Quantum Entanglement Response to Step-like Gate Modulation

Abstract: We examine the influence of a step-like gate voltage on the entanglement formation of two interacting charge qubits, where charge is injected on demand into the qubits. The gate voltage modulates the tunnel coupling between the qubits and two electronic reservoirs (leads), which supply the initial charges to the system. The qubits interact capacitively through Coulomb repulsion, and the interplay between Coulomb interactions and hopping processes leads to the formation of entangled states. Our analysis focuses on how the physical parameters of the gate pulse affect the degree of entanglement. In pursuit of this aim, we calculate fidelity, linear entropy, and negativity within the framework of density matrix formalism. Our analysis demonstrate how to optimize the gate pulse to reach a ``sweet spot'' that maximizes entanglement, even in the presence of additional dephasing sources. These results could contribute to the future experimental realization of entanglement in interacting charge qubits.