A team of physicists at Caltech have discovered a new way to use the natural motion of atoms to store and process quantum information
The research, published in Science, demonstrates the first observation of “hyper-entanglement” in massive particles, such as neutral atoms, opening new avenues for quantum computing and precision measurement technologies.
Led by Caltech physics professor Manuel Endres, the researchers used devices known as optical tweezers, highly focused beams of laser light, to trap and manipulate individual atoms in a tightly controlled array.
Precision control with optical tweezers
These tweezers allowed the team to isolate and precisely control the motion and internal states of alkaline-earth atoms, which are key building blocks for emerging quantum systems.
Typically, the slight jiggling of atoms due to thermal motion has been viewed as a nuisance, making it challenging to maintain the delicate quantum states required for computation or measurement.
But instead of fighting this motion, the Caltech team turned it into a feature. They used it to encode quantum information and create a highly correlated quantum state between atoms.
Quantum Maxwell demon cooling
Their method involved cooling atoms to almost a standstill using a new approach similar to a quantum version of the famous “Maxwell demon” through experiment.
By measuring the motion of each atom and actively correcting any deviations, the team achieved a level of cooling that surpassed even the most advanced laser cooling techniques. This step was critical for achieving the precise control needed for the experiment.
Once cooled, the atoms were made to oscillate like tiny pendulums, but in a quantum twist, each atom was placed in a superposition of two distinct motions simultaneously. This quantum superposition means the atoms were effectively swinging in two directions at once, a behaviour with no classical analogue.
Enlargement over distance
Building on this control, the team entangled pairs of atoms so that their motion became interconnected, even over distances of several micrometres.
More impressively, they achieved hyper-entanglement, a complex quantum state in which two distinct properties of the atoms were entangled simultaneously. In this case, both the motion of the atoms and their internal electronic states were entangled across pairs of atoms.
This dual layer of entanglement increases the amount of quantum information that can be stored and manipulated using each atom. In practical terms, it means that future quantum machines could achieve more with fewer resources, a key step toward scalable quantum computing and simulations.
Beyond computation, the results have implications for high-precision measurements, including the development of ultra-accurate atomic clocks. The techniques developed in this study also provide a foundation for simulating complex quantum systems, potentially offering insights into the fundamental workings of nature.
![Figure 1: Sketch of the evolution of the Universe over the last 13.77 billion years. It started with the Big Bang, followed by an extremely short period of rapid exponential expansion. The furthest we can see is the cosmic microwave background, when radiation decoupled from matter, approximately 380,000 years after the Big Bang. This is followed by the ‘dark ages,’ during which this radiation redshifted from the visible regime into infrared and sub-mm wavelengths. The occurrence of the first stars, about 400 million years after the Big Bang, ended this phase, spearheading the formation of galaxies as we see them today. [Credit: NASA/WMAP Science Team, public domain]](https://www.openaccessgovernment.org/wp-content/uploads/2025/05/Fig-1_1200-100x70.jpg "How did the first stars form in space?")
