Quantum dynamics of Josephson fluxons

• Applicant: Professor Alexey V. Ustinov, Ph.D.
• Subject Area: Experimental Condensed Matter Physics ; Theoretical Condensed Matter Physics
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 405869393

Quantum properties of elementary superconducting quantum circuits, so-called qubits, attracted a lot of interest in the past decade and tremendous improvements in their coherence times have been made. Most of research to date has been aimed at developing building blocks and control tools for universal quantum computer, on the one hand, and at testing fundamental laws of quantum physics with few superconducting qubits and quantum optics with microwave photons, on the other hand. Building and manipulating superconducting circuits with larger number of quantum components remains a big challenge due to the overwhelming complexity of their quantum states and unknown coherence limits. The main idea of the project is to experimentally and theoretically explore quantum dynamics and coherence of collective excitations in networks of superconducting qubits. In particular, our interest will be on exploring and understanding quantum dynamics of their spatially-localized excitations – magnetic fluxons, which are topologically stable magnetic flux quanta formed by vortices of persistent supercurrents. We are aiming at observing coherent tunnelling of fluxons and detecting their Bloch oscillations. We will perform experiments with one-dimensional superconducting networks and measure their excitation spectra in the microwave band. We hope to control the mobility of quantum fluxons by applying gate charges through the Aharonov-Casher interference. The goal of our program will be on finding ways to employ quantum dynamics of fluxons for manipulating entanglement and transferring quantum information across the chip. This should enable development of novel approaches towards scalable quantum processors and their interfaces with classical single-fluxon logic.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Science Foundation
• Cooperation Partner: Dr. Mikhail Fistul