### What is teleportation?
** In the Classical world: **
In o...
![teleportation scheme](http://i.imgur.com/yUuNyuj.png?1 "Teleporta...
An **EPR pair** is a pair of particles that are entangled with each...
The **singlet state** is an entangled state of system of two or mor...
Before discussing the teleportation phenomenon let us first underst...
#### A simple example of teleportation:
Consider two scientists Al...
It is interesting to notice that for the teleportation to be comple...
The teleportation procedure described above uses a system of 2 enta...
**Remarks about human teleportation:**
A human person is composed ...
#### Experimental results about Quantum Teleportation:
In Octobe...
VOLUME
70
29 MARCH l993
NUMBER 13
Teleporting
an Unknown
Quantum
State
via
Dual
Classical and
Einstein-Podolsky-Rosen
Channels
Charles
H.
Bennett,
~
)
Gilles
Brassard,
( )
Claude
Crepeau,
( )
(
)
Richard
Jozsa,
(
)
Asher
Peres,
~4)
and William
K.
Wootters(
)
'
IBM
Research
Division,
T.J.
watson Research
Center,
Yorktomn
Heights,
¹mYork 10598
(
lDepartement
IIto,
Universite
de
Montreal, C.
P
OI28,
Su.
ccursale
"A",
Montreal,
Quebec,
Canada HBC
817
(
lLaboratoire
d'Informatique
de
1'Ecole
Normale
Superieure,
g5
rue
d'Ulm,
7M80 Paris CEDEX
05,
France~
i
l
lDepartment
of
Physics,
Technion Israel
In—
stitute
of
Technology,
MOOO
Haifa,
Israel
l
lDepartment
of
Physics,
Williams
College,
Williamstoivn,
Massachusetts
OIP67
(Received
2 December
1992)
An
unknown
quantum
state
]P)
can be disassembled
into,
then
later reconstructed
from,
purely
classical information
and
purely
nonclassical
Einstein-Podolsky-Rosen
(EPR)
correlations.
To
do
so
the
sender,
"Alice,
"
and the
receiver,
"Bob,
"
must
prearrange
the
sharing
of an
EPR-correlated
pair
of
particles.
Alice
makes a
joint
measurement on her EPR
particle
and the unknown
quantum
system,
and sends Bob the classical result of this measurement.
Knowing
this,
Bob can convert the
state
of
his EPR
particle
into an exact
replica
of
the unknown state
]P)
which
Alice
destroyed.
PACS numbers: 03.65.
Bz,
42.50.
Dv,
89.
70.
+c
The existence
of
long
range
correlations between
Einstein-Podolsky-Rosen
(EP
R)
[1]
pairs
of
particles
raises the
question
of
their
use
for information
transfer.
Einstein
himself
used
the
word
"telepathically"
in
this
contempt
[2].
It
is
known that
instantaneous
information
transfer is definitely
impossible
[3].
Here,
we
show that
EPR
correlations can
nevertheless assist
in
the
"telepor-
tation"
of an intact
quantum
state
from one
place
to
another,
by
a sender who
knows
neither
the state
to be
teleported
nor
the
location of
the intended
receiver.
Suppose
one
observer,
whom we
shall call
"Alice,
"
has
been
given
a
quantum system
such as
a
photon
or
spin-&
particle, prepared
in
a
state
]P)
unknown
to
her,
and she
wishes to
communicate
to
another
observer,
"Bob,
"
suf-
ficient information about the
quantum
system
for him to
make an accurate
copy
of it.
Knowing
the
state vector
]P)
itself would
be
sufficient information,
but in
general
there is
no
way
to
learn it.
Only
if Alice knows
before-
hand that
~qb)
belongs
to a
given
orthonormal set can
she
make
a
measurement whose result
will allow her to make
an
accurate
copy
of
[P).
Conversely,
if
the possibilities
for
~P)
include two or
more
nonorthogonal states,
then
no
measurement
will
yield
sufhcient
information
to
prepare
a
perfectly
accurate
copy.
A
trivial
way
for
Alice
to
provide
Bob
with all the
in-
formation
in
[P)
would be to
send
the
particle
itself. If
she
wants to
avoid transferring
the
original
particle,
she can
make
it.
interact unitarily
with another
system,
or
"an-
cilla,
"
initially
in a known state
~ap),
in such
a
way
that
after
the interaction the
original particle
is left in
a
stan-
dard
state
~Pp)
and the ancilla is in an
unknown
state
]a)
containing complete
information about
~P).
If
Al-
ice now sends
Bob the
ancilla
(perhaps
technically
easier
than
sending
the
original
particle),
Bob can reverse her
actions to
prepare
a
replica
of her original
state
~P).
This
"spin-exchange
measurement"
[4]
illustrates
an
essential
feature
of
quantum
information: it
can be
swapped
from
one
system
to another,
but
it
cannot be duplicated
or
"cloned"
[5].
In this
regard
it
is
quite
unlike
classical
information,
which can be duplicated
at
will. The most
tangible
manifestation
of the nonclassicality
of
quantum
information is
the
violation
of
Bell
s
inequalities
[6)
ob-
served
[7]
in experiments
on
EPR
states.
Other
rnanifes-
tations
include
the
possibility
of
quantum
cryptography
[8),
quantum
parallel
computation
[9],
and
the
superior-
ity
of
interactive
measurements
for
extracting
informa-
1993 The American
Physical
Society
1895