A new quantum oscillator encodes a qutrit protected from phase-flip errors

Driving a nonlinear quantum oscillator with three photons at once produces a ground state that is a superposition of three macroscopically distinct states — a three-legged cat. Unlike standard cat states, these carry an unusual squeezing that can be dialed up, down, or flipped in sign just by tuning the drive frequency. The threefold degeneracy of the ground state naturally protects encoded quantum information against phase-flip errors, pointing toward a hardware-efficient route to error-protected qutrits.