Transcript PPT | 224 KB

Movie stored in atomic vapor
PFC-supported scientists have stored not one but two letters of the
alphabet in a tiny cell filled with rubidium atoms which are tailored
to absorb and later re-emit messages on demand. This is the first
time two images have simultaneously been reliably stored in a nonsolid medium and then played back. In effect, this is the first stored
and replayed atomic movie.
The new storage process was developed by Paul Lett and his
JQI/PFC colleagues. The atomic storage medium is a narrow cell
some 20 centimeters long, which seems pretty large for a quantum
device. That’s how much room is needed to accommodate a
quantum process called gradient echo memory (GEM). While many
storage media try to cram as much information into as small a place
as possible---whether on a magnetized strip or on a compact disk---in
GEM an image is stored over the whole range of that 20-cm-long cell.
The image is stored in this extended way, by being absorbed in
atoms at any one particular place in the cell, depending on whether
those atoms are exposed to three carefully tailored fields: the
electric field of the signal light, the electric field of another “control”
laser pulse, and a magnetic field which makes the Rb atoms precess
about. When the image is absorbed into the atoms in the cell, the
control beam is turned off. Image readout occurs in a sort of reverse
process.
Having stored one image (the letter N), the JQI physicists then
stored a second image, the letter T, before reading both letters back
in quick succession. The JQI image storage method represents a
potentially important support for the establishment of quantum
networks which will exploit quantum effects for computing,
communications, and metrology.
Figure: Gradient echo memory setup. The image to be stored, the letter
N, enters (pink light) the storage cell filled with Rb atoms. The
components of this image will be absorbed by the atoms when, at
locations all over the body of the cell, a part of the signal beam and parts
of a separate “control” beam (shaded green), and the strength of a
magnetic field (the brown coil around the cell) are just right. The stored
image can later be read out and observed with a CCD camera. (Credit
NIST)
“Temporally multiplexed storage of images in a gradient
echo memory,” by Quentin Glorieux, Jeremy B. Clark,
Alberto M. Marino, Zhifan Zhou, Paul D. Lett, Optics
Express 20, 12350 (2012)