@article{62859,
  abstract     = {{<jats:p>Frequency-filtered photon correlations have been proven to be extremely useful in grasping how the detection process alters photon statistics. Harnessing the spectral correlations also permits refinement of the emission and unraveling of previously hidden strong correlations in a plethora of quantum-optical systems under continuous-wave excitation. In this work, we investigate such correlations for time-dependent excitation and develop a methodology to compute efficiently time-integrated correlations, which are at the heart of the photon-counting theory, and subsequently apply it to analyze the photon emission of pulsed systems. By combining this formalism with the —which facilitates frequency-resolved correlations—we demonstrate how spectral filtering enhances single-photon purity and suppresses multiphoton noise in time-bin-encoded quantum states. Specifically, filtering the central spectral peak of a dynamically driven two-level system boosts temporal coherence and improves the fidelity of time-bin entanglement preparation, even under conditions favoring multiphoton emission. These results establish spectral filtering as a critical tool for tailoring photon statistics in pulsed quantum light sources.</jats:p>}},
  author       = {{Bermúdez-Feijóo, Santiago and Zubizarreta Casalengua, Eduardo and Müller, Kai and Jöns, Klaus}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  number       = {{3}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Spectral correlations of dynamical resonance fluorescence}}},
  doi          = {{10.1103/jmy9-bd3l}},
  volume       = {{7}},
  year         = {{2025}},
}

@article{62861,
  author       = {{Laneve, Alessandro and Ronco, Giuseppe and Beccaceci, Mattia and Barigelli, Paolo and Salusti, Francesco and Claro-Rodriguez, Nicolas and De Pascalis, Giorgio and Suprano, Alessia and Chiaudano, Leone and Schöll, Eva and Hanschke, Lukas and Krieger, Tobias M. and Buchinger, Quirin and Covre da Silva, Saimon F. and Neuwirth, Julia and Stroj, Sandra and Höfling, Sven and Huber-Loyola, Tobias and Usuga Castaneda, Mario A. and Carvacho, Gonzalo and Spagnolo, Nicolò and Rota, Michele B. and Basso Basset, Francesco and Rastelli, Armando and Sciarrino, Fabio and Jöns, Klaus and Trotta, Rinaldo}},
  issn         = {{2041-1723}},
  journal      = {{Nature Communications}},
  number       = {{1}},
  publisher    = {{Springer Science and Business Media LLC}},
  title        = {{{Quantum teleportation with dissimilar quantum dots over a hybrid quantum network}}},
  doi          = {{10.1038/s41467-025-65911-9}},
  volume       = {{16}},
  year         = {{2025}},
}

@article{54868,
  abstract     = {{<jats:title>Abstract</jats:title><jats:p>Most properties of solid materials are defined by their internal electric field and charge density distributions which so far are difficult to measure with high spatial resolution. Especially for 2D materials, the atomic electric fields influence the optoelectronic properties. In this study, the atomic‐scale electric field and charge density distribution of WSe<jats:sub>2</jats:sub> bi‐ and trilayers are revealed using an emerging microscopy technique, differential phase contrast (DPC) imaging in scanning transmission electron microscopy (STEM). For pristine material, a higher positive charge density located at the selenium atomic columns compared to the tungsten atomic columns is obtained and tentatively explained by a coherent scattering effect. Furthermore, the change in the electric field distribution induced by a missing selenium atomic column is investigated. A characteristic electric field distribution in the vicinity of the defect with locally reduced magnitudes compared to the pristine lattice is observed. This effect is accompanied by a considerable inward relaxation of the surrounding lattice, which according to first principles DFT calculation is fully compatible with a missing column of Se atoms. This shows that DPC imaging, as an electric field sensitive technique, provides additional and remarkable information to the otherwise only structural analysis obtained with conventional STEM imaging.</jats:p>}},
  author       = {{Groll, Maja and Bürger, Julius and Caltzidis, Ioannis and Jöns, Klaus D. and Schmidt, Wolf Gero and Gerstmann, Uwe and Lindner, Jörg K. N.}},
  issn         = {{1613-6810}},
  journal      = {{Small}},
  publisher    = {{Wiley}},
  title        = {{{DFT‐Assisted Investigation of the Electric Field and Charge Density Distribution of Pristine and Defective 2D WSe<sub>2</sub> by Differential Phase Contrast Imaging}}},
  doi          = {{10.1002/smll.202311635}},
  year         = {{2024}},
}

@article{62853,
  abstract     = {{<jats:title>Abstract</jats:title>
                  <jats:p>Developing coherent excitation methods for quantum emitters ensuring high brightness, optimal single‐photon purity and indistinguishability of the emitted photons has been a key challenge in the past years. While various methods have been proposed and explored, they all have specific advantages and disadvantages. This study investigates the dynamics of the recent swing‐up scheme as an excitation method for a two‐level system and its performance in single‐photon generation. By applying two far red‐detuned laser pulses, the two‐level system can be prepared in the excited state with near‐unity fidelity. The successful operation and coherent character of this technique are demonstrated using a semiconductor quantum dot (QD). Moreover, the multi‐dimensional parameter space of the two laser pulses is explored to analyze its impact on excitation fidelity. Finally, the performance of the scheme as an excitation method for generating high‐quality single photons is analyzed. The swing‐up scheme itself proves effective, exhibiting nearly perfect single‐photon purity, while the observed indistinguishability in the studied sample is limited by the influence of the inevitable high excitation powers on the semiconductor environment of the quantum dot.</jats:p>}},
  author       = {{Boos, Katarina and Sbresny, Friedrich and Kim, Sang Kyu and Kremser, Malte and Riedl, Hubert and Bopp, Frederik W. and Rauhaus, William and Scaparra, Bianca and Jöns, Klaus and Finley, Jonathan J. and Müller, Kai and Hanschke, Lukas}},
  issn         = {{2511-9044}},
  journal      = {{Advanced Quantum Technologies}},
  number       = {{4}},
  publisher    = {{Wiley}},
  title        = {{{Coherent Swing‐Up Excitation for Semiconductor Quantum Dots}}},
  doi          = {{10.1002/qute.202300359}},
  volume       = {{7}},
  year         = {{2024}},
}

@unpublished{62858,
  abstract     = {{Phonons in solid-state quantum emitters play a crucial role in their performance as photon sources in quantum technology. For resonant driving, phonons dampen the Rabi oscillations resulting in reduced preparation fidelities. The phonon spectral density, which quantifies the strength of the carrier-phonon interaction, is non-monotonous as a function of energy. As one of the most prominent consequences, this leads to the reappearance of Rabi rotations for increasing pulse power, which was theoretically predicted in Phys. Rev. Lett. 98, 227403 (2007). In this paper we present the experimental demonstration of the reappearance of Rabi rotations.}},
  author       = {{Hanschke, L. and Bracht, T. K. and Schöll, E. and Bauch, David and Berger, Eva and Kallert, Patricia and Peter, M. and Garcia, A. J. and Silva, S. F. Covre da and Manna, S. and Rastelli, A. and Schumacher, Stefan and Reiter, D. E. and Jöns, Klaus}},
  booktitle    = {{arXiv:2409.19167}},
  title        = {{{Experimental measurement of the reappearance of Rabi rotations in semiconductor quantum dots}}},
  year         = {{2024}},
}

@unpublished{62856,
  abstract     = {{On-chip emitters that can generate single and entangled photons are essential building blocks for developing photonic quantum information processing technologies in a scalable fashion. Semiconductor quantum dots (QDs) are attractive candidates that emit high-quality quantum states of light on demand, however at a rate limited by their spontaneous radiative lifetime. In this study, we utilize the Purcell effect to demonstrate up to a 38-fold enhancement in the emission rate of InAs QDs by coupling them to metal-clad GaAs nanopillars. These cavities, featuring a sub-wavelength mode volume of 4.5x10-4 (λ/n)3 and low quality factor of 62, enable Purcell-enhanced single-photon emission across a large bandwidth of 15 nm. The broadband nature of the cavity eliminates the need for implementing tuning mechanisms typically required to achieve QD-cavity resonance, thus relaxing fabrication constraints. Ultimately, this QD-cavity architecture represents a significant stride towards developing solid-state quantum emitters generating near-ideal single-photon states at GHz-level repetition rates.}},
  author       = {{Jöns, Klaus}},
  title        = {{{Purcell-enhanced single-photon emission from InAs/GaAs quantum dots coupled to broadband cylindrical nanocavities}}},
  year         = {{2024}},
}

@unpublished{42049,
  abstract     = {{Long-range quantum communication requires the development of in-out
light-matter interfaces to achieve a quantum advantage in entanglement
distribution. Ideally, these quantum interconnections should be as fast as
possible to achieve high-rate entangled qubits distribution. Here, we
demonstrate the coherent quanta exchange between single photons generated
on-demand from a GaAs quantum dot and atomic ensemble in a $^{87}$Rb vapor
quantum memory. Through an open quantum system analysis, we demonstrate the
mapping between the quantized electric field of photons and the coherence of
the atomic ensemble. Our results play a pivotal role in understanding quantum
light-matter interactions at the short time scales required to build fast
hybrid quantum networks.}},
  author       = {{Cui, Guo-Dong and Schweickert, Lucas and Jöns, Klaus D. and Namazi, Mehdi and Lettner, Thomas and Zeuner, Katharina D. and Montaña, Lara Scavuzzo and Silva, Saimon Filipe Covre da and Reindl, Marcus and Huang, Huiying and Trotta, Rinaldo and Rastelli, Armando and Zwiller, Val and Figueroa, Eden}},
  booktitle    = {{arXiv:2301.10326}},
  title        = {{{Coherent Quantum Interconnection between On-Demand Quantum Dot Single  Photons and a Resonant Atomic Quantum Memory}}},
  year         = {{2023}},
}

@article{61252,
  abstract     = {{<jats:title>Abstract</jats:title><jats:p>The biexciton‐exciton emission cascade commonly used in quantum‐dot systems to generate polarization entanglement yields photons with intrinsically limited indistinguishability. In the present work, it focuses on the generation of pairs of photons with high degrees of polarization entanglement and simultaneously high indistinguishability. It achieves this goal by selectively reducing the biexciton lifetime with an optical resonator. It demonstrates that a suitably tailored circular Bragg reflector fulfills the requirements of sufficient selective Purcell enhancement of biexciton emission paired with spectrally broad photon extraction and twofold degenerate optical modes. The in‐depth theoretical study combines (i) the optimization of realistic photonic structures solving Maxwell's equations from which model parameters are extracted as input for (ii) microscopic simulations of quantum‐dot cavity excitation dynamics with full access to photon properties. It reports non‐trivial dependencies on system parameters and use the predictive power of the combined theoretical approach to determine the optimal range of Purcell enhancement that maximizes indistinguishability and entanglement to near unity values, here specifically for the telecom C‐band at 1550 nm.</jats:p>}},
  author       = {{Bauch, David and Siebert, Dustin and Jöns, Klaus D. and Förstner, Jens and Schumacher, Stefan}},
  issn         = {{2511-9044}},
  journal      = {{Advanced Quantum Technologies}},
  number       = {{1}},
  publisher    = {{Wiley}},
  title        = {{{On‐Demand Indistinguishable and Entangled Photons Using Tailored Cavity Designs}}},
  doi          = {{10.1002/qute.202300142}},
  volume       = {{7}},
  year         = {{2023}},
}

@article{36471,
  abstract     = {{<jats:p>Superconducting nanowire single-photon detectors (SNSPDs) show near unity efficiency, low dark count rate, and short recovery time. Combining these characteristics with temporal control of SNSPDs broadens their applications as in active de-latching for higher dynamic range counting or temporal filtering for pump-probe spectroscopy or LiDAR. To that end, we demonstrate active gating of an SNSPD with a minimum off-to-on rise time of 2.4 ns and a total gate length of 5.0 ns. We show how the rise time depends on the inductance of the detector in combination with the control electronics. The gate window is demonstrated to be fully and freely, electrically tunable up to 500 ns at a repetition rate of 1.0 MHz, as well as ungated, free-running operation. Control electronics to generate the gating are mounted on the 2.3 K stage of a closed-cycle sorption cryostat, while the detector is operated on the cold stage at 0.8 K. We show that the efficiency and timing jitter of the detector is not altered during the on-time of the gating window. We exploit gated operation to demonstrate a method to increase in the photon counting dynamic range by a factor 11.2, as well as temporal filtering of a strong pump in an emulated pump-probe experiment.</jats:p>}},
  author       = {{Hummel, Thomas and Widhalm, Alex and Höpker, Jan Philipp and Jöns, Klaus and Chang, Jin and Fognini, Andreas and Steinhauer, Stephan and Zwiller, Val and Zrenner, Artur and Bartley, Tim}},
  issn         = {{1094-4087}},
  journal      = {{Optics Express}},
  keywords     = {{Atomic and Molecular Physics, and Optics}},
  number       = {{1}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Nanosecond gating of superconducting nanowire single-photon detectors using cryogenic bias circuitry}}},
  doi          = {{10.1364/oe.472058}},
  volume       = {{31}},
  year         = {{2023}},
}

@misc{40428,
  author       = {{Jonas, Björn and Heinze, Dirk Florian and Schöll, Eva and Kallert, Patricia and Langer, Timo and Krehs, Sebastian and Widhalm, Alex and Jöns, Klaus and Reuter, Dirk and Zrenner, Artur}},
  publisher    = {{LibreCat University}},
  title        = {{{Nonlinear down-conversion in a single quantum dot}}},
  doi          = {{10.5281/ZENODO.6024228}},
  year         = {{2022}},
}

@inproceedings{41800,
  author       = {{Sartison, M and  Camacho Ibarra, O and Jöns, Klaus D. and Caltzidis, I and Reuter, Dirk}},
  title        = {{{Scalable integration of quantum emitters into photonic integrated circuits}}},
  doi          = {{https://doi.org/10.1088/2633-4356/ac6f3e}},
  volume       = {{2}},
  year         = {{2022}},
}

@unpublished{42048,
  abstract     = {{Long range quantum communication and quantum information processing require
the development of light-matter interfaces for distributed quantum networks.
Even though photons are ideal candidates for network links to transfer quantum
information, the system of choice for the realization of quantum nodes has not
been identified yet. Ideally, one strives for a hybrid network architecture,
which will consist of different quantum systems, combining the strengths of
each system. However, interfacing different quantum systems via photonic
channels remains a major challenge because a detailed understanding of the
underlying light-matter interaction is missing. Here, we show the coherent
manipulation of single photons generated on-demand from a semiconductor quantum
dot using a rubidium vapor quantum memory, forming a hybrid quantum network. We
demonstrate the engineering of the photons' temporal wave function using
four-level atoms and the creation of a new type of electromagnetic induced
transparency for quantum dot photons on resonance with rubidium transitions.
Given the short lifetime of our quantum dot transition the observed dynamics
cannot be explained in the established steady-state picture. Our results play a
pivotal role in understanding quantum light-matter interactions at short time
scales. These findings demonstrate a fundamental active node to construct
future large-scale hybrid quantum networks.}},
  author       = {{Schweickert, Lucas and Jöns, Klaus D. and Namazi, Mehdi and Cui, Guodong and Lettner, Thomas and Zeuner, Katharina D. and Montaña, Lara Scavuzzo and Silva, Saimon Filipe Covre da and Reindl, Marcus and Huang, Huiying and Trotta, Rinaldo and Rastelli, Armando and Zwiller, Val and Figueroa, Eden}},
  booktitle    = {{arXiv:1808.05921}},
  title        = {{{Electromagnetically Induced Transparency of On-demand Single Photons in  a Hybrid Quantum Network}}},
  year         = {{2018}},
}