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Figure 4 | EPJ Quantum Technology

Figure 4

From: A model study of present-day Hall-effect circulators

Figure 4

Q -parameters of a perfectly matched three terminal circulator. The device geometry is shown in Figure 1, and we use a capacitance \(cL=50~\mbox{fF}\); the magnitude of the conductivity tensor \(\sigma=\sqrt{\sigma_{xx}^{2}+\sigma_{xy}^{2}}\) and the Hall angle \(\theta_{H}\) are extracted from the experimental data in Figure 3. Along the blue lines, corresponding to Eq. (8), the value \(Q_{\circlearrowleft}=3\) is exactly attained in the limit \(\theta_{H}=\pi/2\), giving perfect circulation in the anticlockwise direction. We indicate the plateaus corresponding to filling factors \(\nu=20\) and \(\nu=8\), where impedance matching will be performed.

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