This edition contains carefully selected contributions by leading scientists in high-resolution laser spectroscopy, quantum optics and laser physics. Emphasis is given to ultrafast laser phenomena, implementations of frequency combs, precision spectroscopy and high resolution metrology. Furthermore, applications of the fundamentals of quantum mechanics are widely covered. This book is dedicated to Nobel prize winner Theodor W. Hänsch on the occasion of his 75th birthday. The contributions are reprinted from a topical collection published in Applied Physics B, 2016.
Selected contributions are available open access under a CC BY 4.0 license via link.springer.com. Please see the copyright page for further details.

Prof. Dr. Tilman Esslinger

Head of the Quantum Optics Group, ETH Zürich, Switzerland

Research area: Quantum gases, quantum simulation, quantum optics

Major scientific accomplishments: first experimental realization of a Fermi-Hubbard model and the Mott insulator using a fermionic quantum gas trapped in an optical lattice, measurement of the critical exponent of the correlation length in a Bose gas, first realization of a one-dimensional atomic quantum gas, cavity QED and cavity opto-mechanics with Bose- Einstein condensates, observation of the Dicke quantum phase transition, optical lattices with Dirac points, realization of the topological Haldane model, observation of quantized conductance in a Fermi gas.

Prof. Dr. Dieter Meschede

Head of Quantum Technology group at University Bonn, Germany

Editor-in-Chief of the journal Applied Physics B Lasers and Optics,

Research interests: Quantum technologies with single neutral atoms, few-atom quantum systems, discrete-time quantum walks, cavity QED, digital quantum simulators

Prof. Dr. Thomas Udem

Permanent research associate at the Laser spectroscopy division / Max Planck Institute of Quantum Optics / Garching and Institute of Physics Ludwig Maximilian University, Munich, Germany.

Research interests: Ultraprecise laser spectroscopy, Frequency combs in the extreme ultraviolet, High harmonic generation, Atomic physics with ion traps, Precision spectroscopy of single atoms, hydrogen and hoydrogen-like systems, Test of fundamental laws, Search for slowly varying constants, Frequency combs infrared and extreme ultraviolet, Ion traps, Intra-cavity high harmonic generation

From quantum transitions to electronic motions.- Nonadiabatic molecular alignment of linear molecules probed by photoelectron ionization yields.- Ultracold metastable helium: Ramsey fringes and atom interferometry.- Monolayer graphene as dissipative membrane in an optical resonator.- Cavity ring-up spectroscopy for dissipative and dispersive sensing in a whispering gallery mode resonator.- Quantum electrodynamics, high-resolution spectroscopy, and fundamental constants.- Yb fiber amplifier at 972.5 nm with frequency quadrupling to 243.1 nm.- Absorption spectroscopy of xenon and ethylene-noble gas mixtures at high pressure: Towards Bose-Einstein condensation of vacuum ultraviolet photons.- Ranging with frequency-shifted feedback lasers: from  $\mu$m-range accuracy to MHz-range measurement rate.- Laser phase spectroscopy in closed-loop multilevel schemes.- Sensitivity and resolution in frequency comb spectroscopy of buffer gas cooled polyatomic molecules.- Precision measurements and test of molecular theory in highly-excited vibrational states of H_2 _(v=11).- Quantum regime of a free-electron laser: relativistic approach.- Coherence in laser-driven electrons at and in solid matter.- Unexpectedly large difference of the electron density at the nucleus in the 4p 2P1/2,3/2 fine-structure doublet of Ca+.- A 10^15 watt laser for DT Fusion Experiments at Livermore.- New avenues for matter-wave enhanced spectroscopy.- Extraction of enhanced, ultrashort laser pulses from a passive 10-MHz stack-and-dump cavity.- Adjacency Graphs and Long-Range Interactions of Atoms in Quasi-Degenerate States: Applied Graph Theory.- External Cavity Diode Laser Setup with Two Interference Filters.- Phase-stable, multi-µJ femtosecond pulses from a repetition-rate tuneable Ti:Sa-oscillator-seeded Yb-fiber amplifier.- High-precision spectroscopy of the HD+ molecule at the 1-p.p.b. level.- Bose-Einstein condensates in an optical cavity with sub-recoil bandwidth.- Ultrafast optomechanical pulse picking.- Parity-nonconserving interaction induced light shifts in the 7S_{1/2} - 6D_{3/2} transition of the ultracold Fr-210 atoms to probe new physics beyond the standard model.- High-accuracy deep-UV Ramsey-comb spectroscopy in krypton.- Optical Autler-Townes spectroscopy in a heteronuclear mixture of laser-cooled atoms.- A compact echelle spectrograph for characterization of astro-combs.- Measuring and imaging nanomechanical motion with laser light.- Shifting the phase of a coherent beam with a Yb-174 ion: influence of the scattering cross section.- Orientational dependence of optically detected magnetic resonance signals in laser-driven atomic magnetometers.- ^nd many-body QED tests.- Index.