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MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov 

Carolina Martinez (818) 354-9382
Jet Propulsion Laboratory, Pasadena, Calif.                
April 2, 2003                   
NEWS RELEASE: 2003-047      

NASA Researchers Put New Spin on Einstein's Relativity Theory

Albert Einstein might be astonished to learn that NASA physicists
have applied his relativity theory to a concept he introduced but
later disliked namely that two particles that interact could maintain
a connection even if separated by a vast distance.  Researchers often
refer to this connection as "entanglement." 

Researchers at NASA's Jet Propulsion Laboratory, Pasadena, Calif.,
have discovered that this entanglement is relative, depending on how
fast an observer moves with respect to the particles, and that
entanglement can be created or destroyed just by relative motion.
This might change the way entanglement is used on future spacecraft
that move with respect to Earth or with each other.

"Imagine a particle on Earth entangled with a particle light years
away," said Dr. Christoph Adami, principal scientist in the Quantum
Computing Technologies Group at JPL.  "Whatever happens to particle A
on Earth happens to particle B, even if it is on another planet. 
Einstein referred to this connection as 'spooky'."

Einstein thought this connection violated the relativity rule that
information can't travel faster than the speed of light.  Adami and
Dr. Robert Gingrich, also of JPL, are the first to apply Einstein's
relativity theory to quantum entanglement between particles.  They
compared the amount of entanglement when the particles were at rest
to when they were given a boost. Their findings show that while
speeding up ordinary entangled pairs would lead to a loss of the
precious entanglement, certain special pairs can be created whose
entanglement is increased instead.  This increases the connection
between them. 

Understanding how some of the characteristics of a particle can
become entangled through relative motion alone when they seemed to
be unentangled or unconnected when at rest could have many
applications. For example, entangled particles could be used to
synchronize atomic clocks, which are essential for navigating
spacecraft in deep space. 

"One of the amazing things about entanglement is that it connects
objects over arbitrary distances, so that in principle the two clocks
could be started and stopped simply by acting on only one of them,"
said Adami.  "However, no workable protocol has been found to date to
achieve that." 

Because the creation of entanglement in the laboratory is usually a
delicate matter, discovering new ways to create entanglement is
always a goal of the quantum technology community.

"If you can create entanglement just by moving with respect to what
you're measuring, then seemingly you've created something from
nothing," said Gingrich.

Another possible application of entanglement is quantum
teleportation: the ability to transfer the precise quantum state of
one microscopic object to another, while using only traditional
communications, such as a phone line. This technique, which has been
demonstrated experimentally, requires that the sender and receiver
share pairs of entangled particles. But until now nobody knew what
would happen to these pairs if the sender and receiver move with
respect to each other, or if an observer moves with respect to them.
This new theory gives researchers a whole new outlook on what happens
to particle pairs when you apply the relativity theory.

The research also has ramifications for ongoing work in the area of
quantum computation, which seeks to use the subtle effects of quantum
mechanics to build faster and more efficient computers. 

"Whenever new ground is treaded by theory, new applications are sure
to follow in its wake," said Adami.

Gingrich and Adami's findings appeared in a paper they co-authored
titled, "Quantum Entanglement of Moving Bodies," which appeared in
the December 2002 issue of the journal Physical Review Letters.

The Quantum Computing Technologies Group at JPL investigates the
design and capabilities of hypothetical computing and measurement
devices that use delicate quantum effects for enhanced power and
accuracy for future space missions.

More information is available at http://cs.jpl.nasa.gov/qct/qat.html

NASA's Office of Earth Science, Washington, D.C. provided funding for
this work. The California Institute of Technology in Pasadena manages
JPL for NASA.

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