Quantum teleportation of photons

teleportation of photons

Such a mixed pair in a single quantum system, equivalent to a superposition of States
|↔|2 | |3 and | |2 |↔|3. A mixed state does not contain any information about individual particles; It only indicates, the particles will be in opposite conditions. An important property of the mixed pairs is, as soon as the State of one particle is measured, such polarization is able |↔|, the other particle would have no middle ground (orthogonally P.g.) | |, and vice versa. How measuring one particle instantly affects the State of the other particle, which can reside indefinitely far? Einstein among the many achievements of the physicists did not recognize this action of ghosts at a distance ". But the disputed status of the sputannogo property is demonstrated by numerous experiments [see. 9 reviews,10].
Teleportation scheme works as follows:. Alice has a particle 1 in the initial state |Ψ|1 and particle 2. Particle 2 confused with the particle 3, that goes to Bob. A special moment – a special dimension to particles 1 and 2, that translates into sputannoe State: (3)
|Ψ-|1 2=1/√2 |↔|2 | |3 – | |2 |↔|3
This is just one of the possible maximum tangled State, in which two particles can be translated. Prediction of the indeterminate state of two particles based on their (the likely? P.G.) four States called Bellovskoe status measurement (Bell state measurement). State Of The, given in the equation (3), finds himself of the other three most confusing State of the, that its change is based on the changes of intermediate particle 1 and particle 2. This unique property antisimmetričeskoe |Ψ-|February 1 will play an important role in the experimental identification, that is, the dimension of this condition.
Quantum physics predicts [1], that if the particles 1 and 2 are predicted in the state of |Ψ-|1 2, the particle 3 immediately revert to the initial state of a particle 1. The reason for this is the following. As we watch the particles 1 and 2 in the state |Ψ-|1 2, then we know, that at a certain state of particle 1, particle 2 will be in the opposite state, ie in a state of orthogonal particle 1. But we immediately transferred particles 2, and 3 in state |Ψ-|2 3, and that means, 2 that the particle also orthogonal particle 3. This is only possible, If the particle 3 is in the same state, and that the particle 1 was initially. The final state of the particle 3 so: (4)
|Ψ|3 = a|↔|3 + b| |3
Note, that during Bell's measurement of particle 1 is losing self-identity, as starting entangled with particle 2. Therefore, in the process of teleportation State |Ψ|1 Alice is lost.
This result (equation (4)) deserves some comments. The transfer quantum information from one particle to particle 3 may occur over any distance, and that is by teleportation. Experiments show [11], that quantum entanglement remains at distances greater than 10 km. Also,, that in the scheme of teleportation is not necessary, Alice to know where is Bob. Moreover, the initial state of a particle 1 may be completely unknown, not only to Alice, but to anyone. The full quantum-mechanical uncertainty can occur even if, When the Bellovskoe status measurement. This is then, as has been mentioned by Bennett et al [1], when the particle itself is one member of a pair of entangled and therefore does not have well-defined properties. This eventually leads to procrastination in confusion [12,13].
It is also important to stress, that Bellovskoe status measurement do not reveal any information about the properties of any particles. It Is Clear, why quantum mechanics works using coherent ensembles of superpozicionnyh pairs of particles, While any measurement on single superpozicionnyh particles would be doomed to failure. The, that absolutely no information is acquired by any particle – also the reason why quantum teleportation avoids verdict analogue of a theorem [14]. After the successful teleportation of particle 1 is already no longer available in its natural state, and therefore the particle 3 is not an analogue, She – the result of actual teleportation (and transport properties from 1 to 3 (P.G.)).
Full Bellovskoe status measurement can provide not only the result of, that two particles 1 and 2 are in the state of antisymmetric, but a 25% chance we can find them in any of the other three entangled states. When this happens, particles 3 included in one of three different states. Bob then it is translated to the original state of the particle 1 in accordance with the selected transform, independent of the state of a particle 1. This is after taking a classical communication channel information, that Alice was based on analysis of Bellovskogo. Finally, Special note, even if we wanted to identify only one of the four Bellovskih States, as discussed above, Teleport will be successful, Although only a quarter of the cases.