The Gunners won courtesy of Noni Madueke, Gabriel Martinelli, Gabriel Jesus and an own goal.
Arteta said: "It was great. Straight away you could see that things were clicking. Players were really alive, really sharp. And yeah, we caused a lot of damage to them.
"Very happy we are in the next round. That’s what we wanted to achieve and I think the manner that we’ve done it as well, making a lot of changes. But the team showed a real desire first of all, which is the most important thing when you play these kinds of teams in the competition.
"Then cohesion, which normally is not there from the beginning because of the amount of changes that you’ve made. But the team, I think, played with a lot of intensity, great intentions to play forward, to constantly threaten the opposition, and we scored some incredible goals in the first half. That made a difference."
The win marked a 22nd clean sheet for the season.
Arteta also said: "It's a big number (22 clean sheets) obviously, and we’re still in February. So that’s the platform to win games. When you see we are 4-0, the ball is over and 10 players sprinting back, that’s the desire that you have to play with.
"The excitement is just for tonight. Tomorrow we start with Wolves and we know how tough that game is going to be in the Premier League. So let’s keep going."