Current comparator for both AC and DC ratio measurements with 10-8-level accuracy

Hidekazu Muramatsu; Yuta Kainuma; Hiromitsu Kato; Norihiko Sakamoto; Tatsuji Yamada; Chiharu Urano; Hiroshi Abe; Shinobu Onoda; Takeshi Ohshima; Yuji Hatano; Mutsuko Hatano; Nobu-Hisa Kaneko; Yasutaka Amagai; Takayuki Iwasaki

arXiv · 2508.05140

Current comparator for both AC and DC ratio measurements with 10-8-level accuracy

Hidekazu Muramatsu·Yuta Kainuma·Hiromitsu Kato·Norihiko Sakamoto·Tatsuji Yamada·Chiharu Urano·Hiroshi Abe·Shinobu Onoda·Takeshi Ohshima·Yuji Hatano·Mutsuko Hatano·Nobu-Hisa Kaneko·Yasutaka Amagai·Takayuki Iwasaki

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Abstract

Accurate measurements of alternating current (AC) and direct current(DC) ratios are fundamental to electric power metrology. However, conventional current comparators for AC and DC typically rely on distinct technologies-electromagnetic induction for AC and superconducting quantum interference devices for DC. This technological divide leads to a fragmented and complex traceability system. Bridging this gap is critical for developing unified current standards that meet the demands of emerging power technologies. In this work, we present a compact, room-temperature AC/DC current comparator that integrates a diamond-based magnetometer using nitrogen-vacancy centers. The device achieves an accuracy of 10-8 for both AC and DC signals and supports a system bandwidth up to 300 Hz, without the need for cryogenics. It surpasses the performance of typical AC comparators, offering ten-fold higher accuracy, and matches that of state-of-the-art DC comparators. This unified, cryogenics-free solution not only enhances precision and versatility but also expands the applicability of the system to DC resistance bridges in quantum electrical standards.

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Hidekazu Muramatsu, Yuta Kainuma, Hiromitsu Kato, Norihiko Sakamoto, Tatsuji Yamada, Chiharu Urano, Hiroshi Abe, Shinobu Onoda, Takeshi Ohshima, Yuji Hatano, Mutsuko Hatano, Nobu-Hisa Kaneko, Yasutaka Amagai, Takayuki Iwasaki. 2025-08-07. Current comparator for both AC and DC ratio measurements with 10-8-level accuracy. https://arxiv.org/abs/2508.05140

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