Quantum circuits for measuring weak values, Kirkwood--Dirac quasiprobability distributions, and state spectra
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arXiv
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| Autori principali: | , , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2023
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| _version_ | 1866929197869432832 |
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| author | Wagner, Rafael Schwartzman-Nowik, Zohar Paiva, Ismael L. Te'eni, Amit Ruiz-Molero, Antonio Barbosa, Rui Soares Cohen, Eliahu Galvão, Ernesto F. |
| author_facet | Wagner, Rafael Schwartzman-Nowik, Zohar Paiva, Ismael L. Te'eni, Amit Ruiz-Molero, Antonio Barbosa, Rui Soares Cohen, Eliahu Galvão, Ernesto F. |
| contents | Weak values and Kirkwood--Dirac (KD) quasiprobability distributions have been independently associated with both foundational issues in quantum theory and advantages in quantum metrology. We propose simple quantum circuits to measure weak values, KD distributions, and spectra of density matrices without the need for post-selection. This is achieved by measuring unitary-invariant, relational properties of quantum states, which are functions of Bargmann invariants, the concept that underpins our unified perspective. Our circuits also enable experimental implementation of various functions of KD distributions, such as out-of-time-ordered correlators (OTOCs) and the quantum Fisher information in post-selected parameter estimation, among others. An upshot is a unified view of nonclassicality in all those tasks. In particular, we discuss how negativity and imaginarity of Bargmann invariants relate to set coherence. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2302_00705 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Quantum circuits for measuring weak values, Kirkwood--Dirac quasiprobability distributions, and state spectra Wagner, Rafael Schwartzman-Nowik, Zohar Paiva, Ismael L. Te'eni, Amit Ruiz-Molero, Antonio Barbosa, Rui Soares Cohen, Eliahu Galvão, Ernesto F. Quantum Physics Weak values and Kirkwood--Dirac (KD) quasiprobability distributions have been independently associated with both foundational issues in quantum theory and advantages in quantum metrology. We propose simple quantum circuits to measure weak values, KD distributions, and spectra of density matrices without the need for post-selection. This is achieved by measuring unitary-invariant, relational properties of quantum states, which are functions of Bargmann invariants, the concept that underpins our unified perspective. Our circuits also enable experimental implementation of various functions of KD distributions, such as out-of-time-ordered correlators (OTOCs) and the quantum Fisher information in post-selected parameter estimation, among others. An upshot is a unified view of nonclassicality in all those tasks. In particular, we discuss how negativity and imaginarity of Bargmann invariants relate to set coherence. |
| title | Quantum circuits for measuring weak values, Kirkwood--Dirac quasiprobability distributions, and state spectra |
| topic | Quantum Physics |
| url | https://arxiv.org/abs/2302.00705 |