Conference

The renaissance in stellar intensity interferometry has resulted in two main types of telescope arrays: those using large "light bucket" telescopes and photomultiplier tubes, such as CTA, VERITAS, MAGIC, and others, and those that instead use smaller, more traditional astronomical telescopes with high-grade optics, such as the systems at the Cote d'Azur and Asiago Observatories. To detect and timestamp photons, these latter systems have used single-photon avalanche diode (SPAD) detectors. This talk will focus on the latter type of instrument, which is also being pursued at Southern Connecticut State University. The current status of our instrument, the Southern Connecticut Stellar Interferometer (SCSI), will be reviewed, and prospects for improved sensitivity will be discussed. Principal among these is the use of SPAD arrays, which are increasingly available, to record different wavelengths simultaneously. If a sufficient number of channels can be employed, this type of intensity interferometer can reach much fainter magnitudes than currently possible. The talk will also briefly discuss work toward wireless intensity interferometry with SCSI, which will make larger baselines easier to set up and use, and ideas for quantum-assisted intensity interferometry that might be employed with SCSI in the future.

Intensity Interferometry (II) is a method that can achieve high angular resolution and was first employed in the 1960s by Robert Brown and Richard Q. Twiss (HBT). Since then, significant advancements have been made, particularly in the construction of telescopes with large light collection areas, such as Imaging Atmospheric Cherenkov Telescopes (IACTs), exemplified by instruments like H.E.S.S. , MAGIC and VERITAS. Our II setup was designed to be mounted on the lid of the Phase I H.E.S.S. telescopes in Namibia. In April 2022, our first observation campaign was conducted, during which two telescopes operated in a single wavelength band. In April-May 2023, a third telescope was added, and observations were performed in two colors simultaneously for the first time in II. In this contribution I will introduce our setup and compare the different configurations, as well as present the latest results of four southern hemisphere stars.

In this talk, I will give an introduction to intensity correlations for astrophysical imaging, as pioneered by Hanbury Brown and Twiss. This triggered a wider effort for the field of quantum optics, which I will put into a larger context beyond astrophysical imaging. I will also give an overview of the past results on intensity correlations for astrophysical imaging by our group in Nice and present the ongoing effort towards resolving a white dwarf and to search for signatures of random lasing in space.

* Introduction to resonant light matter interaction (coherent and incoherent scattering, Rabi oscillations, Mollow triplets) * Origin of antibunching in resonance fluorescence (L. Hanschke et al. Phys. Rev. Lett. 125, 170402 (2020)) * Doubly-dressed Mollow triplets (C. Gustin et al. Phys. Rev. Research 3, 013044 (2021) * Dynamic Mollow triplets from Janes-Cummins systems (K. Fischer et al. Nature Photonics 10, 163–166 (2016)) * Dynamic Mollow triplets from two-level systems (K. Boos et al. arXiv:2305.15827 (2023) – accepted at PRL)