Instead of expelling Jews without regard to their usefulness, starting as soon as Hitler takes power, Jewish scientists become well-kept prisoners of the Gestapo.
While many of them would of course refuse to work and be prepared to endure torture, Himmler hits on an idea: torture not the scientists, but rather Jewish children, in front of them.
Imagine:
Himmler ( holding a little girl under the chin) " Come now, Professor Einstein. Surely you wish to end this poor waif's pain? Surely your pride means less to you than her suffering? No? Very well."
(Himmler gestures to one of the SS men with him) " Come here. 'Play' with her."
Einstein " In God's name , NO! I will do as you ask!" (sobs)
Himmler " Of course you will , Professor Einstein. Get to work." (chuckles)
Nazis have the A-bomb by the Battle of Britain. London/Birmingham/Edinburgh nuked. Shortly thereafter the same fate befalls Leningrad, Stalingrad, Kiev, Minsk, and Moscow.
USA begins a crash program to develop a bomb. Japan ( shocked by the power of the A-bomb and fearful that Hitler will eventually repudiate their alliance because they are not white) does the same and avoids attacking the USA.
With no ICBMs to carry nukes, the USA and Japan concentrate on deploying swarms of fighters to shoot down anything approaching their territory.
The cold war ITTL is 3 way: Imperial Japan, Nazi Germany, and the world's remaining democracies led by the USA.