[EDP1] SQUID, Detector, Metrology, Novel Device

[EDP1-10] Simultaneous Operation of Josephson Voltage Standard and Quantized Hall Resistance Array in a Dilution Refrigerator

*Daiki Matsumaru^1,2, Takehiko Oe¹, Shuji Nakamura¹, Hirotake Yamamori¹, Michitaka Maruyama¹, Nobu-Hisa Kaneko¹ (1. AIST (Japan), 2. Univ. of Tsukuba (Japan))

Keywords:

Magnetic Field,Superconducting Shield,Quantum Hall Effect,Josephson Effect,Voltage Standard

We have successfully operated a Josephson voltage standard (JVS) and a quantized Hall resistance (QHR) array simultaneously in one dilution refrigerator toward the realization of a quantum metrology triangle (QMT) experiment conducted in a single cooling system. QMT is one of the cross validations among three quantum phenomena (or their measurement systems), which realize electrical quantities (i.e., quantized voltage by the Josephson effect (JE), quantized resistance by the quantum Hall effect (QHE), and quantized current by the single electron tunneling (SET) effect) based on Ohm’s law. To achieve low measurement uncertainty (i.e., combined uncertainty when comparing the voltage drop generated by flowing the current generated by the SET effect through the resistance generated by QHE with the voltage generated by JE) below 0.1 μV/V, it is desirable to connect each device directly in a cryogenic environment without passing through a room temperature environment. However, in this situation, the strong magnetic field required for QHR operation would be detrimental to JVS operation. In our previous studies, a JVS operation in a magnetic field environment was successfully demonstrated by using a superconducting magnetic shield structure. In this study, 79 element QHR array devices designed to be 1 MΩ were implemented in a dilution refrigerator with a JVS device for simultaneous operation of both devices. The QHR array devices showed a quantized, step-like magnetic field dependence, exhibiting well-defined plateaus in the Hall resistance, and quantized Hall resistance at filling factor ν = 2 were observed at around 10 T. The temperature of the QHR devices in this measurement was ~30 mK. The JVS device was surrounded by a hybrid magnetic shield structure of superconductors and permalloy, which shields the residual magnetic field leaking from a cancellation coil. Under these circumstances, the JVS device showed a quantized voltage of 1 mV with a bias-current margin of ±0.5 mA. The temperature of the JVS device in this measurement was ~12.1 K.