Quantum Money from Knots

Google Tech Talk May 24, 2010 ABSTRACT Presented by Edward Farhi. 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. Quantum money is a cryptographic protocol in which a mint can produce a quantum state, no one else 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 present a concrete quantum money scheme based on quantum superpositions of diagrams that encode knots. This scheme is hopefully secure against computationally bounded adversaries. This may be the basis of E-commerce on a future quantum internet which would not require communication with a central server such as the credit card company, PayPal or Google Checkout. Edward (Eddie) Farhi went to the Bronx High School of Science and Brandeis University before getting his Ph.D. from Harvard in 1978. He was then on the staff at the Stanford Linear Accelerator Center and at CERN in Geneva Switzerland before coming to MIT, where he joined the faculty in 1982. Farhi has given lectures on his own research at many of the major physics research centers in the world. At MIT, he has taught undergraduate courses in quantum mechanics and special relativity. At the graduate level he has taught quantum mechanics, quantum field theory, particle physics and general relativity. Farhi won three teaching awards at MIT and in 2000, 2001, and 2002 he lectured the big freshman physics course, "8.01." In July 2005, he was appointed the Director of MIT's Center for Theoretical Physics.