[Laser] 143 km quantum DX

[bernieS]

http://www.sciencedaily.com/releases/2012/09/120905134356.htm

Quantum Teleportation Goes the Distance: 
Record-Breaking Distance of 143 Kilometers Through Free Space

ScienceDaily (Sep. 5, 2012) ­ An international 
research team including several scientists from 
the University of Waterloo has achieved quantum 
teleportation over a record-breaking distance of 
143 kilometres through free space.

The experiment saw the successful teleportation 
of quantum information -- in this case, the 
states of light particles, or photons -- between 
the Canary Islands of La Palma and Tenerife. The 
breakthrough is a crucial step toward quantum communications via satellite.

Unlike the teleportation of solid objects 
popularized in science fiction, the experiment 
involved the teleportation of quantum states, an 
essential pre-requisite of quantum computing, 
quantum communication and other powerful 
technologies under development at the Institute 
for Quantum Computing (IQC) at Waterloo.

The project, led by researchers from Vienna's 
Institute for Quantum Optics and Quantum 
Information, relied on algorithms and equipment 
developed in Waterloo. Their results were published this week in Nature.

Teleportation across 143 kilometres is a crucial 
milestone in this research, since that is roughly 
the minimum distance between the ground and 
orbiting satellites. This achievement leads to 
the possibility of quantum teleportation between 
ground stations and orbiting satellites, a key 
goal in the research of Professor Thomas 
Jennewein, an IQC faculty member and collaborator 
on the record-setting experiment.

For this experiment, Jennewein developed the 
coincidence algorithm, which synchronized and 
measured the transfer of photons between the two sites in the Canary Islands.

The ultra-precise clocks needed to measure the 
teleportation of photon states were aligned to 
each other to within a nanosecond, or 
one-billionth of a second. Such precision will be 
necessary in the development of satellite-based 
quantum communications networks.

"The experiment paves the way toward 
teleportation of signals over free space, or even 
using satellites," said Jennewein, whose research 
is largely focused on the creation of large-scale 
quantum communications networks. "This is useful 
for applications in secure communication, as well 
as the possibility of networking full-scale 
quantum computers, once they exist."

IQC research assistant professor Vadim Makarov, 
along with PhD student Elena Anisimova, designed 
the highly sensitive photon detectors, which 
allowed the teleportation to occur with high 
precision despite some hazy air conditions.

Makarov and Anisimova were recruited to help 
overcome inclement atmospheric conditions caused 
by dust whipped up from the Sahara Desert in the 
summer of 2011 that foiled the first attempt at 
the teleportation experiment. Makarov's photon 
detectors, and more cooperative weather, allowed 
for a successful experiment last April.

Because there is less atmospheric disturbance 
when communicating upwards to space than between 
the Canary Islands, Makarov says the next logical 
step is to attempt teleportation between Earth and a satellite.

Makarov was in the Canary Islands for the 
experiment, but Jennewein stayed in Waterloo, 
connecting with his international colleagues via 
Skype to lend troubleshooting tips and scientific expertise.

Abstract of full paper: 
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11472.html