#qotojournal
I am a #Berlin based quantum information scientist with a Masters degree in #physics. My research topic is quantum computing and if you have any questions about it feel free to reach out. In my free time I am interested in demography, climate change, psychopharmacology, biophysics, IT security, computers in general and trying out various shades of lipstick. I toot mostly in German, sometimes in English, depending on the topic and my mood. And yes, I belong to the lazy species of people that comments their code in their native language, in my case German.
@sycramore
I am interested of quantum science.
Could you explain how entanglement works and why information is not transformed between particles with higher speed than light´s speed limit according Einstein?
@humandemocracy Ok, I got a pretty laptop on my hands now.
So the main core about entanglement is that it is dependent on the basis one measures in. Given the so called Bell states, 4 maximally entangled states, you could just switch the measurement basis from the normal computational basis to the Bell state basis. In this basis none of the Bell states would be entangled, but the computational basis is.
Why is this important?
Information "transfer" via entanglement describes quantum protocols where one of the qubits is measured in one basis by Alice and then the other qubit is measured by Bob (or vice versa). If Alice measures first, her outcome is completely random but Bob's outcome is predetermined given that he measures in the same basis as Alice. But the information exchange relies on knowing who chose which basis.
If they communicate the basis choice beforehand they have already exchanged all information about the process. If they communicate their basis choice after the measurements they need to communicate it classically. In that case the communication is only as fast as the communication of the basis choice. This is why you cannot communicate information superlumically fast.
There is another thing though. You can design a strategy to win games with higher probability when all parties share an entangled state over multiple qubits. This is called pseudo telepathy and allows for something "communication like" (the communication to share the information needed to win the game with higher probability). I know that it works mathematically and a reversed version of this winning strategy can be used to verify quantum states so that indirectly one could argue that physically the winning strategy works. Why this is philosophically the case is still beyond me. I once had the discussion with a physics professor and he just said that quantum information in that regard is somehow "more" than classical information. Yet it still amazes me every time I see it.
Here is the paper
https://arxiv.org/pdf/quant-ph/0407221.pdf
and this is the verification protocol for the GHZ state which plays the Mermin parity game in reverse
https://arxiv.org/abs/1112.5064
and the experiment for the verification is here
https://www.nature.com/articles/ncomms13251
The answer is according to my knowledge. There might be other physical explanations which I have no idea of which might be just as valid. I recently came across a paper on Twitter or Mastodon that draws a relationship between black holes and quantum cryptography, so I could imagine that there are also many different physical answers to that question. My answer comes from how I understand entanglement.
@sycramore
Thank you for your answer. I will study those sites you mentioned.
I like to describe my question in another way.
I have read in a scientific magazine that observations have reveal that matter can be created in vacuum of notheing. But always at least to particles with positive and negative energy are created so if they come together they disapear and nothing will be left. But as long as they exist what happens to one of these particles affects even the other instantly irrespective of the distance between them so they together still will have zero energy and can disapeer if they come together.
My question is how one particle can get information and change status when another entangled particle long away from it change status.
Two Nobel price holders have explained that it is because entangled particles go back in time to the time they were created and were together to exchange information and then back to present time.
I do not know their definition of time to understand their explanation.
@humandemocracy Hm, I don't know enough about high energy physics but the explanation makes kind of sense except for one thing. For time travel you need to achieve close to light velocity. That means that the particles must not have any mass. But you can also entangle heavy particles with mass. Maybe the concept doesn't apply in that case and only works for stiff with mass. Given that quantum mechanics is time invariant it could even work. But it still does not answer the entire discussion about direction I'd the arrow of time, why entropy always increases etc
The papers mentioned will certainly not answer that question. I can tell because I read them.
@sycramore
I am no expert but I think time elapses as long as even one quantum paricle in world change status. Of course in a black hole, perhaps no paritcle change status and we experience that time satnds still. But even if we can not provide knowlsedge about particles outside black hole they perhaps still change status and we can say that time is elapsing.
So if entangled particles go back in time they should not only be able to stop all quantums in the world still, but also turn their status back exactly to the time when entangled particles were emerged.
What do you think?
@humandemocracy Long story. I will explain when I get access to a decent keyboard