Courtesy of the
researchers and Lauren Alexa Kaye
(October 15, 2015) Researchers
use engineered viruses to provide quantum-based enhancement of energy
transport.
Nature has had billions of years to perfect photosynthesis,
which directly or indirectly supports virtually all life on Earth. In that
time, the process has achieved almost 100 percent efficiency in transporting
the energy of sunlight from receptors to reaction centers where it can be
harnessed — a performance vastly better than even the best solar cells.
One way plants achieve this efficiency is by making use of
the exotic effects of quantum mechanics — effects sometimes known as “quantum
weirdness.” These effects, which include the ability of a particle to exist in
more than one place at a time, have now been used by engineers at MIT to
achieve a significant efficiency boost in a light-harvesting system.
Surprisingly, the MIT researchers achieved this new approach
to solar energy not with high-tech materials or microchips — but by using
genetically engineered viruses.
This achievement in coupling quantum research and genetic
manipulation, described this week in the journal Nature Materials, was the work
of MIT professors Angela Belcher, an expert on engineering viruses to carry out
energy-related tasks, and Seth Lloyd, an expert on quantum theory and its
potential applications; research associate Heechul Park; and 14 collaborators
at MIT and in Italy.
Lloyd, a professor of mechanical engineering, explains that
in photosynthesis, a photon hits a receptor called a chromophore, which in turn
produces an exciton — a quantum particle of energy. This exciton jumps from one
chromophore to another until it reaches a reaction center, where that energy is
harnessed to build the molecules that support life.
But the hopping pathway is random and inefficient unless it
takes advantage of quantum effects that allow it, in effect, to take multiple
pathways at once and select the best ones, behaving more like a wave than a
particle.
This efficient movement of excitons has one key requirement:
The chromophores have to be arranged just right, with exactly the right amount
of space between them. This, Lloyd explains, is known as the “Quantum Goldilocks
Effect.”
That’s where the virus comes in. By engineering a virus that
Belcher has worked with for years, the team was able to get it to bond with
multiple synthetic chromophores — or, in this case, organic dyes. The
researchers were then able to produce many varieties of the virus, with
slightly different spacings between those synthetic chromophores, and select
the ones that performed best.