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arXiv · 2002.05496

Finite-system Multicriticality at the Superradiant Quantum Phase Transition

Han-Jie Zhu·Kai Xu·Guo-Feng Zhang·Wu-Ming Liu
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Abstract

We demonstrate the existence of finite-system multicriticality in a qubit-boson model where biased qubits collectively coupled to a single-mode bosonic field. The interplay between biases and boson-qubit coupling produces a rich phase diagram showing multiple superradiant phases and phase boundaries of different orders. In particular, multiple phases can become indistinguishable in appropriate bias configurations, which is the signature of multicriticality. A series of universality classes characterizing these multicritical points are identified. Moreover, we present a trapped-ion realization with the potential to explore the multicritical phenomena experimentally using a small number of ions. The results open a novel way to probe multicritical universality classes in experiments.

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Han-Jie Zhu, Kai Xu, Guo-Feng Zhang, Wu-Ming Liu. 2020-02-13. Finite-system Multicriticality at the Superradiant Quantum Phase Transition. https://doi.org/10.1103/physrevlett.125.050402

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