Stanford watches a microscopic tuning fork lose its last phonon
Quantum jumps were caught in trapped ions in 1986 and in photons in 2007. A resonator that rings for two milliseconds, read out by a superconducting qubit, now shows a single phonon going to zero as it happens.
The Scientist · Science desk
What happened
- Stanford physicists report in Science the observation of a real-time quantum jump in phonons, the quantised units of vibration, caught as it happened rather than inferred afterwards.
- The device is a mechanical resonator, described as a little like a microscopic tuning fork, that can ring for periods of two milliseconds.
- The team held back its first jump data and refined the technology to cut noise so the result would, in its lead author's word, pop out.
Why it matters
- What's now possible capability Hundreds of readings on one quantum of vibration means a mechanical resonator can be watched continuously through a state change, so the timing of the jump becomes data instead of a statistical inference.
- What it limits constraint Safavi-Naeini's caveat that the measurement is not perfectly non-destructive limits how far this supports the idea that mechanical systems now sit on the same measurement footing as ions and photons.
- What it sets up precedent The group's stated next steps set the bar for anyone building on this: jumps with more than one phonon, and several resonators wired together, are what would turn a single measurement into a platform.
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Two milliseconds of ringing is what made the experiment possible. The Stanford resonator holds its vibration for periods of two milliseconds [9], which Discover reports is equivalent to a normal-sized vibration lasting hours [11]. The long ring time means the device can take hundreds of readings and pinpoint the exact moment the energy state changes [12]. Read "hundreds" as two hundred and each reading has roughly ten microseconds to work in [24].
"A normal tuning fork sounds like it gradually gets quieter and quieter," said Amir Safavi-Naeini, associate professor of applied physics at Stanford [8]. "The quantum version is more like an extremely tiny tuning fork where, if you could directly measure its energy, the last unit of vibration stays there for some random amount of time and then disappears all at once." [10]
A phonon is the coordinated movement of many atoms [7], so the thing making the jump here is a mechanical object with many degrees of freedom. The harder problem was reading it without disturbing the phonon [14]. Takuma Makihara and Erik Szakiel, the paper's co-first authors, established a process that couples the resonator to a superconducting qubit, which acts as the detector and identifies the moment the phonon count goes from one to zero [15]. "Physically, the resonator goes from having one quantum of vibrational energy, one phonon, to having zero," said Safavi-Naeini [13].
Bohr put jumps into theory in the 1910s, according to the American Physical Society [4]. Direct observation waited until 1986 in trapped ions [5] and 2007 in photons [6]: twenty-one years between those two [22], and eighteen more before the Stanford group had its first jump data in the spring of 2025 [23].
The group did not publish that data. "But you had to squint to see the jumps," Safavi-Naeini told Discover of those first measurements [17], and the team refined the technology to reduce noise until the result would "pop out" [18]. "When they showed me the results from the new chip, it was clear that we had the result; I was extremely excited," he said [19].
The readout still perturbs what it measures. "Our measurement is very good but not perfectly non-destructive," said Safavi-Naeini [20]. Whether the same phonon can be interrogated twice depends on how large that disturbance is, and Discover's account puts no number on it.
Discover reports that jumps had already been recorded in ions and in photons, and that earlier phonon experiments found evidence of such leaps without observing one directly [2]. The researchers said the ability to detect phonon jumps could one day lead to advances in quantum computing, quantum sensing, and everyday technologies that involve sound [16].
What to watch
- Whether a follow-up quantifies how much the qubit readout disturbs the phonon, the figure that decides if the same phonon can be measured twice.
- Safavi-Naeini said the group wants to observe jumps involving higher numbers of phonons and to connect several mechanical resonators together; either would test whether the method scales.
- Whether another lab reproduces real-time phonon jumps on a different resonator design.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence62
- Adoption
- Not scored
- Hype gap+20
- Incentives55
- Confidence68
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
A quantum jump is the sudden transition of a quantum system from one energy state to another.
- [2]
Quantum jumps had already been recorded in ions and in photons, but quantum jumps in phonons had remained elusive; previous experiments found evidence of such leaps without observing one directly.
- [3]
A team of physicists from Stanford University describes the observation of a real-time quantum jump in phonons, in research published in the journal Science.
- [4]
Quantum jumps have been theorized since the 1910s, when Niels Bohr produced his model of the atom, according to the American Physical Society.
- [5]
The first direct observation of a quantum jump came in 1986, in trapped ions.
- [6]
A quantum jump was directly observed in photons in 2007.
- [7]
Phonons, unlike photons, are not a singular particle but the coordinated movement of multiple atoms.
- [8]
Amir Safavi-Naeini is associate professor of applied physics in the Stanford School of Humanities and Sciences.
- [9]
To detect a quantum jump the team built a mechanical resonator, described as a little like a microscopic tuning fork, that can ring or vibrate for periods of two milliseconds.
- [10]
"A normal tuning fork sounds like it gradually gets quieter and quieter. The quantum version is more like an extremely tiny tuning fork where, if you could directly measure its energy, the last unit of vibration stays there for some random amount of time and then disappears all at once."
- [11]
Two milliseconds of vibration is equivalent to a normal-sized vibration lasting hours.
- [12]
The relatively long vibration time means the device can take hundreds of readings and can pinpoint the exact time the sound jumps and changes energy state.
- [13]
"Physically, the resonator goes from having one quantum of vibrational energy, one phonon, to having zero."
- [14]
The obstacle the team had to contend with was how to measure the signals without disturbing the phonon.
- [15]
Takuma Makihara and Erik Szakiel, the paper's co-first authors, established a process that couples the resonator to a superconducting qubit, which acts as a detector identifying the moment the number of phonons goes from one to zero.
- [16]
The researchers said being able to detect quantum jumps of phonons could one day lead to advancements in areas such as quantum computing, quantum sensing, and everyday technologies that involve sound.
- [17]
Safavi-Naeini told Discover that the team first collected measurements of the jumps in the spring of 2025, "but you had to squint to see the jumps."
- [18]
The team decided against publishing the spring 2025 results and instead refined the technology to reduce the noise so the result could "pop out."
- [19]
"When they showed me the results from the new chip, it was clear that we had the result; I was extremely excited. This is something I had wanted to see since I was a graduate student."
- [20]
"Our measurement is very good but not perfectly non-destructive."
- [21]
Safavi-Naeini said the team would like to reduce that disturbance, observe jumps involving higher numbers of phonons, and connect several mechanical resonators together.
- [22]
Twenty-one years separated the 1986 trapped-ion observation from the 2007 photon observation.
- [23]
Eighteen years separated the 2007 photon observation from the Stanford group's first phonon jump measurements in spring 2025.
- [24]
Hundreds of readings inside a two-millisecond ring time works out to roughly ten microseconds per reading, taking "hundreds" as two hundred.
Sources
2 independent publishers whose own reporting we read for this story.
- discovermagazine.comScientists Catch Sound Making a Quantum Jump With a Microscopic Tuning Fork
1 article · September 21, 2026
- sciencedaily.comFor the first time, scientists watch sound jump between quantum states
1 article · September 22, 2026
Topics and entities
Topics
- Superconducting qubits
- Quantum Error Correction
- Quantum acoustics
- Quantum Sensing
Entities
- California Institute of Technology
- American Physical Society
- Science
- Stanford University
- Amir Safavi-Naeini