Move over Doctor Who: Physicists create a ‘time machine’

Researchers from the Moscow Institute of Physics and Technology, helped by colleagues in Switzerland and the US, expect the technique to become more efficient.

A team of scientists from the Moscow Institute of Physics and Technology, the USA, and Switzerland, published their findings in Scientific Reports, and said they reversed time by a fraction of a second on an IBM quantum computer, New York Daily News reported.

Normally, the universe's trend toward disorder is a fundamental law: the second law of thermodynamics.

Most laws of physics do not make a distinction between the past and future, but the scientists claim that their experiment, which involved "reversing time", showed that these laws can be violated. The scientists' experiment challenged the second law of thermodynamics, which dictates the direction of events from the past to the future and involves the transition of energy within a system from usable to unusable, The Daily Mail reported.

"We have artificially created a state that evolves in a direction opposite to that of the thermodynamic arrow of time", Lesovik said. The region of space containing the electron quickly expands.

Study co-author Andrey Lebedev from MIPT and ETH Zurich said: "Suppose the electron is localised when we begin observing it".

Schrödinger's equation describes the evolution of a particle's electron state. "The laws of quantum mechanics prevent us from knowing it with absolute precision, but we can outline a small region where the electron is localized". Each of the three systems initially evolves from order toward chaos, but then a perfectly timed external disturbance reverses this process.

"However, Schrödinger's equation is reversible", said Valerii Vinokur, a researcher at the Argonne National Laboratory in the United States. This doesn't mean we'll be visiting with dinosaurs or Napoleon any time soon, but for physicists, the idea that time can run backward at all is still a pretty big deal.

But by forcing order to rise from disorder with a quantum computer program, scientists may have found a way around this basic physical law.

However, the quantum computer can be described as a semi-time machine and has defied the second law of thermodynamics, which is the arrow of time.

A qubit is a unit of information described by a "one", a "zero", or a mixed "superposition" of both states. For stage four, the evolution program is relaunched from the second stage, causing the qubits to reverse time and revert to their earlier state.

Stage 2: Degradation. The order is lost. This state meant that the qubits were rewound back in its original starting pattern.

The scientists found that, working with just two qubits, "time reversal" was achieved with a success rate of 85 per cent. Just like the electron is smeared out over an increasingly large region of space, or the rack is broken on the pool table, the state of the qubits becomes an ever more complex changing pattern of zeros and ones.

But then another program modified the state of the quantum computer in such a way that it evolved "backwards", from chaos to order. When they introduced a third qubit, the computer produced more errors, and the qubits were able to reverse time only half of the time.

The error rate is expected to drop as scientists improve the devices used to be more sophisticated, the researchers behind the discovery said. With this experiment, time reversal can help make quantum computers more accurate in the future. "Our algorithm could be updated and used to test programs written for quantum computers and eliminate noise and errors".