Structures called metamaterials and the merging of two technologies under development are promising the emergence of new quantum information systems far more powerful than today’s computers. The concept hinges on using single photons—the tiny particles that make up light—for switching and routing in future computers that might harness the exotic principles of quantum mechanics. The image at left depicts a spherical dispersion of light in a conventional material, and the image at right shows the design of a metamaterial that has a hyperbolic dispersion not found in any conventional material, potentially producing quantum-optical applications. Image: Zubin Jacob
The merging of two technologies under development—plasmonics
and nanophotonics—is promising the emergence of new quantum information systems
far more powerful than today’s computers.
The technology hinges on using single photons—the tiny
particles that make up light—for switching and routing in future computers that
might harness the exotic principles of quantum mechanics.
The quantum information processing technology would use structures
The metamaterials, when combined with tiny optical
emitters, could make possible a new hybrid technology that uses quantum light
in future computers, says Vladimir Shalaev, scientific director of
nanophotonics at Purdue University’s Birck Nanotechnology Center and a
distinguished professor of electrical and computer engineering.
The concept is described in an article to be published in Science. The article was written by
Shalaev and Zubin Jacob, an assistant professor of electrical and computer
engineering at the University of Alberta, Canada.
“A seamless interface between plasmonics and
nanophotonics could guarantee the use of light to overcome limitations in the
operational speed of conventional integrated circuits,” Shalaev says.
Researchers are proposing the use of plasmon-mediated
interactions, or devices that manipulate individual photons and quasiparticles
called plasmons that combine electrons and photons.
One of the approaches, pioneered at Harvard University,
is a tiny nanowire that couples individual photons and plasmons. Another
approach is to use hyperbolic metamaterials, suggested by Jacob; Igor
Smolyaninov, a visiting research scientist at the University of Maryland; and Evgenii
Narimanov, an associate professor of electrical and computer engineering at
Purdue. Quantum-device applications using building blocks for such hyperbolic
metamaterials have been demonstrated in Shalaev’s group.
“We would like to record and read information with
single photons, but we need a very efficient source of single photons,”
Shalaev says. “The challenge here is to increase the efficiency of
generation of single photons in a broad spectrum, and that is where plasmonics
and metamaterials come in.”
Today’s computers work by representing information as a
series of ones and zeros, or binary digits called bits.
Computers based on quantum physics would have quantum
bits, or qubits, that exist in both the on and off states simultaneously,
dramatically increasing the computer’s power and memory. Quantum computers
would take advantage of a strange phenomenon described by quantum theory called
entanglement. Instead of only the states of one and zero, there are many
possible entangled quantum states in between one and zero.
An obstacle in developing quantum information systems is
finding a way to preserve the quantum information long enough to read and
record it. One possible solution might be to use diamond with nitrogen
vacancies, defects that often occur naturally in the crystal lattice of
diamonds but can also be produced by exposure to high-energy particles and
“The nitrogen vacancy in diamond operates in a very
broad spectral range and at room temperature, which is very important,”
The work is part of a new research field, called diamond
photonics. Hyperbolic metamaterials integrated with nitrogen vacancies in
diamond are expected to work as efficient “guns” of single photons
generated in a broad spectral range, which could bring quantum information
systems, he says.