Physicists at the University of Oxford have created a new type of quantum state that could help advance quantum computing and deepen our understanding of the strange rules of the quantum world.
The research builds on one of the most famous ideas in physics: Schrödinger’s cat.
Proposed by physicist Erwin Schrödinger in 1935, the thought experiment imagines a cat that is both alive and dead at the same time until someone looks inside the box.
While no real cats are involved in modern experiments, the idea illustrates a key feature of quantum mechanics—the ability of particles and systems to exist in multiple states at once.
Scientists can create real versions of these quantum superpositions in the laboratory.
These states are important because they form the foundation of quantum technologies such as quantum computers, highly accurate clocks, and advanced sensors.
In a traditional quantum computer, information is stored in quantum bits, or qubits. Unlike ordinary computer bits, which are either 0 or 1, a qubit can exist as both 0 and 1 at the same time. However, quantum systems can be much more complex than simple qubits.
Many physical systems, including light, vibrations, and the motion of particles, behave like what physicists call quantum harmonic oscillators. These systems can occupy many different energy levels, allowing scientists to create a wider range of quantum states.
One well-known example is a “cat state,” where a quantum system exists in a combination of two distinct states at the same time. Traditionally, these cat states are built from special quantum wave packets known as coherent states.
The Oxford team developed something new. Instead of using these standard building blocks, they created a whole new family of quantum superpositions using highly unusual and strongly quantum states. Some of these states involve “squeezing,” a process that shifts quantum uncertainty from one property to another.
To create the new states, the researchers used a single trapped ion—an electrically charged atom held in place by electromagnetic fields. The ion has two important quantum features. Its internal state behaves like a qubit, while its motion acts like a quantum harmonic oscillator.
The team carefully linked, or entangled, these two quantum properties. They then performed a special measurement that allowed them to shape the ion’s motion into a desired quantum superposition.
According to the researchers, the method gives them remarkable control over the final quantum state. By adjusting experimental settings, they can change the size, orientation, and separation of different components within the superposition.
The scientists confirmed that the states they created were truly quantum by measuring characteristic interference patterns and other signatures that cannot be explained by classical physics.
The discovery could have practical benefits in the future. Some of these new quantum states may be better at resisting errors, one of the biggest challenges facing quantum computers today. They could also make error correction simpler and more reliable.
Beyond technology, the work provides a new way to explore one of science’s deepest mysteries: where the familiar classical world ends and the strange quantum world begins. The researchers believe they have only begun to explore the possibilities offered by this new family of quantum states.
