Evidence of quantum phase transition in real-space vacuum entanglement of higher derivative scalar quantum field theories

TL;DR

This paper demonstrates a violation of the area law in a higher-dimensional Bosonic system, providing evidence of a quantum phase transition driven by long-range interactions and zero modes, with implications for condensed matter physics.

Contribution

It presents the first observed violation of the area law in higher-dimensional Bosonic systems and links it to a quantum phase transition caused by next-to-next-to-next nearest neighbor couplings.

Findings

Area law violation observed in a 2D Bosonic model

Quantum phase transition evidenced by entanglement spectra and fidelity

Transition driven by accumulation of angular zero modes

Abstract

In a bipartite set-up, the vacuum state of a free Bosonic scalar field is entangled in real space and satisfies the area-law--- entanglement entropy scales linearly with area of the boundary between the two partitions. In this work, we show that the area law is violated in two spatial dimensional model Hamiltonian having dynamical critical exponent z=3. The model physically corresponds to next-to-next-to-next nearest neighbour coupling terms on a lattice. The result reported here is the first of its kind of violation of area law in Bosonic systems in higher dimensions and signals the evidence of a quantum phase transition. We provide evidence for quantum phase transition both numerically and analytically using quantum Information tools like entanglement spectra, quantum fidelity, and gap in the energy spectra. We identify the cause for this transition due to the accumulation of large number of angular zero modes around the critical point which catalyses the change in the ground state wave function due to the next-to-next-to-next nearest neighbor coupling. Lastly, using Hubbard-Stratanovich transformation, we show that the effective Bosonic Hamiltonian can be obtained from an interacting fermionic theory and provide possible implications for condensed matter systems.