PHYSICS AND ASTRONOMY COLLOQUIUM

Thursday, October 19, 2006
4:10 p.m.

1415 Biomedical & Physical Sciences Bldg.
Refreshments at 3:30p.m., Rm. 1400 BPS Bldg

Speaker: Carlo Piermarocchi
         Michigan State University

Title:   Cavity Quantum Electrodynamics & Quantum Computing Architectures

Abstract:

A quantum computer is a device for computation that makes direct use of
distinctively quantum mechanical phenomena, such as superposition and
entanglement, to perform operations on data.  The logical unit of a
quantum computer is the qubit, and, as in a classical computer, complex
algorithms can be built from simpler single-qubit and two-qubit
operations.  In many quantum computing architectures individual qubits
need to be placed close enough -- nanometers apart -- to ensure an
effective two-qubit operation.  This is technologically challenging,
especially in the case of semiconductor-based implementations with
quantum dots or localized impurities.

One way to overcome these limitations involves the use of Cavity Quantum
Electrodynamics, i.e. the physics of confined photons interacting with
matter.  I will show how cavity QED effects can be used to couple qubits
at large separation in a semiconductor-based quantum computer.  The key
role in the two-qubit operation is played by peculiar states, called
cavity polaritons, with a half-matter and half-light character.