  The Josephson diode (JD) is a non-reciprocal circuit element that supports a
larger critical current in one direction compared to the other. This effect has
gained a growing interest because of promising applications in superconducting
electronic circuits with low power consumption. Some implementations of a JD
rely on breaking the inversion symmetry in the material used to realize
Josephson junctions (JJs), but two recent theoretical proposals have suggested
that the effect can also be engineered by combining two JJs hosting highly
transmitting Andreev bound states in a Superconducting Quantum Interference
Device (SQUID) at a small, but finite flux bias [1, 2]. We have realized a
SQUID with two JJs fabricated in a proximitized InAs two-dimensional electron
gas (2DEG). We demonstrate gate control of the diode efficiency from zero up to
around 30% at specific flux bias values which comes close to the maximum of
approxiomately 40% predicated in Ref. [1]. The key ingredients to the JD effect
in the SQUID arrangement is the presence of highly transmitting channels in the
JJs, a flux bias and an asymmetry between the two SQUID arms.
