Scientists have successfully prepared and cooled radioactive radium molecules for precise laser-based experiments, creating a new tool to study one of the biggest unanswered questions in physics.
The achievement allows researchers to examine tiny energy changes that may reveal new particles and forces beyond current scientific understanding. The work also establishes a practical method for preparing other complex molecules for advanced quantum measurements.
Researchers led by Professor Nick Hutzler at the California Institute of Technology (Caltech) developed the new technique after several years of experimentation.
Their findings, published in the journal Science, mark the first successful preparation of cold radium-containing molecules for tabletop quantum experiments. The study represents an important step toward using these rare molecules to investigate why matter dominates the universe.
Matter Antimatter Mystery Explained
Scientists believe that matter and antimatter formed in equal amounts shortly after the universe began. Every particle of matter has an antimatter partner with the same mass but opposite electrical charge. When matter and antimatter meet, they destroy each other and release energy.
This raises one of the biggest questions in modern physics. If both forms were created equally, scientists want to know why almost all antimatter disappeared while matter remained. The answer may lie in tiny differences between the two that existing theories have not yet explained.
Researchers search for these hidden differences using several methods. Large particle accelerators investigate high-energy collisions, while another smaller group uses extremely sensitive laboratory experiments. The Caltech team belongs to the second group, using specially designed molecules as highly accurate measuring tools.
Professor Hutzler explained that the molecules act like antennas, amplifying extremely small physical effects. If unknown particles or forces exist, they may slightly change the energy levels inside these molecules. Detecting such tiny changes would provide evidence of physics beyond current theories.
READ ALSO: China’s Upgraded Y-9 Anti-Submarine Aircraft Enters Operational Training Phase
Radioactive Radium Offers Unique Advantage
The research focuses on molecules containing radium because the element has an unusual atomic nucleus. Unlike most atomic nuclei, which are nearly round like an orange or stretched like an American football, radium’s nucleus has a pear-like shape. This rare structure makes the atom especially sensitive to the effects scientists hope to detect.
Hutzler said pear-shaped nuclei greatly amplify the signals researchers are searching for to explain the matter-antimatter imbalance.
He added that radium has already been studied extensively by nuclear physicists and also forms molecules that respond well to laser-based measurements. These characteristics make it an excellent candidate for precision quantum research.
Working with radium, however, presents significant technical challenges. The element, discovered by Marie Curie in 1898, is radioactive, chemically reactive, and available only in extremely small amounts. These factors make handling and studying it far more difficult than many other elements.
The new study is the first to prepare radium molecules in a cold state suitable for detailed laser analysis. Cooling the molecules is essential because slower-moving molecules are easier to measure with high precision. The researchers also demonstrated that the same preparation method may be adapted for molecules containing other heavy elements.
Complex Laboratory Preparation
The research team included scientists from Johns Hopkins University and Michigan State University. Because radium is radioactive, the researchers worked only with microscopic quantities under carefully controlled laboratory conditions. Developing a safe and reliable preparation method required years of repeated testing.
The first challenge involved stabilizing the radium before using it in experiments. Researchers wanted to embed the material inside a thick substance that would hold it securely and allow safe handling. Finding the right material became an unexpected part of the project.
The solution came from a process resembling candy making. Scientists mixed radium with water and a sweet-tasting material, then evaporated the water to create a thick, protective substance. After several unsuccessful attempts with ordinary sugar, they discovered that the sugar-free sweetener xylitol produced more reliable results.
The prepared material was placed on a thin gold foil before being installed inside a laboratory chamber about the size of a small refrigerator. Helium gas cooled the chamber to nearly minus 450 degrees Fahrenheit. The extremely low temperature prepared the molecules for detailed quantum measurements.
Researchers then used lasers to excite the radium atoms into a chemically active state. This allowed the atoms to combine with target molecules and form the desired radium-containing compounds. Another set of lasers measured the properties of the newly created molecules with high accuracy.
READ ALSO: US Navy Awards Ursa Major $10M to Advance MK 104 Solid Rocket Motor Development
Hutzler said the molecules are now ready for quantum precision measurements. According to him, the team spent years developing a complete process for handling the radium, creating the molecules, detecting them, and measuring their properties. The successful preparation now opens the door to more advanced scientific studies.
Future Quantum Research Ahead
The work forms part of a growing field known as quantum precision measurement. Instead of smashing particles together, researchers use carefully controlled atoms and molecules to search for tiny effects that existing theories cannot explain. These experiments require exceptional accuracy because the signals being measured are extremely small.
In a separate study that will appear in Physical Review X, Hutzler and his colleagues developed another technique using molecules containing the heavy element ytterbium. The approach introduces what the researchers call engineered molecular clocks. These systems improve measurement accuracy by reducing interference from environmental noise.
External disturbances often disrupt delicate quantum experiments through a process known as decoherence. This process causes molecules to lose the special quantum behavior needed for accurate measurements. The new preparation method makes the molecules far less sensitive to these unwanted effects.
The engineered molecular clock system is already being used to search for evidence of unknown particles and forces inside the ytterbium nucleus. Researchers plan to apply the same measurement strategy to radium molecules in future experiments. Combining improved molecular preparation with advanced measurement techniques is expected to strengthen the search for new physics.
Hutzler said the team’s goal is to build the best possible quantum tools from these complex molecules. He explained that the researchers are engineering molecules to achieve precise quantum control for future studies.
As these methods continue to improve, they are expected to expand scientists’ ability to investigate the fundamental laws governing matter, antimatter, and the evolution of the universe.
