| Physicists from the Solid State Physics Laboratory (CNRS/Université Paris-Saclay) have demonstrated that it is possible to efficiently convert a flow of microwave photons into a flow of electrons. This efficient conversion is made possible by using a quantum circuit based on granular aluminum and a superconducting tunnel junction. |
A large part of processing information stored in quantum bits (qubits) relies on the sensitive measurement of microwave photons. However, detecting these photons precisely and at high rates is challenging due to their very low energy, about 100,000 times less than visible or infrared photons. This low energy makes the commonly used photoelectric effect very difficult to implement. This challenge has been successfully addressed by the NS2 team at the Solid State Physics Laboratory.
The research group demonstrated that it is possible to achieve an efficient and continuous converter of microwave photons into electrons with high quantum efficiency (83%) and a low dark current (in the absence of light). These unique properties are made possible by using a disordered superconductor with high kinetic inductance, granular aluminum, to enhance the light-matter interaction and the coupling of microwave photons to electron tunneling processes. As a result of this strong coupling, the researchers were able to observe both linear and nonlinear photon-assisted processes, where two, three, and four photons are converted into a single electron at exceptionally low light intensities. Theoretical predictions, which require quantizing the photon field, match the experimental data well. This experimental breakthrough lays the groundwork for high-efficiency detection of individual microwave photons using charge-based detection techniques.
Simplified explanations are also available online here : https://physics.aps.org/articles/v17/127
Contributors
NS2 Team
Fundings
LabEx PALM, ANR JCJC, DIM SIRTEQ
References
Efficient Microwave Photon-to-Electron Conversion in a High-Impedance Quantum Circuit
Ognjen Stanisavljević, Jean-Côme Philippe, Julien Gabelli, Marco Aprili, Jérôme Estève, and Julien Basset
Phys. Rev. Lett. 133, 076302 (2024) Editor’s suggestion and Featured in Physics
doi: https://doi.org/10.1103/PhysRevLett.133.076302
Contacts
Julien Basset – julien.basset@universite-paris-saclay.fr