Bit by Bit: NIST Advances Quantum Computing

Sep 23, 2015

 

What happened?

Teleportation has long been the realm of science fiction. From Douglas Adams to Isaac Asimov, storytellers have ensnared us with visions of instantaneous travel.  Physical teleportation remains a fantasy. Quantum teleportation, the transfer of quantum information in matter or light, is on its way to becoming a reality. Quantum teleportation is a building block in quantum communications and computing. It is difficult to understate the potential of these future technologies.

Scientists at the National Institute of Standards and Technology (NIST) transferred quantum information in light a distance of over 100 kilometres. Their success, using fibre optic cable, was four times farther than a 25 kilometre record set in 2014. The transfer took place in NIST’s Colorado laboratory. 

The key takeaway is that fibre optic cable is a suitable vector for quantum communication over a long distance. Older research groups have achieved higher distances, but in a vacuum, and not fibre’s more practical solid mass.

Quantum teleportation transfers or reconstructs quantum data contained in matter or light particles. An international group outlined the fundamentals in 1993. The intermediate years have seen advances and successful experiments performed by other research groups.

How does it work?

Hiroki Takesue from NTT Corp, Japan, was a guest researcher with NIST and led the study. NIST’s advanced photon detectors were the cornerstone of this new achievement.

Components of quantum state information can carry useful data. In the NIST experiment, the setup used four of the group’s photon detectors to filter out irrelevant quantum information. The encoded data was the time, to the nanosecond, that the photon would arrive.

NIST based the construction of the detectors on nanowire superconductors. They were able to capture 80% of incoming photon data, and calculate whether they arrived in the correct timeslot. 

Why is it important?                                                              

This new revelation breaks down previous barriers to using fibre optics in quantum teleportation.  Before, it was believed light was an impossible vector.  Quantum communications research faced the engineering challenge of using quantum states of matter. Earlier versions of the experiment saw so much data lost at distance that transmission rates were too low. The new study’s findings could create quantum repeaters; a type of device that could extend a quantum network further and one day build a “quantum internet”.

What’s the big deal with quantum teleportation? The practical application of quantum teleportation is fundamental to quantum communications and quantum computing.

Quantum communication would enable the fabled unbreakable quantum security. Photons in transport can only be read using the correct measurement, which irrevocably transforms them. Long distance secure transmissions would be possible, including into space and to satellites.

There are still significant barriers to overcome. While the solution has been successful in an experimental setup, practical implementation would present new challenges. Yet the use of quantum teleportation would be practical and possible in a much shorter timeframe within a quantum computer.

Quantum computing would provide processing power and capabilities  beyond our current grasp. A quantum computer’s strength would be able to bypass a large part of the world’s digital security. That includes the common RSA algorithm and other types based on factoring and discrete logarithms. Certain experiments which have been impossible to simulate thus far would become possible, an area known as “Quantum simulation”. This could be used to replicate the behaviours of atoms from systems like the Large Hadron Collider to complex chemical reactions. A quantum computer could find the metaphorical “needle in a haystack” in a variety of data sources using a fraction of the computational effort expected now.

Just as quantum teleportation is a foundation for quantum computing and communication, quantum computing is the foundation for a new generation of scientific inquiry. We would gain the ability to unravel more of the mysteries of the universe. That might include the secret to physical teleportation.  NIST is taking the first steps.


Vijay Michalik

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