### HMC Physics Colloquium

*Tuesdays at 16:30 in Shanahan Center for Teaching and Learning, Room B460*

## Joseph Altepeter

Northwestern University

A Tale of Two Qubits

March 1, 2011

The nascent field of quantum information science is built on an irresistibly intriguing principle: knowledge is physical. The consequences of this deceptively simple statement include the possibility of quantum computers capable of solving certain problems exponentially faster than their classical counterparts and communication protocols whose security is guaranteed by the laws of physics. This talk will present the fundamentals of these quantum algorithms and protocols by focusing on small systems of only two quantum bits—two qubits—in order to provide an intuition for the dynamics of the quantum world. In addition to the theory of two-qubit systems, this talk will describe the experimental creation, manipulation, and measurement of the crown jewel of quantum mechanical phenomena: entanglement. Using photonic entanglement, we will (almost) solve one of the most famous scientific mysteries of the 20th century: the Einstein-Podolsky-Rosen Paradox and Bell’s inequality.