Can the quantum effects that govern electrons and atoms be used to move an object large enough to see? This is one of the key questions in research exploring the boundary between quantum and classical mechanics.
Quantum mechanics underpins modern science and technology, from semiconductors to nuclear magnetic resonance. But for macroscopic objects, interactions with surrounding heat and vibration are strong, making it difficult to preserve quantum properties or measure their effects precisely. As a result, most studies linking electron spins to the motion of objects have targeted tiny structures.
A research team at the Okinawa Institute of Science and Technology Graduate University (OIST) took the opposite approach.
The team built an oscillator with a mass of 128 mg, levitated in the air using diamagnetism. They controlled electron spins in a diamond crystal with laser light and succeeded in moving the entire oscillator up and down using the tiny force arising from those spins.
In the experiment, oscillations of about 100 nm were observed in air and up to about 1.5 µm in vacuum.
The results were published on October 7, 2026, in the peer-reviewed journal Science Advances in a paper titled "Spin-force from a Nitrogen-Vacancy ensemble drives a 100 mg levitated resonator." A preceding preprint was released on May 18 of the same year on arXiv (2605.17750).
The result shows that a force derived from electron spin, a quantum-mechanical property, can be used to control the motion of an object exceeding 100 mg. It is an important step in extending spin-mechanics research, which has so far focused mainly on tiny mechanical systems, to macroscopic objects.
Moving a 128 mg Levitated Object with the Force of Electron Spins
What stands out in this study is that the tiny force generated by electron spins was applied to a far heavier object than before, and its motion was directly observed.
The research was led by Professor Jason Twamley of OIST's Quantum Machines Unit. The paper's authors include first author Anshuman Nayak, Daehee Kim, and Shilu Tian, who is also affiliated with Institute of Science Tokyo.
OIST's official announcement describes it as the world's first observation of centimeter-scale objects being moved by the force of electron spins.
According to the paper, the total mass of the oscillator used in the experiment was 128 mg. Professor Twamley of OIST explains that this is 8 to 9 orders of magnitude, or 100 million to 1 billion times, larger than the objects handled in previous state-of-the-art spin-mechanics experiments.
Previous research mainly used extremely light particles or fine mechanical structures to examine the relationship between quantum spins and motion. In contrast, this study took the approach of levitating a relatively large object from the outset and applying the force of electron spins to it.
Rather than gradually scaling up the object, the approach applies a tiny force to a macroscopic object.
That said, the experimental subject was a precision apparatus set up in a laboratory. No human body or living organism was moved, and no outdoor application tests were conducted.
The result is best regarded as a basic-physics demonstration, showing in a tightly controlled experimental environment that a force derived from electron spins can move a 128 mg oscillator.
Combining Diamagnetic Levitation with Diamond NV Centers
The apparatus developed by the team combines a mechanism that levitates an object using diamagnetism with one that controls electron spins in diamond.
The levitated body is supported by a carbon material called pyrolytic graphite.
Graphite has a property called diamagnetism, in which it magnetizes in the direction that cancels an applied external magnetic field. Using this property, a graphite plate can be levitated above properly arranged permanent magnets without any external power supply.
In this apparatus, a graphite plate with slits floats above four permanent magnets arranged in a checkerboard pattern of magnetization directions.
The main purpose of the slits in the graphite plate is to suppress eddy currents generated by the object's motion and reduce magnetic damping. This produces a structure in which vibrations are less easily damped.
A small mirror for measuring vibration is mounted on top of the graphite plate.
A thin carbon-fiber rod extends downward from the center of the plate, with a diamond crystal fixed at its tip.
The diamond sample measures 3 × 3 × 0.5 mm and contains crystal defects called nitrogen-vacancy (NV) centers at a concentration of about 4.5 ppm.
The graphite plate and diamond are joined by the rod, and the total mass of the moving part is 128 mg. In other words, it is the structure including the levitation mechanism that is centimeter-scale; the diamond crystal itself is millimeter-scale.
The magnets that levitate the graphite plate and the magnet that applies force to the diamond are arranged separately.
The carbon-fiber rod passes through the center of the magnet array and extends downward through a magnetic shield. This shield suppresses, on the diamond side, the influence of the magnetic field produced by the levitation magnets.
Below the diamond sits a separate cylindrical permanent magnet used to apply force to the spins.
The main components used in the experiment are summarized below.
| Component | Role and specifications in this experiment |
|---|---|
| Levitated body | 128 mg composite oscillator consisting of a graphite plate, carbon-fiber rod, diamond, etc. |
| Levitation mechanism | Diamagnetic levitation of the graphite plate above permanent magnets |
| Graphite plate | 10 × 10 × 1 mm. Slits added to suppress damping from eddy currents |
| Diamond | 3 × 3 × 0.5 mm. Contains about 4.5 ppm NV centers |
| Spin control | Periodic irradiation with a 532 nm green laser |
| Magnetic field gradient | Generated by the permanent magnet below the diamond. Range used in the experiment: about 10–100 T/m |
| Vibration measurement | Laser interferometer using the mirror on the graphite plate |
| Observed motion | Classical center-of-mass oscillation driven by a force derived from electron spins |
The NV centers inside the diamond play the key role in this apparatus.
An NV center is a crystal defect in which a carbon atom in the diamond is replaced by a nitrogen atom, with a vacant carbon site next to it.
The electronic state of an NV center includes a spin quantum number S = 1 state that can be controlled with light and microwaves. This electron spin has a magnetic moment and behaves like a tiny magnet.
The team applied force to the oscillator by periodically changing the state of these electron spins.
Specifically, they used a green laser with a wavelength of 532 nm and a power of 50 mW, switching it on and off repeatedly in step with the oscillator's natural frequency.
When the laser is on, the electrons of the NV centers are optically excited and polarized into the state with spin magnetic quantum number mₛ = 0. When irradiation stops, the spins return to thermal equilibrium through relaxation processes.
This operation periodically changes the magnetic moment of the NV ensemble.
In a "magnetic field gradient," where field strength varies with position, a force acts on an object with a magnetic moment.
In simplified form, the force from a magnetic field gradient can be expressed by the following relation:
Fz ≈ μz × ∂Bz/∂z
Here, μz is the vertical component of the magnetic moment, and ∂Bz/∂z is the vertical rate of change of the magnetic field.
The permanent magnet placed below the diamond creates this field gradient.
When the spin state of the NV centers changes, the force acting on the diamond also changes. As a result, the force pulling toward the lower magnet periodically strengthens and weakens, making the entire levitated body, integrated with the diamond, oscillate.
By matching the laser's irradiation period to the oscillator's natural frequency, resonance occurs, so even a tiny force can produce a relatively large displacement.
The team used a seven-level model that includes the NV center's ground, excited, and intermediate states to numerically calculate the spin polarization produced by laser irradiation and the resulting change in force.
The model approximates the magnetic moment as uniform within the roughly 1 mm laser spot and applies a constant correction factor to the calculated results.
As a result, it reproduced the changes in force when the laser power and the distance between the diamond and the magnet were varied, in good agreement with the experimental results.
100 nm Oscillation at 17.6 Hz Resonance, Up to 1.5 µm in Vacuum
The team measured the motion of the levitated body with a laser interferometer.
The interferometer compares laser light reflected from the mirror on the graphite plate with reference light, detecting changes in the object's position with high precision.
In principle, the measurement system used here is capable of detecting tiny displacements on the order of picometers (one trillionth of a meter).
The measurements showed that the oscillator's natural vertical frequency was 17.6 Hz. Its mechanical quality factor (Q) at atmospheric pressure was 55.
The Q factor is an indicator of how resistant vibration is to damping; the larger the value, the longer the vibration can be sustained.
When the team periodically irradiated the green laser at the 17.6 Hz resonance frequency, the oscillator's center of mass began moving up and down.
The steady-state amplitude observed at atmospheric pressure was about 100 nm.
This amplitude far exceeds the nanometer-scale fluctuations from thermal Brownian motion that occur without laser irradiation.
Furthermore, measurements in a vacuum environment produced an amplitude of up to about 1.5 µm.
In air, resistance from the surrounding air damps the vibration. In a vacuum, this resistance is smaller, so even a similarly tiny driving force can more easily produce larger oscillations.
It was also confirmed that the observed motion was not a chance fluctuation but a periodic motion corresponding to the laser irradiation.
The team divided the recorded vibration waveform into single periods and averaged them. A clear sinusoidal oscillation remained, consistent with the prediction for a harmonic oscillator driven by a square-wave periodic force.
This indicates that the vibration maintains a stable phase relationship with the laser's driving period.
Moreover, because the oscillator was displaced toward the permanent magnet below, it was also confirmed that the force acting was directed toward the magnet, as predicted by the theoretical model.
A Force Above 5 nN, Estimated from Vibration Measurements
Using the observed amplitude, the oscillator's mass, resonance frequency, Q factor, and other parameters, the team estimated the magnitude of the force derived from electron spins.
The results showed that, depending on experimental conditions, a force exceeding 5 nN (nanonewtons) was being generated.
1 nN is one billionth of a newton, an extremely small force.
However, if a force is applied repeatedly at the natural frequency of an oscillator with reduced losses from friction and air resistance, even a force of this size can produce an observable displacement.
Importantly, this force was not produced by completely flipping all of the NV centers' spins.
According to the paper, even a partial change in the state of the spin ensemble produced sufficient driving force through its interaction with the magnetic field gradient.
However, the 5 nN value was not measured by a device that reads force directly. It is an estimate obtained by combining the resonator's displacement data with a mechanical model.
To confirm that this force truly originates from electron spins, the team also conducted additional control experiments.
First, when the permanent magnet providing the magnetic field gradient to the diamond was removed, the characteristic resonance peak disappeared.
Also, when an infrared laser with a wavelength of 980 nm, which does not optically polarize NV centers, was used, the strong oscillation seen with the green laser did not appear.
These results support the conclusion that the observed vibration was caused by the interaction between the NV centers' spin state and the magnetic field gradient, rather than by simple laser heating or the direct force of light.
Meanwhile, limits on measurement sensitivity remain in the experiment.
According to the paper, the noise level in the displacement measurement during the experiment was about 1 nm.
This limit was set not by the interferometer's own performance but by noise from the external environment, such as laboratory floor vibration and ambient sound.
The team says that further improving vibration isolation could improve measurement sensitivity by about three orders of magnitude from the current level, approaching the interferometer's intrinsic picometer range.
However, this is a prospect based on future improvements; it does not mean that picometer-precision vibration measurement has already been achieved in this experiment.
Has a "Schrödinger's Cat" Been Realized?
In this study, a macroscopic object was successfully moved by a force derived from electron spins. However, the object itself did not enter a quantum state of motion.
This is the key point separating what was confirmed in the experiment from future research goals.
In quantum mechanics, "superposition of position" refers to a phenomenon in which an object simultaneously occupies multiple quantum states corresponding to different positions. This is fundamentally different from an object simply moving back and forth between two positions.
The oscillation observed here was a classical harmonic oscillation that can be explained by Newton's equations of motion.
The experiment did not confirm that the entire levitated body entered a quantum superposition of different positions, nor that quantum entanglement formed between the electron spins and the oscillator's motion. Nor was the oscillator cooled to its quantum-mechanical ground state.
The stable phase relationship seen in the vibration waveform described above shows synchronization between the periodic laser drive and the oscillator's motion; it is not evidence of macroscopic quantum coherence.
Professor Twamley of OIST likewise characterizes the result as an experiment that drew a large classical response from a small quantum effect.
Looking ahead, what the team expects to be useful for achieving macroscopic quantum states is a property of the NV centers in diamond.
Co-author Kim cites the NV center's ability to maintain a relatively long coherence time even at room temperature as an advantage of this research approach.
Quantum coherence refers to the property of maintaining phase relationships between multiple quantum states. NV centers can maintain this property relatively well and are used in research on quantum sensors and quantum information processing.
However, there is a large technical gap between being able to maintain the quantum state of an electron spin and being able to control an entire 128 mg oscillator as a quantum state.
To realize quantum superposition in a macroscopic object, it is necessary to couple the spin and the object's motion quantum-mechanically and sufficiently suppress "decoherence," the loss of quantum coherence caused by surrounding heat and vibration.
In OIST's announcement, Professor Twamley also mentions the possibility of observing a "Schrödinger's cat" in the real world with roughly one more order of magnitude of progress.
This is a future research vision starting from the present result; it does not mean the necessary conditions are already in place.
Can Heat and Vibration Be Suppressed to Reach Control of Quantum States?
To develop this apparatus into future precision sensors or fundamental quantum-mechanics experiments, several challenges must be solved.
One is the effect of heating from laser irradiation.
The 532 nm green laser used here was necessary to optically polarize the NV centers in the diamond.
However, when diamond absorbs laser light, its temperature rises. The paper estimates that irradiation may raise the temperature of the whole diamond by about 3 K.
Such temperature changes could cause mechanical displacement unrelated to spin, through interactions with the surrounding gas or thermal expansion of materials.
To suppress this effect, the team placed the diamond away from surrounding solid surfaces, adopting a structure in which thermally driven gas forces are less likely to act.
The team also verified, through the magnet-removal experiment and the infrared-laser control experiment described above, that the strong observed oscillation originates from electron spins.
Thus, the influence of heat has not gone entirely unexamined. However, if the aim is more precise control of quantum states, unwanted motion from laser heating will need to be reduced even further.
As future improvements, the team lists shorter laser pulses and methods that use microwaves to control electron spins coherently.
If spin states can be manipulated precisely with microwaves, it may be possible to control the interaction between the spins and the oscillator to a higher degree than with the current method of repeated optical polarization and thermal relaxation.
In the future, this is expected to lead to technologies that induce quantum energy exchange between spins and mechanical vibration, or that use spins to cool the oscillator's motion.
A Plan to Raise Q from 55 to the 100,000 Range
Another important challenge is to reduce vibration damping further.
In this apparatus, the mechanical Q factor at atmospheric pressure was 55. Evacuating the chamber can reduce damping from air resistance and yield larger amplitudes.
However, air resistance is not the only cause of damping.
When graphite moves in the magnetic field created by the permanent magnets, eddy currents arise inside the material. Because these eddy currents dissipate energy, improving the vacuum alone cannot eliminate vibration damping entirely.
The team is considering ways to further reduce such losses by improving the structure of the graphite plate or using composite materials.
The paper indicates that combining a high-vacuum environment with low-loss composite materials could raise the Q factor to around 100,000.
In that case, it predicts that even the force from relatively weak spin polarization could increase the amplitude to about 100 µm.
However, a Q factor of 100,000 and an amplitude of 100 µm are estimates assuming future improvements. They are not values actually achieved in this experiment.
Applications to Quantum Gravity Tests and Sensitive Sensors Lie Ahead
The OIST team hopes to build on this apparatus for future fundamental experiments probing the relationship between quantum mechanics and gravity, and for developing high-precision sensors.
Specific research directions mentioned include, in addition to generating macroscopic quantum states, searches for dark matter, detection of gravitational waves, and tests for unknown weak interactions.
However, this experiment did not detect dark matter or gravitational waves. Nor did it demonstrate specific detection sensitivity for such signals.
At this stage, it is a demonstration of a basic technology showing that a macroscopic levitated body can be driven precisely using a force derived from electron spins.
To move on to such applied research, it will be necessary to suppress environmental vibration and thermal noise further, and to develop techniques for controlling quantum interactions between spins and the motion of the object.
In addition, these results were obtained with an experimental apparatus built by the research team itself, and as of October 9, 2026, no replication results from independent research groups have been confirmed.
Whether other institutions can reproduce the same phenomenon, and whether stable measurements are possible when the apparatus configuration or environmental conditions change, will also be important questions for future verification.
The significance of this result is that it shows the tiny force of electron spins can be linked to the motion of an object 100 million to 1 billion times heavier than before.
If damping and environmental noise can be reduced further and the interaction between the spins and the oscillator controlled precisely, a path may open to more directly testing how quantum mechanics manifests in macroscopic objects.
The experiment can be said to have demonstrated a new research foundation for that purpose.