TELEPORTATION
Ever
since the invention of the wheel
5,000 years ago, people have been inventing new ways to travel faster. The chariot, bicycle, automobile and airplane have all been invented in
order to decrease the amount of time we spend to travel. Travelling by these
takes few minutes to several hours depending upon the starting and the ending
points. Many scientists are working on such a technology of travel, combining
the properties of telecommunications
and transportation to achieve a
system called “TELEPORTATION”.
TELEPORTATION
is
the transmission of 3-D image of a
person by scanning his physical body and make it to appear within a room
which is at a distant location where the person has telepresence for engaging in natural face to face with people at distant location. The image of the
person appears within a 3-D environment and can make eye to eye contact with individuals and can hold true two-way conversations.
TELEPORTATION systems are far better than videoconferencing. With videoconferencing people feel uncomfortable by being on camera and
feel disconnected from the people shown on the screen. The leading asset of
this technology is it requires no
expensive training and technical expertise.
INTRODUCTION
Teleportation
technology was invented in the golden age of 20th century. It was invented
as an alternative to travel. It can save our organization time and
money and enhance our internal and external communication network.
Teleportation is the name given by science fiction writers to the feat of
making an object or a person disintegrate in one place while a perfect replica
appears somewhere else. A teleportation machine would be like a fax machine
except that it would work on three-dimensional objects as well as documents, it
would produce an exact copy rather than an approximate facsimile and it would
destroy the original in the processing of scanning it. Teleportation was not
taken seriously by scientists, because it would violate the uncertainty
principle of quantum mechanics, which forbids any measuring or scanning process
from extracting all the information in an atom or other object.
Teleportation
involves dematerializing an object at one point, and sending the details of
that object’s precise atomic configuration to another location, where it will
be reconstructed. What this means is that time and space could be eliminated
from travel - we could be transported to any location instantly, without
actually crossing a physical distance.
WHAT IS
TELEPORTATION TECHNOLOGY?
The
Teleportec communications system is unique and has been designed to enable a
life-size image of a person to appear within a 3D environment. You can make eye
contact with individuals, use props and hold true two-way conversations-communicating
naturally with anyone or any group of people anywhere in the world, as you
would if you were there. After all 80% of communication is non-verbal. The only
thing you can’t do is shake hand.
HISTORY
In 1993 an
international group of six scientists Richard Jozsa, Willian K. Wpploters,
Gilles Brassard, Claude Crepeau, Asher Peres and IBM Fellow Charles H. Bennett,
confirmed the intuitions of the majority of science fiction writers by showing
that perfect teleportation is indeed possible in principle, but only if the
original is destroyed.
This revelation, first announced by
Bennett at an annual meeting of the American Physical Society in March 1993,
was followed by a report on his findings in the March 29, 1993 issue of
Physical Review Letters. Since that time, experiments using photons have proven
that quantum teleportation is in fact possible. In
1998, physicists at the California Institute of Technology (Caltech), along
with two European groups, turned the IBM ideas into reality by successfully
teleporting a photon, a particle
of energy that carries light. The Caltech group was able to read the atomic
structure of a photon, send this information across 3.28 feet (about 1 meter)
of coaxial cable and create a replica
of the photon. As predicted, the original photon no longer existed once the
replica was made.
In
subsequent years, other scientists have demonstrated teleportation
experimentally in a variety of systems, including single photons, coherent
light fields, nuclear spins, and trapped ions.
STEPS INVOLVED
The general
idea behind the process of teleportation seems to be that the original object
is scanned in such a way as to extract all the information from it, then this
information is transmitted to the receiving location and used to construct the
replica, not necessarily from the actual material of the original, but perhaps
from atoms of the same kinds, arranged in exactly the same pattern as the
original. The steps are:
1. SCANNING: Firstly,
the object is completely scanned to extract all the information about it. For
example, this may mean that some device scans a space explorer on board her
spaceship to find out what she's like. This includes finding her height, her
mass, the colour of her hair, what sort of shoes she is wearing etc.
2. DISASSEMBLING: As it’s
difficult to send the whole information simultaneously thus after the
extraction of data at the sending station the object is disassembled to send
the bit by bit information about the object to the receiving end. It means neatly the machine
"disassembles" the space explorer and sends or "beams" all
the things that she's made up of to some uncharted planet nearby. These
include, for example, all the atoms in her body. The machine also sends a
message to the planet containing everything that it found out about her.
3.
REASSEMBLING:
Finally, after collecting all the data sent, at the receiving station the
object is again reassembled to get the exact replica of the object sent that is
we resemble the space explorer on the nearby planet using all the things
she's made up of and the message. Teleportation is now complete.
PRINCIPLES
OF TELEPORTATION
In performing the experiment, the Caltech group was
able to get around the two principles. They are:
Heisenberg
Uncertainty Principle: This principle states that it’s impossible to
determine both the location and speed of an object simultaneously. Measurement
of one value changes the others value.
Limitation: According
to the uncertainty principle, the more accurately an object is scanned, the
more it is disturbed by the scanning process, until one reaches a point where
the object's original state has been completely disrupted, still without having
extracted enough information to make a perfect replica. These sounds like a
solid argument against teleportation: if one cannot extract enough information
from an object to make a perfect copy, it would seem that a perfect copy cannot
be made. In order to teleport a photon without violating the Heisenberg
Principle, the Caltech physicists used a phenomenon known as entanglement.
Entanglement: It solves the difficulty of
measuring that we encountered in Heisenberg Uncertainty principle. Two
particles are said to be entangled when they come in contact. Measurement of
one of the entangled sub-system puts the other sub-system in the corresponding
state.
What
is Entanglement??
Entanglement is a term used in quantum theory to
describe the way that particles of energy/matter can become correlated to
predictably interact with each other regardless of how far apart they are.
Particles, such as photons,
electrons, or qubits that have interacted with each other retain a type of
connection and can be entangled with each other in pairs, in the process known
as correlation. Knowing the spin state of one entangled particle - whether the
direction of the spin is up or down - allows one to know that the spin of its
mate is in the opposite direction. Even more amazing is the knowledge that, due
to the phenomenon of superposition, the measured particle has no single spin
direction before being measured, but is simultaneously in both a spin-up and
spin-down state. The spin state of the particle being measured is decided at
the time of measurement and communicated to the correlated particle, which
simultaneously assumes the opposite spin direction to that of the measured
particle.
Principle:
Two
photon E1, K, and beam splitters are required. We direct one of the
entangled photons, say E1, to
the beam splitter. Meanwhile, we prepare another photon with a polarization of
45 degree, and direct it to the same beam splitter from the other side. This is
the photon whose properties will be transported; we label it K. We time it so
that both E1 and K reach the beam splitter at the same time. The E1 photon incident from above will be
reflected by the beam splitter some of the time and will be transmitted some of
the time. Similarly for the K
photon that is incident from below. So sometimes both photons will end up going
up and to the right. Similarly, sometimes both photons will end up going down
and to the right. However, in the case of one photon going upwards and the
other going downwards, we cannot tell which is which. Perhaps both photons were
reflected by the beam splitter, but perhaps both were transmitted. This means
that the two photons have become entangled.
How Entanglement is performed??
In entanglement, at least three photons are
needed to achieve quantum teleportation:
Photon A:
The photon to be teleported
Photon B:
The transporting photon
Photon C:
The photon that is entangled with photon B
If
researchers tried to look too closely at photon A without entanglement, they
would bump it, and thereby change it. By entangling photons B and C,
researchers can extract some information about photon A, and the remaining
information would be passed on to B by way of entanglement, and then on to
photon C. When researchers apply the information from photon A to photon C,
they can create an exact replica of photon A. However, photon A no longer
exists as it did before the information was sent to photon C.
Quantum entanglement allows qubits that are separated
by incredible distances to interact with each other immediately, in a
communication that is not limited to the speed of light. No matter how great
the distance between the correlated particles, they will remain entangled as
long as they are isolated.
Entanglement is a real phenomenon, which has
been demonstrated repeatedly through experimentation. Much current research is
focusing on how to harness the potential of entanglement in developing systems
for quantum cryptography, quantum computing and teleportation.
QUANTUM
TELEPORTATION
It is a
technique used to transfer quantum information from one quantum system to
another. It does not transport the system itself, nor does it
allow communication of information at superluminal (faster than light) speed.
Neither does it concern rearranging the particles of a macroscopic object to
copy the form of another object. Its distinguishing feature is that it can transmit
the information present in a quantum superposition, useful for quantum
communication and computation.
Procedure:
Stated more
precisely, quantum teleportation is a quantum protocol by which a qubit a
(the basic unit of quantum information) can be transmitted exactly (in
principle) from one location to another. The prerequisites are a conventional
communication channel capable of transmitting two classical bits, and an
entangled Bell pair of qubits, with b at the origin and c at the
destination.
Quantum teleportation involves
entangling two things, like photons or ions, so their states are dependent on
one another and each can be affected by the measurement of the other's state. When one of
the items is sent a distance away, entanglement ensures that changing the state
of one causes the other to change as well, allowing the teleportation of
quantum information, if not matter. However, the distance particles can be from
each other has been limited so far to a number of meters. Teleportation
over distances of a few hundred meters has previously only been accomplished
with the photons travelling in fibre channels to help preserve their state. The
two photons are entangled using both spatial and polarization modes and sent
the one with higher energy through a ten-mile-long free space channel. It was
found that the distant photon was still able to respond to changes in state of
the photon they held onto even at this unprecedented distance.
As the
figure suggests, the unscanned part of the information is conveyed from A to C
by an intermediary object B, which interacts first with C and then with A.
What? Can it really be correct to say "first with C and then with A"?
Surely, in order to convey something from A to C,
the
delivery vehicle must visit A before C, not the other way around. But there is
a subtle, unscannable kind of information that, unlike any material cargo, and
even unlike ordinary information, can indeed be delivered in such a backward
fashion. This subtle kind of information, also called
"Einstein-Podolsky-Rosen (EPR) correlation" or "entanglement",
has been at least partly understood since the 1930s when it was discussed in a
famous paper by Albert Einstein, Boris Podolsky, and Nathan Rosen. In the
1960s, John Bell showed that a pair of entangled particles, which were once in
contact but later move too far apart to interact directly, can exhibit
individually random behavior that is too strongly correlated to be explained by
classical statistics. Experiments on photons and other particles have
repeatedly confirmed
these
correlations, thereby providing strong evidence for the validity of quantum
mechanics, which neatly explains them.
Another
well-known fact about EPR correlations is that they cannot by themselves
deliver a meaningful and controllable message. It was thought that their only
usefulness was in proving the validity of quantum mechanics. Now it is known
that, through the phenomenon of quantum teleportation, they can deliver exactly
that part of the information in an
object,
which is too delicate to be scanned out, and delivered by conventional methods.
CLASSICAL TELEPORTATION
This figure
compares conventional facsimile transmission with quantum teleportation (see
above). In conventional facsimile transmission, the original is scanned,
extracting partial information about it, but remains more or less intact after
the scanning process. The scanned information is sent to the receiving station,
where it is imprinted on some raw material (e.g. paper) to produce an
approximate copy of the original. In quantum teleportation, two objects B and C
are first brought into contact and then separated. Object B is taken to the
sending station, while object C is taken to the receiving station. At the
sending station object B is scanned together with the original object A which
one wishes to teleport, yielding some information and totally disrupting the
state of A and B. The scanned information is sent to the receiving station,
where it is used to select one of several treatments to be applied to object C,
thereby putting C into an exact replica of the former state of A.
THE
INNSBRUCK EXPERIMENT
IMAGE
DEPICTS the University of Innsbruck experimental setup for quantum
teleportation. In the quantum teleportation process, physicists take a photon
(or any other quantum-scale particle, such as an electron or an atom) and transfer
its properties (such as its polarization, the direction in which its electric
field vibrates) to another photon even if the two photons are at remote
locations. The scheme does not teleport the photon itself; only its properties
are imparted to another, remote photon.
Here is how it works: At the sending station of the quantum
teleporter, Alice encodes a "messenger" photon (M) with a specific
state: 45 degrees polarization. This travels towards a beam splitter. Meanwhile,
two additional "entangled" photons (A and B) are created. The
polarization of each photon is in a fuzzy, undetermined state, yet the two
photons have a precisely defined interrelationship. Specifically, they must
have complementary polarizations. For example, if photon A is later measured to
have horizontal (0 degrees) polarization, then the other photon must
"collapse" into the complementary state of vertical (90 degrees)
polarization.
Entangled
photon A arrives at the beam splitter at the same time as the message photon M.
The beam splitter causes each photon to either continue toward detector 1 or
change course and travel to detector 2. In 25% of all cases, in which the two
photons go off into different detectors, Alice does not know which photon went
to which detector. This inability for Alice to distinguish between the two
photons causes quantum weirdness to kick in. Just by the very fact that the two
photons are now indistinguishable, the M photon loses its original identity and
becomes entangled with A. The polarization value for each photon is now
indeterminate, but since they, travel toward different detectors Alice knows
that the two photons must have complementary polarizations.
Since message photon M must have
complementary polarization to photon A, then the other entangled photon (B)
must now attain the same polarization value as M. Therefore, teleportation is
successful. Indeed, Bob sees that the polarization value of photon B is 45
degrees the initial value of the message photon.
POLARIZATION
ANALYSIS OF THE
TELEPORTED PHOTON
The data
shows the polarization of the teleported photon as a function of the delay
between the arrival of photon 1 and 2 at Alice’s beam splitter (when
translating the retroflecting UV-mirror). Only around zero delay, interference
occurs and allows registration of a Bell-state. The polarization of photon 3 is
analyzed if detector p has indicated that there is a photon to be teleported
and if Alice’s Bell-state analyzer has registered the state. Photon 3 shows the
polarization defined by the polarizer acting on photon 1.
The
polarization, without any background subtraction, is 70%±3%. The results for
the two non-orthogonal states (45° and 90°) prove teleportation of the quantum
state of a single photon.
HUMAN
TELEPORTATION
We are
years away from the development of a teleportation machine like the transporter
room on Star Trek's Enterprise spaceship. The laws of physics may even make it
impossible to create a transporter that enables a person to be sent
instantaneously to another location, which would require travel at the speed of
light.
For a person to be transported, a
machine would have to be built that can pinpoint and analyze all of the 10^28
atoms that make up the human body. That's more than a trillion atoms. This
machine would then have to send this information to another location, where the
person's body would be reconstructed with exact precision. Molecules couldn't
be even a millimeter out of place, lest the person arrive with some severe
neurological or physiological defect.
In the Star Trek episodes, and the
spin-off series that followed it, teleportation was performed by a machine
called a transporter. This was a platform that the characters stood on, while Scotty
adjusted switches on the transporter room control boards. The transporter
machine then locked onto each atom of each person on the platform, and used a
transporter carrier wave to transmit those molecules to wherever the crew
wanted to go. Viewers watching at home witnessed Captain Kirk and his crew
dissolving into a shiny glitter before disappearing, rematerializing instantly
on some distant planet.
If such a machine were possible,
it's unlikely that the person being transported would actually be "transported."
It would work more like a fax machine a duplicate of the person would be made
at the receiving end, but with much greater precision than a fax machine. But
what would happen to the original? One theory suggests that teleportation would
combine genetic cloning with digitization.
In this biodigital cloning,
tele-travelers would have to die, in a sense. Their original mind and body
would no longer exist. Instead, their atomic structure would be recreated in
another location, and digitization would recreate the travelers' memories,
emotions, hopes and dreams. So the travelers would still exist, but they would
do so in a new body, of the same atomic structure as the original body,
programmed with the same information.
ADVANTAGES
Teleportation
Technology is now being used by organizations across the world to enable people
to be in two (or more) places at once. These organizations have recognized the
substantial communication benefits of the technology:
1. Genuine
eye-to-eye contact with individuals or audiences in the distant location, which
means you, can make that personal connection count wherever you are.
2. The quality
of the communication means that you are able to see and respond to the mood and
body language of the person you are speaking with to build trust and
understanding.
3. The
financial benefits are significant too.
4.
Substantial savings in travel and accommodation costs.
5. No expensive training required. The
technology is very easy to use.
CONCLUSION
Like all
technologies, scientists are sure to continue to improve upon the ideas of
teleportation, to the point that we may one day be able to avoid such harsh
methods. One day, one of your descendants could finish up a work day at a space
office above some far away planet in a galaxy many light years from Earth, tell
his or her wristwatch that it's time to beam home for dinner on planet X below
and sit down at the dinner table as soon as the words leave his mouth.
References:
1.C.H.
Bennett, G. Brassard, C. Crepeau, R. Jozsa, A. Peres, and W. Wootters,
"Teleporting an Unknown Quantum State via Dual Classical and EPR.
2.
Channels", Phys. Rev. Lett. vol. 70, pp 1895-1899 (1993) (the original
6-author research article).
3. Tony
Sudbury, "Instant Teleportation", Nature vol.362, pp 586-
587 (1993)
(a semi popular account).
4. Ivars
Peterson, Science News, April 10, 1993, p. 229. (another
semi
popular account).
5. Samuel
Braunstein, A fun talk on teleportation
No comments:
Post a Comment