Development of a carrier-envelope phase stabilized, few-cycle laser system for precision spectroscopy in the time domain

Summary form only given. While the method of attosecond physics enables us to understand the fast motion of atoms, molecules, and electrons [1-4], it was not clear whether the method can contribute to fundamental physics such as quantum electrodynamics (QED), quantum chromodynamics (QCD), and physics beyond the standard model. The ultimate objective of the present study is to demonstrate that the method of attosecond physic is crucial for fundamental physics and to show one direction for attosecond physics to take.fundamental physics and to show one direction for attosecond physics to take. The concrete final goal is to measure the lifetimes of unstable particles (states) with ~100 attosecond precision by using a pair of isolated attosecond pulses (IAP) with stabilized intensity. As target unstable particles, we are investigating positroniums, excited states of multi-charged heavy ions, antiprotonic helium, etc., and the point is that these lifetimes has been measured only with ~100 ps precision by the beam foil method or by tracking the decay mode electrically and e.g., if the time resolution for the para-positronium lifetime (~123 ps) is improved up to attosecond region (Fig. (1)), the method becomes promising candidate for the test of QED which is equivalent to the measurement of electron g-factor. In this paper, we report on our novel methodology of attosecond physics and the present status of our laser and spectroscopy system, which was specially designed for this purpose from scratch. Major necessary conditions were found to be stabilized carrier-envelope phase (CEP), tunability of laser wavelength, stabilized and extremely high laser intensity. To satisfy all of them, we designed an optically synchronized hybrid laser system composed of a CEP stabilized [6] commercial Ti:S laser (Femtopower X (Femtolasers GmbH), pulse duration ~ 25 fs, center wavelength ~ 795 nm, pulse energy ~ 10 mJ, repetition rate ~1 kHz), a homemade density gradient hollow fiber (DGHF) s- stem [7-9], a homemade optical parametric amplification (OPA) laser with wavelength tunability, and a homemade phase matched high harmonic generation system. Here, it is significant that stabilization of CEP is crucial just like in the case of precision spectroscopy in the frequency domain. Figure (2) shows a typical spectra generated in our DGHF system within the system (Ne gas 2.5 atm, core diameter ~ 250 Pm, core length ~1.0 m). In the talk, we will discuss the details of our system, methodology, and possible physical constant that can be determined.