Entanglement-Forged Variational Diagonalisation for Low-Energy Subspaces

POSTER

Abstract

We address the variational preparation of Thermofield Doubles (TFD) as ground states of suitably engineered Hamiltonians acting on a doubled Hilbert space with of N qubits.

Through the use of the Entanglement Forging ansatz, we propose a variational method that involves only circuits of width N/2, and we illustrate the method with generic Fermionic Hamiltonians. The free Fermion case can be solved in closed form, and yields a warm start state for the variational circuits whenever interaction are present.

As a result of the variational optimization, the unitary matrix that diagonalises the low-energy spectrum of the local system becomes available.

*The work of J.SS. and J.M. was supported by Xunta de Galicia (Centro Singular de Investigacion de Galicia (accreditation 2019-2022) and by the Spanish Research State Agency under grant PID2020-114157GB-I00, and by the European Union FEDER. The work of J.SS. was supported by MICIN through the European Union NextGenerationEU recovery plan (PRTR-C17.I1), and by the Galician Regional Government through the "Planes Complementarios de I+D+I con las Comunidades Autónomas" in Quantum Communication. D.F. was supported by Axencia Galega de Innovación through the Grant Agreement ``Despregamento dunha infraestructura baseada en tecnoloxías cuánticas da información que permita impulsar a I+D+I en Galicia'' within the program FEDER Galicia 2014-2020. Simulations in this work were performed using the Finisterrae III Supercomputer, funded by the project CESGA-01 FINISTERRAE III. D.H.M. - CEA's Science Impulse Program and the France 2030 HQI project (ref. ANR-22-PNCQ-0002).

Publication: https://arxiv.org/pdf/2311.10566

Presenters

  • David A Herrera Marti

    • Université Grenoble Alpes and CEA List
    • Université Grenoble Alpes, CEA List

Authors

  • David A Herrera Marti

    • Université Grenoble Alpes and CEA List
    • Université Grenoble Alpes, CEA List
  • Javier Mas

    • Departamento de Física de Partículas, Universidade de Santiago de Compostela and Instituto Galego de Física de Altas Enerxías (IGFAE)
  • Daniel Faílde

    • Galicia Supercomputing Center (CESGA), Santiago de Compostela, Spain
  • Juan Santos Suarez

    • Departamento de Física de Partículas, Universidade de Santiago de Compostela and Instituto Galego de Física de Altas Enerxías (IGFAE)