The PSI Laboratory for Advanced Spectroscopy and X-ray Sources develops X-ray sources and advanced spectroscopic techniques and applies them to study a broad range of complex material systems.
Lab News & Scientific Highlights
The role of dimensionality, symmetry, and correlation in quantum time scales
Time, though ubiquitous in our daily experience, is a physical quantity not very well understood. It lies at the crux of efforts to unify the physical paradigms, being regarded as a constant background in some paradigms such as Newtonian mechanics or quantum mechanics, while completely internal to the objects in other paradigms such as general relativity. In quantum mechanics, specifically, the inability to find an operator for time as for spatial positions indicates the impossibility to find an observable which represents the external time coordinate. Nevertheless, an operator can often be found to represent the internal time duration of some certain process. The Eisenbud-Wigner-Smith (EWS) time scale is a famous example of such a time duration operator, which describes the single-particle scattering or ionization time scale.
Measuring time at the quantum level
Physicists using the Swiss Light Source SLS have found a way to measure the time involved in quantum events and found it depends on the symmetry of the material.
Chiral phonons in polar LiNbO3
Resonant inelastic x-ray scattering reveals that lattice vibrations can be chiral in a polar material, with phonons having opposite handedness depending on their direction in momentum space.