Subir Sachdev Public Lecture: Quantum Entanglement & Superconductivity
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- Опубліковано 20 жов 2024
- Dr. Subir Sachdev (Perimeter Institute and Harvard University) delivers the kick-off lecture of the 2014/15 Perimeter Institute Public Lecture Series, in Waterloo, Ontario, Canada. Held at Perimeter Institute and webcast live worldwide on Oct. 1, 2014, Sachdev's lecture explores the fascinating and surprising connections between quantum mechanics, the phenomenon of superconductivity, and string theory.
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Very interesting insight into superconductivity, strings and entanglement if not about the true nature of QM. Thank you Subir.
Sean Hartnoll showed how BH is a superconducting entity while Maldacena showed how BH and entanglement function together. Sean took a step further to show how the BH have a coating of charges around the BH, acting like a stator of a motor, while the BH is the rotor (made of quarks and gluons), resulting in huge currents that spins the BH very fast.
Did you miss last night's public lecture? Here it is. Enjoy, share, and discuss!
"we dont know"...that statement just swells up my confidence in the speaker...for when we admit we are lost only then can progress be made
Got in at number 2 for viewers! This is up my alley, quantum physics and entanglement! I know I am not a scientists, but this stuff fascinates me. Multiple universes, no way, but this is cool. Thank you.
This PI institute is a dream came true for a millenium, both people called millenials and the also called timed thousand years. Hope i'll probably visit you flying out from here, Brazil. Maybe something with music waves and creating reality.. why not? Congrays and thnks
1. Holes in the AFM separates the spins as we separated the electrons in thd H molecule one on the earth abd another on the moon and we get the EPR pair.
2. Certain flavours of this entanglement (they do not move. They just exchange partners) combinex with the holes give rise to HTC.
48:10 That's interesting. Maybe I do not know much about string theory, but I always thought that "D" in D-brane is for Dirichlet boundary conditions, not D-dimensional. Anyhow, funny thing is, I got interested in string theory mainly because of prof. Sachdev's work :)
Yes, that's what Suskind says. It is "p-dimensional" and referring to a D-brane of specific dimensionality is called a "p-brane". So he's using a different variable name for the second name.
I never thought to do this until recently , but if you go to PI's Internet site , all the public lectures are there. There's like twelve pages with eight to ten talks on each page, I've seen all of them so if anybody knows of any good shit out there.... let me know .
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42:18 how the electrons moving in the lattice of Cu sites in YBCO entangle in strange ways leading to not only the quantum critical points, where the patterns that I showed you in the phase diagram disappear, but also HTc.
very difficult 'stuff' for a beloved amateur physics hobbyist. BUT, yet, a very illuminating lecture---truly. (D-Brane>>think of a pane of one way glass&put 5fingers on it. the hand moves the tips, but on the brane, the tips SEEM to move without cause.)
Nice video, learned a lot, speaker visited our institute, but I wasn't able to learn any thing from him, that time.
Really enjoyable lecture. I found about prof. Sadchev in quantum magazine article.
You should have added a theremin sound effect during the levitation experiment.
This is for PI. I am subscribed to PI and should hope to have been 'recommended' long ago. Could PI can make it possible to avoid future mistakes of this nature. Thank you.
If anybody didn't see the lecture on the neutrino SNO lab it was fucking awesome I just saw it.
Link please.
Art Mcdonald public lecture ; a deeper understanding of the universe from 2 km deep. It's a PI lecture .
Bill Hampton
Thanks.
My comments on Dr. Sachdev's lecture appear to be deliberately blocked to the public. Anyone know why?
At "Shrodinger's Cat (Sort of) Explained" I explained why the "mysteriousness" of Quantum Superposition is a crock:
==
Wave-particle duality doesn't exist. It is a misinterpretation of data that results when one rejects the concept of an "aether". Proof of aether is that an electron passing through a shielded wire generates an EM wave which is detectable even in a vacuum. Obviously the electron is separate from the wave. Much like a boat is separate from the wave it produces. It is not a wave-boat duality.
As you should be aware, a wave is the result of the compaction and expansion of a medium. Suggesting that even in a vacuum there is an underlying substrate ie. aether. Just because air is transparent, doesn't mean it isn't there. Just because we can't see aether doesn't mean it isn't there. Modern science is finally coming back around to the idea that a vacuum (empty space) isn't empty.
Thus in the "famous double slit experiment" which seemingly defies logic, what is actually happening is the wave fronts, split into 2 by the slits, combine on the other side to form a standing wave pattern. Which the photons position themselves on, revealing the interference pattern of the waves they created but are separate from. With one slit, no such interference pattern arises because there are no interacting waves.
==
Electrons and photons aren't waves. Rather they have waves associated with them because of their movement.
In Dr. Subir Sachdev's coverage of Quantum Superposition, he claims that QS is a strange property that "has no classical analog. So Newton would have no idea what you're talking about. Because you can't deform Newton's laws in anyway to get QS." He "proves" this with the double slit experiment using electrons where the interference pattern mysteriously disappears when light is shined on it. That this is somehow unexplainable using classical mechanics.
Wrong!
Why? Because whether it is electrons or photons generating the interference pattern, the medium, aether, is the same. So just like a boat causes waves in water and a rock dropped in causes waves in water, a rock dropped in water can mess up the wave pattern caused by a boat. Or photons can mess up wave patterns in aether caused by electrons AND vice versa.
It would be unexplainable if the interference pattern had remained.
There's nothing counterintuitive about Entanglement. In Dr. Sachdev's example a hydrogen molecule is used to provide the two entangled electrons. Since the electrons by necessity to form a hydrogen molecule have opposite spin, it makes sense that when removed from the molecule, they would maintain their opposite spins (unless acted upon) regardless of the distance that separates them. So if one determines the spin of one electron, one then knows the spin of the other (which will be opposite).
If you have two coats, one red and one green and you go out wearing one. Guess what, if someone checks your closet and finds the red one there, then they "instantaneously" know the color of the coat you are wearing regardless of where you are. "Spooky"? Counterintuitive?
Well that is what the introduction for "quantum entanglement and superconductivity" stated:
"Einstein called it “spooky action at a distance.” Entanglement is a counterintuitive feature of quantum theory by which two particles are deeply correlated even when separated by vast distances, such that a measurement of one particle instantaneously determines the state of another."
I think the problem lies with math's disconnect from reality. At "Shrodinger's Cat (Sort of) Explained", I explained that, "The problem with physicists is that they confuse math with reality. Probability vs. actuality. Instead of Shrodinger's Cat you can flip a coin and hide the result. Math tells you it exists in a 50/50 state. Reality (familiar classical concepts) tells you that it is either heads or tails, not both."
Dr. Sachdev's lecture is an attempt by a theoretical physicist to explain superconductivity using theoretical physics. So we are presented with superposition (the mechanism which isn't explainable by theoretical physics) and entanglement (the mechanism which also is not explainable by theoretical physics) to explain superconductivity which might not be explainable if the bases for it aren't.
Personally, I would have preferred that Dr. Sachdev explained what causes resistance and normal conductivity using classical means and then tried to explain superconductivity in the same manner. For example, he could have explained why aluminum is a conductor at normal temperatures and then explained why it becomes a superconductor when it is cooled. And then proceeded to try to explain how YBCO may work. But classical physics isn't his forte.
Entanglement and nonlocality can be understood in terms of scale invariant quantum impedances (quantum Hall impedance is the most obvious example), which cannot communicate energy/information, but rather only quantum phase. See
vixra.org/abs/1303.0039
"Quantum Impedances, Entanglement, and State Reduction"
cool!
i'm not sure i understand. is he not explaining well enough? what's surprising about looking at one electron, seeing its spin state and thus knowing the other electron's state?
You are only seeing what states they are in.
Now if you said you forced a state that'd be different. force the local one to be up then we're forcing the remote one down. now that's something.
but he's not saying that is he?
he seems to be just saying that we force only that the local electron adopts a spin and this forces the other to adopt a spin.
the surprise being that the 'collapse' from a state of superposition is transmitted instantly to the remote one. Right?
is that the surprising thing? is that what he's saying?
+Steve Bergman
Firstly: thankyou for attempting to enlighten me. I need enlightenment that's for sure, but whether it will ever be possible to enlighten me is a different matter.
Anyway, these are the thoughts in my head:
If there's no way to transmit information then no information was transmitted and if it takes information to be transmitted for the instantly decided state of one particle to influence the state of another it therefore did not happen and another explanation must be found?
I don't understand the 'collapsing wave function'. I know it is a phrase used everywhere all the time but I can't see it. A wave function is a mathematical expression of relationships I think. i.e. various factors are measured and related and that's the function.
In maths you can 'collapse' the function but in reality something else is happening. It's mixing maths and reality. When an ocean wave collapses we don't say the wave function collapsed we say the wave collapsed.
How much correspondence can we find between our ocean waves and this wave function? Any at all? Is there any correspondence between say the action of an ocean wave when it hits a high breakwater it cannot surmount and loses its identity as a wave entirely (does it?) ? Has it then passed into a different state somewhat analogous to the state of a particle?
But I suspect that this wave function in a superposition of states is a mathematical entity to be understood only by those with adequate mathematics training. I don't have that.
If so I should be told so.
How do we know it is in the 'superposition of states' if it has not had its state measured? I know this is a question that has been addressed I'm just ignorant of what the answer is. So for me it is not answered yet.
How much rubbish did I just speak then?
"Remember, until the measurement is made, neither particle has a definite spin state"
Wrong. Read my comment regarding Entanglement on this page. Each particle has a definite spin state but we don't know what it is/was until we measure it. We aren't causing it to achieve a state.
You have a name. Someone meets you and until you tell them your name, it could be any of hundreds (thousands?) of possibilities to them. So if you tell them your name, is it they who have determined your name from those many possibilities? Ie. Did they give you your name?
"The surprise here is that measuring the spin state of the particle on Earth can instantly collapse the wave function for the other particle,"
Sure call it a "collapse of wave function". I call it a "Duh" moment, as in "if this coat is red then the other must be green", duh.
Basically entanglement is a fictional result of math which is itself a fabrication designed to model reality but can also model fantasy. If one doesn't distinguish between math and reality, one can easily get lost in mathematical fantasy as happens in theoretical physics.
@Arthur Brogard
Read my comment to Steve Bergman.
"It's mixing maths and reality."
Yes. There is math and then there is reality. Many people confuse the two. Ie. They think math is reality or vice versa.
"But I suspect that this wave function in a superposition of states is a mathematical entity to be understood only by those with adequate mathematics training. I don't have that."
You don't always need math to understand reality. Common sense and logic work fine. Smell the rose, watch the sunset, don't waste your time on the math involved.
"How do we know it is in the 'superposition of states' if it has not had its state measured?"
It is human ego and arrogance that suggests that spin states and possibly the very existence of the universe depends on human acknowledgement. After all, the math proves it.
Prof. Sachdev's a bit nervous (seems to be) when he's doing the experiment
just need to breathe sir. :)
what kind of wink noise was that lol. #tink
Sets a jaw-droppingly terrible example for safety, holding a cup with bare hands while pouring liquid nitrogen into it/out of it.
With all due respect but I think this was a poor lecture. Here the speaker is talking about not well understood quantum weirdness and the highly inconsistent string theory as means to “explain” superconductivity, which he himself does not understand, his words. So the result of all this seems to be a messy entanglement between quantum and string theories? I pity his students.
These rich people wasting liquid nitrogen and here in India we don't get liquid nitrogen for experiment purpose....
Glad he's not a surgeon