🐱 Oxford Physicists Just Made Schrödinger’s Cat Even Weirder

Schrödinger’s cat was never really about a cat. It was a way to show how strange quantum mechanics becomes when one object is treated as being in two states at once.

Now physicists at the University of Oxford have created a new family of “cat-like” quantum states — but with an extra twist: the two parts of the superposition are not ordinary, classical-looking wave packets. They are already deeply quantum objects.

In standard lab versions of Schrödinger-cat states, researchers usually combine coherent states — the closest thing quantum physics has to classical motion. The Oxford team went further. Using a single trapped strontium-88 ion, they built superpositions from squeezed, trisqueezed and quadsqueezed motional states: exotic states where quantum uncertainty is reshaped in unusual ways.

The setup is elegant. The ion’s internal electronic state acts like a qubit, while its motion behaves like a quantum harmonic oscillator — a system that can occupy many energy levels. By entangling these two parts and then performing a mid-circuit measurement, the team could “sculpt” the ion’s motion into highly programmable quantum superpositions.

Why is this interesting?

• The states are built from nonclassical components, not just classical-like wave packets
• Their size, orientation and separation can be tuned experimentally
• Wigner-function measurements showed interference and negativity — signatures of genuinely quantum behavior
• Some states displayed striking geometric patterns, including sixfold symmetry in a trisqueezed example
• At the same average energy, these states can be more “quantum-resourceful” than standard cat states or Fock states

This matters because future quantum computers may not rely only on simple qubits. Quantum oscillators can store information across many energy levels, opening a richer route toward bosonic quantum error correction — where information is encoded in oscillator states rather than many separate physical qubits.

It is still early-stage physics, not a ready-made quantum computer. But it gives researchers a new way to build, control and study quantum states that sit far beyond everyday intuition.

And it brings us back to the original question Schrödinger wanted to provoke:

Where does the quantum world end — and the classical world begin?

Source: https://doi.org/10.1103/k1xk-yt42

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