Quantum ground state of rotation achieved for the first time in two dimensions
image from grok
Physicists have achieved the first quantum ground state of rotation in two dimensions by cooling a levitated silica dumbbell nanoparticle (~100 million atoms) to 20 microkelvin using coherent scattering cooling with a single intense laser. The rotor's angular uncertainty is only ~20 microradians, representing sub-atomic positional control. This six-year effort extends prior translational ground state cooling work and demonstrates a scalable approach that favors larger particles, positioning levitated nanoparticles as a potential third pillar of quantum technology alongside superconducting qubits and trapped ions.
A levitated nanoparticle dumbbell has been cooled to its quantum ground state along two rotational axes for the first time, according to a paper published April 6 in Nature Physics. The result comes from physicists at the University of Vienna, TU Wien, and Ulm University, led by Markus Arndt, Uroš Delić, and Benjamin Stickler respectively, with Stephan Troyer listed as lead author.
The nanoparticle is a silica dumbbell composed of two fused spheres each 150 nanometers in diameter, containing on the order of 100 million atoms. Cooled to 20 microkelvin using coherent scattering cooling at 100 megawatts per square centimeter of light intensity, the rotor's orientation becomes uncertain by only about 20 microradians. For scale: the tip of the dumbbell wobbles less than one hundredth of an atom's diameter, and its angular position is known to better than the width of a bacterium.
The result extends a program six years in the making. Delić and Aspelmeyer achieved translational quantum ground state cooling of a levitated particle in Science 2020, demonstrating control over an object's position and momentum. The new paper tackles rotation: two librational modes corresponding to tilting in orthogonal directions. The prior rotational cooling record was one-dimensional, set by Lukas Novotny's group at ETH Zurich and published in Nature Physics in 2025.
The distinction that matters is the cooling method. Coherent scattering cooling uses a single intense laser to remove rotational kinetic energy directly via radiation pressure, without the multi-stage sympathetic cooling required in earlier work. The paper's own framing notes the approach scales favorably: larger particles are easier to cool this way. The implication is that the same technique could eventually reach molecules and molecular assemblies light enough to exhibit quantum wave behavior.
Levitated nanoparticle systems occupy an unusual position in quantum hardware. They are massive enough to potentially detect gravitational coupling effects but isolated enough from their environment to maintain quantum coherence for useful timescales. The field has described them as a potential third pillar of quantum technology alongside superconducting qubits and trapped ions, a framing that appears explicitly in a 2025 arXiv paper on nanorotor initialization.
The 2026 result does not settle what that third pillar will look like. Ground state cooling in two rotational modes is not coherent control, entanglement, or computation. The paper shows the particle is in its quantum ground state. It does not show what happens next. The researchers state they intend to push toward smaller structures, including entities roughly 100 times lighter than their current particle, where rotational quantum interference effects become potentially observable. Observing quantum interference is not the same as building with it. No levitated nanoparticle has been used in a quantum logic gate.
"This is a genuinely nice result in a system that has been trying to get here for a while," said a researcher in the field who asked not to be named. "The 2D aspect is real. Whether it changes anything practically depends on what you were planning to do with a levitated rotor."
The paper is in Nature Physics, DOI 10.1038/s41567-026-03219-1.
Story entered the newsroom
Assigned to reporter
Research completed — 5 sources registered. First 2D quantum ground state of rotation achieved in levitated silica nanorotor. Nano-dumbbell (2x 150nm spheres, ~100M atoms) cooled to 20 microkelv
Draft (507 words)
Approved for publication
Published (506 words)
Get the best frontier systems analysis delivered weekly. No spam, no fluff.
Quantum Computing · 2h 19m ago · 3 min read
Quantum Computing · 16h 19m ago · 3 min read
