2025-06-10 理化学研究所
超伝導量子ビットの多重読み出しの概念図
＜関連情報＞
- https://www.riken.jp/press/2025/20250610_1/index.html
- https://journals.aps.org/prxquantum/abstract/10.1103/PRXQuantum.6.020345
多半導体伝送線路を用いた本質的パーセルフィルタリングによる高速多重超伝導キュビット読み出し Fast Multiplexed Superconducting-Qubit Readout with Intrinsic Purcell Filtering Using a Multiconductor Transmission Line
Peter A. Spring, Luka Milanovic, Yoshiki Sunada, Shiyu Wang, Arjan F. van Loo, Shuhei Tamate, and Yasunobu Nakamura
Physical Review X Quantum Published: 5 June, 2025
DOI: https://doi.org/10.1103/PRXQuantum.6.020345
Abstract
Fast and accurate qubit measurement remains a critical challenge on the path to fault-tolerant quantum computing. In superconducting quantum circuits, fast qubit measurement has been achieved using a dispersively coupled resonator with a large externally limited linewidth. This necessitates the use of a Purcell filter that protects the qubit from relaxation through the readout channel. Here, we show that a readout resonator and filter resonator, coupled to each other both capacitively and inductively via a multiconductor transmission line, can produce a compact notch-filter circuit that effectively eliminates the Purcell decay channel through destructive interference. By utilizing linewidths as large as 42 MHz, we perform simultaneous readout of four qubits using a 56-ns integration window and benchmark an average assignment fidelity of 99.77%, with the highest qubit assignment fidelity exceeding 99.9%. Including the simulated readout ring-down time, the total readout duration was between 115 and 215 ns for the four qubits, which we anticipate can be reduced to around 100 ns with active ring-down pulse shaping. These results demonstrate a significant advancement in speed and fidelity for multiplexed superconducting-qubit readout.
