Mollow triplet: pump probe single photon spectroscopy of artificial atoms

TL;DR

This paper investigates the quantum optical properties of a qubit coupled to a microwave cavity within a waveguide, deriving analytic expressions for photon transport and revealing the quantum nature of the Mollow triplet spectrum.

Contribution

It develops a one-photon approximation scheme to analyze photon transport and spectral features in a waveguide-cavity-qubit system, providing general analytic formulas.

Findings

The Mollow spectrum shows four spectral lines for small photon numbers.

Analytic expressions for transmission and reflection reveal qubit parameters.

Results are applicable to various types of qubits.

Abstract

We analyze a photon transport through an 1D open waveguide side coupled to the $N$-photon microwave cavity with embedded artificial two- level atom (qubit). The qubit state is probed by a weak signal at the fundamental frequency of the waveguide. Within the formalism of projection operators and non-Hermitian Hamiltonian approach we develop a one-photon approximation scheme to obtain the photon wavefunction which allows for the calculation of the probability amplitudes of the spontaneous transitions between the levels of two Rabi doublets in $N$- photon cavity. We obtain analytic expressions for the transmission and reflection factors of the microwave signal through a waveguide, which contain the information of the qubit parameters. We show that for small number of cavity photons the Mollow spectrum consists of four spectral lines which is a direct manifestation of quantum nature of light. The results obtained in the paper are of general nature and can be applied to any type of qubits. The specific properties of the qubit are only encoded in the two parameters: the energy $\Omega$ of the qubit and its coupling $\lambda$ to the cavity photons.