Ed Farhi

Title

Quantum Money from Knots?

Abstract

Money, either in the form of bills or information on a computer, should be impossible to copy and also verifiable as good money when tendered to a merchant. Quantum mechanics may make this possible to achieve with far greater security than can be achieved without quantum mechanics. Ideally Quantum Money is a cryptographic protocol in which a mint can produce a quantum state, no one can copy the state, and anyone (with a quantum computer) can verify that the state came from the mint without sending the money back to the mint. I will discuss Quantum Money generally and present our scheme based on quantum superpositions of diagrams that encode knots. This scheme is hopefully secure against computationally bounded adversaries and has not yet been broken. Quantum Money may be the basis of E-commerce on a future quantum internet and would not require communication with a central server such as a credit card company.