# What is D-Wave's “Pegasus” architecture?

How is D-Wave's Pegasus architecture different from the Chimera architecture?

Pegasus is the first fundamental change in D-Wave's architecture since the D-Wave One.

The D-Wave Two, 2X, and 2000Q all used the "Chimera" architecture, which consisted of unit cells of $K_{4,4}$ graphs. The four generations of D-Wave machines just added more qubits by adding more and more unit cells that were the same.

In Pegasus, the actual structure of the unit cells has fundamentally changed for the first time. Instead of the Chimera graph where each qubit can have at most 6 qubits, the Pegasus graph allows each qubit to couple to 15 other qubits.

A machine has been made already with 680 Pegasus qubits (compare this to 2048 Chimera qubits in the D-Wave 2000Q).

The work was presented by Trevor Lanting of D-Wave, four days ago:

• Oh, did you attend AQC? I was there also. – Andrew O Jun 29 at 21:52
• I got these pictures from my Wife because I was at a different conference in Chicago. – user1271772 Jun 29 at 21:53
• It would have been nice to meet in person though!! – user1271772 Jun 29 at 22:23
• You can generate Pegasus graphs with D-Wave's version of networkx now. Combined with their minorminer algorithm you can check if your problems will embed on their new architecture: github.com/dwavesystems/dwave_networkx/commit/… – Mark Fingerhuth Jun 30 at 1:32