  We propose to develop a new method of information storage to replace magnetic
hard disk drives and other instruments of secondary/backup data storage. The
proposed method stores petabytes of user-data in a sugar cube (1 cm3), and can
read/write that information at hundreds of megabits/sec. Digital information is
recorded and stored in the form of a long macromolecule consisting of at least
two bases, A and B. (This would be similar to DNA strands constructed from the
four nucleic acids G,C,A,T.) The macromolecules initially enter the system as
blank slates. A macromolecule with, say, 10,000 identical bases in the form of
AAAAA....AAA may be used to record a kilobyte block of user-data (including
modulation and error-correction coding), although, in this blank state, it can
only represent the null sequence 00000....000. Suppose this blank string of A's
is dragged before an atomically-sharp needle of a scanning tunneling microscope
(STM). When electric pulses are applied to the needle in accordance with the
sequence of 0s and 1s of a 1 kB block of user-data, selected A molecules will
be transformed into B molecules (e.g., a fraction of A will be broken off and
discarded). The resulting string now encodes the user-data in the form of
AABABBA...BAB. The same STM needle can subsequently read the recorded
information, as A and B would produce different electric signals when the
strand passes under the needle. The macromolecule now represents a data block
to be stored in a "parking lot" within the sugar cube, and later brought to a
read station on demand. Millions of parking spots and thousands of Read/Write
stations may be integrated within the micro-fabricated sugar cube, thus
providing access to petabytes of user-data in a scheme that benefits from the
massive parallelism of thousands of Read/Write stations within the same
three-dimensionally micro-structured device.
