In our latest publication, Patrick Folge, Laura Serino and co-authors investigate the fundamental limits in the detection of frequency and time of arrival of optical pulses. The work was carried out in collaboration with colleagues from Palacký University in the Czech Republic under the direction of Zdeněk Hradil.
It is usually assumed that the simultaneous measurement of the frequency and arrival time of an optical pulse is subject to a Heisenberg uncertainty principle, which defines the fundamental limits of precision. However, this assumption is based on the assumption of an infinitely long detection window - a condition that is not fulfilled in real experiments.
In our work, we show that the problem can be mapped to the description of a so-called quantum rotor under the assumption of a finite measurement window. This results in new fundamental limits for the achievable measurement precision.
However, we not only describe these limits theoretically, but also present an experimental scheme with which this maximum precision can actually be achieved. We use a so-called quantum pulse gate, which makes it possible to project a test pulse onto a freely selectable pulse base. Through a suitable election of this base, the fundamental limit of the uncertainty product of frequency and arrival time can be achieved.
The aim of this work is initially to develop a better physical understanding of scenarios that have been insufficiently understood to date and to demonstrate the underlying fundamental limits. At the same time, the combined detection of time and frequency has numerous practical applications - from LIDAR systems to information coding in quantum computers. Our results can also help to better understand the limits of such applications.
This work has received funding from the European Union's Horizon Europe research and innovation programme (grant no. 899587, STORMYTUNE).
P. Folge, et al, Quantum-limited detection of the arrival time and the carrier frequency of time-dependent signals, Optica 13, 548 (2026); DOI: https://doi.org/10.1364/OPTICA.579459
