Experise: Quantum optics, condensed matter physics, quantum control
Research directions: Floquet theory, Polaritons, Spectroscopy, Quantum sensing
Languages: German (native), English (native-like), Chinese (fluent)
Scientific Genealogy: Tobias Brandes (1994); Bernhard Kramer (1967); Otfried Madelung (1950);
Werner Heisenberg (1923); Arnold Sommerfeld (1891); Carl Lindemann (1873); Christian Felix Klein (1868); Julius Pluecker (1823);
Christian Ludwig Gerling (1812); Carl Friedrich Gauss (1799).
Reviewer activity: Phys. Rev. Lett. , Phys. Rev. A, Phys. Rev. B, Phys. Rev. X, Journal of Chemical Physics, Quantum
CV
2024-now:Researcher, Shenzhen International Quantum Academy (SIQA)
2021-2024:Associate Researcher, Shenzhen Institute of Quantum Science and Engineering (SUSTech)
2017-2021: Postdoc, Beijing Computational Science Research Center. Supervisor: Jianshu Cao (MIT)
2017: PhD, TU Berlin, Supervisor: Tobias Brandes
2013: Master of Science, TU Berlin, Supervisor: Tobias Brandes
2012: Bachelor of Science, TU Berlin, Supervisor: Tobias Brandes
Motivation and achievements
My research investigates principles of light-matter interaction
in the quantum optical and semiclassical regimes. In this context, I develop protocols for
quantum control and quantum sensing. Besides others, my research has contributed to the
understanding of the exciton-polariton dynamics and the quantum control of Floquet systems.
Honors and Awards
2025:National Natural Science Foundation of China, International (Regional) Cooperation and Exchange Project, Research Fund for International Excellent Young Scientists
2020:National Natural Science Foundation of China, International (Regional) Cooperation and Exchange Project, Research Fund for International Young Scientists
2018:International Postdoctoral Fellowship Program 2018 (Talent-Introduction Program)
2018:First-Class Grant from the 64th Batch of General Funding by the China Postdoctoral Science Foundation
2014:Physics Studies Award: Physik-Studienpreis der Physikalischen Gesellschaft zu Berlin
Research highlights
Full-counting statistics and quantum information of dispersive readout with a squeezed environment
Li Ming, JunYan Luo, Gloria Platero, Georg Engelhardt
Dispersive readout is a key method for measuring superconducting qubits. Its basic idea is that the qubit induces a tiny change in the resonator,
and this change is then extracted from the output signal. Conventional theories are usually well suited to analyzing average signals,
but they become limited when the measurement process is more complex or when one needs to further study the statistical patterns
that emerge as the signal accumulates over time. To address this problem, we designed a dispersive-readout scheme
based on a squeezed environment and developed a corresponding full-counting-statistics approach to describe more completely how the
measurement signal evolves during temporal accumulation, as well as how these statistical features are connected to measurement precision.
The results show that a squeezed environment can significantly enhance the system’s response to tiny changes while suppressing measurement
noise, thereby improving readout precision. Under strong squeezing, this improvement can even approach the quantum limit.
Further study also shows that the scheme remains relatively stable in the presence of weak nonlinear disturbances.
This work provides a new theoretical perspective for the design and improvement of continuous quantum measurements and high-fidelity readout of superconducting quantum devices.
Photon-resolved Floquet theory approach to spectroscopic quantum sensing
Georg Engelhardt, Konstantin Dorfman, and Zhedong Zhang
Spectroscopic quantum sensing uses the quantized nature of matter to develop metrological methods beyond classical means. For instance, electric-field sensing using Rydberg atoms
and optical magnetometry are currently already highly-sensitivity techniques deployed in the tedious search for the elusive dark matter. Yet, the lack of suitable theoretical
methods to predict photonic measurement statistics beyond the mean value inhibits the improvement of such spectroscopic quantum sensing devices.
A new theoretical framework combining the celebrated Floquet theory and full-counting statistics, which is dubbed Photon-resolved Floquet theory, now offers assistance
in the quest for better spectroscopic sensing protocols. Relying only on semiclassical simulations of the light-matter interaction, it constitutes a flexible tool to optimize
existing experimental setups and the development of new measurement protocols. Besides others, it explains a diverging measurement noise in the weak dissipation regime as a
generic consequence of the quantized nature of quantum matter. Intriguingly, the Photon-resolved Floquet theory predicts that electric field sensing with Rydberg atoms might
be improved by several orders of magnitude by measuring the laser phase instead of its intensity. Similarly, the framework can unlock the full potential of other spectroscopic
quantum sensing protocols.
Polariton Localization and Dispersion Properties of Disordered Quantum Emitters in Multimode Microcavities
Georg Engelhardt and Jianshu Cao
Experiments have demonstrated that the strong light-matter coupling in polaritonic microcavities
significantly enhances transport. Motivated by these experiments, we have solved the disordered
multimode Tavis-Cummings model in the thermodynamic limit and used this solution to analyze its
dispersion and localization properties. The solution implies that wave-vector-resolved spectroscopic
quantities can be described by single-mode models, but spatially resolved quantities require the
multimode solution. Nondiagonal elements of the Green’s function decay exponentially with distance,
which defines the coherence length. The coherent length is strongly correlated with the photon weight and
exhibits inverse scaling with respect to the Rabi frequency and an unusual dependence on disorder. For
energies away from the average molecular energy and above the confinement energy, the
coherence length rapidly diverges such that it exceeds the photon resonance wavelength λ. The rapid
divergence allows us to differentiate the localized and delocalized regimes and identify the transition from
diffusive to ballistic transport.
