Abstract
We present a new method for the spectral characterization of pulsed twin-beam sources in the high-gain regime, using cascaded stimulated emission. We show an implementation of this method for a periodically poled potassium titanyl phosphate spontaneous parametric down-conversion source generating up to 60 photon pairs per pulse, and we demonstrate excellent agreement between our experiments and our theory. This work enables the complete and accurate experimental characterization of high-gain effects in parametric down-conversion, including self- and cross-phase modulation. Moreover, our theory allows the exploration of designs with the goal of improving the specifications of twin-beam sources for application in quantum information, computation, sampling, and metrology.
- Received 17 February 2020
- Revised 11 August 2020
- Accepted 13 August 2020
DOI:https://doi.org/10.1103/PhysRevX.10.031063
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Many applications in quantum information processing and quantum metrology require the ability to generate bright, correlated pairs of light beams. Recent advances have led to the generation of twin beams in single optical modes—a crucial requirement for many applications—as well as with a brightness well beyond that of single-photon pairs. However, most characterization techniques and theoretical descriptions have focused on single-photon pairs and have not included additional effects that become important at higher brightness. Here, we develop the necessary theoretical and experimental methods to match this new high-brightness regime and demonstrate them on the brightest source design reported to date.
Seeding the source with a laser beam, we measure the spectrum of the generated light as a function of the laser wavelength. The unseeded mode spectrum has been previously used as a characterization tool. We now measure broadband light generation in the same mode as the seed and relate this to the theoretical description of the source. This allows us to robustly characterize the source brightness, nonperturbative effects, and parasitic effects such as pump self-phase modulation, which have not been accurately quantified before.
Our model allows us to explore new designs with the goal of improving twin-beam sources for quantum information and metrology applications.
