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arXiv · 2601.18839

Quantum Computing Demonstration of the Polaron-Molecule Transition on a NISQ Device

Hugo Catala·Ezequiel Valero·German Rodrigo
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Abstract

The simulation of strongly correlated fermionic systems remains a significant challenge in computational physics due to the exponential growth of the Hilbert space and the fermionic sign problem. In this work, we report a quantum computing demonstration exploring the unified physics of the Fermi polaron and the Bose-Einstein Condensate (BEC) to Bardeen-Cooper-Schrieffer (BCS) crossover. We develop an effective Hamiltonian formalism that bridges pairing superfluidity and impurity physics, mapping the system onto a gate-based quantum processor via the Jordan-Wigner transformation. By utilizing a first-order Trotter-Suzuki decomposition, we implement an ancilla-controlled Ramsey interferometry protocol to resolve the system's spectral response. Our implementation captures the smooth transition from a dressed quasiparticle (polaron) regime to a stable molecular bound state, characterized by a linear energy renormalization in the strong-coupling limit. We benchmark the quantum protocol against exact diagonalization and demonstrate its execution on the Barcelona Supercomputing Center (BSC-CNS) quantum hardware. To ensure reproducibility, we provide comprehensive device calibration metrics, including qubit coherence times and gate fidelities at the time of execution. Despite inherent hardware noise, the hybrid variational approach qualitatively observes the bifurcation of the spectral density.

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Hugo Catala, Ezequiel Valero, German Rodrigo. 2026-07-10. Quantum Computing Demonstration of the Polaron-Molecule Transition on a NISQ Device. https://doi.org/10.1103/2kdj-6pdz

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