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Tiny bubbles bring a huge leap



Tiny bubbles bring a huge leap

Schematic diagram of a laser-illuminated nano-optical probe that studies strained nanobubbles of a two-dimensional semiconductor tungsten diselenide (WSe2; green and yellow balls). A single layer of WSe2 is located on the boron nitride layer (blue and gray balls). Photo Credit: Nicholas Borys/Montana State University

July 1

3, 2020-Researchers at Columbia Engineering Corporation and Montana State University today reported that they found that applying sufficient strain in the 2-D material (tungsten diselenide (WSe2)) would produce single photons The local state of the transmitter. Using the advanced optical microscope technology developed in Colombia in the past three years, the team was able to directly image these states for the first time, thereby revealing that they are highly tunable even at room temperature and can be used as quantum dots, sealed Semiconductor fragments, glowing.


“Our findings are very exciting because it means that we can now place the single-photon emitter wherever we want, and just bend or tighten the material at a specific location to adjust its characteristics, such as the Color.” said James Schuck, associate professor of mechanical engineering, who co-led the study published today Natural Nanotechnology. “Knowing where and how to tune single-photon emitters is critical to creating so-called “quantum” simulators for quantum computers that even simulate physical phenomena that cannot be modeled with today’s computers.

As researchers discover how to use the unique characteristics of quantum physics to create devices that are more efficient, faster, and more sensitive than existing technologies, developing quantum technologies such as quantum computers and quantum sensors is a rapidly evolving field of research. For example, quantum information (think encrypted messages) will be more secure.

Light consists of discrete energy packets (called photons), and light-based quantum technology relies on the creation and manipulation of single photons. Nicholas Borys, an assistant professor of physics at Montana State University and co-PI researcher on this new study, pointed out: “For example, a typical green laser pointer only needs to press a button and emits every second. 1016 (10 trillion) photons.” “However, it is very difficult to develop a device that can generate a single controllable photon with only a switch.”

Researchers have known for five years that single-photon emitters exist in ultra-thin two-dimensional materials. Their discovery caused great excitement, because compared to most other single photon emitters, single photon emitters in two-dimensional materials can be more easily tuned and easier to integrate into the device. But no one knows the potential material properties that lead to single photon emission in these two-dimensional materials. Shuke said: “We know there is a single photon emitter, but we don’t know why.”

In 2019, Frank Jahnke, a professor at the Institute of Theoretical Physics at the University of Bremen, Germany, published a paper that gave a theoretical analysis of how the strain in the bubbles caused wrinkles and the local state of single-photon emission. Schuck, who focuses on sensing and engineering phenomena generated from nanostructures and interfaces, was immediately interested in working with Jahnke. He and Borys hope to focus on tiny nano-scale wrinkles, which are formed in the shape of donuts around the bubbles that exist in these ultra-thin two-dimensional layers. Air bubbles, usually small fluid or gas capsules sandwiched between two layers of two-dimensional material, can cause strain in the material and cause wrinkling.

Tiny bubbles bring a huge leap

Atomic force microscope image showing nanobubbles formed between a single layer (1L-WSe2) of two-dimensional semiconductor WSe2 and an insulating material hexagonal boron nitride (hBN) layer. On the left, the WSe2 layer folds back on itself, forming a double layer (2L-WSe2), which contains other bubbles and wrinkles. Photo Credit: Thomas Darlington/Columbia Engineering

Schuck’s group and the field of two-dimensional materials faced major challenges when studying the origin of these single-photon emitters: the nano-scale strain region that emits the light of interest is much smaller, about 50,000 times smaller than the thickness. Hair, which cannot be solved with any conventional optical microscope.

“It makes it difficult to understand what exactly causes single-photon emission in the material: is it just high strain? Is it due to defects hidden in the strained area?” Tom Darlington, lead author of the study Said that he is a postdoctoral and former graduate student of Schuck. “You need light to observe these states, but their size is so small that it cannot be studied with a standard microscope.”

The team collaborated with other laboratories at the Columbia Nano Research Institute, leveraging their decades of nano-level research expertise. They used advanced optical microscope technology, including its new microscope function, not only to observe nano bubbles, but even nano bubbles. Their advanced “nano-optical” microscope technology (ie “nano-mirror”) enables them to image these materials with a resolution of about 10 nm, while traditional optical microscopes can achieve a resolution of about 500 nm.

Many researchers believe that defects are the source of single-photon emission sources in 2D materials because they are usually defects in 3D materials such as diamonds. To eliminate the effect of defects and show that strain is the cause of single-photon emitters in two-dimensional materials, Schuck’s team studied ultra-low defect materials developed by Jim Hone’s group of Columbia Engineering, a NSF-funded materials company, Columbia Engineering. Research Science and Engineering Center. They also took advantage of the new double-layer structure developed at the Programmable Quantum Materials Center (US Department of Energy’s Center for Energy Frontier Research), which provides clear bubbles on a platform that is easily studied by Schuck’s optical “nanomirrors.”

Jeffrey Neton, a professor of physics at the University of California at Berkeley and director of the Lawrence Berkeley National Laboratory’s Deputy Laboratory of Energy Science, said: “Atomic defects are usually attributed to localized sources of light in these materials.” “The focus of this work is the fact that individual strains may have an effect without the need for atomic-scale defects.[s] Applications range from low-power light-emitting diodes to quantum computers. “

Schuck, Borys and his team are now studying how to use strain to precisely tailor the specific properties of these single photon emitters, and to develop ways to engineer addressable and tunable arrays of these emitters for future quantum technologies.

Schuck observed: “Our results mean that it is now possible to master single-photon emitters tunable at room temperature, thus paving the way for controllable and practical quantum photonic devices.” “These devices can become the basis of quantum technology Quantum technology will profoundly change what we know about computing, sensing and information technology.”


Scientists have created new devices that have opened the way for quantum technology


More information:
Imaging strain-localized excitons in a single layer of WSe2 nanobubbles at room temperature, Natural Nanotechnology (2020). DOI: 10.1038/s41565-020-0730-5

Provided by Columbia University School of Engineering and Applied Science

Citations: Tiny bubbles made a huge leap (July 13, 2020), retrieved from July 13, 2020 from https://phys.org/news/2020-07-tiny-quantum.html

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