Quantum world without the butterfly effect

American physicists have carried out a quantum experiment, is similar to a journey back in time during which the sender has encoded qubit of information, and then restored the corrupted measurement of the qubit by using the inverse transform. In the case of a classical system this would lead to loss of the original information, but in the quantum case the butterfly effect is not found — an intricate system was able to restore the original information. Article published in the journal Physical Review Letters.

The butterfly effect States that small effects can have large consequences elsewhere. Well this effect is demonstrated in the fiction literature and movies about time travel: for example, in the movie “Back to the future” and science-fiction short story by ray Bradbury “a sound of thunder”. These two works time is one and indivisible stream which can be navigated.

However, there are quantum approach to time travel — introduction of the multiverse theory, when some change in the past is blurred with the future probabilistic set of outcomes (for example, in the movie “the Avengers: Finale”). But it is still not clear which view of time travel more real and possible.

Bin Yan Bin (Yan), and Nikolai Sinitsyn (Nikolai Sinitsyn) from Los Alamos national laboratory implemented an experiment with sending encrypted information “in the past”. In the experiment, the information reads “in the past”, and then the sender verified the information and compared it with the original.

Scientists realized the model of “past” by using the following algorithm. Alice (sender) encrypts data one qubit with the help of reversible evolution of interacting qubits: so it turns out the system from the encrypted qubit and the pool of the remaining qubits, through which it is encrypted. To retrieve the information Alice, it is sufficient to apply the inverse transform, which is analogous to travel into the past.

In the process between the encryption and the decryption can interfere with the Bob and measure the state of one qubit, breaking the confusion between him and the rest of the system. According to the theorem about the concealment of information can not disappear — it remains in the encrypted state of the other qubits. Despite the fact that Alice about their condition knows nothing, it turned out that she still can apply the reverse transformation and with the help of quantum tomography to reconstruct the information from the qubit.

Such recovery information applicable to all systems with quantum encryption. As an example of efficiency of such a Protocol, the scientists calculated the numerical model of the pool of nuclear spins is a Central nucleus with spin 1/2 interacts with a pool of N nuclei with spin 1/2. In the initial state of the spin was directed vertically, and the condition of the pool was chosen as mixed. The researchers then modeled the Schrodinger equation to obtain the unitary effect of evolution. In the end, they received the probability distribution to detect the spin of the Central nucleus in the initial state. At the same time encryption and decryption of physics found the echo that was predicted by their model.

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