quantum entanglement.

quantum entanglement.
let’s get (meta) physical! quantum entanglement is a super tricky concept, so buckle up. in the simplest terms, q.e. happens when two particles “link up” in a way that lets us learn info about both particles by examining just one of them. it happens on the molecular level, and the link is not affected by things like physical distance
  • q.e. can loosely be described as “spooky action at a distance”
  • remember that in the quantum world, we never know exactly where things are, we can only approximate
  • distance doesn’t matter for q.e. -- all that matters is that the 2 particles are strongly linked
another important thing to note, from azo quantum -- if you change the state of one entangled particle, its partner’s state also changes (instantly!). einstein referred to this as “spooky action from a distance”
  • at the time of the einstein quote, quantum physics had been deemed an incomplete theory
  • he proposed that there were “hidden variables” that would crack open the field
  • however, decades of research has disproven this idea
confused? that’s ok, let’s use an analogy. picture the 2 particles as 2 cakes that can be either round or square. if the cakes are entangled, then the info that cake 1 is round gives us info about what the shape of cake 2 is
  • obviously, cakes aren’t quantum, but the principle applies well at microscopic levels
  • we know that particle collision can lead to q.e
  • q.e. theory uses a concept called “complementarity”, the concept that explains why light is both a wave and a particle
to continue, we need to understand the heisenberg uncertainty principle -- basically, if we know the position of something, we cannot know its wave function (and vice versa). for the cake example, let’s say that if we know the shape of a cake, we can’t know its color (and vice versa)
  • the principle applies to all objects, but it’s very noticeable on the quantum level
  • for instance, we’re able to measure an electron’s position but not its speed
  • think of it like this: if you took a pic of a moving car, you would be able to tell where it is -- but not how fast it was going at the time of the pic. if you play a video of a moving car, it’s impossible to tell exactly where the car is (without pausing) -- meaning you know its speed, but not its position
now consider the entangled cakes again, but this time, they can also be either red or blue. we know that if cake 1 is round, then cake 2 must be square, and if cake 1 is blue, then cake 2 must be red. now, let’s pretend the cakes are in two different labs across the world. in lab a, they measure the shape of cake 1 -- round. in lab b, they measure the color of cake 2 -- red. since the cakes are entangled, we can fill in the gaps -- cake 1 is round and blue, and cake 2 is square and red. this is why q.e. is so interesting -- it breaks the heisenberg uncertainty principle!
  • epr stands for einstein-podolsky-rosen paradox, and it comes from a paper written by podolsky in 1935
phew! that was a lot of info -- don’t worry if that was hard to grasp, itmo says quantum physics is the one of the most difficult fields to understand
  • quantum physics is so tough to understand because it’s highly theoretical, and doesn’t follow the rules that we’re used to
  • particles can exist in several different places at the same time
  • and, they can change based on how they are observed
even the geniuses get it confused -- famous physicist erwin schrödinger once said of quantum mechanics “i don’t like it, and i’m sorry if i ever had anything to do with it”
    back to modernity -- in 2020, chinese physicists set up a quantum communication between earth and a satellite called micus -- they say the connection is truly unhackable!
    • the connection was made by giving micus two “secret keys” -- the trick was that micus didn’t know what the keys contained
    • physicist jian-wei pan came up with the solution
    • pan says he will try to replicate the experiment with a satellite farther away from earth
    in december 2021, scientists tried to q.e. a tardigrade, and claimed to be successful! some physicists are skeptical of the results, but they say biology might be a useful tool for testing q.e. in the future -- gizmodo
    • a tardigrade is a super tiny creature that can survive in some crazy conditions -- including the vacuum of space
    • the researchers claim to have successfully entangled a tardigrade by exposing it to super low temps, but it’s unclear if that claim is valid
    • the team was multinational -- from singapore, denmark and poland
    in january 2022, researchers finally found a way to measure long-distance q.e. -- this was a huge breakthrough, says physicsworld -- q.e. isn’t just theoretical anymore!
    • the experiment was done by introducing extremely low temps to particles, and then putting the particles through a series of tests
    • the particles that were used have “topologically ordered states”, which make them easier to measure in terms of q.e.
    • two independent labs confirmed the results
    then in mid-july, researchers set a new quantum entanglement distance record at 20.5 miles -- the breakthrough brings us closer to a functional, practical quantum internet
    • they got it to 20 miles by altering the wavelength of the photons
    • it’s a great step towards practical quantum computers
    • it means that new infrastructure isn’t needed -- the quantum internet could use existing fiber optic networks
    so what else is in store? deltec says q.e. can be used to improve security, coding, expand computer storage systems, and maybe allow us to communicate faster than the speed of light
    • also, q.e. can be used in cryptography
    • and maybe even teleportation!
    • the finance and banking industries are very interested in these advancements
    phys.org thinks it’ll be tough tho, measuring quantum efficiency is actually really hard -- especially with larger systems
    • setting up the system is the easy part
    • but our detection capabilities are limited
    • when the system is large, scientists have to have all variables under control -- without that, detection is nearly impossible
    but pop mechanics is hyped -- q.e. might give us clues about human consciousness! some researchers have a crazy idea: our observation of the world is a quantum function, meaning when we perceive things, we are actually *changing* them ever so slightly
    • researchers from the fields of cog sci, philosophy, and quantum physics are studying this question
    • some are seriously doubtful -- they say the connection is a stretch
    • others say it makes sense, consciousness is super weird in the same way that quantum physics is super weird. it’s worth looking into
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