When Richard Feynman gave
his famous 1959
speech suggesting that there is “[p]lentyof room at the bottom,” he not only created a vision for the development of
nanotechnology, he also created a school of thought at its extreme limit: he
speculated about the possibility of arranging single atoms as sufficiently
stable building blocks. His idea moved within realistic reach following the 1981
development of the scanning
tunneling microscope that not only enabled imaging surfaces at the atomic
level but also arranging and rearranging individual atoms, a breakthrough that
earned Gerd Binning and Heinrich Rohrer at IBM Zurich labs the 1986
Nobel Prize in Physics. Feynman himself, along with others, had received
the Nobel Prize in Physics already
in 1965 for other contributions, primarily to the development of quantum electrodynamics.
Now, a team of
physicists at the Delft University of Technology succeeded in manipulating gaps
in a chlorine atomic grid on a copper surface in a manner that enables a never
before accomplished density of data storage, some 100 times more dense than
in the case of the smallest known storage media and about 500 times more dense
than contemporary hard disk drives. Given the massive increase in the size and
energy consumption of data centers in the age of cloud computing, getting away
from the contemporary standard of writable memories that still encompass many
thousand atoms, miniaturization of storage media to the submolecular nanolevel
is key.
The Delft team’s
discovery may lead to a result that would permit to store the data of any and
all books ever written by mankind on a single storage media the size of a
postal stamp. This is possible because chlorine atoms automatically form a
two-dimensional grid on a flat copper surface. By providing fewer chorine atoms
than would be required to cover the copper surface in its entirety, vacancies
are created in the grid. One bit is comprised of a chlorine atom and a vacancy.
To store data, atoms are moved individually by a scanning tunneling microscope
(STM). The STM’s ultrafine measuring tip creates electric interaction as it
does to analyze the atomic structure of surfaces. If current of about 1 µA flows through the tip, it becomes possible to
move a chlorine atom into a vacancy. This process can, of course, be automated
and chlorine atoms are moved into vacancies until the desired field of bits
emerges. To keep the chlorine atom grid stable, each bit needs to be limited by
chlorine atoms. Therefore, bits are never positioned directly adjacent to each
other.
It is fair to note that this technology
is still very far removed from
commercialization: reading a 64-bit block by STM takes about one minute while
writing the same 64 bits takes two minutes. To date, a kilobyte rewritable
atomic memory has been created – and while 8000 atomic bits are by far the
largest atomic precision structure ever created by humans, it is not at all
impressive in an era that considers a 1TB laptop a middle-of-the-road standard.
This becomes even more clear if one realizes that the entire procedure only
works in an ultra-clean laboratory environment and at temperatures of -196 º C lest chlorine atoms start to
clot. But regardless, the experiment demonstrated proof of
concept and the first viable path for further development on the road to space
reduction for atomic-level data storage, currently a central issue in the advancement
of storage technology, and it would hardly be the first concept that evolved
explosively following fundamental experimental proof.
