Efficient Variational Generation of Thermofield Double States on a Superconducting Quantum Processor: Experiment (Part 2)

Recent progress on Near Intermediate Small Quantum devices has allowed the field of quantum simulation to experimentally investigate many interesting systems such as spin lattices, Fermi-Hubbard models and electronic orbitals of molecules. Most of this work focuses on preparing low-energy eigenstates of a known target Hamiltonian. Here, we experimentally investigate finite-temperature effects on a transverse-field Ising chain using four qubits of a seven-transmon quantum processor. Specifically, we variationally approximate thermofield double (TFD) states through minimization of the constructed cost function described in Part 1. We extract various correlation functions over a range of simulated temperatures, showing good agreement to those of an exact TFD.