Artist’s impression of a platform for linear mechanical quantum computing . The central transparent element is a phonon beam splitter. Blue and red marbles represent individual phonons, which are the collective mechanical motions of quadrillions of atoms. These mechanical motions can be visualized as surface acoustic waves coming into the beam splitter from opposite directions. The two-phonon interference at the beam splitter is central to LMQC.
In first-of-their-kind experiments, a research team at the Pritzker School of Molecular Engineering took critical steps toward creating a linear mechanical quantum computer. Credit: Joel WintermantleIn the experiments, researchers used phonons that have roughly a million times higher pitch than can be heard with the human ear.
The team found a way to maintain that superposition state by capturing the phonon in two qubits. A qubit is the basic unit of information in. Only one qubit actually captures the phonon, but researchers cannot tell which qubit until post-measurement: In other words, the quantum superposition is transferred from the phonon to the two qubits.
Importantly, the same happened when the team did the experiment with phonons – the superposed output means that only one of the two detector qubits captures phonons, going one way but not the other. Though the qubits only have the ability to capture a single phonon at a time, not two, the qubit placed in the opposite direction never “hears” a phonon, giving proof that both phonons are going in the same direction. This phenomenon is called two-phonon interference.
“Those atoms all have to behave coherently together to support what quantum mechanics says they should do,” Cleland said. “It’s kind of amazingCreating a new linear mechanical quantum computer