Fig. 3: Effect of interjunction spacing, dx, and temperature, T, on DC voltage-tunable Josephson emission in NbTiN Josephson junction arrays (JJAs).
From: DC-operated Josephson junction arrays as a cryogenic on-chip microwave measurement platform
a Junction resistance Rj as function of temperature for NbTiN100–400 and MoGe-bot. The vertical gray dashed lines indicate the weak link critical temperature \({T}_{{{{\rm{c}}}}}^{{{{\rm{wl}}}}}\) for the NbTiN array with dx = 400 nm, the superconducting critical temperature, Tc, of MoGe at 6.5 K and of NbTiN at 12 K. The inset shows a zoom near the transition of MoGe at Tc = 6.5 K. b The dependency of the weak link critical current, \({I}_{{{{\rm{c}}}}}^{{{{\rm{wl}}}}}\), on dx for NbTiN100–400 at 0.3 K. c VI curves for NbTiN100 (blue) and NbTiN200 at 0.3 K (red line) and 2 K (red dashed line). d Power spectral density S as a function of frequency, ν, and junction voltage Vj, converted to units of Hz using the Josephson equation. Data is for NbTiN200 at 2 K.
