Fig. 2: Giant Shapiro step response and frequency dependence of the Shapiro steps.
From: Giant fractional Shapiro steps in anisotropic Josephson junction arrays
a A typical Shapiro response curve of Device 1, where both the time averaged voltage, VT, versus current, IT, at T = 3 K and the differential resistance, dVT/dIT, simultaneously measured by a standard lock-in technique are shown. The radio frequency (RF) excitation parameters are Vrf = 100 mV and νrf = 200 MHz. The x-axis is scaled by \(V_1^{\mathrm{T}} = (N_{\mathrm{x}} - 1){\mathrm{\Phi }}_0\nu _{{\mathrm{rf}}} = 82.3\,\mu {\mathrm{V}}\), where Φ0 is the fluxquantum, νrf the RF frequency of the drive and Nx = 200. b The experimentally measured frequency dependence of the Shapiro steps for a fixed RF excitation amplitude of Vrf = 100 mV for Device 1. Shapiro steps are clearly reflected in the map, as the zones of low differential resistance (yellow). The black stripe lines indicate the expected theoretical nth Shapiro step response according to \(V_n^{\mathrm{T}} = n(N_{\mathrm{x}} - 1)\Phi _0\nu _{{\mathrm{rf}}}\).
