The images were generated using a stencil of a cat and entangled photons. The spooky part is that the photons that generated the image never interacted with the stencil, while the photons that illuminated the stencil were never seen by the camera.
When two separate particles are entangled, measurements of their physical properties are correlated, and they effectively share a single quantum state. Gabriela Barreto Lemos at the Austrian Academy of Sciences in Vienna and her colleagues used this quantum connection between particles to make images of a cat without directly photographing it.
To do it, the researchers created yellow and red pairs of entangled photons. The yellow photons were fired at the cat stencil, while the red photons were sent to the camera. Thanks to their entanglement, the red photons formed the image of the cat because of the quantum link to their yellow twins.
The silicon stencil was transparent to red light and the camera could only detect red light. This demonstrates that the technique can image objects that are invisible to the detected photons.