An international team of physicists may have solved a critical problem in quantum computing by isolating quantum information in “open timelike curves.”
A new paper published in the journal npj Quantum Information, suggests that time travelling quantum particles in quantum computers can solve insolvable problems while travelling along “open timelike curves”, which don’t cause causality problems. Previously, quantum computers with “closed timelike curves” created several causality issues.
Threatening causality in the world of time-travelling quantum computer particles has consequences. In the classic/ simplified example, someone could travel back in time and kill their grandfather, negating their own existence. These type of paradoxes, though admittedly much more complex, happen at the particle level too. Over the last 20 years, scientists found out that the foundational principals of quantum physics break down when using closed timelike curves in entangled quantum systems.
The new study shows that quantum computers using open timelike curves can solve insolvable problems without creating causality issues. This happens as long as researchers entangle the time travelling particle with one kept in the present. The reason these curves don’t break the causal flow of time is because they don’t allow interaction with anything in the past – in other words, the time travelling entangled particles, or data they contain, never interact with themselves. Even though they never interact, the strange quantum properties that allow for impossible computations are still left intact.
So how can scientists specifically know that these “open timelike curves” don’t create causality problems. Apparently the “information is stored in the entangling correlations: this is what we’re harnessing,” said co-author of the study Jayne Thompson.
Material provided by National University of Singapore.