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Picosecond-resolution single-photon time lens for temporal mode quantum processing
Published
Author(s)
Chaitali Joshi, Ben Sparkes, Alessandro Farsi, Thomas Gerrits, Sae Woo Nam, Varun Verma, Sven Ramelow, Alex Gaeta
Abstract
Techniques to control the spectro-temporal properties of quantum states of light at ultrafast time scales are crucial for several applications in quantum information science. In this work, we report an all-optical time lens based on Bragg-scattering four-wave mixing with picosecond resolution. Our system achieves a temporal magnification factor of 158 with single-photon level inputs, which is sufficient to overcome the intrinsic timing jitter of superconducting nanowire single-photon detectors. We demonstrate discrimination of two terahartz-bandwidth, single-photon level pulses with 2.1-picosecond resolution (electronic jitter corrected resolution of 1.25 ps). We draw on elegant tools from Fourier optics to further show that the time-lens framework can be extended to perform complex unitary spectro-temporal transformations by imparting optimized temporal and spectral phase profiles to the input waveforms. Using numerical optimization techniques, we show that a 4-stage transformation can realize an efficient temporal mode sorter that demultiplexes 10 Hermite-Gaussian (HG) modes. Our time-lens based framework represents a new toolkit for arbitrary spectro-temporal processing of single-photons, with applications in temporal mode quantum processing, high-dimensional quantum key distribution, temporal mode matching for quantum networks and quantum-enhanced sensing with time-frequency entangled states.
Joshi, C.
, Sparkes, B.
, Farsi, A.
, Gerrits, T.
, Nam, S.
, Verma, V.
, Ramelow, S.
and Gaeta, A.
(2022),
Picosecond-resolution single-photon time lens for temporal mode quantum processing, Optica, [online], https://doi.org/10.1364/OPTICA.439827, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932718
(Accessed October 20, 2025)