The ability to control light pulses on an integrated chip-based platform is a major step toward the realization of all-optical quantum communication networks, with potentially vast improvements in ultra-low-power performance. Holger Schmidt, professor of electrical engineering in the Baskin School of Engineering at the University of California, Santa Cruz, leads the team of researchers at UC Santa Cruz and Brigham Young University that developed the new device.
"Slow light and other quantum coherence effects have been known for quite awhile, but in order to use them in practical applications we have to be able to implement them on a platform that can be mass-produced and will work at room temperature or higher, and that's what our chips accomplish," Schmidt said.
Whereas optical fibers routinely transmit data at light speed, routing and data processing operations still require converting light signals to electronic signals. All-optical data processing will require compact, reliable devices that can slow, store, and process light pulses.
"The simplest example of how slow light can be used is to provide a data buffer or tunable signal delay in an optical network, but we are looking beyond that with our integrated photonic chip," Schmidt said.
The device relies on quantum interference effects in a rubidium vapor inside a hollow-core optical waveguide that is built into a silicon chip using standard manufacturing techniques. It builds on earlier work by Schmidt and his collaborators that enabled them to perform atomic spectroscopy on a chip (http://press.ucsc.edu/text.asp?pid=1356). The first author of the new paper is Bin Wu, a graduate student in electrical engineering at UCSC. The coauthors include John Hulbert, Evan Lunt, Katie Hurd, and Aaron Hawkins of Brigham Young University.
Several different techniques have been used to slow light to a crawl and even bring it to a complete halt for a few hundredths of a millisecond. Previously, however, systems based on quantum interference required low temperatures or laboratory setups too elaborate for practical use. In 2008, researchers at NTT Laboratories in Japan developed a specially structured silicon chip that could slow light pulses by a factor of 170. Called a photonic crystal waveguide, it has advantages for certain applications, but it does not produce the quantum effects of the atomic spectroscopy chip developed by Schmidt's group.
Those quantum effects produce not only slow light but other interactions between light and matter that raise the possibility of radically new optical devices for quantum computing and quantum communication systems, according to Schmidt. In addition, the system makes it easy to turn the effect on and off and tune it to the desired speed of light.
"By changing the power of a control laser, we can change the speed of light--just by turning the power control knob," he said.
The control laser modifies the optical properties of the rubidium vapor in the hollow-core waveguide. Under the combined action of two laser fields (control and signal), electrons in the rubidium atoms are transferred into a coherent superposition of two quantum states. In the strange world of quantum physics, they exist in two different states at the same time. One result is an effect known as electromagnetically induced transparency, which is key to producing slow light.
"Normally, the rubidium vapor absorbs the light from the signal laser, so nothing gets through. Then you turn on the control laser and boom, the material becomes transparent and the signal pulse not only makes it through, but it also moves significantly more slowly," Schmidt said.
This study is the first demonstration of electromagnetically induced transparency and slow light on a fully self-contained atomic spectroscopy chip.
"This has implications for looking at nonlinear optical effects beyond slow light," Schmidt said. "We can potentially use this to create all-optical switches, single-photon detectors, quantum memory devices, and other exciting possibilities."
This research was funded by the Defense Advanced Research Projects Agency (DARPA) and the National Science Foundation (NSF).
Tim Stephens | EurekAlert!
Sharpening the X-ray view of the nanocosm
23.03.2018 | Changchun Institute of Optics, Fine Mechanics and Physics
Drug or duplicate?
23.03.2018 | Fraunhofer-Institut für Angewandte Festkörperphysik IAF
Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.
The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...
An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.
The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
23.03.2018 | Event News
19.03.2018 | Event News
16.03.2018 | Event News
23.03.2018 | Materials Sciences
23.03.2018 | Agricultural and Forestry Science
23.03.2018 | Physics and Astronomy