aiqbench analysis
This research proposes deterministic unitary protocols using multiple quantum system copies and controlled-SWAP operations to approximate imaginary-time evolution for efficient ground state preparation. The study evaluates two distinct circuit architectures—a tree design with polynomial depth convergence versus a compact "hedge" approach—and demonstrates that mid-circuit post-selection can accelerate convergence while trading circuit volume against shot complexity in observable estimation. These findings offer concrete pathways for hybrid analog-digital circuits to enhance near-term quantum simulation capabilities without relying on probabilistic variational methods alone.
Imaginary time evolution and ground state preparation using unitary multi-copy protocols
arXiv:2603.11208v3 Announce Type: replace Abstract: Efficient low-energy state preparation is a key objective in quantum computation and quantum simulation. Quantum imaginary-time evolution replaces real-time dynamics with imaginary-time dynamics, exponentially suppressing higher-energy eigenstates. We introduce deterministic unitary protocols that approximate imaginary-time evolution for ground state preparation. The protocols require multiple copies of the system, real-time evolution under the system Hamiltonian, and controlled-SWAP operations (or more general SWAP-generated unitaries). Our analysis focuses on two concrete circuit families: a tree architecture with provable polynomial-in-depth convergence but rapidly growing width, and a compact "hedge" architecture that achieves comparable accuracy with only polynomial width in a heuristic construction supported by numerics. Numerical evidence indicates that mid-circuit post-selection can accelerate convergence with practical success probabilities. Separately, we demonstrate that circuit volume can be traded for the shot complexity of post-circuit observable estimation in the ground state preparation setting. Finally, we outline concrete platform-specific implementations in which multi-copy registers and SWAP-mediated couplings are natural, illustrating how these hybrid analog-digital circuits can complement existing state-preparation methods in the near term.
Abstract:Efficient low-energy state preparation is a key objective in quantum computation and quantum simulation. Quantum imaginary-time evolution replaces real-time dynamics with imaginary-time dynamics, exponentially suppressing higher-energy eigenstates. We introduce deterministic unitary protocols that approximate imaginary-time evolution for ground state preparation. The protocols require multiple copies of the system, real-time evolution under the system Hamiltonian, and controlled-SWAP operations (or more general SWAP-generated unitaries). Our analysis focuses on two concrete circuit families: a tree architecture with provable polynomial-in-depth convergence but rapidly growing width, and a compact "hedge" architecture that achieves comparable accuracy with only polynomial width in a heuristic construction supported by numerics. Numerical evidence indicates that mid-circuit post-selection can accelerate convergence with practical success probabilities. Separately, we demonstrate that circuit volume can be traded for the shot complexity of post-circuit observable estimation in the ground state preparation setting. Finally, we outline concrete platform-specific implementations in which multi-copy registers and SWAP-mediated couplings are natural, illustrating how these hybrid analog-digital circuits can complement existing state-preparation methods in the near term.
Quantum Physics (quant-ph); High Energy Physics - Theory (hep-th); Atomic Physics (physics.atom-ph)
arXiv:2603.11208 [quant-ph]
(or arXiv:2603.11208v3 [quant-ph] for this version)
https://doi.org/10.48550/arXiv.2603.11208 Focus to learn more arXiv-issued DOI via DataCite
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Full text under the publisher's open licence · 268 words
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