The tech that makes green laser pointers work might be accidentally creating 'Schrödinger's cat' states of light.
March 26, 2026
Original Paper
Towards Schrödinger Cat States in the Second Harmonic Generation
arXiv · 2603.24067
The Takeaway
Creating macroscopic quantum superpositions (cat states) usually requires extremely delicate and complex equipment. This study shows that the standard process of 'frequency doubling'—changing one color of light to another—can naturally push light into these exotic, non-classical states.
From the abstract
We investigate the quantum evolution of the pump field in second-harmonic generation under strong pump depletion. Starting from a coherent state, the pump develops a nonclassical phase-space structure resembling a Schrödinger cat state. This behavior originates from phase instability induced by vacuum fluctuations of the harmonic mode. A rigorous quantum analysis has been performed for mean photon numbers up to $\langle \hat n \rangle = 100$ in pump mode. For larger photon numbers, up to $\langl