Understanding Quantum Mechanics #5: Decoherence

The physics survey that I mention is here:

If you want to know more technical details, this is a really excellent review article that will tell you all you ever wanted to know about decoherence:

[wholenutsanddonuts]

This is brilliantly described. So many physics teachers I had did such a poor job and in 12 minutes you finally got me to have a good intuition of decoherence. Thank you!

[rc]

Wow! If Sabine had dropped this a year ago, I would be lost. However, she has provided so many great videos building up to this that I can receive a valid familiarity with this important open question in physics.

Thank you very much Sabine!

[uvofsam]

Please just let this series continue

You are doing a great job
Thanks a lot really

[special-delivery]

I have a request. In your upcoming videos about the measurement problem, please shed some light on how such measurements are irreversible and might have something to do with the direction of time. I don’t know much about this but would love to know what our current stage of knowledge is about this issue. Thank you for your amazing videos.

[jamesblank]

An excellent video that frames the decoherence problem well. Thank you. That so many physicists don't understand there is a problem exemplifies apparently simple effects require detailed study. A problem must be fully understood if there is any hope of solution. Perhaps this is one reason fundamental physics discoveries have stalled.

Note: the ket-bra notation are touching so they look like a big X, which is visually confusing at first.

[thelocalsage]

Wow! What a succinct way of conveying this, I’d never even heard of a real mechanism for decoherence, and being able to peak at a bit of the math was very helpful. Fascinating!

[fluffy_tail]

Wow, finally a good explanation of decoherence, I never got how it would affect the measurement itself....because it doesn't in the end.

[jarnoldp]

I’m a physicist MS. You do a very good job breaking down the topics and illustrating the key points. Please keep up the good work.

Also, not to be too forward, but that dress works very well for you. Goes well with your eyes. I hope you have nice day.

[DanielL]

Best physics educator ! Thanks very much. The scope and level of your videos are perfect. You hit the key ideas and treat them in a serious and appropriate fashion while also making quantum mechanics comprehensible.

[michaelblacktree]

That was a very coherent explanation of decoherence. Thanks! 😎

[musicalfringe]

Nitpicks/clarifications:
7:31 - The animation actually illustrates e^(i*theta) with theta decreasing from pi/2 to -3*pi/2 . Ranging from theta to 2*pi would have the vector starting/ending parallel to the R axis and rotating anticlockwise.
9:12 - I believe she's saying that for one of the coefficients to be zero means that one or more PRIME-diagonal elements must also be zero, which it plainly is not in the wave function.

[DumblyDorr]

I do enjoy that you are one of the few science communicators who i) presents this extremely important idea (and presents it well!) and even more so that ii) you are one of the not-too-many physicists who take conceptual & methodological problems - and in general philosophy of science seriously (I was very glad about the references wrt Popper and Feyerabend during the recent two discussions - would have loved to throw Lakatos, Duhem-Quine, Sneed and Suppes in there).

Thank you for both of those things - they are very much appreciated :)

[FractalTeapot]

You are truly a gifted teacher - clear, vivid and direct. Thankyou! 🙏

[HidekazuOki]

This is an absolutely EXCELLENT VIDEO! Thank you!!!

[thePronto]

When you showed me a Danish, I instantly thought: "It's been a long time since I had a nice cup of coffee and a pastry in a nice coffee shop." But then I remembered why...

[hesitantjaguar]

I stopped eating squid when I realized they had simian level problem solving abilities. It seems now that my love of pastries has come to an end, Danish are obviously intelligent enough to participate in surveys.

[EugeneKhutoryansky]

The survey mentioned at the beginning of the video was biased based on the list of options given to the respondents. If it had instead given a reasonably comprehensive list of philosophical interpretations of Quantum Mechanics, and asked them to pick their favorite, or to pick "other", then the percentage who would have picked "decoherence" would be much smaller.

[MrDecato]

This is awesome. Thanks for these videos. Just a small nitpick: I think the complex phase angle is measured from the +ve real axis and in counterclockwise direction (there is an animation that shows it from the complex axis and clockwise direction).

[mrgadget]

I've never seen decoherence explained as simple and beautifully as you did. This concept was introduced to me in Quantum Statistics course in the context of ensembles - very different kind of approach.

[alexaserna]

Thank you so much! really. With this video I remebered why I love the pyshics <3 I finally understood why exist the differenciation between the classical an quantum theory and why it's so important to understand the wuantum theory. You have helped me regain my motivation to continue studying. <3 loveee for you
As soon as possible, I support you!