Probing the superfluid-insulator phase transition by a non-Hermitian external field

Abstract

We study the response of a thermal state of the Hubbard-like system to either global or local non-Hermitian perturbation, which coalesces the degenerate ground state within the $U(1)$ symmetry breaking phase. We show that the dynamical response of the system is strongly sensitive to the underlying quantum phase transition (QPT) from a Mott insulator to a superfluid state. The Uhlmann fidelity in the superfluid phase decays to a steady value determined by the order of the exceptional point (EP) within the subspace spanned by the degenerate ground states but remains almost unchanged in the Mott insulating phase. It demonstrates that the phase diagram at zero temperature is preserved even though a local probing field is applied. Specifically, two celebrated models including the Bose-Hubbard model and the Jaynes-Cummings-Hubbard model are employed to demonstrate this property in the finite-size system, wherein fluctuations of the boson and polariton number are observed based on EP dynamics. This work presents an alternative approach to probe the superfluid-insulator QPT at non-zero temperature.

8 pages, 5 figures

References in corpus (20)

• Quantum fluids of light
• Cold atoms in cavity-generated dynamical optical potentials
• Quantum trajectories and open many-body quantum systems
• Quantum phase transitions of light
• Bose-Einstein Condensation in Magnetic Insulators
• Tuning the scattering length with an optically induced Feshbach resonance
• Fidelity, dynamic structure factor, and susceptibility in critical phenomena
• Quantum critical scaling of the geometric tensors
• Quantum Many-Body Phenomena in Coupled Cavity Arrays
• Observation of a dissipative phase transition in a one-dimensional circuit QED lattice
• Mixed-state fidelity and quantum criticality at finite temperature
• Mott insulator to superfluid transition in the Bose-Hubbard model: a strong-coupling approach
• Superfluid-Mott Insulator Transition of Light in the Jaynes-Cummings Lattice
• Quantum phase transitions and quantum fidelity in free fermion graphs
• Phase transitions in a non-Hermitian Aubry-André-Harper model
• Loschmidt Echo Revivals: Critical and Noncritical
• Superfluid to Mott-insulator transition in Bose-Hubbard models
• Exceptional points and Bloch oscillations in non-Hermitian lattices with unidirectional hopping
• Dynamic magnetization in non-Hermitian quantum spin system
• Quantum mold casting for topological insulating and edge states