  Three different implementations of interaction-free measurements (IFMs) in
solid-state nanodevices are discussed. The first one is based on a series of
concatenated Mach-Zehnder interferometers, in analogy to optical-IFM setups.
The second one consists of a single interferometer and concatenation is
achieved in the time domain making use of a quantized electron emitter. The
third implementation consists of an asymmetric Aharonov-Bohm ring. For all
three cases we show that the presence of a dephasing source acting on one arm
of the interferometer can be detected without degrading the coherence of the
measured current. Electronic implementations of IFMs in nanoelectronics may
play a fundamental role as very accurate and noninvasive measuring schemes for
quantum devices.
