What can be done to limit the brain-drain of our best physicists to foreign shores?

Who is 'our'? What country are you even talking about? Countries don't own physicists. Are you concerned about physicists leaving the country where they became physicists? Where they were born? Why is it a problem? I would want research physicists to go wherever they can best do their work. If their country is oppressive, or if their collaborators are elsewhere, they should go elsewhere. If a country considers applied physicists to be of value to their society, they should see to it that the environment is conducive and attractive to them, and that they are suitably rewarded.