Emission and Absorption of Microwave Photons in Orthogonal Temporal Modes across a 30-Meter Two-Node Network

TL;DR

This paper demonstrates the generation and transfer of microwave photons in orthogonal temporal modes over a 30-meter quantum network, enabling mode-selective absorption and expanding quantum communication capabilities.

Contribution

It introduces the experimental use of orthogonal temporal modes in microwave photons for quantum networking, with mode-selective transfer over a long-distance link.

Findings

Orthogonal temporal modes enable mode-selective photon absorption.

Successful transfer of microwave photons across a 30-meter link.

Achieved a selectivity ratio of 40 for mode discrimination.

Abstract

The tunable interaction between stationary quantum bits and propagating modes of light allows for the encoding of quantum information in the state of itinerant photons. This ability fulfills a central requirement for quantum networking, enabling quantum state transfer between distant quantum devices. Conventionally, a symmetric envelope of the photon wavepacket is used for such purposes. Yet, the use of alternative \textit{temporal modes} enables multiple applications in waveguide quantum electrodynamics that remain unexplored experimentally. Here, we use superconducting quantum circuits to generate individual itinerant microwave photons shaped in three mutually orthogonal temporal modes. We transfer the created photons across a 30-m cryogenic link, showing that the orthogonality allows us to decide at the receiver which mode to absorb, reflecting the other two with a selectivity ratio of 40. This experimental capability extends the microwave-frequency quantum communication toolbox, enabling a new photonic degree of freedom.