Nonlinear Light-Matter Interactions with Entangled Photons and Bright Squeezed Vacuum
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Date
2023-03-24
Authors
Landes, Tiemo
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
We investigate the role of time-frequency entanglement in nonlinear interactions of both low- and high-gain broadband squeezed vacuum. Our work is motivated by the large body of research proposing the use of time-frequency entanglement in nonlinear spectroscopy, as well as reports of enhancements in two-photon absorption efficiencies 10 orders of magnitude larger than expected.
We theoretically investigate two-photon absorption, deriving a generalized form capable of rigorously predicting efficiencies for time-frequency entangled states. We find good agreement between our theory and previously expected efficiencies and find no explanation for large enhancements reported elsewhere. Experimentally, we replicate experiments that reported large enhancements, finding no evidence of enhancement beyond what is expected by theory.
We further develop an analytically tractable model for broadband squeezed vacuum valid at both high- and low-gain, which we apply to sum-frequency generation and two-photon absorption. Our model demonstrates the persistence of time-frequency correlations at high gain and predicts the cross-over between scaling regimes and absolute efficiencies in agreement with previous calculations.
We verify key components of our theory experimentally using both low- and high-gain squeezed vacuum. We demonstrate the persistence of time-frequency correlations at high-gain via dispersion sensitivity as well as direct measurement of coherence time via time-delayed sum frequency generation. We confirm the cross-over between low- and high-gain regimes via sum frequency generation. Finally, we confirm predictions about two-photon absorption efficiencies of high-gain squeezed vacuum, by direct comparison to classical two-photon absorption.
Description
Keywords
Bright Squeezed Vacuum, Quantum Optics, Spontaneous Parametric Down-Conversion, Time-Frequency Entanglement