Ytterbium Ions Remain Stable for 30+ Seconds, Boosting Quantum Tech

Researchers at the UvA-Institute of Physics have discovered that ytterbium ions (Yb⁺) can remain in stable, “metastable” states for over 30 seconds, a duration previously unexplored. The team, led by Rene Gerritsma, achieved this by laser-exciting Yb⁺ ions held in an ion trap and carefully observing their decay into these long-lived states. This method utilized two Yb⁺ ions; one was excited into metastable states, while the other served as a visual indicator of the first ion’s stability. PhD student Zeger Ackerman, first author of the publication, explains: “To make the measurements possible, we did not just trap one single ion, but in fact we trapped two ions together.” These findings, recently published in Physical Review A, could significantly improve the detection of quantum bits in ytterbium ions and advance both quantum computing and atomic clock technologies. The 1-second lifetime state is particularly promising, as calculations suggest it may be reached from the ground state using a single laser pulse.

This finding addresses a decades-old question regarding the existence and duration of these states in ytterbium, a leading candidate material for both quantum computers and atomic clocks. This approach allowed precise measurement of the metastable state’s lifetime by recording when the initially “dark” ion began to fluoresce again. One ion was used for spectroscopy measurements, and the other to continuously cool and stabilize the system without disturbing the metastable state being studied. The team recorded decay signals revealing lifetimes of approximately one second, ten seconds, and evidence of a state exceeding 30 seconds. These results align closely with a 35-year-old theoretical prediction by Fawcett and Wilson, who estimated a 5.2-second lifetime for the same state; their calculations proved remarkably accurate given the complex energy level structure of Yb⁺.

The pursuit of stable, long-lived quantum states in trapped ions is currently a central focus for developers of both atomic clocks and quantum computing technologies; ions serve as ideal qubits due to their inherent charge, allowing for precise electromagnetic suspension and control of energy levels. The team, led by Rene Gerritsma and in collaboration with researchers from the University of New South Wales, published their findings in the journal Physical Review A, detailing the confirmation of Fawcett and Wilson’s work and opening avenues for improved qubit detection and manipulation within ytterbium-based quantum systems.