Quantum impurity models using superpositions of fermionic Gaussian states: Practical methods and applications
The coherent superposition of nonorthogonal fermionic Gaussian states has been shown to be an efficient approximation to the ground states of quantum impurity problems [Bravyi and Gosset, Commun. Math. Phys. 356, 451 (2017)CMPHAY0010-361610.1007/s00220-017-2976-9]. We propose a practical approach fo...
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| Format: | Article |
| Language: | English |
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American Physical Society
2021-08-01
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| Series: | Physical Review Research |
| Online Access: | http://doi.org/10.1103/PhysRevResearch.3.033188 |
| _version_ | 1797210910612258816 |
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| author | Samuel Boutin Bela Bauer |
| author_facet | Samuel Boutin Bela Bauer |
| author_sort | Samuel Boutin |
| collection | DOAJ |
| description | The coherent superposition of nonorthogonal fermionic Gaussian states has been shown to be an efficient approximation to the ground states of quantum impurity problems [Bravyi and Gosset, Commun. Math. Phys. 356, 451 (2017)CMPHAY0010-361610.1007/s00220-017-2976-9]. We propose a practical approach for performing a variational calculation based on such states. Our method is based on approximate imaginary-time equations of motion that decouple the dynamics of each Gaussian state forming the ansatz. It is independent of the lattice connectivity of the model and the implementation is highly parallelizable. To benchmark our variational method, we calculate the spin-spin correlation function and Rényi entanglement entropy of an Anderson impurity, allowing us to identify the screening cloud and compare to density matrix renormalization group calculations. Secondly, we study the screening cloud of the two-channel Kondo model, a problem difficult to tackle using existing numerical tools. |
| first_indexed | 2024-04-24T10:18:06Z |
| format | Article |
| id | doaj.art-1fb0a88bf59a4fc98389cf7be18997d2 |
| institution | Directory Open Access Journal |
| issn | 2643-1564 |
| language | English |
| last_indexed | 2024-04-24T10:18:06Z |
| publishDate | 2021-08-01 |
| publisher | American Physical Society |
| record_format | Article |
| series | Physical Review Research |
| spelling | doaj.art-1fb0a88bf59a4fc98389cf7be18997d22024-04-12T17:13:18ZengAmerican Physical SocietyPhysical Review Research2643-15642021-08-013303318810.1103/PhysRevResearch.3.033188Quantum impurity models using superpositions of fermionic Gaussian states: Practical methods and applicationsSamuel BoutinBela BauerThe coherent superposition of nonorthogonal fermionic Gaussian states has been shown to be an efficient approximation to the ground states of quantum impurity problems [Bravyi and Gosset, Commun. Math. Phys. 356, 451 (2017)CMPHAY0010-361610.1007/s00220-017-2976-9]. We propose a practical approach for performing a variational calculation based on such states. Our method is based on approximate imaginary-time equations of motion that decouple the dynamics of each Gaussian state forming the ansatz. It is independent of the lattice connectivity of the model and the implementation is highly parallelizable. To benchmark our variational method, we calculate the spin-spin correlation function and Rényi entanglement entropy of an Anderson impurity, allowing us to identify the screening cloud and compare to density matrix renormalization group calculations. Secondly, we study the screening cloud of the two-channel Kondo model, a problem difficult to tackle using existing numerical tools.http://doi.org/10.1103/PhysRevResearch.3.033188 |
| spellingShingle | Samuel Boutin Bela Bauer Quantum impurity models using superpositions of fermionic Gaussian states: Practical methods and applications Physical Review Research |
| title | Quantum impurity models using superpositions of fermionic Gaussian states: Practical methods and applications |
| title_full | Quantum impurity models using superpositions of fermionic Gaussian states: Practical methods and applications |
| title_fullStr | Quantum impurity models using superpositions of fermionic Gaussian states: Practical methods and applications |
| title_full_unstemmed | Quantum impurity models using superpositions of fermionic Gaussian states: Practical methods and applications |
| title_short | Quantum impurity models using superpositions of fermionic Gaussian states: Practical methods and applications |
| title_sort | quantum impurity models using superpositions of fermionic gaussian states practical methods and applications |
| url | http://doi.org/10.1103/PhysRevResearch.3.033188 |
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