Measuring ultrafast time-bin qudits

TL;DR

This paper introduces an efficient method for measuring arbitrary superposition states of ultrafast time-bin qudits, enabling practical quantum photonic applications by using phase-stable interferometers up to dimension 4.

Contribution

It proposes a novel measurement technique for ultrafast time-bin qudits that allows for single-shot, basis-independent detection up to four dimensions.

Findings

Validated the measurement method up to dimension 4.

Enabled phase-stable measurements in different bases.

Improved practicality of time-bin qudit detection.

Abstract

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.