What if the invention of dr. Brown was not so crazy? What if the Delorean was getting closer? To anyone who has dreamed of going back to the past -eye, without altering the events, which is already known to have consequences-, let him know that a group of scientists has taken the first step to make it happen. An international team of Russian, Swiss and American physicists have managed to reverse time a fraction of a second thanks to a quantum computer. They also calculated the probability that an electron traveling through interstellar space will spontaneously return to the recent past. All these findings have been published in "Scientic Reports" and represent a breakthrough in the field of Physics. The fact that they have managed to reverse, although briefly the time, calls into question the second principle of thermodynamics. "This law is closely related to the notion of the arrow of time, and forces time to flow in only one direction: from the past to the future." "This is just one of a series of articles about the possibility of violating this law," explained Gordey Lesovik, lead author of the research.
The "time machine" described in the journal "Scientific Reports" consists of a rudimentary quantum computer composed of "qubits" of electrons. A qubit is an information unit described by a "one", a "zero" or an "overlay" "Mixed of both states. In the experiment, an "evolution program" was launched that made the "qubits" become an increasingly complex changing pattern of zeros and ones.
During this process, order was lost, such as when the billiard balls are hit and scattered with a signal. But then another program modified the state of the quantum computer in such a way that it evolved "backwards", from chaos to order. It meant that the status of the "qubits" was returned to its original starting point.
Most laws of physics make no distinction between the future and the past. If we represent the collision of two billiard balls in an equation, the equation would be valid if we see them colliding as if we recorded it with a video and we reproduce it in reverse. Another thing is if we record, at the beginning of a game, the white ball that hits the triangle and causes all the other balls to be scattered around the table. Seeing that sequence in reverse would be absurd, since we have internalized that second principle of thermodynamics: either the systems remain ordered or evolve towards a chaotic state, never the other way around.
The large-scale phenomena involving billiard balls, volcanoes, etc., objects formed by billions of particles and not by a single one, develop on enormous time scales. It was very clear, then, that the probabilities of observing some natural phenomenon, however minute it might be, spontaneously changing the arrow of time to advance towards the past, was practically ruled out. Now, would it be possible to force the situation in some way to get the time back in the laboratory?
To find out, the researchers devised an ingenious experiment in four phases to reverse time. And instead of an electron, they decided to observe the state of a quantum computer formed first by two and then by three superconducting quantum bits (qubits).
Stage 1: Order. Each qubit begins in a fundamental state that we will call zero. It is a highly ordered configuration analogous to an electron located in a small region or to a group of billiard balls before being hit by the cue ball.
Stage 2: Degradation. The order is lost. Just as billiard balls are hit and separated, the state of the qubits becomes an increasingly complex changing pattern of zeros and ones. This is achieved by initiating the evolutionary program in the quantum computer.
Stage 3: Investment of time. A special program modifies the state of the quantum computer in such a way that it evolves "backwards", from chaos to order. This operation is similar to the one produced by the random fluctuation of the microwave background in the case of the electron, but this time it is not random but is deliberately induced.
Stage 4: Regeneration. The second phase of the evolution program starts on the computer. Whenever step 3 has been successful, the program does not cause more chaos, but manages to rewind the state of the qubits to the past, in the same way that the billiard balls would return on their trajectories and form a triangle again.
The researchers found that 85% of the time, the two-qubits computer managed to return to its initial state. When, later, three qubits were involved, more errors occurred and the success rate was reduced to approximately 50%. According to the authors, these errors are due to imperfections in the quantum computer, so as more sophisticated devices are designed, they expect the error rate to decrease.