Stanford physicists have, for the first time, directly observed a quantum jump in sound, documenting the instantaneous shift of a tiny unit of vibration, a phonon, from one energy level to another. Led by Professor Amir Safavi-Naeini of the Stanford School of Humanities and Sciences, the team pinpointed this fleeting moment within two milliseconds by taking hundreds of measurements of a specially fabricated mechanical resonator.
“What this study shows will allow us to move forward with developing new quantum technologies with sound,” said Safavi-Naeini, completing an arc of scientific exploration begun over a century ago and opening possibilities for advances in quantum computing and sensing. The research, published in Science, builds on demonstrations of quantum jumps first achieved in trapped ions in 1986 and later in photons, but marks the first such observation with phonons.
Real-Time Detection of Quantum Sound Jumps
Employing a microscopic resonator, a vibrating structure enabling the detection of single sound quanta, or phonons, the team pinpointed quantum jumps occurring within it. Achieving this required overcoming a significant hurdle in quantum engineering; researchers had to extract signals from a quantum system without disrupting its delicate state. The qubit served as a detector, repeatedly checking the phonon’s energy level, either 1 or 0, over two milliseconds to record the precise moment of a quantum jump.
“We had to continually develop new processes to make this extremely long-lived, vibrating object and then integrate it with the qubit, which is our little electrical detector—without ruining either subsystem,” explained a researcher. This demonstration builds on earlier work establishing quantum jumps in trapped ions dating back to 1986, and expands the phenomenon to mechanical systems.
Stanford University’s longstanding investment in both superconducting and trapped-ion qubit technologies, alongside partnerships with AWS, IBM Quantum, and Google Quantum AI, provided a strong foundation for this interdisciplinary research. The university’s Q-FARM initiative, uniting experts from Stanford and SLAC National Accelerator Laboratory, further facilitated collaboration across physics and engineering. Detecting these jumps in sound isn’t merely an academic exercise; it addresses a critical challenge in building practical quantum computers. Quantum states are inherently fragile, prone to errors before calculations complete, and in many architectures, a quantum jump signifies an error.
Identifying when these jumps occur has proven difficult, hindering error correction efforts. “We have seen that vibrating objects can exhibit quantum behavior, which is the prerequisite for many of the operations needed by quantum computing and sensing,” the team reports.
The ability to precisely control sound, as demonstrated by this work, suggests potential improvements for devices relying on sound as a fundamental technology, opening avenues for more refined quantum sensors and potentially more stable quantum processors. “This shows we can have incredibly fine-tuned control of sound, which might mean that devices that use sound as a fundamental technology can get much better.”
What this study shows will allow us to move forward with developing new quantum technologies with sound.
Amir Safavi-Naeini, associate professor of applied physics in the Stanford School of Humanities and Sciences
Phonon Resonator Design Enables Precise Measurement
This extended analogous to a standard tuning fork ringing for hours if scaled up proved critical for accurately capturing the transition of the phonon within the resonator between energy states of 1 and 0. The qubit integrated with the resonator repeatedly checked this energy level throughout the two-millisecond vibration, recording the instant the quantum jump occurred. This capability extends beyond mere observation; the researchers are already applying the platform to new sensing applications, collaborating with Michael Roukes’ team at Caltech to detect and identify proteins within cells.
The combination of a highly sensitive mechanical resonator and a qubit offers potential for extremely precise measurements at a microscopic scale, opening avenues for advancements in biological and materials science. Said Szakiel, a doctoral student working with Professor Safavi-Naeini, indicating a rapid translation of this fundamental research toward practical technologies.
Superconducting Qubit Integration for Quantum Readout
The integration of a superconducting qubit with the mechanical resonator enabled hundreds of measurements within a two-millisecond timeframe, pinpointing the precise moment of phonon energy jumps with a level of accuracy previously unattainable with sound. This pairing, developed by co-first authors Takuma Makihara and Erik Szakiel, addressed a core challenge in quantum engineering: extracting signals from delicate quantum systems without disrupting them.
This shows we can have incredibly fine-tuned control of sound, which might mean that devices that use sound as a fundamental technology can get much better.
Potential Applications in Quantum Computing & Sensing
Identifying when quantum errors occur has long hampered progress, as these fragile states are easily disrupted, but this new method offers a pathway to real-time error correction. The team’s device doesn’t merely observe the phenomenon; it pinpoints the precise moment of energy level change, a level of granularity previously unattainable with phonons. This achievement extends beyond error mitigation, potentially enabling new approaches to quantum sensing.
Unlike photons, discrete units of light, phonons represent the collective movement of atoms, making their quantum behavior more complex to observe and control. Successfully demonstrating quantum jumps in these mechanical resonators opens possibilities for sensors that could detect incredibly subtle changes in force, acceleration, or temperature. The university’s 2026 modeling of many-body effects for turbulent quantum hydrodynamics further demonstrates its commitment to advancing quantum information science, and the team is already applying this platform to explore the limits of quantum control with sound.
We have seen that vibrating objects can exhibit quantum behavior, which is the prerequisite for many of the operations needed by quantum computing and sensing.
The university’s partnerships with AWS, IBM Quantum, and Microsoft Quantum further bolster its position in quantum information science, as evidenced by a 2020 research collaboration with Microsoft on topological and algorithmic quantum computing.
We had to continually develop new processes to make this extremely long-lived, vibrating object and then integrate it with the qubit, which is our little electrical detector, without ruining either subsystem.
Takuma Makihara, a recent Stanford doctoral graduate
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