2025/06/03 by Francesco Di Lena, Fabrizio Sgobba, Di Lena, Francesco +17 · 2 citations
Physics and Astronomy · #Advanced Fiber Laser Technologies #Advanced Frequency and Time Standards #FOS: Physical sciences #Quantum Physics (quant-ph) #Quantum optics and atomic interactions
paper · pdf · doi:10.48550/arxiv.2506.03098
openalex publication_date 2025/06/03 · openalex created_date 2025/10/14 · openalex updated_date 2026/07/31
We demonstrate a scheme for high-precision measurements of time delay based on frequency-resolved Hong-Ou-Mandel (HOM) interference. Our approach is applied to weak coherent states and exploits an array of single-photon avalanche diodes (SPADs). Unlike conventional HOM experiments, our setup enables high-precision measurements producing an uncertainty per coincidence of about ∼ 10 ps even for photons separated by delays up to ∼ 4 ps so much greater than their coherence time where ordinary non-resolved HOM fails. This result confirms our newly developed theoretical predictions that consider, differently from previous theoretical results, a finite frequency resolution in the detection. We compare the performance of this scheme against the conventional non-resolved case. Experimental data align well with the predictions of quantum estimation theory, demonstrating a significant reduction in the uncertainty. Due to the physics of the frequency-resolved HOM effect, the gain in precision is particularly high when the estimated time delay is much longer than the coherence time.