Optical chirality and its interaction with matter: Super-Twisty Light
Scientists have discovered a new property of light called “optical
chirality” that measures how different a light wave is from its mirror
image. They used this measure to design super-chiral electromagnetic
fields: fields that have left-right asymmetry in some regions of space
hundreds of times larger than that found in circularly polarized
light.
Ever since Louis Pasteur’s experiments on tartaric acid in 1848,
scientists have known that some molecules—called chiral
molecules—exist in distinct mirror-image forms. Electromagnetic
fields, e.g. light, can also be chiral. Circularly polarized light is
the best known chiral electromagnetic field, and is often used to
study chiral molecules. But until now, nobody asked whether some
fields could be more chiral than others, or how one would quantify the
chirality of an electromagnetic field.
The theoretical discovery of optical chirality sheds new light on the
fundamental symmetries of the electromagnetic field, and paves the way
to ultrasensitive detection and control of chiral molecules with
light.
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LN11781
Computing with a molecule
A simple diatomic molecule on the angstrom scale has executed
ultrafast Fourier transform (UFFT) within femtoseconds.
Wave functions of atoms and molecules can be used as information
carriers to replace real charges in the present Si-based circuit,
whose further integration will result in a possible disaster where
current-leakage is unavoidable with insulators thinned to atomic
levels. Furthermore, a shaped femtosecond laser pulse can access many
vibrational wave functions in a single molecule simultaneously,
encoding more than one million different kinds of information to a
simple diatomic molecule on the angstrom scale. This information
density is higher than the best possible DRAM to be developed by 2020
by two orders of magnitudes. We have experimentally demonstrated a
new logic gate based on the temporal evolution of molecular wave
functions. Optically tailored wave functions in a simple diatomic
molecule on the angstrom scale implements 4- and 8-element discrete
Fourier-transform with arbitrary real and imaginary inputs. The
evolution time is 145 femtoseconds, which is shorter than the typical
clock period of the current fastest Si-based computers by three
orders of magnitudes (the maximum clock rate of IBM Power 6 is 5.0
GHz, giving its clock period to be 200 picoseconds).
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LL11852
NEW QUANTUM SENSOR BEATS OLD QUANTUM LIMIT
Researchers have invented an optical sensor that beats an unbeatable quantum limit to sensitivity. The breakthrough has a broad array of applications — from gravity wave observatories seeking to observe distant and bizarre astrophysical phenomena, to optical gyroscopes used in commercial navigation. Optical interferometers are some of the most sensitive devices on Earth, and they have a 100 year long history at the forefront of breakthroughs in science — from turn-of-the-century experiments measuring the speed of light (and paving the way for Einstein’s theory of relativity) — to current-day laser interferometer antennas that scan the skies for evidence of gravity waves emitted from colliding black holes. Practical applications are navigational gyroscopes found in jet planes and magnetic field sensors used in oil drills. It was thought that there was an ultimate limit on the sensitivity of such devices imposed by the laws of quantum physics. Research has now demonstrated conclusively that this limit can be broken. This work exploits quantum properties of light to design the most sensitive optical interferometer ever devised.
