I've been studying quantum computers and while it's apparent to me how electrons are used as qubits, through their spin number, it's not as clear what makes a photon a viable candidate to be used as a qubit.
I understand how entanglement between qubits works, and how quantum gates work (though I haven't looked into optical gates yet) but I just can't seem to figure out how a photon could carry information!
Could anyone solve this conundrum? Thanks!
A photon is a massless spin-1 particle. This means that a photon has exactly two spin states, just like an electron.
Just to add, any system that can be in two states can serve as qubit. So any elementary particle having two or more values of spin can be a qubit. Moreover, another parameter of a particle can be used for representing a qubit, for example location (you can have one electron and you are looking where is is placed).
Photons have polarization state, so called right circularly polarized and left circularly polarized.
