About the paper "Traversable wormhole dynamics on a quantum processor" Recently a paper titled "Traversable wormhole dynamics on a quantum processor" was published in Nature.
From what I understand they are simulating these wormholes (dual of an $AdS_2$ wormhole) using a quantum computer.
This is being sold as a "step towards a program for studying quantum gravity in the laboratory".
Is their experiment classically simulatable though (it seems to be a quantum circuit with 9 qubits, which would be simulatable)? If so, how does it specifically help with studying quantum gravity?
 A: It is just a calculation with 9 (noisy) qubits, easily simulated on a classical computer. There is no reason to do it on real quantum hardware except to demonstrate that the hardware functions as designed. (Or, less charitably, so that it can be hyped up in press releases.)
Peter Woit writes:

Almost all the calculations in the paper were done on paper or on a classical computer. As far as I can tell, all they did was perform elaborate SYK calculations on a classical computer, together with simulations of noise on the Google quantum computer, trying to find a possible calculation on the quantum computer that would have signal, not just noise. Once such an N=7 SYK calculation was identified, they used a 9 qubit quantum computer and the noisy result matched the simulation result from the classical computer, exactly as expected.

Andreas Karch, a particle physicist, wrote on Twitter:

What’s interesting about SYK is that it’s a solvable and well understood QM system. I don’t think we’ll learn anything about it from this. And we surely will learn nothing of use about the gravity dual. We already learned what SYK can teach us without simulating.
Experimentally it's of course cool they can do SYK - as a demonstration they have control over their device. They can couple 9 qbits in a pre-specified way. But I guess we knew they could do this before. Going after SYK in particular, in my mind, is mostly a publicity stunt.

