Difference-Frequency Generation with and without Quantum Interference in Superconducting Circuits

Electromagnetically induced transparency (EIT) plays an important role in enhancing nonlinear optical processes at the quantum level. This paper proposes an accessible scheme for realizing high-efficiency second-order nonlinear difference-frequency generation beyond the conventional EIT technique in superconducting circuits. By designing two subsystems to create two transparency windows from Autler-Townes splitting (ATS), a dual-ATS mechanism is triggered in the scheme. This mechanism leads to an efficient difference-frequency generation, and the efficiency obtained here can be four orders of magnitude larger than that of the EIT scheme. This study may pave a way for exploring ATS-enhanced nonlinear optics. This paper proposes an efficient scheme for achieving giant enhancement of nonlinear difference-frequency generation in superconducting circuits. Instead of conventional electromagnetically induced transparency (EIT) technique, a dual Autler-Townes-splitting mechanism is used to assist the difference-frequency generation. The efficiency obtained here can be four orders of magnitude larger than that of the EIT scheme.image