To a certain extend experimental quantum teleportation has been demonstrated. A minimal scheme to teleport an unknown quantum multiple times is described which can be used for chaining of quantum teleportation. The scheme is combined with results from special relativity. A conventional idealized computation is conducted which would yield the predictions that it would be possible to teleport with given idealized probability an unknown quantum state to a point in spacetime which is, e.g., slightly within the past of the starting point. Conducting this scheme in a certain way multiple times would lead to the idealized predictions that multiple special kinds of perfect clones of an unknown quantum state can be obtained with given probability. A feature of such clones is elucidated according to which one may call them ‘dependent’ clones. The results are in accordance with the no-cloning theorem, because the clones would be generated only with given idealized probability, and, of course, using this scheme classical information cannot be transmitted superluminal, and it cannot be transmitted into the past. Quantum states, idealized probabilities for the different possible states, and parameters for the experiments are computed.
To a certain extend experimental quantum teleportation has been demonstrated. A minimal scheme to teleport an unknown quantum multiple times is described which can be used for chaining of quantum teleportation. The scheme is combined with results from special relativity. A conventional idealized computation is conducted which would yield the predictions that it would be possible to teleport with given idealized probability an unknown quantum state to a point in spacetime which is, e.g., slightly within the past of the starting point. Conducting this scheme in a certain way multiple times would lead to the idealized predictions that multiple special kinds of perfect clones of an unknown quantum state can be obtained with given probability. A feature of such clones is elucidated according to which one may call them ‘dependent’ clones. The results are in accordance with the no-cloning theorem, because the clones would be generated only with given idealized probability, and, of course, using this scheme classical information cannot be transmitted superluminal, and it cannot be transmitted into the past. Quantum states, idealized probabilities for the different possible states, and parameters for the experiments are computed.
To a certain extend experimental quantum teleportation has been demonstrated. A minimal scheme to teleport an unknown quantum multiple times is described which can be used for chaining of quantum teleportation. The scheme is combined with results from special relativity. A conventional idealized computation is conducted which would yield the predictions that it would be possible to teleport with given idealized probability an unknown quantum state to a point in spacetime which is, e.g., slightly within the past of the starting point. Conducting this scheme in a certain way multiple times would lead to the idealized predictions that multiple special kinds of perfect clones of an unknown quantum state can be obtained with given probability. A feature of such clones is elucidated according to which one may call them ‘dependent’ clones. The results are in accordance with the no‐cloning theorem, because the clones would be generated only with given idealized probability, and, of course, using this scheme classical information cannot be transmitted superluminal, and it cannot be transmitted into the past. Quantum states, idealized probabilities for the different possible states, and parameters for the experiments are computed.
Using the usual simplified quantum teleportation theory of Bennett et al. we describe a scheme to teleport an unknown quantum multiple times and combine this scheme with results from special relativity. This would yield the prediction that it is possible to teleport an arbitrary unknown quantum state within an experimental setup with given probability to a point slightly within the past of the starting point. Using these results we give a theoretical proposal for that what one might call a time loop experiment with photons. The polarization state of a photon is teleported to a far distant location with given probability, and from there within a second quantum teleportation setup, which moves with high speed in direction to the distant point, back close to the starting point with given probability. Due to special relativity, for a suitable experimental setup, the final photon would be close to the starting point, however, slightly in the past of it. Using appropriate moving and non‐moving mirrors the frequency of the latter photon might be shifted so that it equals that of the starting photon. The polarization phase of the final photon could be shifted using non‐moving mirrors. Then the final photon might be used as input instead of the original photon completing in principle a space time loop. Adjusting the time loop parameters in a certain way, and including some transformations, an in principle instantaneous quantum teleportation with in principle 100% success rate might be achieved. The experiment would lead to a very slight extension of the no‐cloning theorem: an arbitrary unknown quantum cannot be cloned, except within certain time loop experiments. The original no‐cloning theorem would remain almost unchanged, because we cannot ascertain a cloned unknown state in the time loop experiment, and therefore, we cannot use these special clones, as it is well known, to transmit classical information superluminally, and we cannot transmit it into the past. The extension of the no‐cloning theorem would be due to the fact that special relativity is taken into account in our analysis. Further extensions of the experiments are described, and the results are discussed. The case that the accuracy necessary for these loop experiments cannot be achieved practically is discussed. This might lead to interesting effects, e.g. to a suppression of the generation of EPR‐pairs, which yields that the corresponding photon detectors do not detect such photons. An analysis beyond this usual quantum teleportation and relativity theory which will include quantum field theory remains to be conducted in future.
Recently, there is much interest in the study of quantum teleportation. Its marvelous security property makes it particularly attractive as potential means for future communication. Uncertain principal and no-cloning theories of quantum mechanics forbid exact copy of quantum states. To solve the problem, quantum teleportation devides message state into two parts: classical message and quantum message which are transmitted through relevant classical and quantum channels from a sender Alice to a distant receiver Bob, respectively. According to both message states, Bob can recover the original message state with certain possibility. Utilizing the general quantum teleportation protocol, in this scheme, a new method is presented by which multi-qubit quantum information can be teleported in a much easier way. It has been extended to teleportation of an arbitrary N-qubit state via entanglement swapping and probabilistic teleportation is investigated as well, which has a more general meaning. N non-maximally entangled triplet GHZ states (Greenberger-Home-Zeilinger), taking the place of the previous EPR states (Einstein-Podolsky-Rosen), serve as quantum channels, which avoids introducing extra auxiliary qubit. In order to complete the teleportation, Alice has to devide all qubits into N parts and make Bell-State measurement on qubit pair (i, x(subscript i)) and tell Bob the measurement result through classical channel, then Bob perform some simple local operations on qubits (y(subscript i), z(subscript i)) to finish teleporting the i-th qubit. Conditioned on N-times similar repeat, Bob can faithfully reconstruct the initial state. Results show that, in this method, the identification difficulty of entangled states is considerably reduced, the new method is more feasible in technique. And the total possibility of successful teleportation is (The equation is abbreviated). As a special case, teleportation of an arbitrary two-qubit state is proposed.
Due to the Heisemberg uncertainty principle, it is impossible to design a procedure which permits perfect cloning of an arbitrary, unknown "qubit" (the spin or polarization state of a single quantum system)1,2. However, it is believed that a perfect copying protocol can be achieved, at least in principle, if the qubit to be copied is destroyed in the original system. Quantum teleportation3,4 is supposed to allow for such a result. Here, this belief is shown to be invalidated by a fundamental uncertainty about the number of particles involved in any process, as predicted by Quantum Field Theory. As a result, teleportation cannot provide an infallible copying procedure for the single qubits, not even in the limit of perfect experimental sensitivities. The no-cloning theorem1,2 can then be generalized to the case of destroying the original. Teleportation remains an interesting statistical procedure, having an unavoidable theoretical error at the percent level or few orders of magnitude smaller, depending on the physical process that is used. Although it cannot be made arbitrarily small, such an error is small enough to remain hidden in present experiments.
The scheme of quantum teleportation, where Bob has multiple (N) output ports and obtains the teleported state by simply selecting one of the N ports, is thoroughly studied. We consider both the deterministic version and probabilistic version of the teleportation scheme aiming to teleport an unknown state of a qubit. Moreover, we consider two cases for each version: (i) the state employed for the teleportation is fixed to a maximally entangled state and (ii) the state is also optimized as well as Alice's measurement. We analytically determine the optimal protocols for all the four cases and show the corresponding optimal fidelity or optimal success probability. All these protocols can achieve the perfect teleportation in the asymptotic limit of $N\ensuremath{\rightarrow}\ensuremath{\infty}$. The entanglement properties of the teleportation scheme are also discussed.