Symmetry: a fundamental resource for quantum coherence and metrology
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arXiv
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| Hauptverfasser: | , |
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| Format: | Preprint |
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2024
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| _version_ | 1866917890516582400 |
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| author | Frérot, Irénée Roscilde, Tommaso |
| author_facet | Frérot, Irénée Roscilde, Tommaso |
| contents | We introduce a new paradigm for the preparation of deeply entangled states useful for quantum metrology. We show that when the quantum state is an eigenstate of an operator $A$, observables $G$ which are completely off-diagonal with respect to $A$ have purely quantum fluctuations, as quantified by the quantum Fisher information, namely $F_Q(G)=4\langle G^2 \rangle$. This property holds regardless of the purity of the quantum state, and it implies that off-diagonal fluctuations represent a metrological resource for phase estimation. In particular, for many-body systems such as quantum spin ensembles or bosonic gases, the presence of off-diagonal long-range order (for a spin observable, or for bosonic operators) directly translates into a metrological resource, provided that the system remains in a well-defined symmetry sector. The latter is defined e.g. by one component of the collective spin or by its parity in spin systems; and by a particle-number sector for bosons. Our results establish the optimal use for metrology of arbitrarily non-Gaussian quantum correlations in a large variety of many-body systems. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2407_01025 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Symmetry: a fundamental resource for quantum coherence and metrology Frérot, Irénée Roscilde, Tommaso Quantum Physics Quantum Gases We introduce a new paradigm for the preparation of deeply entangled states useful for quantum metrology. We show that when the quantum state is an eigenstate of an operator $A$, observables $G$ which are completely off-diagonal with respect to $A$ have purely quantum fluctuations, as quantified by the quantum Fisher information, namely $F_Q(G)=4\langle G^2 \rangle$. This property holds regardless of the purity of the quantum state, and it implies that off-diagonal fluctuations represent a metrological resource for phase estimation. In particular, for many-body systems such as quantum spin ensembles or bosonic gases, the presence of off-diagonal long-range order (for a spin observable, or for bosonic operators) directly translates into a metrological resource, provided that the system remains in a well-defined symmetry sector. The latter is defined e.g. by one component of the collective spin or by its parity in spin systems; and by a particle-number sector for bosons. Our results establish the optimal use for metrology of arbitrarily non-Gaussian quantum correlations in a large variety of many-body systems. |
| title | Symmetry: a fundamental resource for quantum coherence and metrology |
| topic | Quantum Physics Quantum Gases |
| url | https://arxiv.org/abs/2407.01025 |