Butterfly Effect in Quantum Realm Disproven by Simulating Quantum ‘Time Travel’ - SciTechDaily

Evolving quantum processes backwards on a quantum computer to damage information in the simulated past causes little change when returned to the ‘present.’.

Using a quantum computer to simulate time travel, researchers have demonstrated that, in the quantum realm, there is no “butterfly effect.” In the research, information—qubits, or quantum bits—“time travel” into the simulated past.

“On a quantum computer, there is no problem simulating opposite-in-time evolution, or simulating running a process backwards into the past,” said Nikolai Sinitsyn, a theoretical physicist at Los Alamos National Laboratory and coauthor of the paper with Bin Yan, a post doc in the Center for Nonlinear Studies, also at Los Alamos.

“So we can actually see what happens with a complex quantum world if we travel back in time, add small damage, and return.

We found that our world survives, which means there’s no butterfly effect in quantum mechanics.”.

Instead, Yan and Sinitsyn found that simulating a return to the past to cause small local damage in a quantum system leads to only small, insignificant local damage in the present.

This effect has potential applications in information-hiding hardware and testing quantum information devices.

Information can be hidden by a computer by converting the initial state into a strongly entangled one.

“We found that even if an intruder performs state-damaging measurements on the strongly entangled state, we still can easily recover the useful information because this damage is not magnified by a decoding process,” Yan said.

“This justifies talks about creating quantum hardware that will be used to hide information.”.

“On a quantum computer, there is no problem simulating opposite-in-time evolution, or simulating running a process backwards into the past.” — Nikolai Sinitsyn.

This new finding could also be used to test whether a quantum processor is, in fact, working by quantum principles.

Since the newfound no-butterfly effect is purely quantum, if a processor runs Yan and Sinitsyn’s system and shows this effect, then it must be a quantum processor.

To test the butterfly effect in quantum systems, Yan and Sinitsyn used theory and simulations with the IBM-Q quantum processor to show how a circuit could evolve a complex system by applying quantum gates, with forwards and backwards cause and effect.

In the team’s experiment, Alice, a favorite stand-in agent used for quantum thought experiments, prepares one of her qubits in the present time and runs it backwards through the quantum computer.

This action disturbs the qubit and destroys all its quantum correlations with the rest of the world.

Yan and Sinitsyn found that most of the presently local information was hidden in the deep past in the form of essentially quantum correlations that could not be damaged by minor tampering.