Interestingly, Paul Krugman after getting his doctorate from MIT, served on Ronald Reagan's Council of Economic Advisers. Whether Krugman approved of "trickle down" at the time, I don't know, but since then he has written extensively for the popular audience that "trickle down" or supply side economics is a hoax to justify tax cuts for the wealthy. His Nobel Prize was for development of mathematical models in international economics, 

To my knowledge Krugman had no official role in the Fed policy of low short-term interest rates and quantitative easing, although he defended those at home and abroad, where higher bank rates were causing deflation, and he may have swayed the Euro bank to stimulate with low rates. But Ben Bernanke was the force behind low overnight rates and QE, the buying of bonds. Conservatives said hyperinflation would result, but it did not. As it turned out, those rates didn't need to be lowered any further, were that possible (some nations tried it).