Fig. 2: Setup for the back-action supercurrent rectifier.
a Circuit schematic to realize a supercurrent rectifier by back-action mechanism. The cross represents a weak link measured in a current-biased (I) setup by monitoring the voltage drop across it (V). A gate electrode at nominal voltage \({V}_{g}^{0}\) tunes the critical current of the weak link nearby. A control resistor in series, Rc, modifies \({V}_{g}^{0}\) into \({V}_{g}={V}_{g}^{0}-I{R}_{c}\), depending on the sign of the current bias I. b Effect of the circuitry presented in a on a representative critical current vs. gate voltage trace. At a certain gate voltage bias \({V}_{g}^{0}\), the positive critical current \({I}_{c}^{+}\) (red dot) at \({V}_{g}^{+}\) differs from the negative critical current \({I}_{c}^{-}\) (blue dot) at \({V}_{g}^{-}\) resulting in a finite diode effect, i.e., \({I}_{c}^{+}\ne | {I}_{c}^{-}|\). c, Scanning electron micrograph of a niobium (Nb) strip (orange) with a nanoconstriction (characteristic dimensions l ~ 80 nm and w ~ 180 nm) to implement the superconducting weak link. The gate voltage \({V}_{g}^{0}\) is applied through a side gate (light blue) located at distance g ~ 50 nm. d Experimental gate voltage dependence of the average critical current \(\langle {I}_{c}\rangle =({I}_{c}^{+}+| {I}_{c}^{-}| )/2\) recorded at T = 1 K with Rc = 2 kΩ.
