From non-hermitian linear response to dynamical correlations and fluctuation-dissipation relations in quantum many-body systems
Quantum many-body systems are characterized by their correlations. While equal-time correlators and unequal-time commutators between operators are standard observables, the direct access to unequal-time anticommutators poses a formidable experimental challenge. Here, we propose a general technique f...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
15 July 2022
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| In: |
PRX quantum
Year: 2022, Volume: 3, Issue: 3, Pages: 1-34 |
| ISSN: | 2691-3399 |
| DOI: | 10.1103/PRXQuantum.3.030308 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1103/PRXQuantum.3.030308 Verlag, lizenzpflichtig, Volltext: https://link.aps.org/doi/10.1103/PRXQuantum.3.030308 
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| Author Notes: | Kevin T. Geier and Philipp Hauke |
| Summary: | Quantum many-body systems are characterized by their correlations. While equal-time correlators and unequal-time commutators between operators are standard observables, the direct access to unequal-time anticommutators poses a formidable experimental challenge. Here, we propose a general technique for measuring unequal-time anticommutators using the linear response of a system to a non-Hermitian perturbation. We illustrate the protocol at the example of a Bose-Hubbard model, where the approach to thermal equilibrium in a closed quantum system can be tracked by measuring both sides of the fluctuation-dissipation relation. We relate the scheme to the quantum Zeno effect and weak measurements, and illustrate possible implementations at the example of a cold-atom system. Our proposal provides a way of characterizing dynamical correlations in quantum many-body systems with potential applications in understanding strongly correlated matter as well as for novel quantum technologies. |
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| Item Description: | Gesehen am 05.12.20ww |
| Physical Description: | Online Resource |
| ISSN: | 2691-3399 |
| DOI: | 10.1103/PRXQuantum.3.030308 |