It's half term! And with holidays come blog posts. This week, the topic will be quantum entanglement. This topic is very much relevant in the current quantum physics scene because it links to the science of teleportation and whether it is possible or not (I will cover this later on in the next post).
A particle with no net spin spontaneously splits. When it does so, it splits into two daughter particles, each with their own net spins(P1 and S1, P2 and S2) . Each daughter particle can be in two possible spin states: Up or Down, and according to the Schrodinger's Cat experiment, both spin states are present in the particle until the spin is measured. So at one, point, when the spin is both up and down, there are two states of spin simultaneously existing at the same time. This is called the superposition phenomenon. When the S1 (spin) of P1 is measured, only then will there be a particular spin state. This is also called a wave function collapsing onto a certain value because the particle and its superposition state of having multiple spin states can be regarded as a wave function (the wave-particle duality), and when one spin state emerges at the point of measurement, one of the possible values on the wave is being picked. If we say that S1 is a spin-up state, then P2 must have a spin-down state, in order to conserve the spin angular momentum (similar to the conservation of momentum we learn in KS3 or GCSE physics. But if P2 is also a similar particle to P1 and therefore undergoes the superposition phenomenon, when the spin state of P1 is at the point of measurement, P2 is unambiguously determined to be S2. For this to happen, there must be some sort of signal sent from P1 and P2 in order to make P2's wave function collapse to a spin-down value. And this signal transmission is done at a much faster speed than the speed of light; perhaps even instantaneously!
Through various experiments that have been carried out be physicists, they have confirmed that there is no medium that is transferring this signal in between particles. Therefore, the properties of the particles (the information carried by it) is "entangled"! If a particle splits into two, its daughter particles' properties are entangled. There have been many misconceptions that the particles itself are entangled and can instantaneously be teleported (thanks Star Trek(!)) But it is only the information carried by the particle that is transported.
Thanks for reading and I will be uploading the post of quantum teleportation next week!
A particle with no net spin spontaneously splits. When it does so, it splits into two daughter particles, each with their own net spins(P1 and S1, P2 and S2) . Each daughter particle can be in two possible spin states: Up or Down, and according to the Schrodinger's Cat experiment, both spin states are present in the particle until the spin is measured. So at one, point, when the spin is both up and down, there are two states of spin simultaneously existing at the same time. This is called the superposition phenomenon. When the S1 (spin) of P1 is measured, only then will there be a particular spin state. This is also called a wave function collapsing onto a certain value because the particle and its superposition state of having multiple spin states can be regarded as a wave function (the wave-particle duality), and when one spin state emerges at the point of measurement, one of the possible values on the wave is being picked. If we say that S1 is a spin-up state, then P2 must have a spin-down state, in order to conserve the spin angular momentum (similar to the conservation of momentum we learn in KS3 or GCSE physics. But if P2 is also a similar particle to P1 and therefore undergoes the superposition phenomenon, when the spin state of P1 is at the point of measurement, P2 is unambiguously determined to be S2. For this to happen, there must be some sort of signal sent from P1 and P2 in order to make P2's wave function collapse to a spin-down value. And this signal transmission is done at a much faster speed than the speed of light; perhaps even instantaneously!
Through various experiments that have been carried out be physicists, they have confirmed that there is no medium that is transferring this signal in between particles. Therefore, the properties of the particles (the information carried by it) is "entangled"! If a particle splits into two, its daughter particles' properties are entangled. There have been many misconceptions that the particles itself are entangled and can instantaneously be teleported (thanks Star Trek(!)) But it is only the information carried by the particle that is transported.
Thanks for reading and I will be uploading the post of quantum teleportation next week!
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