A lot of physicists have developed atomic clocks in recent years, which are timekeeping devices based on the quantum states of atoms. Numerous beneficial uses for these clocks include the creation of satellite and navigational systems.
Recently, several researchers have also looked into the potential creation of molecular clocks—atomic clock-like devices based on straightforward molecules. An extremely precise molecular clock was recently developed by a team from Columbia University and the University of Warsaw, and it can be used to examine novel physical phenomena.
“Our recent paper is the result of a multi-year effort to create what is called a molecular clock,” Tanya Zelevinsky, one of the researchers who carried out the study, told Phys.org. “It was inspired by the rapid progress in the precision of atomic clocks, and the realization that molecular clocks rely on a different ‘ticking’ mechanism and thus could be sensitive to complementary phenomena. One of these is the idea that the fundamental constants of nature might change very slightly over time. The other is the possibility that gravity between very small objects may be different from what we experience at larger scales.”
The diatomic molecule Sr2, which structurally resembles two tiny spheres joined by a spring, served as the basis for the molecular clock developed by Zelevinsky and her coworkers. In order to keep track of time, the clock precisely uses the vibrational modes of this molecule as a precise frequency reference.
“Our clock requires the use of lasers to cool atoms near absolute zero and hold them in optical traps, induce them to combine into molecules, and shine highly precise ‘clock’ lasers at them to actually make a measurement,” Zelevinsky explained. “Some of the advantages of the molecular clock include its very low sensitivity to stray magnetic or electric fields, and the very long natural lifetimes of the vibrational modes.”
Zelevinsky and her colleagues tested their molecular clock’s accuracy through a number of experiments in their work, which was published in Physical Review X, evaluating its so-called systematic uncertainty. They discovered that their suggested design considerably reduced the sources of mistakes, and their clock displayed a remarkably high level of precision, achieving a total systematic uncertainty of 4.6 1014.
“Our recent work sets the benchmark for the precision of molecular spectroscopy, with the observed measure of the peak sharpness—or its quality factor—of 3 trillion,” Zelevinsky said. “It also illuminates the effects that limit this precision, in particular, the eventual loss of molecules via scattering of the light in which they are trapped. This inspires us to search for improvements in the optical trapping strategy.”
This group of researchers developed a vibrational molecular clock that has the ability to set standards for terahertz frequency applications and provide guidance for the development of new molecular spectroscopy instruments. Other isotopic variants (with varying mass) could be used in place of the Sr2 molecules in order to change the design, which could help with current efforts to discover novel physical interactions.
“In the future, we hope to apply the molecular clock to understand molecular structure at the highest precision and to study any possible signatures of non-Newtonian gravity at nanometer size scales,” Zelevinsky added.
