticles in arbitrary single-particle bases.
Summary: We present an efficient universal method for mapping polynomial-size superpositions of occupation-number configurations into first-quantized states for fermions, bosons, and Green’s paraparticles in arbitrary single-particle bases.
G. Saxena, J. S. Baker, P. Díez-Valle, W. E. Salazar, K. Ferreira, and T. H. Kyaw, Quantum Resilience: Canadian Innovations in Quantum Error Correction and Quantum Error Mitigation, arXiv preprint arXiv:2505.20534 (2025).
Summary: We survey landmark Canadian contributions to quantum error correction and error mitigation across academia and industry, highlighting emerging approaches for reducing or eliminating errors in quantum computation.
Summary: We survey landmark Canadian contributions to quantum error correction and error mitigation across academia and industry, highlighting emerging approaches for reducing or eliminating errors in quantum computation.
J. S. Baker, P. A. M. Casares, M. S. Zini, J. Thik, D. Banerjee, C. Ling, A. Delgado, and J. M. Arrazola, Simulating optically active spin defects with a quantum computer, Physical Review A 110, 032606, arXiv:2405.13115 (2024).
Summary: We combine quantum defect embedding theory, block-encoding, and quantum phase estimation to calculate the emission spectra and radiative properties of spin-active quantum defects in materials.
Summary: We combine quantum defect embedding theory, block-encoding, and quantum phase estimation to calculate the emission spectra and radiative properties of spin-active quantum defects in materials.
P. A. M. Casares, J. S. Baker, M. Medvidović, R. D. Reis, and J. M. Arrazola, GradDFT: a software library for machine learning enhanced density functional theory, The Journal of Chemical Physics 160, 062501, arXiv:2309.15127 (2024).
Summary: We introduce a Pythonic playground for experimentation with exchange & correlation functionals in DFT based on neural networks. Check out the code.
Summary: We introduce a Pythonic playground for experimentation with exchange & correlation functionals in DFT based on neural networks. Check out the code.
J. S. Baker, G. Park, K. Yu, A. Ghukasyan, O. Goktas, and S. K. Radha, Parallel hybrid quantum-classical machine learning for kernelized time-series classification, Quantum Machine Intelligence 6, 18, arXiv:2305.05881 (2024).
Summary: A trainable time-dependent inner product space is devised using time evolution operators from quantum mechanics. We use this inner product space to define a time-series Hamiltonian kernel function, which, alongside classical SVM, we use to classify time-series on 127 qubit superconducting transmon chips. We speed up the algorithm by computing the kernel matrices in parallel using many quantum threads spread throughout the chip.
Summary: A trainable time-dependent inner product space is devised using time evolution operators from quantum mechanics. We use this inner product space to define a time-series Hamiltonian kernel function, which, alongside classical SVM, we use to classify time-series on 127 qubit superconducting transmon chips. We speed up the algorithm by computing the kernel matrices in parallel using many quantum threads spread throughout the chip.
A. Ghukasyan, J. S. Baker, O. Goktas, J. Carrasquilla, and S. K. Radha, Quantum-Classical Multiple Kernel Learning, arXiv preprint arXiv:2305.17707 (2023).
Summary: We classify quantum–quantum, classical–classical, and quantum–classical multiple-kernel learning and introduce QCC-nets, a trainable architecture that learns weighted combinations of parameterized classical and quantum kernels.
Summary: We classify quantum–quantum, classical–classical, and quantum–classical multiple-kernel learning and introduce QCC-nets, a trainable architecture that learns weighted combinations of parameterized classical and quantum kernels.
H. Guo, J. S. Baker, W. Wu, and K. L. Choy, High Dielectric Constants in BaTiO3 Due to Phonon Mode Softening Induced by Lattice Strains: First Principles Calculations, Advanced Physics Research, 2300001 (2023).
Summary: Hybrid DFT calculations show that certain strains enhance the dielectric constant of BaTiO3 through softening of a zone-centre phonon mode.
Summary: Hybrid DFT calculations show that certain strains enhance the dielectric constant of BaTiO3 through softening of a zone-centre phonon mode.
K. Roleder, G. Catalan, A. M. Glazer, J. S. Baker, J. H. Ko, F. H. Naqvi, S. B. Junaid, A. Majchrowski, Z. Trybuła, J. Zaręba, I. Lazar, D. Kajewski, J. Koperski, and A. Soszyński, Weak low-temperature polarity in a PbZrO3 single crystal, Physical Review B 107, L140102 (2023).
Summary: We find experimental evidence for a new low-temperature phase transition to a polar state in the purported archetypal antiferroelectric PbZrO3.
Summary: We find experimental evidence for a new low-temperature phase transition to a polar state in the purported archetypal antiferroelectric PbZrO3.
A. G. Hughes, J. S. Baker, and S. K. Radha. A Quantum-Inspired Binary Optimization Algorithm for Representative Selection. arXiv preprint arXiv:2301.01836 (2023).
Summary: We develop a new binary objective function for representative selection and use it to perform portfolio diversification and index reconstruction using D-Wave quantum annealers.
Summary: We develop a new binary objective function for representative selection and use it to perform portfolio diversification and index reconstruction using D-Wave quantum annealers.
J. S. Baker, S. K. Radha, B. C. Sanders, P. Lamontagne, H. Horowitz, S. Fernandes, C. Jones, N. Noorani, and V. Skavysh, Time series anomaly detection using superconducting transmon quantum computers and error mitigation, APS March Meeting Abstracts 68(3), S64.013 (2023).
Summary: We present Quantum Variational Rewinding for anomaly detection in cryptocurrency time series and demonstrate on IBM superconducting hardware that Pauli twirling and dynamical decoupling improve its performance.
Summary: We present Quantum Variational Rewinding for anomaly detection in cryptocurrency time series and demonstrate on IBM superconducting hardware that Pauli twirling and dynamical decoupling improve its performance.
J. S. Baker, S. K. Radha, and W. Cunningham, A bridge between quantum and classical difficulty in portfolio optimization using the Quantum Approximate Optimization Algorithm, APS March Meeting Abstracts 67(3), G38.008 (2022).
Summary: We use a normalized complementary Wasserstein distance to relate QAOA portfolio quality to the number of classically viable portfolios and demonstrate the method on a trapped-ion quantum computer.
Summary: We use a normalized complementary Wasserstein distance to relate QAOA portfolio quality to the number of classically viable portfolios and demonstrate the method on a trapped-ion quantum computer.
A. Hughes, S. K. Radha, and J. S. Baker, Quantum Supervised Learning Method for Outlier Detection, APS March Meeting Abstracts 67(3), Z38.009 (2022).
Summary: We present a supervised quantum-learning method for identifying outliers in data.
Summary: We present a supervised quantum-learning method for identifying outliers in data.
J. S. Baker and D. R. Bowler, Permanent manipulation of polar textures in thin ferroelectric films: insights from large scale density functional theory, APS March Meeting Abstracts 67(3), T00.076 (2022).
Summary: We use large-scale DFT to show how built-in bias fields and engineered surface trenches can permanently control polar textures in PbTiO3/SrTiO3 films.
Summary: We use large-scale DFT to show how built-in bias fields and engineered surface trenches can permanently control polar textures in PbTiO3/SrTiO3 films.
J. S. Baker and S. K. Radha, Wasserstein solution quality and the quantum approximate optimization algorithm: a portfolio optimization case study, arXiv preprint arXiv:2202.06782 (2022).
Summary: We explore a new way of looking at the quality of solutions from approximate optimizations algorithms like the QAOA and quantum annealing using Wasserstein distances. We use this new metric to benchmark the performance of several superconducting transmon and trapped ion quantum computers.
Summary: We explore a new way of looking at the quality of solutions from approximate optimizations algorithms like the QAOA and quantum annealing using Wasserstein distances. We use this new metric to benchmark the performance of several superconducting transmon and trapped ion quantum computers.
J. S. Baker, M. Paściak, J. K. Shenton, P. Vales-Castro, B. Xu, J. Hlinka, P. Márton, R. G. Burkovsky, G. Catalan, A. M. Glazer, D. R. Bowler A re-examination of antiferroelectric PbZrO3 and PbHfO3: an 80-atom Pnam structure, arXiv preprint arXiv:2102.08856 (2021).
Summary: Surprisingly, the long-standing antiferroelectric groundstates of PbZrO3 and PbHfO3 are each found with an unstable phonon mode at 0K. The displacement pattern of this mode informs a new lower symmetry structure whoose energy is lower (according to DFT) than the presently supposed ground state.
Summary: Surprisingly, the long-standing antiferroelectric groundstates of PbZrO3 and PbHfO3 are each found with an unstable phonon mode at 0K. The displacement pattern of this mode informs a new lower symmetry structure whoose energy is lower (according to DFT) than the presently supposed ground state.
J. S. Baker and D. R. Bowler, Origin of ferroelectric domain wall alignment with surface trenches in ultrathin films, Physical Review Letters 127, 247601, arXiv:2104.12750 (2021).
Summary: We reveal the microscopic mechanism responsible for how ferroelectric domain walls align with surface trenches in ferroelectric films. We use large scale DFT calculations with thousands of atoms and thousands of physical cores using the UK national supercomputer: ARCHER2.
J. S. Baker and D. R. Bowler, Polar morphologies from first principles: PbTiO3 films on SrTiO3 substrates and the p(2 × Λ) surface reconstruction, Advanced Theory and Simulations 3(11), 2000154, arXiv:2007.00787 (2020).
Summary: Large scale DFT simulations are used to investigate polar vortices and polar waves in thin ferroelectric films. We find that asymmetrical polar textures can arise from broken inversion symmetries.
Summary: Large scale DFT simulations are used to investigate polar vortices and polar waves in thin ferroelectric films. We find that asymmetrical polar textures can arise from broken inversion symmetries.
A. Nakata, J. S. Baker, S. Y. Mujahed, J. T. L. Poulton, S. Arapan, J. Lin, Z. Raza, S. Yadav, L. Truflandier, T. Miyazaki, and D. R. Bowler, Large scale and linear scaling DFT with the CONQUEST code, The Journal of Chemical Physics 152(16), 164112, arXiv:2002.07704 (2020).
Summary: A review of the large scale DFT code: CONQUEST. The theory behind the code is divulged and recent use cases are presented.
Summary: A review of the large scale DFT code: CONQUEST. The theory behind the code is divulged and recent use cases are presented.
J. S. Baker, T. Miyazaki, and D. R. Bowler, The pseudoatomic orbital basis: electronic accuracy and soft-mode distortions in ABO3 perovskites, Electronic Structure 2(2), 025002, arXiv:2003.05327 (2020).
Summary: Using a selection of technologically relevant ferroelectric and antiferroelectric perovskite oxides, we study the suitability of DFT simulations using pseudoatomic orbital basis sets to describe their properties.
Summary: Using a selection of technologically relevant ferroelectric and antiferroelectric perovskite oxides, we study the suitability of DFT simulations using pseudoatomic orbital basis sets to describe their properties.
J. S. Baker, Long Range Order in Ferroelectric and Antiferroelectric Perovskites Meets Large Scale Density Functional Theory, University of London, University College London (United Kingdom), (2020).
Summary: My Ph.D. thesis. I studied long range behaviour in ferroelectric and antiferroelectric perovskite oxides using conventional and large scale DFT simulations. Systems of interest include bulk PZT, PbZrO3, PbHfO3 and thin films of PbTiO3. New emergent behviours were found including exotic polarization textures, new complex low energy structures in PbZrO3 and uncovering the mechanism behind the alignment of ferroelectric domain walls with engineered surface trenches.
Summary: My Ph.D. thesis. I studied long range behaviour in ferroelectric and antiferroelectric perovskite oxides using conventional and large scale DFT simulations. Systems of interest include bulk PZT, PbZrO3, PbHfO3 and thin films of PbTiO3. New emergent behviours were found including exotic polarization textures, new complex low energy structures in PbZrO3 and uncovering the mechanism behind the alignment of ferroelectric domain walls with engineered surface trenches.
J. S. Baker and D. R. Bowler, First-principles soft-mode lattice dynamics of PbZr0.5Ti0.5O3 and shortcomings of the virtual crystal approximation, Physical Review B 100, 224305, arXiv:1910.01685 (2019)
Summary: New long wavelength crystal vibrations are found in the industrial piezoelectric PZT using DFT-based phonon calculations. We describe why the popular virtual crystal approximation cannot be used to accurately describe such patterns in PZT and similar materials.
Summary: New long wavelength crystal vibrations are found in the industrial piezoelectric PZT using DFT-based phonon calculations. We describe why the popular virtual crystal approximation cannot be used to accurately describe such patterns in PZT and similar materials.
D. R. Bowler, J. S. Baker, J. T. L. Poulton, S. Y. Mujahed, J. Lin, S. Yadav, Z. Raza, and T. Miyazaki, Highly accurate local basis sets for large-scale DFT calculations in CONQUEST, Japanese Journal of Applied Physics 58(10), 100503, arXiv:1908.02707 (2019).
Summary: We develop new heuristic methods for generating reliable basis sets of pseudoatomic orbitals for DFT calculations using CONQUEST. We study the accuracy of these basis sets using several popular materials.
Summary: We develop new heuristic methods for generating reliable basis sets of pseudoatomic orbitals for DFT calculations using CONQUEST. We study the accuracy of these basis sets using several popular materials.
W. Dunn, K. L. Chubb, M. Tessenyi, J. Tennyson, T. James, D. Darby, M. Niculescu-Duvaz, R. Meyer, J. Holdship, J. S. Baker, J. Smutna, M. Virdee, S. Brannan, G. Tinetti, A. Heward, C. Sousa-Silva, M. Gorman, L. K. McKemmish, and T. Rivlin, Involving school students in exoplanet research through the Twinkle Space Mission—ORBYTS, European Planetary Science Congress, EPSC2018-970 (2018).
Summary: We describe how ORBYTS pairs researchers with secondary schools so pupils can contribute to publishable exoplanet research connected to the Twinkle space mission.
Summary: We describe how ORBYTS pairs researchers with secondary schools so pupils can contribute to publishable exoplanet research connected to the Twinkle space mission.
C. Sousa-Silva, L. K. McKemmish, K. L. Chubb, M. N. Gorman, J. S. Baker, E. J. Barton, T. Rivlin, and J. Tennyson, Original Research By Young Twinkle Students (ORBYTS): when can students start performing original research?, Physics Education 53(1), 015020 (2018).
Summary: We outline how ORBYTS teaches research skills to school-aged scientists and supports them in publishing peer-reviewed work under the supervision of early-career researchers.
Summary: We outline how ORBYTS teaches research skills to school-aged scientists and supports them in publishing peer-reviewed work under the supervision of early-career researchers.
L. K. McKemmish, K. L. Chubb, T. Rivlin, J. S. Baker, M. Gorman, A. Heward, W. Dunn, and M. Tessenyi, Bringing pupils into the ORBYTS of research, Astronomy & Geophysics 58(5), 5.11 (2017).
Summary: The Twinkle ORBYTS team discuss their approach to conducting original research with school-aged scientists.
Summary: The Twinkle ORBYTS team discuss their approach to conducting original research with school-aged scientists.
