Entanglement in conformal field theories with boundaries and interfaces

Entanglement, one of the quintessential properties of quantum mechanics, plays a central role in the development of long-range correlations in quantum critical phenomena. In this work, we investigate ground-state entanglement in quantum critical systems described by conformal field theories (CFTs) in the presence of boundaries and interfaces. In particular, we analytically compute entanglement entropies and entanglement spectra for the Ising and free, compactified boson CFTs for different boundary conditions. We compare the analytical predictions with numerical results obtained using the density matrix renormalization group technique. Furthermore, we investigate entanglement entropies across interfaces separating CFTs having identical conformal anomaly parameters. Finally, we describe a general scheme of experimentally realizing conformal interfaces and boundaries of the free, compactified boson CFT with superconducting quantum electronic circuits.