NICT's research paper on nitride superconducting qubits, published on Monday, September 20, 2021, was selected as a featured image highlight in Communications Materials (an open-access journal from Nature Research), so an optical micrograph image of a nitride superconducting qubit circuit is displayed as the main screen view of the journal.

Overview / Background

This paper presents a new type of superconducting qubit based on nitride superconducting junctions which do not use conventional aluminum and aluminum oxide film as superconductor/insulating film/superconductor junctions, a core part of a superconducting qubit.
NICT has been developing an all-nitride superconducting qubit using niobium nitride (NbN)/aluminum nitride/NbN epitaxial junctions grown on a magnesium oxide (MgO) substrate for a few years, but its coherence time was around 0.5 microseconds because of the dominant dielectric loss from the MgO substrate.
Recently, by utilizing the NbN-based fabrication techniques on a silicon substrate with a TiN buffer to eliminate the dielectric loss from the MgO substrate, we have successfully observed a greatly enhanced coherence time in the order of tens of microseconds. These results are an important step towards constructing a new platform for superconducting quantum information devices.
Using this new material platform that may replace conventional aluminum, we will accelerate the research and development of quantum information processing, which will contribute to the realization of more power-saving information processing and the realization of quantum nodes necessary for the construction of safe and secure quantum networks.

Main web page of the journal

(An optical micrograph image of a nitride superconducting qubit circuit used in NICT’s research paper on the nitride superconducting qubits was displayed in the main web page as a featured image highlight at Communications Materials.)

Information of the published article

Journal: Communications Materials
DOI: 10.1038/s43246-021-00204-4
Title: Enhanced coherence of all-nitride superconducting qubit epitaxially grown on silicon substrate
Authors: Sunmi Kim, Hirotaka Terai, Taro Yamashita, Wei Qiu, Tomoko Fuse, Fumiki Yoshihara, Sahel Ashhab, Kunihiro Inomata, Kouichi Semba

Related past press releases

Date: September 20, 2021
Title: All-nitride Superconducting Qubit Made on a Silicon Substrate
- New material platform for large-scale integration of superconducting qubits -


Contact information

KIM Sunmi, SEMBA Kouichi
Quantum ICT Laboratory
Advanced ICT Research Institute

Tel: +81-42-327-5684


Tel: +81-42-327-7611


TERAI Hirotaka
Superconductive ICT Laboratory
Advanced ICT Research Institute

Tel: +81-78-969-2191