# Tunable Microwave Single-photon Source Based on Transmon Qubit with High Efficiency

## TL;DR

This paper demonstrates a highly efficient, tunable microwave single-photon source using a transmon qubit, achieving over 98% emission efficiency and negligible dephasing, suitable for quantum communication and information processing.

## Contribution

The work introduces a tunable microwave single-photon source with over 98% efficiency based on a transmon qubit, enabling high-quality photon generation with minimal dephasing.

## Key findings

- Emission efficiency above 98%
- Achieved simultaneous frequency tunability and negligible pure dephasing
- Confirmed single-photon properties through correlation measurements

## Abstract

Single-photon sources are of great interest because they are key elements in different promising applications of quantum technologies. Here we demonstrate a highly efficient tunable on-demand microwave single-photon source based on a transmon qubit with the intrinsic emission efficiency above 98$\%$. The high efficiency ensures a negligible pure dephasing rate and the necessary condition for generation of indistinguishable photons. We provide an extended discussion and analysis of the efficiency of the photon generation. To further experimentally confirm the single-photon property of the source, correlation functions of the emission field are also measured using linear detectors with a GPU-enhanced signal processing technique. Our results experimentally demonstrate that frequency tunability and negligible pure dephasing rate can be achieved simultaneously and show that such a tunable single-photon source can be good for various practical applications in quantum communication, simulations and information processing in the microwave regime.