All I found was our military disclosed info about their B-41, which had a maximum output of 25 megatons.
But, the article said the B41 output to weight efficiency was better than the tech behind the Russian Tsar Bomba.
Is there any evidence the US military actually created a nuke greater than 50 megaton output, as a one-up to Russia?
The US did not make weapons larger than 25 megatons. They did contemplate weapons in the range of the Tsar Bomba. So there were efforts to develop a 60 Mt weapon (shut down by Eisenhower) and there was serious study of gigaton-range weapons (1,000s of megatons, also shut down), and there were studies of making a 50 or 100 Mt weapon after the Soviet one was tested (again, abandoned). The US could easily have done it and by the estimation of the scientists done it with much better efficiency than the Tsar Bomba. (Note that efficiency is about the yield-to-weight ratio — it means they could get the same output in a weapon that weighed less.)
One of the consequences of signing the Limited Test Ban Treaty in 1963 is that it effectively ended any efforts in the US for "very high yield" (as they called it) weapons (e.g. 50 Mt and up). This was something actively discussed in both classified and open sources at the time. The Kennedy Administration argued that high-yield weapons were not the future of weapon design and thus this wasn't really a sacrifice. They also set up a program so that if the Soviets broke the LTBT, they'd be able to test designs that would give them information about high-yield weapons — so the program did live on in a sense for awhile. But they never tested or fielded anything more than 25 Mt. Instead they developed weapons that had very good yield-to-weight ratios in very compact packaging, and then improved on delivery vehicle accuracy and capabilities (MIRVing, etc.). The modern American (and Russian) stockpiles reflect these priorities, not those of the "very high yield" mindset.
Hi there -- you may be interested in these previous answers from u/restricteddata on the Tsar Bomba and how US nuclear weapons engineers viewed it: