Ultra-fast meets ultra-precise
Prof. Dr. K.S.E. Eikema (Rijksuniversiteit Groningen - KVI)

Since the invention of frequency comb lasers, now slightly over 10 years ago, these devices have made a profound impact in many fields of physics. For this reason Ted Hänsch and John Hall received the Noble Prize 2005 in Physics in part for this invention. Comb lasers are typically (but not exclusively) based on mode-locked lasers, which produce a repetitive train of ultrafast pulses. With these devices it has become possible to control the electromagnetic wave of optical pulses, and to perform extremely precise frequency measurements over a wide range of the electromagnetic spectrum. This has resulted in the emergence of attosecond science, and it makes atomic clocks and tests of the basic laws of physics possible with unprecedented precision. In the talk I will give an overview of these fascinating possibilities with frequency combs, and discuss comb generation in the extreme ultraviolet (and possibly X-rays). This is illustrated with an experiment performed in Amsterdam where comb generation at 51 nm is used to test QED theory in helium atoms.