An Atomic Abacus: Trapped ion quantum computing experiments at NIST – Brian DeMarco

Date: Mon. February 24th, 2003, 12:30 pm-1:30 pm
Location: Rockefeller 221

Trapped atomic ions are an ideal system for exploring quantum information scienc e because deterministic state preparation and efficient state detection are poss ible and coherent manipulation of atomic systems is relatively advanced. In our experiment, a few singly charged Be ions are confined by static and radio-frequ ency electric fields in a micro-machined linear Paul trap. The internal and mot ional states of the ions are coherently manipulated using applied laser light. Our current work focuses on demonstrating the necessary ingredients to produce a scalable quantum computing scheme and on simplifying and improving quantum logi c gates. I will speak about a new set of experiments that was made possible by recent imp rovements in trap technology. A novel trap with multiple trapping regions was u sed to demonstrate the first steps towards a fully scalable quantum computing sc heme. Single ions were “shuttled” between trapping regions without disturbing t he 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 a chieve 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-s ensitive geometric phase. Both gates are simplified over a previous demonstrati on and achieve a logic accuracy of over 95%. I will also briefly mention the de monstration of a technique to engineer arbitrary motional states and the impleme ntation of a simple quantum simulator. I will end with two sneak previews: a quick look at ongoing work using a Mg ion to sympathetically cool a simultaneously trapped Be ion