Project Areas

P – Primitives

P4 – Quantum Key Hubs

The security of Quantum Key Distribution (QKD) is based on laws of nature. The overall goal of this project is to develop a photon-based QKD structure in a star like topology and to comprehensively explore its fundamental quantum features. The individual goals are to implement wavelength-division multiplexing in a QKD structure including a field test in a real telecom network, to determine the multipartite statistical correlations of the realized QKD structure, and to investigate the scalability of the QKD structure beyond four parties.

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Principal Investigators

  Name Working area(s) Contact
Prof. Gernot Alber
Theoretical Quantum Physics
P4, S4
+49 6151 16-20400
Prof. Thomas Walther
Laser and Quantum Optics
+49 6151 16-20830
S2|15 113


  Name Contact
Erik Fitzke
Laser and Quantum Optics
+49 6151 16-20915
S2|15 108
Thorsten Haase
Theoretical Quantum Physics
+49 6151 16-20408
S2|09 100
Jakob Kaltwasser
Laser and Quantum Optics
+49 6151 16-20913
S2|15 117
Alexander Sauer
Theoretical Quantum Physics
+49 6151 16-20408
S2|09 100
Maximilian Tippmann
Laser and Quantum Optics
S2/15 110


Haase, Thorsten ; Alber, Gernot ; Stojanovic, Vladimir M. (2021):
Conversion from W to Greenberger-Horne-Zeilinger states in the Rydberg-blockade regime of neutral-atom systems.
In: Physical Review A, 103 (3), APS Physics, ISSN 2469-9926,
DOI: 10.1103/PhysRevA.103.032427,

Stojanovic, Vladimir M. (2021):
Scalable W-type entanglement resource in neutral-atom arrays with Rydberg-dressed resonant dipole-dipole interaction.
In: Physical Review A, 103 (2), APS Physics, ISSN 2469-9926,
DOI: 10.1103/PhysRevA.103.022410,

Stojanovic, Vladimir M. (2020):
Bare-Excitation Ground State of a Spinless-Fermion–Boson Model and W-State Engineering in an Array of Superconducting Qubits and Resonators.
In: Physical Review Letters, 124 (19), p. 190504. ISSN 0031-9007,
DOI: 10.1103/PhysRevLett.124.190504,

Stojanovic, Vladimir M. (2020):
Entanglement-spectrum characterization of ground-state nonanalyticities in coupled excitation-phonon models.
In: Physical Review B, 101 (13), American Physical Society, ISSN 2469-9950,
DOI: 10.1103/PhysRevB.101.134301,

Stonner, David Jakob ; Kysela, Jaroslav ; Weir, Graeme ; Novotny, Jaroslav ; Alber, Gernot ; Jex, Igor (2020):
Deterministic twirling with low resources.
In: Physics letters A, 384 (8), Elsevier, ISSN 0375-9601,
DOI: 10.1016/j.physleta.2019.126179,

Sauer, Alexander ; Alber, Gernot (2020):
Quantum Bounds on Detector Efficiencies for Violating Bell Inequalities Using Semidefinite Programming.
4, In: Cryptography, 2020 (1), MDPI, DOI: 10.3390/cryptography4010002,

Fladung, Lukas ; Nikolopoulos, Georgios M. ; Alber, Gernot ; Fischlin, Marc (2019):
Intercept-Resend Emulation Attacks against a Continuous-Variable Quantum Authentication Protocol with Physical Unclonable Keys.
In: Cryptography, 3 (4), MDPI, DOI: 10.3390/cryptography3040025,

Stonner, David Jakob (2019):
Construction of Random Unitary Operations for Asymptotic Preparation of Werner States.
Darmstadt, Technische Universität Darmstadt, [Bachelor Thesis]

Nikolopoulos, Georgios M. (2019):
Cryptographic one-way function based on boson sampling.
18, In: Quantum Information Processing, 2019 (8), p. 259. Springer Nature, ISSN 1570-0755, e-ISSN 1573-1332,
DOI: 10.1007/s11128-019-2372-9,

Zucker, René (2019):
Erstellung eines Python-Interfaces für die Erforschung von Polytopen in der Quanteninformationstheorie.
Darmstadt, TU Darmstadt, Fachbereich Informatik, [Bachelor Thesis]

Geihs, Matthias ; Nikiforov, Oleg ; Demirel, Denise ; Sauer, Alexander ; Butin, Denis ; Günther, Felix ; Alber, Gernot ; Walther, Thomas ; Buchmann, Johannes (2019):
The Status of Quantum-Based Long-Term Secure Communication over the Internet.
In: IEEE Transactions on Sustainable Computing, IEEE, ISSN 2377-3782,
DOI: htps://,

Roth, Kai (2019):
Entwicklung eines Schlüsselverwaltungssystems zum Quantenschlüsselaustausch.
Darmstadt, TU Darmstadt, [Master Thesis]

Maier, Christine ; Brydges, Tiff ; Jurcevic, Petar ; Trautmann, Nils ; Hempel, Cornelius ; Lanyon, Ben P. ; Hauke, Philipp ; Blatt, Rainer ; Roos, Christian F. (2019):
Environment-Assisted Quantum Transport in a 10-qubit Network.
In: PHYSICAL REVIEW LETTERS, 122 (5), pp. 050501. American Physical Society, DOI: 10.1103/PhysRevLett.122.050501,

Wegert, Leonard (2019):
Preparations for Assembling Franson Interferometers in a Quantum Key Distributuion Setup.
TU Darmstadt, [Bachelor Thesis]

McCracken, Gabriel (2018):
A Field Theory for Quantum Markov Processes.
TU Darmstadt, [Bachelor Thesis]

Marakis, Vassilios (2018):
Anwendung der semiklassischen Näherung auf Probleme des Zentralkraftfeldes und der Quantendefekttheorie.
TU Darmstadt, [Master Thesis]

Humbert, Marcel Nikolas (2018):
Einführung in die Störungstheorie der Allgemeinen Relativitätstheorie.
TU Darmstadt, [Bachelor Thesis]

Baack, Leon (2018):
Optimisation of parts of a set-up for quantum key distribution.
TU Darmstadt, [Bachelor Thesis]

Gajewski, Marvin (2018):
Asymptotische Eigenschaften offener quantenoptischer Systeme.
TU Darmstadt, [Bachelor Thesis]

Wolf, Yannic (2018):
Eine Faserverstärkerstufe für den Quantenhub.
TU Darmstadt, [Bachelor Thesis]

Brandy, Malte (2018):
Asymptotische Eigenschaften iterierter Quantenoperationen.
TU Darmstadt, [Master Thesis]

Hofmann, Daniel (2018):
Charakterisierung von verschränkten Photonenpaaren.
TU Darmstadt, [Master Thesis]

Trautmann, Nils ; Hauke, Philipp (2018):
Trapped-ion quantum simulation of excitation transport: Disordered, noisy, and long-range connected quantum networks.
In: PHYSICAL REVIEW A, 97, pp. 023606. [Article]

Nikiforov, Oleg ; Sauer, Alexander ; Schickel, Johannes ; Weber, Alexandra ; Alber, Gernot ; Mantel, Heiko ; Walther, Thomas (2018):
Side-Channel Analysis of Privacy Amplification in Postprocessing Software for a Quantum Key Distribution System.

Deller, Yannick (2017):
Zweidimensionale Surface-Kodes und ihre Anwendungen.
TU Darmstadt, [Bachelor Thesis]

Fladung, Lukas (2017):
Semiclassical Laser Cooling of Trapped Ions in a One-Dimensional Standing Wave.
TU Darmstadt, [Bachelor Thesis]

Neumann, Klara Maria (2017):
Aufbau von Empfängerstationen für ein System zum Quantenschlüsselaustausch.
TU Darmstadt, [Bachelor Thesis]

Schürl, Stefan (2017):
Entwicklung eines FPGA-Systems zur hochauflösenden Zeitmessung.
TU Darmstadt, [Master Thesis]

Nauth, Julian (2017):
Charakterisierung von Bellschen Ungleichungen bei nicht-perfekter Detektion.
TU Darmstadt, [Bachelor Thesis]

Langfeld, Benedikt (2017):
Vorbereitende Arbeiten zum Feldtest eines Systems zum Quantenschlüsselaustausch.
Darmstadt, Technische Universität, [Bachelor Thesis]

Trautmann, Nils ; Ferenczi, Gergely ; Croke, Sarah ; Barnett, Stephen (2017):
Holographic quantum imaging: reconstructing spatial properties via two-particle interference.
In: Journal of Optics, 19 (5), IOP Publishing, [Article]

Trautmann, Nils ; Sonnleitner, Matthias ; Barnett, Stephen (2017):
Will a Decaying Atom Feel a Friction Force?
In: Physical Review Letters, [Article]

Trautmann, Nils ; Alber, Gernot ; Leuchs, Gerd (2016):
Efficient single-photon absorption by a trapped moving atom.
In: Physical Review A, p. 8. American Physical Society, [Article]

Alber, Gernot ; Trautmann, Nils (2016):
Cooperative quantum electrodynamical processes in an ellipsoidal cavity.
In: Journal of Physics: Conference Series, [Article]

Trautmann, Nils ; Hauke, Philipp (2016):
Quantum simulation of the dynamical Casimir effect with trapped ions.
In: New Journal of Physics, (18), pp. 043029. [Article]

Trautmann, Nils ; Alber, Gernot (2016):
Dissipation-enabled efficient excitation transfer from a single photon to a single quantum emitter.
In: Physical Review A, p. 9. DOI: 10.1103/PhysRevA.93.053807,

Frydrych, Holger ; Marthaler, Michael ; Alber, Gernot (2015):
Pulse-controlled quantum gate sequences on a strongly coupled qubit chain.
In: Phys. Rev. A, American Physical Society, (92), p. 10. [Article]

Novotny, Jaroslav ; Alber, Gernot ; Jex, Igor (2015):
Universality in random quantum networks.
In: Physical Review A, 92 (062335), DOI: 10.1103/PhysRevA.92.062335,

Frydrych, H. ; Hoskovec, A. ; Jex, I. ; Alber, G. (2015):
Selective dynamical decoupling for quantum state transfer.
In: Journal of Physics B: Atomic, Molecular and Optical Physics, 48 (2), pp. 025501. [Article]

Trautmann, N. ; Alber, G. ; Agarwal, G. S. ; Leuchs, G. (2015):
Time-Reversal-Symmetric Single-Photon Wave Packets for Free-Space Quantum Communication.
In: PHYSICAL REVIEW LETTERS, 114 (17), [Article]

Trautmann, N. ; Bernad, J. Z. ; Sondermann, M. ; Alber, G. ; Sanchez-Soto, L. L. ; Leuchs, G. (2014):
Generation of entangled matter qubits in two opposing parabolic mirrors.
In: PHYSICAL REVIEW A 90, pp. 063814. [Article]