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Vacuum and Surface Science

Development of Superconducting Qubits Based on Nitride Superconductors

Hirotaka Terai, Sunmi Kim, Taro Yamashita, K. Inomata, Kouichi Semba

Published Mar 9, 2025• 0 citations
Publisher

Abstract

Superconducting qubits are one of the promising hardware candidates for quantum computing, and the operation of quantum processors equipped with more than 1000 qubits have been reported. However, to achieve a meaningful quantum computation that has an advantage over classical computation, further improvement in gate fidelity and more precise control of circuit parameters are required, and many challenges remain in realizing such hardware. In this article, we summarize the current status and challenges of superconducting qubits with a focus on the circuit fabrication process and present our research and development of superconducting qubits using nitride superconductors.

DOI
10.1380/vss.68.137

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Superconducting qubits are one of the promising hardware candidates for quantum computing, and the operation of quantum processors equipped with more than 1000 qubits have been reported. However, to achieve a meaningful quantum computation that has an advantage over classical computation, further improvement in gate fidelity and more precise control of circuit parameters are required, and many challenges remain in realizing such hardware. In this article, we summarize the current status and challenges of superconducting qubits with a focus on the circuit fabrication process and present our research and development of superconducting qubits using nitride superconductors.
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Superconducting qubits have emerged as leading candidates for realizing quantum computers, which are particularly useful for solving computational problems that are beyond the capabilities of classical supercomputers. The performance of such systems critically depends on the precision and reliability of their control infrastructure. In this paper, we present an overview of state-of-the-art quantum control systems, including both closed- and open-source solutions, and discuss their respective advantages and limitations. While we review both categories, we focus more extensively on open-source control platforms and explore how their flexibility and programmability can support the research community and drive progress in the field. Lastly, we outline several promising research directions in quantum computing infrastructure, including scalable control, high-precision readout, and leakage suppression. We believe that these areas should be prioritized by the community, as they are critical to realizing fault-tolerant quantum computation.
Abstract Over the last decade, quantum computing has experienced significant changes and captured worldwide attention. In particular, superconducting qubits have become the leading candidates for scalable quantum computers, and a number of cryogenic materials have scientifically demonstrated their potential uses in constructing qubit chips. However, because of insufficient coherence time, establishing a robust and scalable quantum platform is still a long-term goal. Another consideration is the control circuits essential to initializing, operating and measuring the qubits. To keep noise low, control circuits in close proximity to the qubits require superior reliability in the cryogenic environment. The realization of the quantum advantage demands qubits with appropriate circuitry designs to maintain long coherence times and entanglement. In this work, we briefly summarize the current status of cryogenic materials for qubits and discuss typical cryogenic circuitry designs and integration techniques for qubit chips. In the end, we provide an assessment of the prospects of quantum computers and some other promising cryogenic materials.
Quantum computation is a completely new and different paradigm for how to store and process information. It offers the possibility of exponential computational advantage for certain types of hard problems, but the hardware for implementing quantum algorithms is still at an early stage. The basic idea of quantum computing is to replace the ordinary binary bits of conventional computing with their quantum equivalent, or qubit. A qubit can be any quantum system whose states can be prepared and controlled, provided that we can then fabricate them in large quantities and then couple them to one another in prescribed ways. While there are several candidate technologies for building a quantum computer, one of the most promising is superconducting quantum circuits, operated at cryogenic temperatures approaching 0.01 K.