A solution to the longstanding problem of ensuring fair gambling between two separated parties, without the assistance of a trusted third party, is reported in a paper published online this week in npj Quantum Information. The proof-of-principle integrates both quantum mechanics and game theory and could potentially find application in internet gambling and casinos.
Gambling or betting on an event with an uncertain outcome is a widely practiced activity. However, despite its widespread usage and applications, fair gambling between two spatially separated parties cannot be conducted without the assistance of a trusted third party.
Imagine a gambler, Bob, wants to gamble with a casino, Alice. How does Bob know that the gambling machine provided by Alice is fair, especially in the case of online gambling? The standard solution to this problem is to introduce a trusted third party to make sure the gambling is fair to both parties. However, in some cases, a trusted third party does not exist.
Here, Pei Zhang and colleagues experimentally demonstrate a novel gambling protocol that enables fair gambling between two distant parties, without the help of a third party. They incorporate the key concepts and methods of game theory into quantum information theory to create a protocol that will ensure the two parties move their strategies to a Nash-equilibrium point (at this point, no player has anything to gain by unilaterally changing his or her own strategy), guaranteeing fairness through the physical laws of quantum mechanics.
Furthermore, the protocol prevents both parties in the game from tampering with the results. Thus, there is no need for a trusted third party, as any tampering can be easily detected or lowers the tampering party’s chance to win. The authors then show that the protocol can be easily adapted to a biased version, which would possibly allow it to be used in lotteries or casinos.