thenewmans said:Quick question: Do entangled photons have opposite spin? If so, how do we know? I mean I know that they should because of conservation of angular momentum. But Cos(0)^2 = Cos(180)^2. So it looks like they’re the same. Or am I missing something.
thenewmans said:So I guess you mean that they're Type II.
DrChinese said:Type I and Type II are terms for the types of PDC crystal arrangements that are most often used for creating entangled photons. With a Type I arrangement (which is actually 2 crystal arranged perpendicularly), you get identical polarizations. With Type II, you get crossed (opposite) polarizations.
The concept of opposite spin in entangled photons refers to the phenomenon where two particles, in this case photons, are intrinsically linked or entangled in a way that their spin states are always opposite to each other. This means that if one photon has a spin up, the other photon will have a spin down, and vice versa.
Entangled photons with opposite spin can be created through a process called spontaneous parametric down-conversion. This involves passing a high-energy photon through a non-linear crystal, which splits the photon into two entangled photons with opposite spin.
The significance of opposite spin in entangled photons lies in its potential applications in quantum communication and computing. As the spin states of entangled photons are always correlated, any change in one photon's spin will instantly affect the other, allowing for secure and instantaneous communication over long distances.
Yes, entangled photons with opposite spin have already been used to demonstrate quantum teleportation and secure communication protocols. They also have potential applications in quantum computing, where their correlated spin states can be used for encoding and manipulating quantum bits or qubits.
Yes, there have been numerous experiments that have demonstrated the existence of opposite spin in entangled photons. These experiments have shown that entangled photons always have opposite spin states, regardless of the distance between them, further confirming the concept of quantum entanglement.