A New Spin on Quantum Atom-Light Interactions

Project Information

NEWSPIN

Grant agreement ID: 101002107

DOI

10.3030/101002107

EC signature date 17 December 2020

Start date 1 June 2021

End date 31 May 2027

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 921 067,00

EU contribution

€ 1 921 067,00

Coordinated by

FUNDACIO INSTITUT DE CIENCIES FOTONIQUES
Spain

Periodic Reporting for period 3 - NEWSPIN (A New Spin on Quantum Atom-Light Interactions)

Reporting period: 2024-06-01 to 2025-11-30

Summary of the context and overall objectives of the project

The project aims to develop a quantum theory of multiple scattering involving photons and atoms, with the conviction that such a theory can dramatically advance quantum technologies based on atom-light interfaces, reveal exotic new quantum phenomena in such systems, and lead to new insights into fundamental questions in optics. Specifically, from a technological standpoint, we aim to show that interference in light emission is a much more powerful resource than the level that we currently exploit it, based upon conventional theories of collective enhancement. In fact, fully utilizing interference carries the potential to significantly (sometimes even exponentially) enhance the performance limits of such systems in applications. From a foundational standpoint, among other things, our theory can elucidate the physical limits to how large the refractive index of an optical material can be, and how to achieve an ultrahigh index material. Together, our results should lead to a significant change in how future atom-light interfaces are implemented, and add greatly to our understanding of quantum light-matter interactions and their rich possibilities.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Within the first reporting period, we have made significant advances in deriving significantly improved protocols for quantum information processing using interference in atom-light interfaces, unveiled and explained novel fundamental behavior in such systems, and worked with leading experimental groups to bring our theoretical ideas to fruition. Major results include:

• Proposal to realize a quantum photon-photon gate using atom arrays, which exploits “selective radiance” in light emission to achieve a polynomially better error scaling versus atom number, compared to previously known protocols
• Theoretical prediction of a fundamental, density-dependent dephasing mechanism for optical spin waves in an atomic ensemble, due to random near-field interactions, and an experimental collaboration to observe this effect
• Prediction of many-body localization in a one-dimensional waveguide coupled to disordered quantum emitters
• Development of non-equilibrium field theoretical techniques for atom-light interactions
• Experimental collaboration to observe and control atom-photon bound-state interactions in a structured microwave waveguide
• Development of a theory of what limits the refractive index of typical crystals, and a prediction that ultrahigh index materials are theoretically possible

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The project thus far has yielded powerful new protocols for quantum information processing with atoms and light, which should significantly mitigate the error sources facing current approaches and possibly be utilized in future atom-light interfaces. The project has also produced predictions and novel theoretical descriptions of important fundamental quantum optical phenomena. Most notably, we have developed a theory that explains why the refractive index of optical materials used today universally have a value of order unity, and why this empirical fact is not fundamental, possibly paving the way for the design and synthesis of ultrahigh index materials. The development of such materials and their deployment in optics and photonics technologies could be potentially game-changing, due to the new opportunities to confine light at unprecedented scales.

In the remainder of the project, we anticipate that we will develop novel tools to treat quantum multiple light scattering in atomic systems in the many-body regime, allowing for the prediction of exciting strongly correlated phenomena and an expanded set of protocols for the implementation of quantum technologies.

report-figure.jpg