'Time Machine': Russian physicists manage to send particles to the past

A quantum computer has been able to travel in the past for a split second thanks to experiments conducted by Russian scientists, who also calculated the probability of a similar temporal journey for an electron in an interstellar empty space, Phys reports. org.

In his work, researchers from the Moscow University of Physics and Technology have considered the possibility of violating the second principle of thermodynamics.

"This law is closely linked to the notion of time arrow, which postulates the direction of time from the past to the future," said lead author Gordéi Lesovik, director of the laboratory's Quantum Physics Laboratory. university.

It follows from this law that an isolated system either remains static or evolves into chaos rather than order, which means the irreversibility of time.

In this respect, Lesovik baderts that "we have created a state that moves in the opposite direction to the arrow of thermodynamic time".

Spontaneous recoil

The researchers decided to check if the weather could spontaneously regress, at least for a very small particle. To this end, they work at the location of a solitary electron in an empty space, using the Shrödinger equation, which governs the quantum world.

His calculations are based on the theory that the electron gradually diffuses its location – or the function of the quantum wave – into space, succumbing to the thermodynamic spike of time.

However, scientists have taken into account the influence of microwave background fluctuations, theoretically capable at a given moment of bringing back the quantum wave function of the electron to an earlier state, that is to say evolving the electron to the past.

According to his calculations, this regression can only occur for 0.06 nanoseconds and in a period equal to the age of the universe, or 13.7 billion years.

Quantum algorithms

To concretely verify this possibility of violation of the second thermodynamic law, Russian researchers collaborated with physicists from the Argonne National Laboratory (United States) and the Swiss Federal Institute of Technology in Zurich (Switzerland) in a multitude of ways. experiments with a computer. amount of IBM.

They used models of two and then three cubits – the cube (or quantum bit) is a minimum quantum information unit badogous to the bit used in computer science – which has gone through four phases.

Initially, each cube was ordered in a ground state "0", which corresponds to the state of the electron located in a small region.

Just as the electron diffuses across the increasingly larger space, the cubits follow an order of zeros more and more complicated thanks to a special program of quantum evolution.

A special program alters the state of the quantum computer, so that it mimics a push backwards towards evolution.

Phase 2 is restarted: if the "push" is successful, the evolution does not continue towards chaos but rather the reverse, towards the order, phase 1, in other words: "the past".

Experiments have shown that in 85% of cases, the two-cube system returned to the initial configuration, while in the three-party system, the level of success was 49%. The authors of the study allude to the imperfections of the current quantum computer, which know how to adjust.

"Our algorithm can be updated and used to test programs written for quantum computers and to eliminate noise and errors," said Andrei Lebedev, one of the authors of the study.

RT.