Bounding first-order quantum phase transitions in adiabatic quantum computing

In the context of adiabatic quantum computation (AQC), it has been argued that first-order quantum phase transitions (QPTs) due to localization phenomena cause AQC to fail by exponentially decreasing the minimal spectral gap of the Hamiltonian along the annealing path as a function of the qubit numb...

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Main Authors: Matthias Werner, Artur García-Sáez, Marta P. Estarellas
Format: Article
Language:English
Published: American Physical Society 2023-12-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.5.043236
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author Matthias Werner
Artur García-Sáez
Marta P. Estarellas
author_facet Matthias Werner
Artur García-Sáez
Marta P. Estarellas
author_sort Matthias Werner
collection DOAJ
description In the context of adiabatic quantum computation (AQC), it has been argued that first-order quantum phase transitions (QPTs) due to localization phenomena cause AQC to fail by exponentially decreasing the minimal spectral gap of the Hamiltonian along the annealing path as a function of the qubit number. The vanishing of the spectral gap is often linked to the localization of the ground state in a local minimum, requiring the system to tunnel into the global minimum at a later stage of the annealing. Recent methods have been proposed to avoid this phenomenon by carefully designing the involved Hamiltonians. However, it remains a challenge to formulate a comprehensive theory of the effect of the various parameters and the conditions under which QPTs make the AQC algorithm fail. Equipped with concepts from graph theory, in this work we link graph quantities associated with the Hamiltonians along the annealing path with the occurrence of QPTs. These links allow us to derive bounds on the location of the minimal spectral gap along the annealing path, augmenting the toolbox for the analysis of strategies to improve the runtime of AQC algorithms.
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spelling doaj.art-8d2827c7cb2c4343915e6f04093a02d72024-04-12T17:36:57ZengAmerican Physical SocietyPhysical Review Research2643-15642023-12-015404323610.1103/PhysRevResearch.5.043236Bounding first-order quantum phase transitions in adiabatic quantum computingMatthias WernerArtur García-SáezMarta P. EstarellasIn the context of adiabatic quantum computation (AQC), it has been argued that first-order quantum phase transitions (QPTs) due to localization phenomena cause AQC to fail by exponentially decreasing the minimal spectral gap of the Hamiltonian along the annealing path as a function of the qubit number. The vanishing of the spectral gap is often linked to the localization of the ground state in a local minimum, requiring the system to tunnel into the global minimum at a later stage of the annealing. Recent methods have been proposed to avoid this phenomenon by carefully designing the involved Hamiltonians. However, it remains a challenge to formulate a comprehensive theory of the effect of the various parameters and the conditions under which QPTs make the AQC algorithm fail. Equipped with concepts from graph theory, in this work we link graph quantities associated with the Hamiltonians along the annealing path with the occurrence of QPTs. These links allow us to derive bounds on the location of the minimal spectral gap along the annealing path, augmenting the toolbox for the analysis of strategies to improve the runtime of AQC algorithms.http://doi.org/10.1103/PhysRevResearch.5.043236
spellingShingle Matthias Werner
Artur García-Sáez
Marta P. Estarellas
Bounding first-order quantum phase transitions in adiabatic quantum computing
Physical Review Research
title Bounding first-order quantum phase transitions in adiabatic quantum computing
title_full Bounding first-order quantum phase transitions in adiabatic quantum computing
title_fullStr Bounding first-order quantum phase transitions in adiabatic quantum computing
title_full_unstemmed Bounding first-order quantum phase transitions in adiabatic quantum computing
title_short Bounding first-order quantum phase transitions in adiabatic quantum computing
title_sort bounding first order quantum phase transitions in adiabatic quantum computing
url http://doi.org/10.1103/PhysRevResearch.5.043236
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