Comment on Electrons
i_love_FFT@lemmy.ml 5 weeks agoIt’s either up or down whatever the direction.
If you measure 100%up-0%down then you rotate your frame of reference by 90°, you automatically get 50%up-50%down… (iirc)
Comment on Electrons
i_love_FFT@lemmy.ml 5 weeks agoIt’s either up or down whatever the direction.
If you measure 100%up-0%down then you rotate your frame of reference by 90°, you automatically get 50%up-50%down… (iirc)
Ziglin@lemmy.world 5 weeks ago
Just in case it wasn’t clear you can’t measure anything other than “100%” up or down spin. The quantum state of it being 50/50 is described by 1/sqrt{2} times the up and down vector, when you measure it you have a probability of getting either result calculated by the square of the absolute (||psi||^2) that way you avoid getting a complex probability.
btw I was too scared to try in case it doesn’t but can I use LaTeX in Lemmy comments? $\psi$
i_love_FFT@lemmy.ml 5 weeks ago
True! Thanks for the clarification, it’s been a while since i played with the maths of quantum physics!
After you measure a spin as 100% up, the state will be close to that for a while, si the next measurement has higher chance of being up, with this probability slowly decreasing with time.
Ziglin@lemmy.world 4 weeks ago
I think that assuming the particle has no (extra?) energy it’s state does stay the same. That is of course not possible in real life though but the <20 millikelvin in some quantum computers get pretty close.
Also I think nobody says they measure it as 0/100% up, They just say up or down in my limited experience.
Does anyone have any good resources on quantum mechanics? (Most of my information comes from a few professors) There’s some useful stuff on chem libretexts (I think that’s what it’s called) for simple wave functions, but it doesn’t seem perfect.
i_love_FFT@lemmy.ml 4 weeks ago
I have old college textbooks in my library, Cohen-Tannoudji. I’m not sure about online resources though…