# Control of spontaneous emission of qubits from weak to strong coupling

## TL;DR

This paper demonstrates how to control the spontaneous emission of a qubit across different electromagnetic environments, enabling enhancement, inhibition, and spectral filtering of emission through tuning system parameters.

## Contribution

It provides a comprehensive analysis of regimes for controlling qubit emission, including Purcell enhancement, suppression, and spectral filtering, advancing quantum light manipulation techniques.

## Key findings

- Purcell enhancement and inhibition of emission rates.
- Suppression of spontaneous emission when cavity is excited.
- Realization of spectral filtering via steady-state emission control.

## Abstract

Photon emission and absorption by an individual qubit are essential elements for the quantum manipulation of light. Here we demonstrate the controllability of spontaneous emission of a qubit in various electromagnetic environments. The parameter regimes that allow for exible control of the qubit emission routes are comprehensively discussed. By properly tuning the system couplings and decay rates, the spontaneous emission rate of the qubit can undergo Purcell enhancement and inhibition. Particularly, when the cavity is prepared in the excited state, the spontaneous emission rate of the qubit can be significantly suppressed. We also demonstrate a spectral filter effect which can be realised by controlling the steady-state emission spectra of qubits.