Tapping particles of light

November 26, 2015

At the Weizmann Institute of Science, researchers have managed to 'pluck' a single photon -- one particle of light -- out of a pulse of light. The findings of this research, which appeared this week in Nature Photonics, bear both fundamental and practical significance: Light is the workhorse of today's communication systems, and single photons are likely to be the backbone of future quantum communication systems. In addition, say the scientists, the apparatus they have devised will spur further research into the fundamental particle nature of light.

"Once we move over to quantum communication, information will have to be encoded in single photons," says Dr. Barak Dayan, head of the Weizmann Institute Quantum Optics group. "Each photon will then represent a single 'qubit' -- a quantum bit that can exist in more than one state at the same time (for example, an equal combination of both 1 and 0)."

Dayan and his research team, led by Dr. Serge Rosenblum and Orel Bechler, set out to demonstrate a scheme for pulling just one photon out of a stream, on demand. Their mechanism relies on a physical effect that they call single-photon Raman interaction, or SPRINT, which is based on a single atom, or atom-like system. "The advantage of SPRINT," says Dayan, "is that it is completely passive -- it does not require any control fields, just the interaction between the atom and the optical pulse." In previous research, he and his team had employed SPRINT as a switch for single photons that sent them down different pathways, effectively turning the apparatus into a photonic router. In this work, the atom becomes a tap rather than a switch, snatching one photon from the flow and then turning itself off. "It is not trivial," says Dayan, "to have a mechanism that continues to function even in high fluxes of photons and to remove just one photon."

The experimental setup of Weizmann's quantum optics group relies on state-of-the-art technologies: laser cooling and trapping of atoms (in this case rubidium), the fabrication of chip-based, ultrahigh-quality glass microspheres, and optical nanofibers.

"The ability to divert a single photon from a flow could be harnessed for various tasks," says Dayan, "from creating nonclassical states of light that are useful for basic scientific research, through eavesdropping on imperfect quantum-cryptography systems that rely on single photons, to increasing the security of your own quantum-communication systems.

The existence of photons was first suggested by Einstein in 1905, yet many of their properties are just now coming to light. Dayan believes their new method will expand our capabilities to study and control them as individual particles.
Dr. Barak Dayan's research is supported by the Benoziyo Endowment Fund for the Advancement of Science; the Crown Photonics Center; the Rothschild Caesarea Foundation; and the Deloro Institute for Advanced Research in Space and Optics. Dr. Dayan is the incumbent of the Joseph and Celia Reskin Career Development Chair.

The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.

Weizmann Institute of Science

Related Photons Articles from Brightsurf:

An electrical trigger fires single, identical photons
Researchers at Berkeley Lab have found a way to generate single, identical photons on demand.

Single photons from a silicon chip
Quantum technology holds great promise: Quantum computers are expected to revolutionize database searches, AI systems, and computational simulations.

Physicists "trick" photons into behaving like electrons using a "synthetic" magnetic field
Scientists have discovered an elegant way of manipulating light using a ''synthetic'' Lorentz force -- which in nature is responsible for many fascinating phenomena including the Aurora Borealis.

Scientists use photons as threads to weave novel forms of matter
New research from the University of Southampton has successful discovered a way to bind two negatively charged electron-like particles which could create opportunities to form novel materials for use in new technological developments.

The nature of nuclear forces imprinted in photons
IFJ PAN scientists together with colleagues from the University of Milano (Italy) and other countries confirmed the need to include the three-nucleon interactions in the description of electromagnetic transitions in the 20O atomic nucleus.

Pushing photons
UC Santa Barbara researchers continue to push the boundaries of LED design a little further with a new method that could pave the way toward more efficient and versatile LED display and lighting technology.

Photons and electrons one on one
The dynamics of electrons changes ever so slightly on each interaction with a photon.

An advance in molecular moviemaking shows how molecules respond to two photons of light
Some of the molecules' responses were surprising and others had been seen before with other techniques, but never in such detail or so directly, without relying on advance knowledge of what they should look like.

The imitation game: Scientists describe and emulate new quantum state of entangled photons
A research team from ITMO University, MIPT and Politecnico di Torino, has predicted a novel type of topological quantum state of two photons.

What if we could teach photons to behave like electrons?
The researchers tricked photons - which are intrinsically non-magnetic - into behaving like charged electrons.

Read More: Photons News and Photons Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.