From the image caption:

Biphoton state holographic reconstruction. Image reconstruction. a, Coincidence image of interference between a reference SPDC state and a state obtained by a pump beam with the shape of a Ying and Yang symbol (shown in the inset). The inset scale is the same as in the main plot. b, Reconstructed amplitude and phase structure of the image imprinted on the unknown pump. Credit: Nature Photonics (2023). DOI: 10.1038/s41566-023-01272-3

Edit: Sounds like this is actually observed, but I don’t believe this is something one can “see”. The images are constructed from the difference between two states: one a reference state and the other being the state as captured by a pump. This isn’t all different, as I understand, than capturing light in film or a photo sensor: the reference state being the film/sensor detecting no light and the second state being when it exposed to light.

The bigger black and white on the left is the "double exposure" of both the reference state and the unknown state and is observed. But the Yin Yang you see is the shape of the pump beam, which is the smaller black and white inset on the left. The colored one on the right is the reconstructed unknown state (that is, it is computed from b&w one and the reference state (not shown))