Anomalous Josephson Effect in Non-magnetic Andreev Interferometers

Time-reversal and inversion symmetry prevent current flow in Josephson junctions when the phase difference of the superconducting electrodes $\delta$ vanishes. By breaking the underlying symmetries a persistent phase bias $\varphi_0$ across the weak link provides a finite supercurrent when $\delta=0$. This is known as the anomalous Josephson effect. We present the first evidence of anomalous supercurrent in metallic and nonmagnetic Josephson junctions configured as Andreev interferometers. From conductance measurements of the weak link we show that a controllable $\varphi_0$ phase emerges if the occupation of the supercurrent-carrying density of states is modified by an electrostatic potential. The critical voltage $V_{c1}$ required to tune the system to the dissipative regime remains constant with temperature, contrary to predictions, triggered by the anomalous supercurrent. The strong dependence of the $\varphi_0$-states with the electrostatic potential beyond $V_{c1}$ and the unexpected temperature dependence of the $\varphi_0$ -states might be exploited as voltage-controllable superconducting phase batteries.