Quantum Computer with Superconducting Qubits : Elementary Technologies and Scaling up

Hirotaka Terai, Wei Qiu, Taro Yamashita

The superconducting qubit technology based on Josephson junctions is a promising platform for realizing quantum computers. Since being first demonstrated, the coherence time of superconducting qubits has improved from 10 ns to 100 μs over the past 18 years. As a result, high-fidelity qubit operations in a scalable architecture are now becoming possible. In this article, we introduce recent progress in the fabrication process of superconducting qubits for large-scale quantum computation.

J. Q. You, J. S. Tsai, Franco Nori

Nobuyuki Yoshikawa

In this report, we represent current status of quantum computer researches using superconducting technologies and show the direction of the future research and development. A superconducting quantum computer system combining superconducting electronics and superconducting qubits based on superconducting integrated circuit technology is expected to become a more active area in the future as a potential technology for realizing a scalable large-scale quantum computers.

Hiu Yung Wong

The superconducting qubit quantum computer is one of the most promising quantum computing architectures for large-scale integration due to its maturity and close proximity to the well-established semiconductor manufacturing infrastructure. From an education perspective, it also bridges classical microwave electronics and quantum electrodynamics. In this paper, we will review the basics of quantum computers, superconductivity, and Josephson junctions. We then introduce important technologies and concepts related to DiVincenzo's criteria, which are the necessary conditions for the superconducting qubits to work as a useful quantum computer. Firstly, we will discuss various types of superconducting qubits formed with Josephson junctions, from which we will understand the trade-off across multiple design parameters, including their noise immunity. Secondly, we will discuss different schemes to achieve entanglement gate operations, which are a major bottleneck in achieving more efficient fault-tolerant quantum computing. Thirdly, we will review readout engineering, including the implementations of the Purcell filters and quantum-limited amplifiers. Finally, we will discuss the nature and review the studies of two-level system defects, which are currently the limiting factor of qubit coherence time. DiVincenzo's criteria are only the necessary conditions for a technology to be eligible for quantum computing. To have a useful quantum computer, large-scale integration is required. We will review proposals and developments for the large-scale integration of superconducting qubit devices. By comparing with the application of electronic design automation (EDA) in semiconductors, we will also review the use of EDA in superconducting qubit quantum computer design, which is necessary for its large-scale integration.

Daisuke Saida

G. Blatter, V. B. Geshkenbeǐn, Alban L. Fauchère +2 more