Efficient Quantum Cooling Algorithm for Fermionic Systems

Fuente: arXiv
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Autori principali: Marti, Lucas, Mansuroglu, Refik, Hartmann, Michael J.
Natura: Preprint
Pubblicazione: 2024
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author Marti, Lucas
Mansuroglu, Refik
Hartmann, Michael J.
author_facet Marti, Lucas
Mansuroglu, Refik
Hartmann, Michael J.
contents We present a cooling algorithm for ground state preparation of fermionic Hamiltonians. Our algorithm makes use of the Hamiltonian simulation of the considered system coupled to an ancillary fridge, which is regularly reset to its known ground state. We derive suitable interaction Hamiltonians that originate from ladder operators of the free theory and initiate resonant gaps between system and fridge. We further propose a spectroscopic scan to find the relevant eigenenergies of the system using energy measurements on the fridge. With these insights, we design a ground state cooling algorithm for fermionic systems that is efficient, i.e. its runtime is polynomial in the system size, as long as the initial state is prepared in a low-energy sector of polynomial size. We achieve the latter via a pseudo-adiabatic sweep from a parameter regime whose ground state can be easily prepared. We estimate that our algorithm has a polynomial runtime for systems where the spectral gap decreases at most polynomially in system size, and is faster than the adiabatic algorithm for a large range of settings. We generalize the algorithm to prepare thermal states and demonstrate our findings on the Fermi-Hubbard model.
format Preprint
id arxiv_https___arxiv_org_abs_2403_14506
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Efficient Quantum Cooling Algorithm for Fermionic Systems
Marti, Lucas
Mansuroglu, Refik
Hartmann, Michael J.
Quantum Physics
Strongly Correlated Electrons
We present a cooling algorithm for ground state preparation of fermionic Hamiltonians. Our algorithm makes use of the Hamiltonian simulation of the considered system coupled to an ancillary fridge, which is regularly reset to its known ground state. We derive suitable interaction Hamiltonians that originate from ladder operators of the free theory and initiate resonant gaps between system and fridge. We further propose a spectroscopic scan to find the relevant eigenenergies of the system using energy measurements on the fridge. With these insights, we design a ground state cooling algorithm for fermionic systems that is efficient, i.e. its runtime is polynomial in the system size, as long as the initial state is prepared in a low-energy sector of polynomial size. We achieve the latter via a pseudo-adiabatic sweep from a parameter regime whose ground state can be easily prepared. We estimate that our algorithm has a polynomial runtime for systems where the spectral gap decreases at most polynomially in system size, and is faster than the adiabatic algorithm for a large range of settings. We generalize the algorithm to prepare thermal states and demonstrate our findings on the Fermi-Hubbard model.
title Efficient Quantum Cooling Algorithm for Fermionic Systems
topic Quantum Physics
Strongly Correlated Electrons
url https://arxiv.org/abs/2403.14506