Quiet time training. It does require some time but is so worth it. I would recommended getting your wife some time off in the evenings when you can keep an eye on the littles until your child does better at it.
I started by laying out a blanket on the floor in the same room that I was in and giving our child a few quiet toys/books to play with. Tell the child to stay on the blanket and play quietly. For the first day, time them - see how much time they will stay there naturally. After that, start with that amount of time and work up to how much you want/need. At first this will require your wife to supervise constantly and redirect as needed. Best done by having something to work on so it looks like you are not just watching your child - but the "work" needs to be easily interrupt-able so your wife can stop quickly/easily to redirect. But the child should move fairly rapidly to being able to do it without constant input. I do recommend always staying somewhat nearby though - if the child is able to get off the blanket, wander around, do other things, etc, the reward is now too great for getting up and they will continue to do so.
At first, they might throw all the toys/books off the blanket and try to get up to get them. But if you require them to stay on the blanket until the determined time, they will quickly learn to keep the toys so they don't get bored. It's good training for imagination too - they learn many many ways to use different toys when given the quiet, time, and limits. I do recommend that mom picks the toys and gives a limited amount but good variety. Rotate the toys given too to keep them interesting.
I was able to train our kids to do a quiet time for 1-1 1/2 hours a day by the time they were 3-4 (we started at age 1-2 - it's even easier if you teach them to play quietly in their playpen/crib before they can climb out). It also comes in handy at Doctor appts, while waiting at restaurants, waiting for planes, etc. Once they've learned to sit and play quietly that will transfer to all those other situations also.