Microwave degenerate parametric down-conversion with a single cyclic three-level system in circuit QED

TL;DR

This paper theoretically demonstrates enhanced microwave degenerate parametric down-conversion using a single cyclic three-level superconducting system in circuit QED, showing increased efficiency and analyzing squeezing and bunching effects.

Contribution

It introduces a novel scheme for microwave PDC with a cyclic three-level system, achieving higher efficiency than previous two-level qubit systems.

Findings

PDC efficiency surpasses that of two-level qubit systems

Effective Hamiltonian derived via adiabatic elimination

Squeezing and bunching behaviors analyzed

Abstract

With the assistance of a single cyclic three-level system, which can be realized by a superconducting flux qubit, we study theoretically the degenerate microwave parametric down-conversion (PDC) in a superconducting transmission line resonator with the fundamental and second harmonic modes involved. By adiabatically eliminating the excited states of the three-level system, we obtain an effective microwave PDC Hamiltonian for the two resonator modes in such a circuit QED system. The corresponding PDC efficiency in our model can be much larger than that in the similar circuit QED system based on a single two-level superconducting qubit [K. Moon and S. M. Girvin, Phys. Rev. Lett. {\bf 95}, 140504 (2005)]. Furthermore, we consider the squeezing and bunching behavior of the fundamental mode resulting from the coherent drive to the second harmonic one.