  Complementarity, the incomplete nature of a quantum measurement - a core
concept in quantum mechanics - stems from the choice of the measurement
apparatus. The notion of complementarity is closely related to Heisenberg's
uncertainty principle, but the exact relation between the two remains a source
of debate. For example, knowledge of a particle's position in a double slit
interference experiment will quench its wave-like nature and, vice versa,
observing the wave property via interference implies lack of knowledge of the
particle's path. A canonical system for exploring complementarity is the
quantum eraser (QE), predominantly studied thus far in photonic systems. A QE
is an interference experiment consisting of two stages. First, one of the
interfering paths is coupled to a 'which path' (WP) detector - demonstrating
loss of interference due to acquisition of WP information. Second, the WP
information is being 'erased' by projecting the detector's wavefunction on a
particular basis; this renders the WP information inaccessible, thus allowing
reconstruction of the interference pattern. In this work, we present a first
implementation of a QE in an electronic system. Our system consists of two
identical electronic Mach-Zehnder interferometers (MZIs) entangled via Coulomb
interactions. Such novel setup has already attracted a considerable theoretical
attention. With one MZI serving as a path detector and the other as the system
interferometer, the visibility of the Aharonov-Bohm oscillation in the System
can be controlled by the Detector. We demonstrate how a continuous change of
the measurement basis, followed by post selection (via cross correlation of
current fluctuations), allows a smooth transition between keeping and erasing
the WP information.
