Entanglement characteristics of encircling an exceptional point in superconducting circuits
Phys. Rev. A 114, 012430 – Published 10 July, 2026
DOI: https://doi.org/10.1103/vvnv-tsdn
Abstract
Quantum entanglement, one of the most fundamental and nonclassical features of quantum systems, stands in sharp contrast to classical correlations. Meanwhile, exceptional points—spectral degeneracies unique to non-Hermitian systems—possess distinct topological structures that give rise to a range of intriguing phenomena. For example, dynamically encircling an exceptional point (EP) along a closed parameter loop leads to chiral mode transitions that depend critically on the encirclement direction. In this work, we propose a scheme to deterministically generate quantum entangled states by exploiting the chirality associated with different encircling directions in a non-Hermitian superconducting circuit. We reveal that the degree of entanglement is significantly enhanced—reaching its theoretical maximum—only when the encircling trajectory topologically encloses the EP. In realistic superconducting circuits, however, realizing such topological evolution poses a fundamental trade-off between the adiabaticity required for state following and the inevitable signal loss induced by environmental dissipation. To quantitatively resolve this trade-off, we employ dynamic magnetic flux modulation to precisely tune the superconducting parameters, pushing the driving period to its optimal value. These results establish a robust connection between non-Hermitian topology and quantum-state synthesis, suggesting a promising pathway toward novel applications in quantum information processing.