Engineering quantum nano-systems: functional defect sites

Scalable and deterministic single-photon emitters are desirable for applications in modern information and quantum technologies. We established 2D materials as a scalable platform for deterministic and addressable single-photon emitters with unprecedented control of position owing to their all-interfacial nature. On-demand creation and precise positioning of mono-typical single-photon sources in atomically thin semiconducting 2D materials with high fabrication yield is achieved by focused ion beam irradiation with helium ions. Atomistic defects with anti-bunched emission lines with sub-10 nm lateral and <8 nm axial positioning accuracy can be produced in already processed circuitries. We aim to investigate the control of these quantum light sources by external stimuli such as electric fields and to implement them in (2D) plasmonic and opto-electronic circuitries towards real-world quantum applications, e.g. on-chip quantum networks.

Deterministic quantum light by precisely positioned point defects in TMDC monolayers by focused helium ion milling. Excitons localized at the point defects exhibit mono-energetic sharp photoluminescence (PL) from single photon emission events lines at cryogenic temperature.
© AG Wurstbauer

Engineered quantum nano-systems: emergent phenomena

Important for all (quantum) optical technologies is the manipulation of the light-matter interaction to achieve a high level of control, particularly in technologically relevant solid-state quantum-nanomaterials. Atomically thin two-dimensional materials receive great interest in this regard because of their unique properties. Among others, a novel and promising class of atomically thin crystals are 2D polar metals such as 2D Ga, In, Ag, Bi as well as their alloys. Those quantum confined metals exhibit fascinating properties like superconductivity, strong plasmonic responses in the visible range and strong nonlinear optical properties emerging by giant second harmonic generation in the NIR range together tunable epsilon near zero behavior. Due to the half-van der Waals nature, we combine these 2D metals with other van der Waals materials to achieve novel functionalities. Their tunability and possibility for integration in van der Waals heterostacks makes 2D polar metals attractive for realizing quantum engineered metal films, tunable (quantum-)plasmonics and nano-photonics.

2D polar metals such as 2 to 3 atoms thick gallium or indium layers features epsilon near zero in combination with interband plasmons due to quantum confinement.
© AG Wurstbauer

Relevant preliminary work:


  1. Gate-switchable arrays of quantum light emitters in contacted monolayer MoS2 van der Waals heterodevices
    Hötger A, Klein J, Barthelmi K, Sigl L, Sigger F, Männer W, Gyger S, Florian M, Lorke M, Jahnke F, Taniguchi T, Watanabe K, Jöns KD, Wurstbauer U, Kastl C, Müller K, Finley JJ, Holleitner AW. Nano Letters 21, 2, 1040–1046 (2021)
  2. Site-selectively generated photon emitters in monolayer MoS2 via local helium ion irradiation
     Klein J, Lorke M, Florian M, Sigger F, Wierzbowski J, Sigl L , Rey S, Cerne J, Mitterreiter E, Zimmermann P, Müller K, Taniguchi T, Watanabe K, Wurstbauer U, Kaniber M, Knap M, Schmidt R, Finley J, Holleitner A. Nature Communications 10, 10, 2755 (2019)
  3. Light–Matter Interaction in Quantum Confined 2D Polar Metals
    Nisi K, Subramanian S, He W, Ulman KA, El‐Sherif H, Sigger F, Lassaunière M, Wetherington MT, Briggs N, Gray J, Holleitner A, Bassim N, Quek SY, Robinson JA, Wurstbauer U. Advanced Functional Materials 2005977, 1-11 (2020)
  4. Unexpected Near-Infrared to Visible Nonlinear Optical Properties from 2-D Polar Metals
    Steves MA, Wang Y, Briggs N, Zhao T, El-Sherif H, Bersch BM, Subramanian S, Dong C, Bowen T, De La Fuente Duran A, Nisi K, Lassaunière M, Wurstbauer U, Bassim NID, Fonseca J, Robinson JT, Crespi VH, Robinson J, Knappenberger Jr. KL. Nano Letters 20, 11, 8312–8318 (2020)