Place sous vide circulator in a large pot of water (the warmer the water, the faster it will reach your desired cooking temperature) and set to 145F (or 152F for more well-done turkey). If doing a large batch of turkey breasts, I recommend using a large plastic tub instead of a pot.
Place turkey breasts on a cutting board and rub each piece with olive oil, salt, and pepper.
Place seasoned turkey breasts into their own zip-loc bags, add a sprig of rosemary to each, and vacuum seal. If you don't have a vacuum sealer, slowly lower zip-loc bag into pot of water, pressing out all the air and slowly sealing tight.
Once fully sealed and the water has warmed to 145F, place bags with turkey breasts into the large pot of water (or plastic tub) making sure it is fully submerged.
Allow to cook for 2-2.5 hours. I found mine were perfect at 2 hours, but it's always good to use a meat thermometer just to be safe.
Remove cooked turkey breasts from bag and pat dry with a paper towel.
If desired, sear turkey breasts in a pre-heated cast-iron skillet.