March 14 2019

World’s First Quantum ‘Time Machine’ Defies Laws of Physics

Scientists have built the world’s first time machine – sort of. Lead researcher Dr Gordey Lesovik said by putting scattered…

Scientists have built the world’s first time machine – sort of. Lead researcher Dr Gordey Lesovik said by putting scattered electrons back into their original shape they had effectively created a state which went against the ‘direction of time.

Working with electrons in the bizarre realm of quantum mechanics, they first created the equivalent of a break for a game of pool.

The “balls” scattered and, according to the laws of physics, should have appeared to split in a haphazard way. But researchers managed to make them reform in their original order – looking as if they were turning back time.

Lead researcher Dr Gordey Lesovik, of Moscow’s Laboratory of the Physics of Quantum Information, said: “We have artificially created a state that evolves in a direction opposite to that of the thermodynamic arrow of time.”

His team used a rudimentary quantum computer, which carries information on subatomic particles. He hopes their findings, in journal Scientific Reports, will help improve processing power.

Not quite Dr Who, but even Time Lords had to start somewhere . . .

So how does it work? Well the time machine is actually a rudimentary quantum computer made up of electron qubits.

A qubit is the basic unit of quantum information – a unit that represents one, zero, and both one and zero at the same time.

Researchers ran an “evolution program” which caused the qubits to enter a complicated changing pattern of ones and zeroes. And during this process, the order was lost – like hitting balls at the start of a game of pool.

A separate program then modified the state of this quantum computer so that it evolved backwards, returning from chaos to order. This allowed the qubits to return to their original starting point.

Scientists were able to perform this so-called “time reversal” successfully 85 per cent of the time with two qubits, and had a 50 per cent success rate with three qubits.

The idea was to test out a theory about whether time can reverse itself – at least for a single particle for a fraction of a second.

When scientists observe an electron, they can’t figure out its exact position, but can determine where it’s roughly located.

But over time, it becomes more difficult to tell where that electron is, because the region of space containing it “spreads out.” Or rather, it becomes more “chaotic.”

This increases the uncertainty of the electron’s position – a core principle of Schrodinger’s equation.

The team were able to then calculate the probability of a “smeared out” electron spontaneously “localizing” back to its recent past – travelling through time, in effect.

And it turns out that if you observe 10billion freshly localized electrons every second for 13.7billion years, you’d only see this happen once. And even then, the electron would only travel no more than a ten-billionth of a second into the past.

That’s not ideal, because not being able to predict time-reversal makes the system useless to scientists.

That’s why it’s so important that scientists were able to successfully “reverse time on demand” with a quantum computer. (Read More)