Tobias Helbig

All Publications

• How pairing mechanism dictates topology in valley-polarized superconductors with Berry curvature NPJ QUANTUM MATERIALS May-Mann, J., Helbig, T., Devakul, T. 2026; 11 (1)

  View details for DOI 10.1038/s41535-026-00878-4

  View details for Web of Science ID 001797832700001

• Room-temperature quantum nanoplasmonic coherent perfect absorption NATURE COMMUNICATIONS Lai, Y., Clarke, D. D. A., Grimm, P., Devi, A., Wigger, D., Helbig, T., Hofmann, T., Thomale, R., Huang, J., Hecht, B., Hess, O. 2024; 15 (1): 6324

  Abstract

  Light-matter superposition states obtained via strong coupling play a decisive role in quantum information processing, but the deleterious effects of material dissipation and environment-induced decoherence inevitably destroy coherent light-matter polaritons over time. Here, we propose the use of coherent perfect absorption under near-field driving to prepare and protect the polaritonic states of a single quantum emitter interacting with a plasmonic nanocavity at room temperature. Our scheme of quantum nanoplasmonic coherent perfect absorption leverages an inherent frequency specificity to selectively initialize the coupled system in a chosen plasmon-emitter dressed state, while the coherent, unidirectional and non-perturbing near-field energy transfer from a proximal plasmonic waveguide can in principle render the dressed state robust against dynamic dissipation under ambient conditions. Our study establishes a previously unexplored paradigm for quantum state preparation and coherence preservation in plasmonic cavity quantum electrodynamics, offering compelling prospects for elevating quantum nanophotonic technologies to ambient temperatures.

  View details for DOI 10.1038/s41467-024-50574-9

  View details for Web of Science ID 001279103300004

  View details for PubMedID 39060227

  View details for PubMedCentralID PMC11282272

• Topological Defect Engineering and <i>PT</i> Symmetry in Non-Hermitian Electrical Circuits PHYSICAL REVIEW LETTERS Stegmaier, A., Imhof, S., Helbig, T., Hoefmann, T., Lee, C., Kremer, M., Fritzsche, A., Feichtner, T., Klembt, S., Hofling, S., Boettcher, I., Fulga, I., Ma, L., Schmidt, O. G., Greiter, M., Kiessling, T., Szameit, A., Thomale, R. 2021; 126 (21): 215302

  Abstract

  We employ electric circuit networks to study topological states of matter in non-Hermitian systems enriched by parity-time symmetry PT and chiral symmetry anti-PT (APT). The topological structure manifests itself in the complex admittance bands which yields excellent measurability and signal to noise ratio. We analyze the impact of PT-symmetric gain and loss on localized edge and defect states in a non-Hermitian Su-Schrieffer-Heeger (SSH) circuit. We realize all three symmetry phases of the system, including the APT-symmetric regime that occurs at large gain and loss. We measure the admittance spectrum and eigenstates for arbitrary boundary conditions, which allows us to resolve not only topological edge states, but also a novel PT-symmetric Z_{2} invariant of the bulk. We discover the distinct properties of topological edge states and defect states in the phase diagram. In the regime that is not PT symmetric, the topological defect state disappears and only reemerges when APT symmetry is reached, while the topological edge states always prevail and only experience a shift in eigenvalue. Our findings unveil a future route for topological defect engineering and tuning in non-Hermitian systems of arbitrary dimension.

  View details for DOI 10.1103/PhysRevLett.126.215302

  View details for Web of Science ID 000655930100005

  View details for PubMedID 34114871