State Preparation Boosters for Early Fault-Tolerant Quantum Computation

Quantum computing is believed to be particularly useful for the simulation of chemistry and materials, among the various applications. In recent years, there have been significant advancements in the development of near-term quantum algorithms for quantum simulation, including VQE and many of its va...

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Main Authors: Guoming Wang, Sukin Sim, Peter D. Johnson
Format: Article
Language:English
Published: Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften 2022-10-01
Series:Quantum
Online Access:https://quantum-journal.org/papers/q-2022-10-06-829/pdf/
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author Guoming Wang
Sukin Sim
Peter D. Johnson
author_facet Guoming Wang
Sukin Sim
Peter D. Johnson
author_sort Guoming Wang
collection DOAJ
description Quantum computing is believed to be particularly useful for the simulation of chemistry and materials, among the various applications. In recent years, there have been significant advancements in the development of near-term quantum algorithms for quantum simulation, including VQE and many of its variants. However, for such algorithms to be useful, they need to overcome several critical barriers including the inability to prepare high-quality approximations of the ground state. Current challenges to state preparation, including barren plateaus and the high-dimensionality of the optimization landscape, make state preparation through ansatz optimization unreliable. In this work, we introduce the method of ground state boosting, which uses a limited-depth quantum circuit to reliably increase the overlap with the ground state. This circuit, which we call a booster, can be used to augment an ansatz from VQE or be used as a stand-alone state preparation method. The booster converts circuit depth into ground state overlap in a controllable manner. We numerically demonstrate the capabilities of boosters by simulating the performance of a particular type of booster, namely the Gaussian booster, for preparing the ground state of $N_2$ molecular system. Beyond ground state preparation as a direct objective, many quantum algorithms, such as quantum phase estimation, rely on high-quality state preparation as a subroutine. Therefore, we foresee ground state boosting and similar methods as becoming essential algorithmic components as the field transitions into using early fault-tolerant quantum computers.
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spelling doaj.art-b7af55ca67c34dd59b09d5a7bc6c651f2022-12-22T02:26:36ZengVerein zur Förderung des Open Access Publizierens in den QuantenwissenschaftenQuantum2521-327X2022-10-01682910.22331/q-2022-10-06-82910.22331/q-2022-10-06-829State Preparation Boosters for Early Fault-Tolerant Quantum ComputationGuoming WangSukin SimPeter D. JohnsonQuantum computing is believed to be particularly useful for the simulation of chemistry and materials, among the various applications. In recent years, there have been significant advancements in the development of near-term quantum algorithms for quantum simulation, including VQE and many of its variants. However, for such algorithms to be useful, they need to overcome several critical barriers including the inability to prepare high-quality approximations of the ground state. Current challenges to state preparation, including barren plateaus and the high-dimensionality of the optimization landscape, make state preparation through ansatz optimization unreliable. In this work, we introduce the method of ground state boosting, which uses a limited-depth quantum circuit to reliably increase the overlap with the ground state. This circuit, which we call a booster, can be used to augment an ansatz from VQE or be used as a stand-alone state preparation method. The booster converts circuit depth into ground state overlap in a controllable manner. We numerically demonstrate the capabilities of boosters by simulating the performance of a particular type of booster, namely the Gaussian booster, for preparing the ground state of $N_2$ molecular system. Beyond ground state preparation as a direct objective, many quantum algorithms, such as quantum phase estimation, rely on high-quality state preparation as a subroutine. Therefore, we foresee ground state boosting and similar methods as becoming essential algorithmic components as the field transitions into using early fault-tolerant quantum computers.https://quantum-journal.org/papers/q-2022-10-06-829/pdf/
spellingShingle Guoming Wang
Sukin Sim
Peter D. Johnson
State Preparation Boosters for Early Fault-Tolerant Quantum Computation
Quantum
title State Preparation Boosters for Early Fault-Tolerant Quantum Computation
title_full State Preparation Boosters for Early Fault-Tolerant Quantum Computation
title_fullStr State Preparation Boosters for Early Fault-Tolerant Quantum Computation
title_full_unstemmed State Preparation Boosters for Early Fault-Tolerant Quantum Computation
title_short State Preparation Boosters for Early Fault-Tolerant Quantum Computation
title_sort state preparation boosters for early fault tolerant quantum computation
url https://quantum-journal.org/papers/q-2022-10-06-829/pdf/
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