  Time-bin qudits have emerged as a promising encoding platform in many quantum
photonic applications. However, the requirement for efficient single-shot
measurement of time-bin qudits instead of reconstructive detection has
restricted their widespread use in experiments. Here, we propose an efficient
method to measure arbitrary superposition states of time-bin qudits and confirm
it up to dimension 4. This method is based on encoding time bins at the
picosecond time scale, also known as ultrafast time bins. By doing so, we
enable the use of robust and phase-stable single spatial mode temporal
interferometers to measure time-bin qudit in different measurement bases.
