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| Main Authors: | , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2509.02272 |
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| _version_ | 1866911634052612096 |
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| author | Aychet-Claisse, Samuel Lacroix, Denis Somà, Vittorio Zhang, Jing |
| author_facet | Aychet-Claisse, Samuel Lacroix, Denis Somà, Vittorio Zhang, Jing |
| contents | An end-to-end strategy for hybrid quantum-classical computations of Green's functions in many-body systems is presented and applied to the pairing model. The scheme makes explicit use of the spectral representation of the Green's function, which entails the calculation of the $N$-body ground state as well as eigenstates and associated energies of the $(N\pm1)$-body neighbors. While the former is accessed via variational techniques, the latter are constructed by means of the quantum subspace expansion method. Different ansatzes for the ground-state wave function, originating from either classical or quantum approaches, are tested and compared to exact calculations. The resulting one-body Green's functions prove to be accurate approximations of the exact one for a large range of parameters, including across the normal-to-superfluid transition. As a byproduct, this approach yields a good description of odd systems provided that the starting even system is well reproduced by the variational ansatz. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_02272 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Quantum simulations of Green's functions for small superfluid systems Aychet-Claisse, Samuel Lacroix, Denis Somà, Vittorio Zhang, Jing Nuclear Theory Quantum Physics An end-to-end strategy for hybrid quantum-classical computations of Green's functions in many-body systems is presented and applied to the pairing model. The scheme makes explicit use of the spectral representation of the Green's function, which entails the calculation of the $N$-body ground state as well as eigenstates and associated energies of the $(N\pm1)$-body neighbors. While the former is accessed via variational techniques, the latter are constructed by means of the quantum subspace expansion method. Different ansatzes for the ground-state wave function, originating from either classical or quantum approaches, are tested and compared to exact calculations. The resulting one-body Green's functions prove to be accurate approximations of the exact one for a large range of parameters, including across the normal-to-superfluid transition. As a byproduct, this approach yields a good description of odd systems provided that the starting even system is well reproduced by the variational ansatz. |
| title | Quantum simulations of Green's functions for small superfluid systems |
| topic | Nuclear Theory Quantum Physics |
| url | https://arxiv.org/abs/2509.02272 |