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

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.

12 pages, 8 figures

References in corpus (28)

• Many-Body Physics with Ultracold Gases
• A variational eigenvalue solver on a quantum processor
• Feshbach Resonances in Ultracold Gases
• Variational Quantum Algorithms
• Hardware-efficient Variational Quantum Eigensolver for Small Molecules and Quantum Magnets
• Theory of ultracold Fermi gases
• Observation of resonance condensation of fermionic atom pairs
• Error mitigation for short-depth quantum circuits
• Vortices and Superfluidity in a Strongly Interacting Fermi Gas
• Elucidating Reaction Mechanisms on Quantum Computers
• Validating quantum computers using randomized model circuits
• Efficient quantum algorithms for simulating sparse Hamiltonians
• Efficient variational quantum simulator incorporating active error minimisation
• Observation of Fermi Polarons in a Tunable Fermi Liquid of Ultracold Atoms
• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• The Unitary Fermi Gas: From Monte Carlo to Density Functionals
• Theory of variational quantum simulation
• Universal phase diagram of a strongly interacting Fermi gas with unbalanced spin populations
• Polarons, Dressed Molecules, and Itinerant Ferromagnetism in ultracold Fermi gases
• Resonantly-paired fermionic superfluids
• BCS-BEC Crossover and the Unitary Fermi Gas
• The unitary gas in an isotropic harmonic trap: symmetry properties and applications
• Time dependent impurity in ultracold fermions: orthogonality catastrophe and beyond
• Strategies for solving the Fermi-Hubbard model on near-term quantum computers
• Polaron-molecule transitions in a two-dimensional Fermi gas
• Decay of polarons and molecules in a strongly polarized Fermi gas
• Heavy polarons in ultracold atomic Fermi superfluids at the BEC-BCS crossover: formalism and applications
• Thermodynamics of transition to BCS-BEC crossover superconductivity in FeSe${}_{1-x}$S${}_x$