Key experiments in quantum science and technology with photons, ions and atoms (MVSem)

Topics

Below is a list of available topics for presentations in this seminar, each containing a description with central aspects to be covered. The relevant literature will be provided by the lecturers.

• Fr   9.5.2025 11:15   Laser Cooling and Trapping (*)
  Introduce the basis for ultracold neutral experiments. Discuss the basics of atom-field interactions, and the concepts of Zeeman slowing, optical molasses, and magneto-optical trapping, cooling limits (Doppler and sub-Doppler).
• Fr   9.5.2025 12:15   Atomic Fountain Clock
  Discuss the concept of quantum metrology, underlying hyperfine structure of atoms, coupling to fields, Rabi oscillation, Ramsey method, Bloch sphere representation, error budget and uncertainty, and highlight the role of the cooling.
• Fr   16.5.2025 11:15   Bell Test Measurements (*)
  Discuss the basics for quantum information. Introduce some of the concepts of quantum mechanics, e.g. measurement postulate, Heisenberg uncertainty principle, angular momentum, entanglement. Discuss the EPR paradox, the hidden variable theory, Bell inequality, and its experimental tests.
• Fr   16.5.2025 12:15   Quantum Teleportation and Quantum Key Distribution
  Discuss the use of Bell-test-type experiments for quantum information transfer, quantum communication protocols and their intrinsic advantages (no-cloning theorem), classical and quantum communication channels, and examples of realizations.
• Fr   23.5.2025 11:15   Precision mass determinations and test of matter/antimatter symmetry in ion traps
  Introduce the concept of Penning trap, cooling and detection methods of ions, and applications for fundamental physics: weighing atomic excitations, testing E=mc^2.
• Fr   23.5.2025 12:15   g-2: the electron magnetic moment 
  Introduce the g-factor and Feynman diagrams. Discuss continuous Stern Gerlach effect, spin anomaly, muon vs electron, cavity interactions and shifts, quantum cyclotron and Landau levels, fine-structure constant, physics beyond the standard model. 
• Fr   30.5.2025 11:15   Cavity Quantum Electrodynamics Experiments (*)
  Introduce the description of light in high finesse cavity, modification of the modes, and the light-matter-interaction. Discuss Jaynes-Cummings Hamiltonian, modified spontaneous emission, strong and weak coupling regimes, quantum Rabi oscillations, and the non destructive measurement of of photon states, as the key experiment.
• Fr   30.5.2025 12:15   Interacting photons: Photon Blockade
  Discuss one of the illustrative examples of cavity QED experiments: the photon blockade. Introduce light matter interaction of a single atom in an optical cavity, photon antibunching, and discuss the nonlinear effect introduced by the atom, leading to photon interactions. 
• Fr   6.6.2025 11:15   Bose-Einstein condensation of neutral atoms (*)
  Discuss experiments achieving BEC in dilute atomic gases. Introduce concept of magnetic and optical trapping of neutral atoms, evaporative cooling, absorption imaging, Bose-Einstein distribution, BEC phase transition, spontaneous symmetry breaking, phase coherence, and superfluidity. 
• Fr   6.6.2025 12:15   Superfluidity in lower dimensions
  Discuss the realization of atomic quantum gases in low-dimensional optical traps, suppression of long-range order, Mermin-Wagner theorem, topological BKT superfluidity in 2D, elementary excitations as vortices and phonons, along with a discussion of the key experiments.
• Fr   13.6.2025 11:15   Hybrid states of light and matter: Exciton-polaritons
  Introduce hybrid quantum states of light and matter in semiconductor-filled optical resonators. Discuss Bose-Einstein condensates of exciton-polaritons at cryogenic temperatures, the description by driven-dissipative Gross-Pitaevskii equations, and polariton superfluidity, along with the experimental observations.
• Fr   13.6.2025 12:15   Room-temperature Bose–Einstein condensation of photons
  Discuss the basics for trapping photons in optical microcavities, with modified mode structure, two-dimensional dispersion and photon thermalization with molecules. Discuss the concept of Bose-Einstein condensation of photons at room temperature in harmonic and box potentials, and grand canonical particle number fluctuations. 
• Fr   20.6.2025 11:15   Photonic Quantum Computing
  Discuss the basics of gate-based quantum computing and the concept of universal gates. Discuss historical (e.g. first implementation of a cNOT gate) and modern implementation with photons. Discuss challenges, e.g. quantum error corrections, single qubit operations with linear elements, KLM scheme, integration, and boson sampling. 
• Fr   20.6.2025 12:15   Quantum Computing with linear ion chains
  Rediscuss same concepts as for photonic quantum computing (gates) but implementation with ions. Cirac-Zoller scheme, linear ion crystals, experimental achievements and challenges.
• Fr   27.6.2025 11:15   Quantum simulation with ions in Penning traps
  Discuss 2D Coulomb crystals of ions, rotation locking, electromagnetically-induced-transparency cooling, optical detection of ions, quantum simulation of Ising models.
• Fr   27.6.2025 12:15   Atoms in optical lattices: Quantum gas microscopes
  Discuss optical lattices for atoms, applications for simulation of Bose- and Fermi-Hubbard models, their tunability (e.g., superfluid to Mott insulator transition), and the concept of imaging in quantum gas microscopes with single atom resolution.  
• Fr   4.7.2025 11:15   Optical Lattice Clocks
  Discuss the clock operation principle and the effort in pushing the limit of frequency precision with atoms. Introduce the electronic structures of complex atoms with ultranarrow transitions, magic wavelength for optical trapping, cooling techniques, error budget, and applications for precision measurements and quantum information processing. 
• Fr   4.7.2025 12:15   Quantum Logic Spectroscopy with ions
  Introduce the linear Paul trap, laser sideband cooling to the ground state, Coulomb crystals and motional modes, internal state readout, precision laser spectroscopy, from aluminum ion clock to highly charged ions, and search for new physics. 
• Fr   11.7.2025 11:15   Atoms in optical tweezer arrays
  Discuss the trapping of individual atoms in a optical dipole microtrap, known as an optical tweezer, their loading and cooling schemes and schemes to control their arrangement in 1D, 2D and 3D.
• Fr   11.7.2025 12:15   Quantum Simulation with Rydberg-atom arrays
  Discuss the generation of interactions between Rydberg atoms in arrays of optical tweezers, and the experimental achievements on simulation of quantum spin models (Ising, XY, ...) and topological models (SSH), as well as their prospects for computation.
• Fr   18.7.2025 11:15   Twisted light: Photonic topological insulators
  Introduce the concept of photonic waveguide arrays for topological states of light in helical waveguides. Introduce the concept of time-periodic Floquet-engineering to induce topological states and topological robustness; compare photon experiments to experiments realizing Haldane topological insulators in microwave systems.
• Fr   18.7.2025 12:15   Synthetic Landau levels for photons
  Introduce the integer quantum Hall effect, Landau levels and Laughlin states for photons, in analogy to electrons in strong magnetic fields. Discuss topological invariants (e.g. the Chern number), and experiments where synthetic magnetic fields for photon systems were successfully realized.