@article{francis_zelleke_zhang_kemper_freericks_2022, title={Determining Ground-State Phase Diagrams on Quantum Computers via a Generalized Application of Adiabatic State Preparation}, volume={14}, ISSN={["2073-8994"]}, url={https://www.mdpi.com/2073-8994/14/4/809}, DOI={10.3390/sym14040809}, abstractNote={Quantum phase transitions materialize as level crossings in the ground-state energy when the parameters of the Hamiltonian are varied. The resulting ground-state phase diagrams are straightforward to determine by exact diagonalization on classical computers, but are challenging on quantum computers because of the accuracy needed and the near degeneracy of the competing states close to the level crossings. On the other hand, classical computers are limited to small system sizes, which quantum computers may help overcome. In this work, we use a local adiabatic ramp for state preparation to allow us to directly compute ground-state phase diagrams on a quantum computer via time evolution. This methodology is illustrated by examining the ground states of the XY model with a magnetic field in the z-direction in one dimension. We are able to calculate an accurate phase diagram on both two- and three-site systems using IBM quantum machines.}, number={4}, journal={SYMMETRY-BASEL}, publisher={MDPI AG}, author={Francis, Akhil and Zelleke, Ephrata and Zhang, Ziyue and Kemper, Alexander F. and Freericks, James K.}, year={2022}, month={Apr} }
 @article{francis_zhu_alderete_johri_xiao_freericks_monroe_linke_kemper_2021, title={Many-body thermodynamics on quantum computers via partition function zeros}, volume={7}, ISSN={["2375-2548"]}, url={https://doi.org/10.1126/sciadv.abf2447}, DOI={10.1126/sciadv.abf2447}, abstractNote={Quantum computers can study thermodynamics by finding zeros of functions in the complex plane.}, number={34}, journal={SCIENCE ADVANCES}, publisher={American Association for the Advancement of Science (AAAS)}, author={Francis, Akhil and Zhu, Daiwei and Alderete, Cinthia Huerta and Johri, Sonika and Xiao, Xiao and Freericks, James K. and Monroe, Christopher and Linke, Norbert M. and Kemper, Alexander F.}, year={2021}, month={Aug} }
 @article{francis_freericks_kemper_2020, title={Quantum computation of magnon spectra}, volume={101}, ISSN={["2469-9969"]}, url={https://doi.org/10.1103/PhysRevB.101.014411}, DOI={10.1103/PhysRevB.101.014411}, abstractNote={We demonstrate quantum computation of two-point correlation functions for a Heisenberg spin chain. Using the IBM Q 20-qubit quantum machines, we find that, for two sites, the correlation functions produce the exact results reliably. For four sites, results from the IBM Q 20-qubit Tokyo quantum computer are noisy due to read out errors and decoherence. Nevertheless, the correlation functions retain the correct spectral information. This is illustrated in the frequency domain by accurately extracting the magnon energies from peaks in the spectral function.}, number={1}, journal={PHYSICAL REVIEW B}, publisher={American Physical Society (APS)}, author={Francis, Akhil and Freericks, J. K. and Kemper, A. F.}, year={2020}, month={Jan} }