Quantum Fisher information as a signature of the superradiant quantum phase transition

By Tenghui Wang, Ling-Na Wu, Wen Yang, G. Jin, Neill Lambert, Franco Nori. 2013

136 citations recorded by the source corpus.

The single-mode Dicke model is well known to undergo a quantum phase transition from the so-called normal phase to the superradiant phase (hereinafter called the ‘superradiant quantum phase transition’). Normally, quantum phase transitions can be identified by the critical behavior of quantities such as entanglement, quantum fluctuations, and fidelity. In this paper, we study the role of the quantum Fisher information (QFI) of both the field mode and the atoms in the ground state of the Dicke Hamiltonian. For a finite but large number of atoms, our numerical results show that near the critical atom-field coupling, the QFI of the atomic and the field subsystems can surpass their classical limits, due to the appearance of nonclassical quadrature squeezing. As the coupling increases far beyond the critical point, each subsystem becomes a highly mixed state, which degrades the QFI and hence the ultimate phase sensitivity. In the thermodynamic limit, we present the analytical results of the QFI and their relationship with the reduced variances of the field mode and the atoms. For each subsystem, we find that there is a singularity in the derivative of the QFI at the critical point, a clear signature of the quantum criticality in the Dicke model.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/0c23b98078910330dce0cd4124ea8adb454236a6

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In Atomic and Molecular Physics, and Optics

Citations in the corpus

Open quantum systems with local and collective incoherent processes: Efficient numerical simulations using permutational invariance (2018, background): “Since PIQS grants access to the full density matrix, it also allows us to investigate higher-order quantum correlations and other entanglement witnesses, such as the quantum Fisher information [200, 210–213].”