#### Quantum Science Seminar

# Quantum de Finetti Theorems for Local Measurements

The quantum de Finetti theorem states that subsystems of

symmetric quantum states are close to mixtures of i.i.d. states.

Depending on exactly how "close" is quantified, this theorem can have

many applications to quantum information theory, quantum complexity

theory, and even classical optimization algorithms. However, previous

bounds scaled badly with either dimension or the number of systems.

I'll give an overview of why de Finetti theorems are useful, describe

a way to use information theory to improve existing bounds, and

discuss applications and open problems.

Based on 1210.6367, which is joint work with Fernando Brandao.

Aram Harrow grew up in E. Lansing, MI, before attending MIT for

his undergraduate (math and physics) and graduate (physics) degrees.

He then served as a lecturer in the math and CS departments of the

University of Bristol for five years, and as a research assistant

professor in the University of Washington CS department for two years.

In 2013, he joined the MIT physics department as an assistant

professor.

His research focuses on quantum information theory, quantum algorithms

and quantum complexity, and often seeks to make connections to other

areas of math, physics and theoretical computer science.