All articles tagged with #atomic physics
Photons passing through a rubidium atomic cloud can appear to spend a negative amount of time inside the cloud when inferred from their arrival times. By performing ultra-weak measurements of the atoms, researchers found the dwell time measured in the atoms matches this negative value, showing negative time is a real, measurable quantum effect that fits standard physics and is not just an artifact.
Physicists report that photons passing through a cloud of atoms can appear to exit before entering, i.e., negative transit time. In a Physical Review Letters study, the researchers monitored the atoms’ excited state during the photon’s passage with a second readout beam and used weak measurements, requiring about 1 million trials across seven parameter sets to obtain a clear signal. The result, which aligns with standard quantum mechanics, shows transmitted photons can have negative time while scattered photons carry positive time, keeping the beam’s average time nonnegative. The next step is to test time effects for photons that don’t pass through the cloud.
Physicists are using ultra-precise atomic spectroscopy of calcium isotopes to search for a potential fifth fundamental force that could explain dark matter, setting new constraints on its properties, though no definitive discovery has been made yet.
Physicists at the University of Regensburg have observed the shift of a quantized electronic energy level with atomic oscillations faster than a trillionth of a second, using an ultrafast microscope to directly control and observe the process. This breakthrough discovery could be crucial for the development of super-fast quantum technologies, as it enables the local control of discrete energy levels in the most direct way, potentially leading to new functionalities in materials and the unraveling of key processes behind phase transitions like high-temperature superconductivity.