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Q: Fachverband Quantenoptik und Photonik

Q 58: Quantum Optics with Photons I

Q 58.4: Vortrag

Donnerstag, 9. März 2023, 15:15–15:30, F442

Measurement of two-point spectral correlation functions of pulsed quantum states of light — •Abhinandan Bhattacharjee, Patrick Folge, Laura Serino, Benjamin Brecht, and Christine Silberhorn — Paderborn University, Integrated Quantum Optics, Institute for Photonic Quantum Systems (PhoQS), Warburger Straße 100, 33098 Paderborn, Germany

Coherence theory is an established research area for characterizing statistical randomness in an optical field. Typically, coherence is quantified through a two-point correlation function. This is routinely measured in spatial and temporal domains. One can also consider spectral coherence, however, the measurement of spectral two-point correlation function becomes challenging because interferometric techniques generally require high-intensity input fields and reconstruction algorithms do not work well for arbitrary spectral shapes.

Recently, the emergence of the quantum pulse gate (QPG), a frequency up-conversion process, has enabled the projection of an input field onto any desired spectral mode with high fidelity, including in the single photon regime. This device therefore overcomes the challenges of measuring spectral coherence. We propose an interferometric scheme that uses a QPG to project a classical or quantum state of light field onto a superposition of two spectral bins and obtains the two-point correlation function by measuring the intensity of the up-converted field as a function of the bin separation. In the context of parametric down-conversion, the spectral coherence measurement of only one of the arms certifies the spectral entanglement between two outputs.