Thermalization and criticality on an analogue–digital quantum simulator
Trond I. Andersen, Nikita Astrakhantsev, Amir H. Karamlou, Julia Berndtsson, Johannes Motruk, Aaron Szasz, Jonathan A. Gross, Alexander Schuckert, Tom Westerhout, Y. Zhang, Ebrahim Forati, Dario Rossi, Bryce Kobrin, Agustín Di Paolo, A. R. Klots, Ilya Drozdov, Vladislav D. Kurilovich, A. Petukhov, L. B. Ioffe, Andreas Elben, Amiya Kumar Rath, Vittorio Vitale, Benoît Vermersch, Rajeev Acharya, Laleh Aghababaie Beni, K. R. Anderson, M. Ansmann, Frank Arute, Kunal Arya, Abraham Asfaw, Juan Atalaya, B. Ballard, Joseph C. Bardin, Andreas Bengtsson, Alexander Bilmes, Gina Bortoli, Alexandre Bourassa, Jenna Bovaird, L. Brill, Michael Broughton, D. A. Browne, Brett Buchea, B. B. Buckley, D. A. Buell, Tim Burger, Brian Burkett, Nicholas Bushnell, A. Cabrera, Juan Campero, Hung-Shen Chang, Z. Chen, B. Chiaro, Jahan Claes, Agnetta Y. Cleland, J. Cogan, R. Collins, P. Conner, William Courtney, A. L. Crook, Sayan Das, D. M. Debroy, Luis Lorenzo, Alexander Del Toro Barba, Sean Demura, Paul Donohoe, A. Dunsworth, Clifford J. Earle, Alec Eickbusch, Aviv Moshe Elbag, Mahmoud Elzouka, Catherine Erickson, Lara Faoro, Reza Fatemi, V. S. Ferreira, Leslie Flores Burgos, A. G. Fowler, Brooks Foxen, Suhas Ganjam, Rebeca Gasca, William Giang, Craig Gidney, D. Gilboa, M. Giustina, Raja Gosula, Alejandro Grajales Dau, Dietrich Graumann, Alex Greene, Steve Habegger, M. C. Hamilton, M. Hansen, Matthew P. Harrigan, Sean D. Harrington, Stephen Heslin, Paula Heu, Gordon Hill, M. R. Hoffmann, Hanxia Huang, Trent Huang, Ashley Huff, William J. Huggins
Abstract
Abstract Understanding how interacting particles approach thermal equilibrium is a major challenge of quantum simulators 1,2 . Unlocking the full potential of such systems towards this goal requires flexible initial state preparation, precise time evolution and extensive probes for final state characterization. Here we present a quantum simulator comprising 69 superconducting qubits that supports both universal quantum gates and high-fidelity analogue evolution, with performance beyond the reach of classical simulation in cross-entropy benchmarking experiments. This hybrid platform features more versatile measurement capabilities compared with analogue-only simulators, which we leverage here to reveal a coarsening-induced breakdown of Kibble–Zurek scaling predictions 3 in the XY model, as well as signatures of the classical Kosterlitz–Thouless phase transition 4 . Moreover, the digital gates enable precise energy control, allowing us to study the effects of the eigenstate thermalization hypothesis 5–7 in targeted parts of the eigenspectrum. We also demonstrate digital preparation of pairwise-entangled dimer states, and image the transport of energy and vorticity during subsequent thermalization in analogue evolution. These results establish the efficacy of superconducting analogue–digital quantum processors for preparing states across many-body spectra and unveiling their thermalization dynamics.