Physicists reverse the time for tiny particles inside a quantum computer

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "Time goes in one direction: forward. to become old men but not the other way around, tea cups break but never spontaneously gather.This cruel and immutable property of the universe, called the "arrow of time" is basically a consequence of the second law of thermodynamicswhich dictates that systems will always tend to become more disordered over time. But recently, US and Russian researchers have slightly bent this arrow, at least for subatomic particles. "Data-reactid =" 22 "> The time goes in one direction: forward.The little boys become old men, but not the reverse; The tea cups break but never gather spontaneously.This property The cruel and immutable nature of the universe, called the "arrow of time," is fundamentally a consequence of the second law of thermodynamics, according to which systems will always tend to become more disordered over time. and Russian have slightly bent this arrow – at least for subatomic particles.

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "In the new study, published on Tuesday (March). 12) in the newspaper Scientific reports, the researchers manipulated the arrow of time by using a very small quantum computer composed of two quantum particles, known as qubits, that performed calculations.[[[[Twisted physics: 7 amazing discoveries]"data-reactid =" 23 "> In the new study published on Tuesday March 12 in Scientific Reports, researchers manipulated the arrow of time by using a very small quantum computer composed of two quantum particles, known as qubits, calculations done. [Twisted Physics: 7 Mind-Blowing Findings]

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "At the subatomic scale, where the odd rules of Quantum mechanics Physicists describe the state of systems through a mathematical construct called a wave function. This function is an expression of all the possible states in which the system could be located – even in the case of a particle, of all possible locations in which it could be located – and of the probability that the system is located in any of these states at any given time. . Generally, over time, wave functions develop; the possible position of a particle may be further away if you wait an hour than if you wait 5 minutes. "data-reactid =" 24 "> At the subatomic scale, where the strange rules of quantum mechanics rule, physicists describe the state of systems via a mathematical construction called wave function, expression of all the possible states in which the system could be – even in the case of a particle, of all the possible locations in which it could be found – and the probability that the system is present In all the time, the functions wave, the possible location of a particle may be farther away if you wait an hour than if you wait 5 minutes.

To cancel the spread of the wave function is to try to put the spilled milk back into the bottle. But that's exactly what the researchers accomplished in this new experience.

"There is virtually no chance that this will happen alone," Valerii Vinokur, principal investigator at the Argonne National Laboratory in Illinois, told Live Science. "It's like saying, if you give a typewriter to a monkey and that he spends a lot of time, he could write Shakespeare." In other words, it is technically possible but so unlikely that it might as well be impossible.

How did scientists make impossible impossible? By carefully controlling the experience.

"You really need a lot of control to replenish all the pieces of a cup of tea," said Stephen Bartlett, professor of physics at the University of Sydney, at Live Science. Bartlett was not involved in the study. "You have to have a lot of control over the system to be able to do it … and a quantum computer is something that allows us to have a lot of control over a simulated quantum system."

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "Researchers used a quantum computer to simulate a single particle , its wave function propagating in time as a ripple in a pond.Next, they wrote an algorithm in the quantum computer that reversed the temporal evolution of each component of the function of ## EQU1 ## Wave, essentially bringing this ripple back into the particle that created they accomplished this feat without increasing the entropy nor the disorder data-reactid = "29"> The researchers simulated a single particle with the help of a quantum computer, whose wave function was spread over time as a ripple in a pond. wrote an algorithm in the quantum computer that reversed the temporal evolution of each component of the wave function, essentially bringing this ripple back into the particle that created it. This feat has been accomplished without increasing entropy or creating disorder elsewhere in the universe. the arrow of time.

<p class = "canvas-atom-canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "Does this mean that researchers have time Machine? Did they violate the laws of physics? The answer is no to both questions. The second law of thermodynamics says that the order of the universe must decrease with time, but not that it can never remain the same in very special cases. And that experience was small enough, short enough, and controlled enough that the universe did not gain or lose energy. "Data-reactid =" 30 "> Does this mean that researchers have made a machine to go back in time? Did they break the laws of physics? The answer The second law of thermodynamics says that the order of the universe must decrease with time but that it can never remain the same in very particular cases, and this experiment was sufficiently small, sufficiently short, and sufficiently controlled, that the universe has neither gained nor lost energy.

"It's very complicated and complicated to send waves to a pond" once they've been created, Vinokur said, "but we've seen that this was possible in the quantum world, in a very simple case. " In other words, it was possible when they used the control that gave them the quantum computer to cancel the effect of time.

After running the program, the system returned to its original state 85% of the time. However, when a third qubit was introduced, the experiment only succeeded 50% of the time. The researchers said the complexity of the system probably increased too much with the third qubit, making it more difficult for the quantum computer to keep control of all aspects of the system. Without this control, entropy can not be controlled and the time reversal is therefore imperfect. Still, they are targeting larger systems and larger quantum computers for their next steps, Vinokur told Live Science.

"This work is a valuable contribution to the fundamentals of physics," Live Science professor James Whitfield, a physics professor at Dartmouth College in New Hampshire, who did not participate in the study, told Live Science. "This reminds us that not all applications of quantum computing need to be application-oriented to be interesting."

"That's exactly why we're building quantum computers," said Bartlett. "It's a demonstration that quantum computers can enable us to simulate things that should not happen in the real world."

<p class = "canvas-atom canvas-text Mb (1.0em) Mb (0) – sm Mt (0.8em) – sm" type = "text" content = "Originally published on Science live."data-reactid =" 39 ">Originally published on Science live.