In the project C01, new precision experiments have been carried out at the ultimate quantum
limit. Measuring, for example, the time separation of two closely spaced light pulses is a
challenging problem, restricting many applications, including LIDAR, GPS, and interferometry.
Common intensity detection is fundamentally limited by Rayleigh’s resolution limit. However,
approaching this situation with methods from quantum information theory yields fascinating
new insights; quantum mechanics may allow for better measurements. For the situation of
closely spaced light pulses, quantum measurements allow us to estimate not only a single,
but multiple parameters simultaneously with quantum-limited precision that exceeds classical
restrictions. During the project, we realized a setup based on the quantum pulse gate that
demonstrates multiparameter estimation at the ultimate quantum limit. Our results have been
published in PRX Quantum and were popularly featured in Physics and were chosen for the
APS online Journal Club.
Reference: PRX Quantum 2, 010301 (2021)
