Credit: S. Kelley/NIST
Schematic of an interference experiment in which two photons are produced in different buildings, are generated by different sources and have different colors.
Particles can sometimes act like waves, and photons (particles of light) are no exception. Just as waves create an interference pattern, like ripples on a pond, so do photons. Physicists from the National Institute of Standards and Technology (NIST) and their colleagues have achieved a major new feat — creating a bizarre “quantum” interference between two photons of markedly different colors, originating from different buildings on the University of Maryland campus.
The experiment is an important step for future quantum communications and quantum computing, which could potentially do things that classical computers can’t, such as break powerful encryption codes and simulate the behavior of complex new drugs in the body. The interference between two photons could connect distant quantum processors, enabling an internet-like quantum computer network.
Using photons that originally had different colors (wavelengths) is important because it mimics the way a quantum computer would operate. For instance, visible-light photons can interact with trapped atoms, ions or other systems that serve as quantum versions of computer memory while longer-wavelength (near-infrared) photons are able to propagate over long distances through optical fibers.
Just as classical computers needed reliable ways to transmit, store and process electrons before complex, networked computing was possible, the NIST result brings the exchange of quantum computing information an important step closer to reality.
In their study, a collaboration between NIST and the Army Research Laboratory, physicists and engineers in adjacent buildings at the University of Maryland created two different and separate sources of individual photons. In one building, a group of rubidium atoms was prompted to emit single photo ..
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