Teleportation
The quantum transporter transfers data of a quantum system (such as an ion) to
another (one second ion), even though the two are completely isolated from
each other.
In this form of real-life teleportation, only quantum information is carried,
not matter - unlike the Star Trek version of "radiating" entire human beings
from a spacecraft to a planet.
Quantum data teleportation has previously been demonstrated with ions and a
variety of other systems, including a fiber-optic teleportation 6 km away .
Now physicists have been able to teleport not just a die, but a complete
logical operation between two separate ions (electrically charged atoms),
showing how future quantum computer programs can perform tasks on large-scale
networks.
"We found that our logic operation works in all quantum-bit input states with
85-87% probability - far from perfect, but it's a start," said Professor
Dietrich Leibfried of the National Institute of Standards and Technology
NIST).
The work was attended by Professor Hilma Vasconcelos, Federal University of
Ceará.
Teleportation of logical operations
For quantum computers to perform as expected, they are likely to need millions
of quantum bits, or qubits , and ways of conducting operations between qubits
distributed across machines and large-scale networks.
The teleportation of logical operations is one way of doing this without
direct connections of quantum nature - physical connections for the exchange
of classic information will probably still be necessary.
The team teleported an "NOT Controlled" (CNOT) logical operation between two
qubits of beryllium ions located more than 340 micrometers apart, a distance
that excludes any substantial direct interaction.
A logic operation CNOT inverts the second qubit from 0 to 1, or vice versa,
only if the first qubit is 1; nothing happens if the first qubit is 0. In a
typical quantum mode, the two qubits may be in "superposition", in which they
have values of 1 and 0 at the same time.
But the teleportation process depends on another quantum phenomenon, the
interlacing, which "connects" the properties of the particles even when they
are separated. A messenger pair of interlaced magnesium ions is used to
transfer information between beryllium ions.
Quantum truth table
The teletransported CNOT process intertwined the two magnesium ions - an
essential prior step - with a 95% success rate, while teleportation of the
full logical operation succeeded 85% to 87% of the attempts.
To verify that the CNOT port was still functioning after being teleported, the
researchers prepared the first qubit in 16 different combinations of input
states and measured the outputs in the second qubit. This produced a
generalized quantum truth table, showing that the process works.
This technique should become an important tool in the characterization of
quantum information processes in future experiments.
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In this paper, we describe the quantum gate teleportation between separated qubits in a trapped-ion processor , as well as in the case of Yong Wan, Daniel Kienzler, Stephen D. Erickson, Karl H. Mayer, Ting Rei Tan, Jenny J. Wu, Hilma M. Vasconcelos, Scott Glancy, Emanuel Knill, David J. Wineland, Andrew C. Wilson, Dietrich Leibfried Science Vol. 364, Issue 6443, pp. 875-878 DOI: 10.1126 / science.aaw9415 |
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Computing