How and When Does Quantum Advantage Lord Over the Classical World?

Theoretical games explore the limits of quantum entanglement

In brief…

+  As researchers make important steps to further develop quantum computers, one key element called quantum entanglement has proven to be difficult to grasp. Quantum entanglement appears when particles interact, or share properties with each other, even when the particles are separated by a large distance. While dubbed ‘spooky’ by some researchers, for its elusive character, quantum entanglement could enable unparalleled possibilities. One major question in quantum research however, is exactly how and when quantum mechanics provides an advantage over our classical world.

“My PhD research is a small step in better understanding what types of non-local games are interesting to study“, says Bannink. “Many questions remain, though, more research in this direction will definitely be pursued.”

Non-local games

+  To better comprehend the powers and limits of quantum entanglement, researchers use theoretical games called non-local games. These games were proposed by physicist John Stewart Bell in the 1960’s, to better understand how quantum entanglement works. While quantum entanglement is a bizarre and puzzling phenomenon, non-local games are pretty straightforward.

+  In non-local games, two or more players are far away from each other and are not able to communicate. Despite these restrictions, their goal is to win as a group, and not compete with each other.

+  A referee samples a random input question for each player and sends it to them. Without communicating with each other, the players have to provide an answer back to the referee, who checks to see if they won, as a group. The players are allowed to discuss a strategy before the game starts, but once the referee starts handing out the inputs then the players are on their own.

Quantum advantage

+  In the quantum scenario they are allowed to share an entangled quantum state and measure this state. It turns out that for some games the players can achieve a higher winning probability when they use quantum entanglement. For some games the quantum advantage is larger than for others.

+  CWI researcher Tom Bannink identified several types of non-local games for which the advantage is limited. “This research is important because it tells us how and when quantum mechanics provides an advantage over our classical world”, says Bannink. “Although many things are known for 2-player games, in the case of 3 or more players many questions remain about the limits of quantum entanglement.”

Source:  CWI.  CWI,  Theoretical games explore the limits of quantum entanglement…

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