I found this interesting app in Google Play Store: it’s a mobile drag-and-drop quantum circuit builder. Although it doesn’t connect to any real hardware, it looks like a really fast and easy way to test circuits while on-the-go.

Two notes:

1. I used an Identity gate because multi-qubit gates otherwise slide to the left and connect diagonally. The results still look good, but the circuit itself looks weird.

2. There is a built-in SWAP gate, but I used 3 CNOTs to give the app a slight test.

It’s also weird to see non-spherical Bloch spheres, but the results nonetheless look good.

DISCLAIMER: I did not exhaustively test this app. I ran the basics: entanglement, GHZ, and so forth. And, the basics look good.