Bright Ideas — Using Fullerene To Predictably Switch An Electron's Path, Keeping Quantum Computer Cool, Giant Leap Toward 3D Cameras, And More

By John Oncea, Editor

Bright Ideas presents the most captivating news and innovations in optics and photonics. This week, we look at making qubits and controlling them to read and write data, dirt-cheap alternatives to silicon, making phantoms match the optical properties of their target tissue, and more.

An international team of researchers, including those from the University of Tokyo’s Institute for Solid State Physics, demonstrated a switch, analogous to a transistor, made from a single molecule called fullerene. By using a carefully tuned laser pulse, the researchers can use fullerene to switch the path of an incoming electron predictably. This switching process can be three to six orders of magnitude faster than switches in microchips, depending on the laser pulses used. Fullerene switches in a network could produce a computer beyond what is possible with electronic transistors, and they could also lead to unprecedented levels of resolution in microscopic imaging devices. More information is available here.

Researchers at MIT (go Engineers!) have proposed a new approach to making qubits and controlling them to read and write data. The method, which is theoretical at this stage, is based on measuring and controlling the spins of atomic nuclei, using beams of light from two lasers of slightly different colors. “We have found a novel, powerful way to interface nuclear spins with optical photons from lasers,” says Paola Cappellaro, a professor of nuclear science and engineering. “This novel coupling mechanism enables their control and measurement, which now makes using nuclear spins as qubits a much more promising endeavor.” This work “offers new opportunities in quantum technologies, including quantum control and quantum memory,” says Yao Wang, an assistant professor of physics at Clemson University, who was not associated with this work. He adds that “very impressively, this work also provided very quantitative predictions of the expected observations in these application scenarios with accurate first-principles methods. I look forward to the experimental realization of this technique, which I am sure would attract a lot of researchers in the field of quantum science and nuclear technology.”

Keep the cool side cool! A wireless technique enables a super-cold quantum computer to send and receive data without generating too much error-causing heat, MIT News reports. To overcome the challenge of heat-caused errors in quantum systems, an interdisciplinary team of MIT researchers has developed a wireless communication system that enables a quantum computer to send and receive data to and from electronics outside the refrigerator using high-speed terahertz waves. A transceiver chip placed inside the fridge can receive and transmit data. Terahertz waves generated outside the refrigerator are beamed in through a glass window. Data encoded onto these waves can be received by the chip. That chip also acts as a mirror, delivering data from the qubits on the terahertz waves it reflects their source. “By having this reflection mode, you save the power consumption inside the fridge and leave all those dirty jobs on the outside. While this is still just a preliminary prototype and we have some room to improve, even at this point, we have shown low power consumption inside the fridge that is already better than metallic cables. I believe this could be a way to build largescale quantum systems,” says senior author Ruonan Han, an associate professor in the Department of Electrical Engineering and Computer Sciences (EECS) who leads the Terahertz Integrated Electronics Group.

Perovskites, a ‘dirt cheap’ alternative to silicon, just got a lot more efficient, according to the University of Rochester (go Jackets!). Researchers typically synthesize perovskites in a wet lab, and then apply the material as a film on a glass substrate and explore various applications. Chunlei Guo, a professor of optics at the University of Rochester, and his team instead propose a novel, physics-based approach. By using a substrate of either a layer of metal or alternating layers of metal and dielectric material — rather than glass — he and his coauthors found they could increase the perovskite’s light conversion efficiency by 250 percent. “No one else has come to this observation in perovskites,” Guo says. “All of a sudden, we can put a metal platform under a perovskite, utterly changing the interaction of the electrons within the perovskite. Thus, we use a physical method to engineer that interaction.”

Scientists at the University of the Witwatersrand (go Wits!) have discovered a method to “see” objects that always fail to interact with light by enhancing a hi-tech method known as “ghost imaging.” The discovery represents a giant leap toward a 3D quantum camera. Ghost imaging is a technique used by physicists, where two “entangled” photons are used to “see” an object in the dark. Entanglement is a phenomenon where two particles, such as photons, share the same quantum properties, and, where if the properties of one of the particles are changed, the properties of its “entangled” particles are affected in the same way. The entangled photons are created by sending light through a non-linear crystal such that one photon is destroyed to create two entangled ones. The two photons share physical properties, such as wavelength, and one of the photons is then sent through a medium to a remote area, while the other one is kept close to monitor it. “We would send one of the entangled photons to the object that we want to look at in the dark, and by looking at the photon that stays with us, we can see the properties of the object in the dark,” says Bereneice Sephton, the lead author of the study.

Tampere University photonics researchers are developing semiconductor light emission chips for light-based sensing, LIDAR, and health monitoring. The research, according to Tampere, aims to find efficient means to integrate semiconductor chips in low-cost, low-dissipation power, and compact optical circuits using a silicon platform. A specific application target is monitoring harmful greenhouse gas emissions in the atmosphere. According to Nouman Zia, integrated light sources operating at mid-infrared wavelengths are needed because of the high demand for compact sensors in gas detection and medical diagnostics. However, the applications are not limited to sensing, and similar concepts can be deployed in other wavelength domains. Such an integrated light source platform can be harnessed to enable, for example, innovative light-based solutions in the field of quantum photonics or on-chip high-speed optical communication in data centers. “The integrated light sources developed in our study are becoming the key component of a micro gas sensor. The proof-of-concept gas sensor will be demonstrated with partners in the next phase of this project,” Zia says.

The Lighting Research Center (LRC) at Rensselaer Polytechnic Institute (go Engineers!) has partnered with SPIE, the international society for optics and photonics, to initiate a new lighting conference dedicated to the advancement and use of 3D printing for the manufacture of lighting components and systems. The conference will be held as part of SPIE Optics + Photonics 2023, the leading multidisciplinary optical sciences and technology meeting, August 20-24, 2023, in San Diego. Nadarajah Narendran, Ph.D., LRC director of research and co-chair of the conference, said the reason for initiating this conference now is to bring knowledge of this quickly advancing technology to a larger audience who could benefit from learning more about the potential of 3D printing for the lighting industry. “Our goal is to bring awareness of the possibilities that 3D printing holds for lighting, to prompt new research in this field, and to help both lighting manufacturers and 3D printing technology manufacturers to work together,” said Narendran.

Finally, SPIE reports that scientists have developed an innovative approach to making phantoms accurately match the optical properties of their target tissue throughout the optical spectrum. While an ideal phantom should respond exactly as the target tissue across the entire optical spectrum, this is not achievable with current technology. Modern optical phantoms can only mimic some of the target tissue’s properties and that, too, across a narrow band of wavelengths. Although this is sufficient for many imaging techniques, various emerging hybrid modalities and novel instruments depend on a wider band of wavelengths for tissue optical properties (e.g., absorption and scattering). Now, researchers from Vanderbilt University (go Commodores!) developed an innovative platform to produce such adaptative optical phantoms. Their idea is centered around the addition of multiple pigments when fabricating a phantom such that after the epoxy resin solidifies, the optical properties of the final material will accurately reflect those of the target tissue. The process is similar to how hardware store paints are made to match an arbitrary target color by combining a number of set pigments.