Quantum simulation and spectroscopy of entanglement Hamiltonians

The properties of a strongly correlated many-body quantum system, from the presence of topological order to the onset of quantum criticality, leave a footprint in its entanglement spectrum. The entanglement spectrum is composed by the eigenvalues of the density matrix representing a subsystem of the...

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Bibliographic Details
Published in:Nature physics 2018-08, Vol.14 (8), p.827-831
Main Authors: Dalmonte, M., Vermersch, B., Zoller, P.
Format: Article
Language:English
Subjects:
Computer simulation
Couplings
Eigenvalues
Field theory
Hamiltonian functions
Optical lattices
Phase transitions
Quantum entanglement
Quantum field theory
Quantum theory
Spectroscopy
Spectrum analysis
Theorems
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Summary:The properties of a strongly correlated many-body quantum system, from the presence of topological order to the onset of quantum criticality, leave a footprint in its entanglement spectrum. The entanglement spectrum is composed by the eigenvalues of the density matrix representing a subsystem of the whole original system, but its direct measurement has remained elusive due to the lack of direct experimental probes. Here we show that the entanglement spectrum of the ground state of a broad class of Hamiltonians becomes directly accessible via the quantum simulation and spectroscopy of a suitably constructed entanglement Hamiltonian, building on the Bisognano–Wichmann theorem of axiomatic quantum field theory. This theorem gives an explicit physical construction of the entanglement Hamiltonian, identified as the Hamiltonian of the many-body system of interest with spatially varying couplings. On this basis, we propose a scalable recipe for the measurement of a system’s entanglement spectrum via spectroscopy of the corresponding Bisognano–Wichmann Hamiltonian realized in synthetic quantum systems, including atoms in optical lattices and trapped ions. We illustrate and benchmark this scenario on a variety of models, spanning phenomena as diverse as conformal field theories, topological order and quantum phase transitions.
ISSN:1745-2473
1745-2481
DOI:10.1038/s41567-018-0151-7