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AAWSAP DIRD, Quantum Computing and Utilizing Organic Molecules in Automation Technology, December 2010

U.S. Department of War · 2010-12-10 · 54 pages · text from the file's own layer

This Defense Intelligence Reference Document, dated 10 December 2010, was prepared by the Defense Intelligence Agency's Defense Warning Office under the Advanced Aerospace Weapon System Applications program. It examines quantum computing and DNA-based molecular computing as options for onboard supercomputing in future spaceflight. It forecasts working ion trap quantum computers within 10 years, simple DNA tile computing within 20 years, and self-repairing DNA computers and hybrid quantum dot systems on a 40-year horizon.

From the source: Release of 2026-09-18 Incident: 12/10/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys advanced computing concepts for future space and automation applications, focusing on quantum and molecular (DNA-based) computing as potential alternatives to conventional silicon electronics. The report introduces quantum computing principles alongside DNA-based logic gates, self-assembly, and nanoscale repair mechanisms, arguing that these unconventional architectures might eventually offer advantages in radiation tolerance, physical robustness, and specialized onboard processing for space-based platforms. It notes that near-term practical barriers remain substantial. Quantum systems continue to depend on complex cryogenics, shielding, and unsolved reliability challenges, while DNA-based computing remains a far-future concept rather than a viable alternative to general-purpose processors. Overall, the document presents both frameworks as long-term possibilities to complement, rather than immediately replace proven space-qualified electronics. It concludes that the stronger, nearer-term cases for such architectures are in highly specialized or hybrid roles rather than in fully mature general-purpose onboard computing applications.

UNCLASSIFIED//FOR OFFICIAL USE ONLY
Figure 6. Bilayer graphene tunneling device structure. Two sheets of graphene
are separated by a one-nanometer thick insulating of graphene.
Manipulation of Spin Qubits in Graphene Quantum Dots Relative to GaAs
For universal quantum computing, single-qubit and two-qubit manipulations are necessary.
Single-qubit rotations of spin qubits are naturally done by electron spin resonance (ESR) (63)
and by electric- dipole-ind uced spin resonance (EDSR) (64). The Rabi frequency faabl at which
the qubit rotates, for instance, in the ESR experiment (65) is proportional to the electron spin
g-factor, faa bi = gμsBac/2h where μs is the Bohr magneton and Bae the external oscillating
magnetic field used to rotate the spin. Notably, the electron spin g-factor differs for different
materials . In GaAs quantum dots, it has been measured to be lg I < 0.43 (66) whereas, in
graphene quantum dots, it has been determined to be close to lg I = 2. (67) Thus, it is
possible to rotate t he electron spin in graphene quantum dots using ESR about five times
faster than in GaAs quantum dots using the same field strength of the external oscillating
magnetic field. This is an important gain because all qubit manipulations need to be done
fast to avoid decoherence and implement fault-tolerant quantum computing (68).
Another important advantage of graphene spin qubits is related to the small band gap in
graphene nanoribbons . (For a ribbon width of about 30nm, the band gap can be estimated to
be of the order of 60 meV.) This fact yields additional flexibility for two-qubit operations.
Two-qubit operations are usually done via the Heisenberg exchange interaction (69). The
tunneling matrix element can, however, be easily tuned by increasing or decreasing the
overlap of the wave functions of the electrons in the two quantum dots. In graphene or any
small band gap semiconductor, this manipulation can be done in two distinct ways: either
through tunneling via conduction band states (i.e., normal tunneling) or through tu nneling
via valence band states (i.e., Klein tunneli ng) . This has been predicted for graphene
nanoribbons and experimentally realized in carbon nanotube quantum dots in (70)(71).
The most important physical consequence of this additional flexibility is the appearance of a
new type of long-distance coupling between graphene spin qubits as illustrated in Figure 8.
UNCLASSIFIED/ ,'FOA OFFI&il.t.L W&li 8,.LY
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 54 pages are in the text index: search them above, or from the library's search.