Imagine a world where timekeeping is so precise, it could revolutionize how we navigate and communicate, and where computers solve complex problems in the blink of an eye. This isn’t science fiction—it’s the potential of strontium, a lesser-known element that’s quietly becoming a star in the world of physics. But here’s where it gets fascinating: a team of physicists from Amsterdam has just unlocked a new level of precision in measuring strontium atoms, and they did it with a little help from their atomic neighbor, rubidium. Their findings, published this week in Physical Review Letters, could reshape the future of atomic clocks and quantum computing.
Strontium might not be a household name, but in the scientific community, it’s a hero. As one of the six alkaline earth metals, it shares traits with more familiar elements like magnesium and calcium. What makes strontium special, though, is its isotopes—particularly the one with 87 particles in its nucleus. This isotope, known as 87Sr, has an odd number of neutrons, turning its nucleus into a fermion, a type of particle with unique properties. And this is the part most people miss: this oddity gives 87Sr a nonzero nuclear spin, essentially turning it into a tiny bar magnet. This magnetism is the key to its potential in cutting-edge technologies.
But why does this matter? For starters, 87Sr is a prime candidate for the next generation of atomic clocks, known as optical clocks. These clocks rely on the precise frequencies of light that atoms emit or absorb when transitioning between energy states. In strontium, this transition corresponds to a clear, red light with a wavelength of 698 nanometers. However, the bosonic isotopes of strontium (those with even-numbered particles) can’t make this transition due to their zero spin. Enter 87Sr, whose nonzero spin allows it to ‘break the rules’ just enough to enable this critical transition, all while maintaining a stable frequency. This makes it ideal for ultra-precise timekeeping.
But here’s where it gets controversial: while 87Sr’s properties are undeniably powerful, the challenge lies in measuring them with absolute precision. This is where rubidium comes in. By co-trapping rubidium atoms alongside 87Sr using optical trapping, the Amsterdam team was able to calibrate the magnetic field with unprecedented accuracy. Rubidium’s well-established properties served as a reliable benchmark, allowing the researchers to determine the g-factor of 87Sr—a measure of its magnetic moment—with a hundredfold improvement over previous measurements. This breakthrough not only enhances the potential of strontium-based atomic clocks but also opens new doors for quantum computing.
Quantum computers, unlike classical ones, use qubits that can exist in multiple states simultaneously, making them exponentially more powerful for certain tasks. But 87Sr takes this a step further. When exposed to a magnetic field, its energy levels split into ten equally spaced states, enabling the use of qudits—a more versatile version of qubits that can exist in combinations of up to ten states. This could make quantum computers even more powerful and adaptable.
The Zeeman effect, discovered by Dutch Nobel laureate Pieter Zeeman in 1896, plays a central role in all of this. It describes how a magnetic field splits the energy levels of atoms or nuclei, and in 87Sr, this effect is particularly pronounced. By precisely measuring the g-factor, physicists can better understand and control this splitting, paving the way for more accurate atomic clocks and more robust quantum computers.
Lead researcher Premjith Thekkeppatt explains, ‘Our work grew out of an attempt to create rubidium-strontium molecules, which proved incredibly challenging. Instead, we discovered that simply having these atoms in close proximity allowed us to achieve remarkable precision in measuring 87Sr’s properties.’ This serendipitous finding not only sets a new benchmark for atomic structure calculations but also inspires further exploration into other atomic species and their applications.
But here’s the question that lingers: as we push the boundaries of precision in measuring elements like strontium, are we fully prepared for the ethical and practical implications of such advancements? Could ultra-precise atomic clocks or quantum computers disrupt industries, privacy, or even global power dynamics? The science is clear, but the societal impact remains a topic of debate. What do you think? Share your thoughts in the comments below.
More information: Premjith Thekkeppatt et al, Measurement of the g Factor of Ground-State 87Sr at the Parts-per-Million Level Using Co-Trapped Ultracold Atoms, Physical Review Letters (2025). DOI: 10.1103/cjks-9hlp. On arXiv (2025): DOI: 10.48550/arxiv.2504.11242.
