An Atomic Turing Machine: Quantum Computing with Trapped Ions at NIST – Brian DeMarco

Date: Wed. April 30th, 2003, 12:30 pm-1:30 pm
Location: Rockefeller 221

The basic features of quantum information processing using trapped ions will be briefly reviewed from Lecture 1. Our current work focuses on demonstrating the necessary ingredients to produce a scalable quantum computing scheme and on simplifying and improving quantum logic gates. Along these lines, I will speak about a new set of experiments that was made possible by recent improvements in trap technology. A novel trap with multiple trapping regions was used to demonstrate the first steps towards a fully scalable (multiplexed) quantum computing scheme. Single ions were “shuttled” between trapping regions without disturbing the ion’s motional and internal state, and two ions were separated from a single to two different trapping zones.

Improvements in the trap manufacturing process has led to a reduction of nearly two orders of magnitude in the ion’s motional heating rate, making possible two new improved logic gates. The first gate utilizes the wave-packet nature of the ions to tune the laser-atom interaction and achieve a controlled-NOT gate between a single ion’s spin and motional states. The second, a two-ion phase gate, uses phase-space dynamics to produce a state-sensitive geometric phase. Both gates are simplified over a previous demonstration and achieve logic accuracies of 95% and 97%, respectively.

The lecture will end with two sneak previews: a quick look at ongoing work using a Mg ion to sympathetically cool a simultaneously trapped Be ion and a glimpse of the next generation of ions traps currently under construction.