Researchers at the University of Oxford have demonstrated a new type of quantum interaction using a single trapped ion. By creating and controlling increasingly complex forms of “squeezing” – including a fourth-order effect known as quadsqueezing – the team has, for the first time, made previously unreachable quantum effects experimentally accessible.

The approach also provides a new way to engineer these interactions, with potential applications in quantum simulation, sensing, and computing. Their results have been published in Nature Physics.

Many systems in physics behave like tiny objects that vibrate or swing back and forth, like a spring or a pendulum. In quantum physics, these are known as quantum harmonic oscillators. Light waves, vibrations in molecules, and even the motion of a single trapped atom can all be described in this way. Controlling these systems is important for quantum technologies, from ultra-precise sensors to new kinds of quantum computers.