Full text loading...
(a) Hot electron nanowire noise source in its embedding measurement circuit. (b) Schematic of the connection of the nanowire in a thick 50 Ω coplanar waveguide transmission line. (c) SEM picture of the nanowire. (d) Temperature profile (solid line) along the nanowire and effective temperature (dashed line) for a bias voltage . At x = 0 and x = L, the temperature of the reservoirs is set by the temperature of the fridge T 0 (17 mK in this example).
Noise of the hot electron source normalized by the value at V = 0 μV, measured at the output of the refrigerator and integrated over the band 1–2 GHz as a function of the dc voltage across the nanowire, at two different temperatures T 0. The open symbols correspond to the experimental data and the solid lines to the theoretical expression (5).
(a) and (b) Normalized noise PSD at the output of the refrigerator on the LF port (a) and HF port (b) as a function of noise frequency and voltage V across the resistor measured for a 32 dB gain. (c)–(e) Noise PSD referred to the output of the noise source, integrated over a 1 MHz frequency band and expressed in photon units, as a function of V for three different gains. The experimental data (open symbols) are fitted by the theoretical expression (5) of the hot-electron regime (black full lines). The best fits give an added noise of 1.36, 1.475, and 1.575 photon (increasing gain). The theoretical quantum limit (QL) is indicated as reference (dotted lines). The green line corresponds to the expression of quantum shot noise (Eq. (4)). (f)–(h) Noise PSD at the LF and HF port plotted as a function of effective temperature. Open symbols correspond to experimental data and full lines to theory. The theoretical QL is indicated as reference (dotted lines). The dashed lines indicate high temperature variation.
Article metrics loading...