Ion traps will need to be much more
complex than current models for long-term quantum information
applications. While there do not seem to be fundamental limits
to controlling hundreds of ions, there are a host of practical
issues. We are aggresively fabricating next-generation ion traps,
including multizone structures with dozens of electrodes for the
shuttling of ions through the traps with control electrical
potentials. In addition, we are fabricating ion trap
structures at micron dimensions using conventional semiconductor
fabrication procedures.
Microfabricated Ion Traps
One of the main hurdles in the construction of an ion trap
quantum computer is scalability. Currently, most ion traps are
bulky structures which require manual alignment of the electrodes.
As traps become more complex, such an assembly technique becomes
unmanageable.
In pursuing a scalable architecture, we are starting to
manufacture ion traps using semiconductor-MEMS techniques. The
traps are etched from a layered
gallium-arsenide/aluminum-gallium-arsenide (GaAs/AlGaAs)
heterostructure.
The first successful operation of such a trap was published in Nature Physics2, 36 (2006). (See the links below
for the manuscript, or go to group publications.)
GaAs/AlGaAs linear ion trap
electrode heterostructure fabricated at U. Maryland's Laboratory
for Physical Science
Picture of four sections of GaAs/AlGaAs linear trap
with electrode edges visible from scattered laser light. with Single
trapped cadmium ion is visible as bright dot between electrodes. Vertical gap is
60 microns.
1/3/06 Ions confined within an integrated semiconductor chip:
Developing shuttling protocols for scalable quantum computing.
1/17/06 Two-dimensional control of individual
atomic ions demonstrated in a "T"-junction
ion
trap array (including turning corners and swapping positions of two
ions).
Movie of an ion turning corner in T-junction trap:
Movie of a two ion separation protocol:
Composite shuttling protocol: Two ions (a
and b) are trapped, then separated, ion a is shuttled around the
corner, finally ion a is dumped and ion b is shuttled to the
initial trap:
