  We demonstrate two approaches for unbalanced interferometers as time-bin
qubit analyzers for quantum communication, robust against mode distortions and
polarization effects as expected from free-space quantum communication systems
including wavefront deformations, path fluctuations, pointing errors, and
optical elements. Despite strong spatial and temporal distortions of the
optical mode of a time-bin qubit, entangled with a separate polarization qubit,
we verify entanglement using the Negative Partial Transpose, with the measured
visibility of up to 0.85$\pm$0.01. The robustness of the analyzers is further
demonstrated for various angles of incidence up to 0.2$^{\circ}$. The output of
the interferometers is coupled into multimode fiber yielding a high system
throughput of 0.74. Therefore, these analyzers are suitable and efficient for
quantum communication over multimode optical channels.
