Long-Lived Quantum States in Ytterbium Ions: Amsterdam Researchers Revisit a 35-Year-Old Prediction

In 2026, researchers associated with the University of Amsterdam and the University of New South Wales reported experimental measurements of long-lived metastable states in singly ionized ytterbium, written as Yb⁺. Their findings helped resolve a question that theoretical physicists had raised approximately 35 years earlier.

The team measured decay signals corresponding to lifetimes of approximately 0.92 seconds and 9.8 seconds. They also found evidence for a state lasting longer than 30 seconds. The results were published in Physical Review A on June 17, 2026.

These timescales are significant because the researchers were investigating individual trapped ions, not large objects that can be observed directly with the naked eye. At the atomic scale, a state's lifetime can determine how researchers store, manipulate, and measure quantum information.

The experiment does not demonstrate a finished quantum computer or a new kind of clock. Instead, it characterizes unusual atomic states that could become useful components of future quantum technologies.

This laboratory report examines what the researchers measured, how they performed the experiment, why one result revisits an old theoretical prediction, and what the findings could mean for the future of quantum computing.

Atoms and ions cannot possess arbitrary amounts of internal energy. Their electrons occupy allowed quantum states, each associated with particular energy values.

When an electron system absorbs energy, it can transition into an excited state. Eventually, the system may release energy and return to a lower-energy state.

Many excited states decay quickly. Others are metastable.

A metastable state is an excited state that persists for a comparatively long time because the available transitions to lower-energy states are relatively unlikely or restricted by quantum-mechanical selection rules.

Metastability does not mean that a state is permanent. It means that the state can survive much longer than a typical excited state under the relevant conditions.

This distinction is important in quantum technology.

A quantum system must be prepared in a known state, manipulated, and measured. If a useful state disappears before the measurement can be completed, the system becomes more difficult to control or read out reliably.

Long-lived states may provide additional time for certain operations. However, a long lifetime alone does not guarantee that a state is suitable for quantum computing. Researchers must also understand how it can be prepared, controlled, measured, and protected from environmental disturbances.

Ytterbium is a chemical element whose ions have an intricate electronic structure. Singly ionized ytterbium, Yb⁺, has already become an important system for atomic physics experiments, including research relevant to trapped-ion quantum computing and precision timekeeping.

An ion is an atom with a net electric charge. Because of that charge, scientists can confine it using electromagnetic fields.

Once an ion is trapped, carefully selected laser beams can excite it between particular energy states. Researchers can then measure how the ion behaves over time.

Ytterbium presents a particularly interesting challenge because its electronic energy levels are complex. That complexity creates opportunities to investigate states that are difficult to access or characterize, but it also makes precise measurements and theoretical calculations more demanding.

In the 2026 study, the researchers investigated states associated with the 4f¹³5d6s electronic configuration of Yb⁺.

Their objective was not simply to excite the ion. They wanted to determine whether particular states existed with unusually long lifetimes and measure how long those states persisted before decaying.

The study built on earlier theoretical work that predicted a long lifetime for one of these states.

The researchers used a single ytterbium ion as the principal spectroscopy system and a second, co-trapped ion to help stabilize the experiment.

The procedure began by optically pumping the ytterbium ion using laser light at a wavelength of 377.5 nanometers. This prepared the ion in an excited electronic configuration from which the researchers could investigate a range of metastable states.

The second ion served a different purpose: it helped cool the system through a process known as sympathetic cooling.

In sympathetic cooling, one ion is actively cooled, and its interaction with another trapped ion helps reduce the latter's motion. This approach can be useful when directly cooling the ion of interest would interfere with the state being studied.

The team then monitored the spectroscopy ion's subsequent behavior to measure the time associated with its decay.

A key part of the method involved observing the fluorescence of the trapped ions. When the spectroscopy ion occupied certain metastable states, the observed fluorescence pattern changed. By recording when the signal associated with the dark state ended and fluorescence returned, the researchers could infer how long the state had persisted.

This was not a direct photograph of an electron remaining in one location. It was a time-resolved measurement of an atomic state using the ion's observable behavior.

The researchers also compared their experimental observations with atomic-structure calculations. These calculations helped them identify the likely states associated with the measured lifetimes and assess whether the observed decay pathways were consistent with the underlying atomic physics.

The combination of laser preparation, ion trapping, sympathetic cooling, fluorescence detection, and theoretical modeling made it possible to investigate states that had previously been difficult to characterize experimentally.

The central findings were three different lifetime signals.

State one: Approximately 0.92 seconds

The researchers recorded a strong decay signal corresponding to a lifetime of 0.92 ± 0.08 seconds.

For an atomic excited state, a lifetime approaching one second can be useful when considering applications that depend on preparing and detecting specific quantum states.

The team was particularly interested in this state because calculations suggested that it could potentially be reached from the ground state relatively easily, using a single laser pulse.

That combination — a measurable lifetime and a potentially accessible preparation pathway — makes it a promising candidate for further investigation in quantum-state detection.

State two: Approximately 9.8 seconds

The experiment also revealed a weaker decay signal corresponding to a lifetime of approximately 9.8 seconds.

The reported uncertainty was asymmetric: +2.9 seconds and −2.0 seconds.

This longer timescale adds to the evidence that the investigated ytterbium configuration contains multiple states with very different decay behaviors.

The weaker signal also illustrates an important experimental challenge: identifying and measuring states that do not produce equally strong observable signals.

State three: Longer than 30 seconds

The team found evidence for an additional state with a lifetime exceeding 30 seconds.

This result should be interpreted carefully. The researchers reported evidence for a lifetime greater than 30 seconds, rather than an exact, fully determined lifetime of a particular number of seconds.

Nevertheless, the finding points to a state that can persist for a remarkably long time under the experimental conditions.

Together, the measurements demonstrate that the investigated electronic configuration supports a range of metastable states with substantially different lifetimes.

They do not establish that all three states have identical properties or that each one will be useful in a quantum computer.

One of the most interesting aspects of the study is its connection to earlier theoretical work.

In 1991, physicists B. Fawcett and M. Wilson published calculations of atomic properties, including lifetimes, for singly ionized ytterbium.

Their work predicted a lifetime of approximately 5.2 seconds for a particular state relevant to the later experiment. The researchers in 2026 measured a lifetime signal of approximately 0.92 seconds for the state they associated with that prediction.

The measured value differs substantially from the original prediction, but the study's authors noted that the prediction was reasonably close given the complexity of ytterbium's electronic structure. Their calculations supported the qualitative identification of the observed states and their decay pathways.

This is a useful example of how science progresses.

A theoretical calculation can suggest that a physical state should exist and estimate its properties. An experiment can then test that prediction, identify discrepancies, and help scientists refine their understanding.

A prediction made decades earlier does not become correct simply because an experiment finds something interesting. The comparison depends on whether the theoretical and experimental states have been properly identified and whether their measured properties agree within the relevant uncertainties.

Here, the new work provides experimental information about long-lived states in a complex atomic system and helps answer a question that had remained open for decades.

Quantum computers use quantum states to represent and process information.

In trapped-ion systems, individual ions are confined and manipulated using electromagnetic fields and laser pulses. Researchers prepare selected internal states, perform operations, and measure the results.

One major challenge is reading out the state of a quantum bit, or qubit, accurately. A qubit's state must be distinguished from other possible states without introducing unacceptable errors.

The 2026 study identifies long-lived ytterbium states that could provide new options for detecting quantum states. The researchers specifically discuss potential applications in the detection of qubits and qudits.

A qudit is a quantum information system that can represent more than two distinguishable basis states. While a conventional qubit uses a two-level basis, a qudit can use a larger number of levels.

The roughly one-second metastable state is particularly interesting because the researchers' calculations suggest it may be accessible from the ground state with a single laser pulse. Its lifetime and predicted transition strength make it a candidate for improving state detection.

But the distinction between a promising candidate and a demonstrated technological improvement matters.

The paper does not report a completed quantum processor built around these states, nor does it establish a specific improvement in computational speed, error rates, or the number of qubits a system can support.

Those outcomes would require additional experiments.

The immediate contribution is more foundational: researchers have characterized states that may expand the techniques available for controlling and reading trapped-ion quantum systems.

The second major application discussed by the researchers is optical atomic clocks.

An atomic clock measures time by using the frequency of a precisely defined transition between atomic energy states. Optical clocks use transitions in the optical-frequency range and can achieve extremely high precision.

The properties of the atomic states used in a clock affect how the transition can be measured and how sensitive it is to environmental influences.

Long-lived states can be valuable in certain precision-measurement schemes because they may support narrow transitions and provide useful ways to interrogate an atomic system.

However, the relationship between lifetime and clock performance is not automatic. A useful clock transition must also be sufficiently well controlled, accurately characterized, and resistant to systematic shifts.

The ytterbium study therefore opens a possible direction for clock research rather than proving that the newly measured states already improve clock accuracy.

Further work would need to establish which transitions are practical for clock operation, how they respond to external fields, and whether the complete experimental system offers an advantage over existing approaches.

The findings are exciting because they demonstrate measurable properties of quantum systems that are relevant to emerging technologies. But the scientific conclusions should remain tied to the evidence.

What the experiment supports:

• Researchers prepared metastable states in trapped Yb⁺ ions.
• They measured decay signals corresponding to lifetimes of approximately 0.92 seconds and 9.8 seconds.
• They found evidence for a state with a lifetime greater than 30 seconds.
• They used atomic-structure calculations to support their interpretation of the observed states.
• They identified potential applications in qubit and qudit detection and optical clocks.

What the experiment does not establish:

• It does not demonstrate a new commercial quantum computer.
• It does not prove that quantum computers will become error-free.
• It does not show that a long-lived state automatically produces a better atomic clock.
• It does not establish that human consciousness can control atomic decay through thought.
• It does not demonstrate quantum teleportation or faster-than-light communication.

The distinction matters because quantum physics is often used in popular culture to support claims that go far beyond laboratory evidence.

The real discoveries are already significant. They do not need to be exaggerated to be meaningful.

The 2026 ytterbium experiment illustrates how progress in quantum science frequently depends on the ability to measure something that was previously difficult to observe.

A theoretical prediction can remain unresolved for years when the relevant state is hard to prepare, its decay is difficult to distinguish, or the measurement itself disturbs the system.

By combining trapped-ion techniques, sympathetic cooling, laser excitation, fluorescence monitoring, and atomic-structure calculations, the researchers expanded what is experimentally known about a complicated quantum system.

The results could help future scientists develop better approaches to quantum-state detection and investigate new possibilities for optical clocks.

The next stage is to determine how these states behave under controlled operations, whether they can be prepared and measured reliably, and which applications benefit most from their properties.

That is how a fundamental physics result becomes a practical technology: not through a single dramatic claim, but through a sequence of carefully tested advances.

The University of Amsterdam and University of New South Wales team's 2026 study adds important experimental evidence to our understanding of long-lived quantum states in ytterbium ions.

The measured lifetimes — approximately one second, ten seconds, and evidence for more than thirty seconds — show that this complex atomic system contains metastable states with a wide range of persistence times.

The work also revisits a theoretical prediction made decades earlier and identifies potential applications in quantum-state detection and optical clocks.

For quantum computing, the immediate opportunity is to explore whether these states can make trapped-ion systems easier to measure and control. For precision timekeeping, the next question is whether the states can support useful, stable transitions.

Neither application is guaranteed, but both provide compelling reasons for continued investigation.

The most important takeaway is that quantum physics continues to reveal new ways to prepare, measure, and understand matter at its smallest scales. The next breakthrough may depend on turning this improved understanding into a reliable experimental technique.

Read more in my related articles, Quantum Superposition Explained, Quantum Entanglement Explained, and The Optical Magnus Effect.