Stanford records first real-time quantum jumps of sound

Overview

Updated 1 hour ago

A Stanford team has watched a single quantum of sound vanish in real time. A microscopic resonator switched from one phonon to zero mid-ring — the first direct observation of a quantum jump in sound.

The jump was predicted a century ago and first spotted in atoms in 1986 and light in 2007. Sound had resisted observation. The team paired the resonator with a superconducting qubit that checked hundreds of times whether the phonon was still there. Catching the jump matters for quantum computing, where a jump like this is an error and spotting errors as they happen is the hard part.

Why it matters

Catching a phonon jump lets quantum computers spot errors mid-calculation, and it opens a path to sound-based quantum sensing.

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Key Indicators

2 ms

Resonator ringdown time

How long the microscopic tuning fork vibrates — long enough for hundreds of readouts.

294

Quantum readouts per run

The qubit interrogated the resonator 294 times per experimental run.

645 µs

Average time to a quantum jump

Jump times follow an exponential distribution averaging 645 microseconds.

1.3%

Chance each readout removes the phonon

The cost of watching: each measurement has a ~1.3% chance of ejecting the phonon.

Voices

Curated perspectives — historical figures and your fellow readers.

Ever wondered what historical figures would say about today's headlines?

People Involved

Amir Safavi-Naeini

Associate professor of applied physics, Stanford

Leads the lab that conducted the experiment

Takuma Makihara

Co-first author on the study

Researcher in Safavi-Naeini's lab

Erik Szakiel

Co-first author and doctoral student

Doctoral student in Safavi-Naeini's lab

Michael Roukes

Physicist, California Institute of Technology

Collaborating with Safavi-Naeini on protein sensing

Organizations Involved

Stanford School of Humanities and Sciences

University school

Home of the research team

Stanford's largest school, housing the applied physics department where the experiment was built.

Science Corporation

Peer-reviewed journal

Published the findings

A leading peer-reviewed research journal where the study appeared.

California Institute of Technology

Research university

Collaborating on protein-sensing applications

Partner institution where physicist Michael Roukes's team works on using the platform to identify proteins.

Timeline

December 1900 September 2026

4 events Latest: Today

Tap a bar to jump to that date

September 2026
First real-time quantum jump of sound
Today Publication

Stanford team reports the first direct observation of phonon quantum jumps in a mechanical resonator, in Science.
Today
January 2007
Quantum jumps seen in photons
Discovery

Researchers observe a photon switching between discrete states in a cavity, extending jumps to light.
January 1st, 2007
January 1986
Quantum jumps seen in trapped ions
Discovery

Two groups independently observe single ions leaping between energy states — the first proof of discrete jumps.
January 1st, 1986
December 1900
Planck presents quantum hypothesis
Discovery

Max Planck introduces discrete energy quanta before the German Physical Society — the seed of jump theory.
December 14th, 1900

Scenarios

Phonon error correction reaches multi-resonator devices

Likely Resolves by End of 2027

Discussed by: Stanford team and quantum computing researchers

Safavi-Naeini's lab is already building a device with two resonators sharing one qubit. Losing a phonon from either bar would surface as a flagged error, not silent corruption — exactly what error correction needs. The main engineering hurdle is cutting the 1.3% chance that each measurement itself ejects the phonon; both limits the team named are engineering problems, not physics barriers.

Resonator-qubit platform identifies proteins in cells

Possible Resolves by Q2 2028

Discussed by: Stanford-Caltech collaboration (Safavi-Naeini and Michael Roukes)

The resonator weighs less than a trillionth of a gram, light enough to register tiny masses. Safavi-Naeini's group is working with Michael Roukes's team at Caltech to use the platform to detect and identify proteins inside cells. Success gives biologists a single-molecule analysis tool built on quantum acoustics.

Quantum jump detection stays a lab demonstration

Unlikely Resolves by End of 2028

Discussed by: Commentators citing unreported readout fidelity

The public account gives no readout fidelity and no jump count, so phonon hardware cannot yet be scored against photon or ion systems — which have decades of head start. If readout errors prove too costly or the field shifts focus, this could remain a foundational result with no near-term device payoff.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

1986

Trapped ion quantum jumps (1986)

Warren Nagourney, Jon Sandberg, and Hans Dehmelt at the University of Washington, and independently Jim Bergquist's group at NIST, watched a single trapped ion leap between energy states — the first experimental proof of the discrete jumps quantum theory had predicted since Bohr.

Then

Confirmed atomic transitions are genuinely discrete and became a cornerstone of single-atom physics.

Now

The technique fed into atomic clocks and trapped-ion quantum computers.

Why this matters now

It was the first demonstration of the phenomenon Stanford has now extended to sound.

1990

Quantum Zeno effect demonstration (1990)

NIST's Itano group demonstrated the 'watched pot' effect with ions: repeatedly measuring a quantum system froze it in a decaying state, as Misra and Sudarshan had predicted in 1977.

Then

Proved that measurement backaction is real and quantifiable.

Now

Became a standard result in quantum measurement theory.

Why this matters now

The Stanford readout carries a ~1.3% chance per check of ejecting the phonon — the same backaction in reverse. Watching a quantum system always costs something.

2007

Photon quantum jumps (2007)

A research group observed a single photon switch between discrete number states inside an optical cavity, extending the discrete-jump picture from atoms to particles of light.

Then

Confirmed that light's quanta jump the same way ions do.

Now

The result helped consolidate the quantum measurement framework used for light-based quantum technologies.

Why this matters now

Photons made the jump before phonons. Stanford's result completes the trio of ions, photons, and sound.