Quantum physics: Physicists successfully carry out controlled transport
of stored light

Date:
October 13, 2020
Source:
Johannes Gutenberg Universitaet Mainz
Summary:
Physicists have successfully transported light stored in a quantum
memory over a distance of 1.2 millimeters. They have demonstrated
that the controlled transport process and its dynamics has
only little impact on the properties of the stored light. The
researchers used ultra-cold rubidium-87 atoms as a storage medium
for the light as to achieve a high level of storage efficiency
and a long lifetime.



FULL STORY ==========================================================================
A team of physicists led by Professor Patrick Windpassinger at Johannes Gutenberg University Mainz (JGU) has successfully transported light
stored in a quantum memory over a distance of 1.2 millimeters. They have demonstrated that the controlled transport process and its dynamics has
only little impact on the properties of the stored light. The researchers
used ultra-cold rubidium-87 atoms as a storage medium for the light as
to achieve a high level of storage efficiency and a long lifetime.


==========================================================================
"We stored the light by putting it in a suitcase so to speak, only that
in our case the suitcase was made of a cloud of cold atoms. We moved this suitcase over a short distance and then took the light out again. This is
very interesting not only for physics in general, but also for quantum communication, because light is not very easy to 'capture', and if you
want to transport it elsewhere in a controlled manner, it usually ends
up being lost," said Professor Patrick Windpassinger, explaining the complicated process.

The controlled manipulation and storage of quantum information as well
as the ability to retrieve it are essential prerequisites for achieving advances in quantum communication and for performing corresponding
computer operations in the quantum world. Optical quantum memories, which
allow for the storage and on-demand retrieval of quantum information
carried by light, are essential for scalable quantum communication
networks. For instance, they can represent important building blocks of
quantum repeaters or tools in linear quantum computing. In recent years, ensembles of atoms have proven to be media well suited for storing
and retrieving optical quantum information. Using a technique known as electromagnetically induced transparency (EIT), incident light pulses
can be trapped and coherently mapped to create a collective excitation
of the storage atoms. Since the process is largely reversible, the light
can then be retrieved again with high efficiency.

The future objective is to develop a racetrack memory for light In their
recent publication, Professor Patrick Windpassinger and his colleagues
have described the actively controlled transport of such stored light
over distances larger than the size of the storage medium. Some time
ago, they developed a technique that allows ensembles of cold atoms to
be transported on an 'optical conveyor belt' which is produced by two
laser beams. The advantage of this method is that a relatively large
number of atoms can be transported and positioned with a high degree
of accuracy without significant loss of atoms and without the atoms
being unintentionally heated. The physicists have now succeeded in using
this method to transport atomic clouds that serve as a light memory. The
stored information can then be retrieved elsewhere. Refining this concept,
the development of novel quantum devices, such as a racetrack memory for
light with separate reading and writing sections, could be possible in
the future.


========================================================================== Story Source: Materials provided by
Johannes_Gutenberg_Universitaet_Mainz. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Wei Li, Parvez Islam, Patrick Windpassinger. Controlled Transport of
Stored Light. Physical Review Letters, 2020; 125 (15) DOI: 10.1103/
PhysRevLett.125.150501 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201013124101.htm

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