Split-Evolution Quantum Phase Estimation for Particle-Conserving Hamiltonians

Fuente: arXiv
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Main Authors: Rowe, Megan Cerys, Gaggioli, Carlo A., Szulakowska, Ludmila, Ramo, David Muñoz, Manrique, David Zsolt
Format: Preprint
Published: 2026
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author Rowe, Megan Cerys
Gaggioli, Carlo A.
Szulakowska, Ludmila
Ramo, David Muñoz
Manrique, David Zsolt
author_facet Rowe, Megan Cerys
Gaggioli, Carlo A.
Szulakowska, Ludmila
Ramo, David Muñoz
Manrique, David Zsolt
contents We present a hardware demonstration and resource analysis of split-evolution quantum phase estimation (SE-QPE) on a Quantinuum System Model H2 quantum computer. SE-QPE is a modification to canonical QPE for particle-conserving Hamiltonians in which controlled time evolution is replaced by CSWAP-based interference between a target register and a reference register. For factorizations of time evolution with a shared eigenbasis, SE-QPE preserves the phase-register outcome distribution of canonical QPE and, unlike with compute--uncompute substitutions, it remains compatible with non-exact eigenstates. The substitution removes controlled-simulation overhead and enables parallel evolution on two registers, reducing the depth of each phase-kickback block. Resource analysis for Trotterized double-factorized chemistry Hamiltonians shows that the substitution becomes increasingly favorable at higher phase powers, as such combining QPE and SE-QPE implementations can be a useful option. Over a range of FeMoco active spaces, SE-QPE reduces time evolution resources, with asymptotic reductions of about 33% in CX count, 25% in $T$ count, and an asymptotic depth ratio of $3/N$ for CX layers. On Quantinuum H2-2, a four-qubit model ethylene demonstration with explicit inverse QFT and repeated phase-kickback steps up to 6 phase bits yields distinct energies and shows the auxiliary registers provide useful error detection filters.
format Preprint
id arxiv_https___arxiv_org_abs_2604_14921
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Split-Evolution Quantum Phase Estimation for Particle-Conserving Hamiltonians
Rowe, Megan Cerys
Gaggioli, Carlo A.
Szulakowska, Ludmila
Ramo, David Muñoz
Manrique, David Zsolt
Quantum Physics
Computational Physics
We present a hardware demonstration and resource analysis of split-evolution quantum phase estimation (SE-QPE) on a Quantinuum System Model H2 quantum computer. SE-QPE is a modification to canonical QPE for particle-conserving Hamiltonians in which controlled time evolution is replaced by CSWAP-based interference between a target register and a reference register. For factorizations of time evolution with a shared eigenbasis, SE-QPE preserves the phase-register outcome distribution of canonical QPE and, unlike with compute--uncompute substitutions, it remains compatible with non-exact eigenstates. The substitution removes controlled-simulation overhead and enables parallel evolution on two registers, reducing the depth of each phase-kickback block. Resource analysis for Trotterized double-factorized chemistry Hamiltonians shows that the substitution becomes increasingly favorable at higher phase powers, as such combining QPE and SE-QPE implementations can be a useful option. Over a range of FeMoco active spaces, SE-QPE reduces time evolution resources, with asymptotic reductions of about 33% in CX count, 25% in $T$ count, and an asymptotic depth ratio of $3/N$ for CX layers. On Quantinuum H2-2, a four-qubit model ethylene demonstration with explicit inverse QFT and repeated phase-kickback steps up to 6 phase bits yields distinct energies and shows the auxiliary registers provide useful error detection filters.
title Split-Evolution Quantum Phase Estimation for Particle-Conserving Hamiltonians
topic Quantum Physics
Computational Physics
url https://arxiv.org/abs/2604.14921