Li Group

Weibin Li
Correlated Atoms and Photons Theory group
School of Physics and Astronomy, University of Nottingham

Our research focuses on the creation and manipulation of strongly correlated states of light and matter at low temperatures, in the broad area of many-body quantum optics. Our current research covers the following topics: photon-photon nonlinearities, exotic states and dynamics of finite spin chains, many-body models with Rydberg dressed interactions, quantum simulation of molecular physics and chemistry, as well as quantum computation with Rydberg atoms and Rydberg ions.

Interested in knowing more or even considering to join us? please contact me.

News and research highlight

Rydberg superatoms: An artificial quantum system for quantum information processing and quantum optics

Dense atom ensembles with Rydberg excitations display intriguing collective effects mediated by their strong, long-range dipole–dipole interactions. These collective effects, often modeled using Rydberg superatoms, have gained significant attention across various fields due to their potential applications in quantum information processing and quantum optics. In this review article, we delve into the theoretical foundations of Rydberg interactions and explore experimental techniques for their manipulation and detection. We also discuss the latest advancements in harnessing Rydberg collective effects for quantum computation and optical quantum technologies. By synthesizing insights from theoretical studies and experimental demonstrations, we aim to provide a comprehensive overview of this rapidly evolving field and its potential impact on the future of quantum technologies.

This review is published in Applied Physics Reviews (2024). Click here for details.

Ergodicity breaking from Rydberg clusters in a driven-dissipative many-body system

It is challenging to probe ergodicity breaking trends of a quantum many-body system when dissipation inevitably damages quantum coherence originated from coherent coupling and dispersive two-body interactions. Rydberg atoms provide a test bed to detect emergent exotic many-body phases and nonergodic dynamics where the strong Rydberg atom interaction competes with and overtakes dissipative effects even at room temperature. Here, we report experimental evidence of a transition from ergodic toward ergodic breaking dynamics in driven-dissipative Rydberg atomic gases. The broken ergodicity is featured by the long-time phase oscillation, which is attributed to the formation of Rydberg excitation clusters in limit cycle phases. The broken symmetry in the limit cycle is a direct manifestation of many-body collective effects, which is verified experimentally by tuning atomic densities. The reported result reveals that Rydberg many-body systems are a promising candidate to probe ergodicity breaking dynamics, such as limit cycles, and enable the benchmark of nonequilibrium phase transition.

This work is published in Science Advances (2024) (click here for details).

Quantum Sensing of Microwave fields based on Rydberg atoms

Microwave electric field (MW E-field) sensing is important for a wide range of applications in the areas of remote sensing, radar astronomy and communications. This review introduces the basic concepts of quantum sensing, the properties of Rydberg atoms and the principles of quantum sensing of MW E-fields with Rydberg atoms, superheterodyne quantum sensing with microwave-dressed Rydberg atoms, quantum-enhanced sensing of MW E-field and recent advanced quantum measurement systems and approaches to further improve the performance of MW E-field sensing. See Rep. Prog. Phys. 86 106001, (2023) for details.

Summer School and Workshop on New Trends in Quantum Simulation and Computation

We have had a wonderful Summer School and Workshop where industrial and academic experts from the UK, Europe, USA, and India met and discussed exciting development and challenges in quantum simulation and computaiton.

This event is financially supported by a Going Global Partnerships Programme of the British Council and the University of Nottingham.

Creating conical intersection in a Rydberg ion crystal

Conical intersections between electronic potential energy surfaces are paradigmatic for the study of nonadiabatic processes in the excited states of large molecules. We demonstrate that trapped Rydberg ions are a platform to engineer conical intersections and to simulate their ensuing dynamics on larger length scales and timescales of the order of nanometers and microseconds, respectively in a controllable fashion. This paper is published recently in Phys. Rev. Lett. (June 2021).

Hyper chaos in a Rydberg atom chain

Complicated dynamics are expected when many atoms (qubits) are coupled. For a chain of Rydberg atoms, we show that dynamics can enter the so-called hyperchaos regime, where a single Lyapunov exponent is not enough to describe the dynamics. In fact, the number of Lyapunov exponents is linearly proportional to the number of atoms. This research is relevant to the characterisation of quantum computation. This paper is published in NPJ Quantum Information (Jan 2021).

Self-transparency in thermal Rydberg gases

Self induced transparency in a two-level medium can be induced when the pulse area is 2Pi. In a Rydberg gas, the strong and long-range interactions, however, can significantly damage the condition of the self-induced transparency. However, we find, both analytically and numerically, that the transparency can be restored. This happens when the pulse area is adjusted according to the Rydberg states, even at room temperature. The higher the Rydberg states (n), the smaller the area it should be. This research opens new insight in the study of light propagation in Rydberg media. This work was published in Physical Review Letters (Dec, 2020).

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