Placeholder Image

字幕表 動画を再生する

  • Is teleportation possible?

  • Could a baseball transform into something like a radio wave,

  • travel through buildings,

  • bounce around corners,

  • and change back into a baseball?

  • Oddly enough, thanks to quantum mechanics, the answer might actually be yes.

  • Sort of.

  • Here's the trick.

  • The baseball itself couldn't be sent by radio,

  • but all the information about it could.

  • In quantum physics, atoms and electrons

  • are interpreted as a collection of distinct properties,

  • for example, position,

  • momentum,

  • and intrinsic spin.

  • The values of these properties configure the particle,

  • giving it a quantum state identity.

  • If two electrons have the same quantum state,

  • they're identical.

  • In a literal sense, our baseball is defined by a collective quantum state

  • resulting from its many atoms.

  • If this quantum state information could be read in Boston

  • and sent around the world,

  • atoms for the same chemical elements could have this information

  • imprinted on them in Bangalore

  • and be carefully directed to assemble,

  • becoming the exact same baseball.

  • There's a wrinkle though.

  • Quantum states aren't so easy to measure.

  • The uncertainty principle in quantum physics

  • implies the position and momentum of a particle

  • can't be measured at the same time.

  • The simplest way to measure the exact position of an electron

  • requires scattering a particle of light, a photon, from it,

  • and collecting the light in a microscope.

  • But that scattering changes the momentum of the electron in an unpredictable way.

  • We lose all previous information about momentum.

  • In a sense, quantum information is fragile.

  • Measuring the information changes it.

  • So how can we transmit something

  • we're not permitted to fully read without destroying it?

  • The answer can be found in the strange phenomena of quantum entanglement.

  • Entanglement is an old mystery from the early days of quantum physics

  • and it's still not entirely understood.

  • Entangling the spin of two electrons results in an influence

  • that transcends distance.

  • Measuring the spin of the first electron

  • determines what spin will measure for the second,

  • whether the two particles are a mile or a light year apart.

  • Somehow, information about the first electron's quantum state,

  • called a qubit of data,

  • influences its partner without transmission across the intervening space.

  • Einstein and his colleagues called this strange communcation

  • spooky action at a distance.

  • While it does seem that entanglement between two particles

  • helps transfer a qubit instantaneously across the space between them,

  • there's a catch.

  • This interaction must begin locally.

  • The two electrons must be entangled in close proximity

  • before one of them is transported to a new site.

  • By itself, quantum entanglement isn't teleportation.

  • To complete the teleport,

  • we need a digital message to help interpret the qubit at the receiving end.

  • Two bits of data created by measuring the first particle.

  • These digital bits must be transmitted by a classical channel

  • that's limited by the speed of light, radio, microwaves, or perhaps fiberoptics.

  • When we measure a particle for this digital message,

  • we destroy its quantum information,

  • which means the baseball must disappear from Boston

  • for it to teleport to Bangalore.

  • Thanks to the uncertainty principle,

  • teleportation transfers the information about the baseball

  • between the two cities and never duplicates it.

  • So in principle, we could teleport objects, even people,

  • but at present, it seems unlikely we can measure the quantum states

  • of the trillion trillion or more atoms in large objects

  • and then recreate them elsewhere.

  • The complexity of this task and the energy needed is astronomical.

  • For now, we can reliably teleport single electrons and atoms,

  • which may lead to super-secured data encryption

  • for future quantum computers.

  • The philosophical implications of quantum teleportation are subtle.

  • A teleported object doesn't exactly transport across space

  • like tangible matter,

  • nor does it exactly transmit across space, like intangible information.

  • It seems to do a little of both.

  • Quantum physics gives us a strange new vision

  • for all the matter in our universe as collections of fragile information.

  • And quantum teleportation reveals new ways to influence this fragility.

  • And remember, never say never.

  • In a little over a century,

  • mankind has advanced from an uncertain new understanding

  • of the behavior of electrons at the atomic scale

  • to reliably teleporting them across a room.

  • What new technical mastery of such phenomena

  • might we have in 1,000, or even 10,000 years?

  • Only time and space will tell.

Is teleportation possible?

字幕と単語

動画の操作 ここで「動画」の調整と「字幕」の表示を設定することができます

B2 中上級

TED-ED】テレポートができるようになるのか?- サジャン・サイニ (【TED-Ed】Will we ever be able to teleport? - Sajan Saini)

  • 941 104
    April Lu に公開 2021 年 01 月 14 日
動画の中の単語