Quantum technologies to address pressing environmental needs
Friday, August 25, 2023
Quantum methods can lead to more efficient and precise solutions to environmental issues over conventional methods, accelerating the path to sustainability. Already, TQT-supported researchers have used quantum-based techniques to address environmental needs such as heavy metal detection, energy-efficient electronics, sustainable computing, and atmospheric monitoring.
Detection of toxic heavy metals in water sources
Monitoring water sources to detect heavy metals is essential to ensure clean drinking water (especially in remote settings or developing Countries) and appropriate regulatory measures. Accelerating the identification of heavy metal pollutants in aquatic environments by facilitating field analysis will enable faster remediation to protect both human lives and fragile marine ecosystems. Unfortunately, lab techniques for detecting heavy metals are unsuitable for on-site analysis due to costly and bulky equipment. Two-dimensional quantum dots (2D-QDs) have been shown to provide highly sensitive and selective fluorescence-based detection of heavy metals while having properties ideal for water-based detection, such as water solubility and stability. Vassili Karanassios, professor in the Department of Chemistry, and Kevin Musselman, professor in the Department of Mechanical and Mechatronics Engineering, are exploring these QDs as potential on-site water contaminant sensors.
Karanassios uses functionalized 2D-QDs (QDs with added molecular components tailored to specific ions of interest) as element-specific, highly-selective chemical sensors of toxic heavy metal pollutants. When irradiated by light, these QDs fluoresce at a wavelength that matches the heavy metal of interest at an intensity that depends on the concentration of metal in the sample. To make an instrument feasible for on-site measurements, Karanassios is developing a portable fluorescence-measurement system that includes a battery-operated light source and detector and data acquisition electronics that can send digital data to a smartphone. The optical filters within the sensor will be designed to be easy to replace with QDs optimized to detect different pollutants. This instrument will allow for rapid, near real-time measurement of heavy metals in the field.
While Musselman is also functionalizing 2D-QDs to detect specific pollutants, his research aims to vary the degree of quantum confinement for each analyte to produce distinguishable optical signals. This could lead to a sensitive and selective multimodal sensing platform, wherein the differently functionalized 2D-QDs are combined into a single solution and can simultaneously identify different heavy metal ions, even in the presence of other aquatic contaminants. Musselman has demonstrated the ability of this platform to detect metal ions with detection limits three times lower than the safe concentration limits reported by the World Health Organization. This project has also mobilized the use of these 2D-QDs in other environmental applications, such as perovskite solar cells.
Energy-efficient electronics and sustainable computing
The need for data centres and transmission networks grows with the increasing demand for digital services. Unfortunately, these data systems consume vast amounts of energy, resulting in nearly 1% of all energy-related greenhouse gas emissions. One way to address this issue is by minimizing electronics and energy storage devices. Reducing the number of transistors needed to perform the same function as a classical system will also reduce the overall power consumption of computing. Unfortunately, traditional silicon-based semiconductors are nearing their theoretical performance limits due to increasingly high leakage current in electrical components and subsequent battery drainage. Several TQT-supported researchers are using quantum materials to overcome this limitation.
Aiping Yu, University Research Chair and professor in the Department of Chemical Engineering, recently showed that micro-supercapacitors (MCs) developed using graphene QDs have increased energy density over conventional energy storage devices. To further improve the energy storage performance and durability of MCs, Yu is developing QDs from MXene, a class of layered transition metal carbides, carbonitrides or nitrides. These optimized MXene QD MC devices will be commercially feasible technology suited for the next generation of flexible electronic and clean energy storage. Along with her proposed solution to energy problems, Yu also implements a green synthesis protocol into her research by using an environmentally friendly etching method to produce MXene.
Youngki Yoon, a professor in the Department of Electrical and Computer Engineering, is harnessing the potential of quantum materials for future electronic devices. In one project, Yoon integrates 2D quantum materials with ferroelectric (FE) layers to simultaneously achieve low-power and high-performance devices. Already, 2D quantum material field-effect transistors (FETs) provide a potential benefit for energy-efficient electronics; however, these conventional FET structures are insufficient for ultra-low-power features. Adding an FE capacitor to induce negative capacitance can boost the performance beyond the classical limit so that low-power yet high-performance quantum electronic devices can be realized. In a second project, Yoon will combine quantum materials with antiferroelectric (AFE) stacks to form a multi-valued-logic quantum device for computing applications. Integrating these technologies with tunnel devices can decrease the power supply voltage required for each transistor while transforming binary logic switches into ternary logic devices to allow fewer transistors to perform the same function with reduced overall power consumption. This project presents a step towards building ultra-low-power electronics for sustainable computing that may reduce the global digital carbon footprint.
Spintronics use electron spin for information transfer, processing, and storage instead of electric charges, alleviating the risk of leakage current. Pavle Radovanovic, professor in the Department of Chemistry, is developing a new class of low-dimensional quantum materials based on colloidal metal halide perovskite semiconductor nanostructures for spintronics applications. Exploring the ability to tune these semiconductor nanostructures’ electronic states and optoelectronic properties has potential applications in spintronics and quantum computing. In particular, manipulating the spin spates and quantum interactions enables a potential pathway to more energy-efficient quantum information processing and non-volatile quantum computing.
Guo-Xing Miao, a professor in the Department of Electrical and Computer Engineering and the Institute for Quantum Computing (IQC), combines spintronics with semiconductor devices to enable a new route towards higher-performing electronics. Spin torque transfer (STT)-magnetic random access memory (MRAM) has a much lower power and energy footprint than traditional, volatile memories, and the devices are further integrated into in-memory computation architectures to overcome the von Neumann bottleneck. Thus, combining spintronics with conventional semiconductor-based technology will improve processor speed, data retention, and power consumption, leading to greener computation. In a related project, spins are directly activated inside the layered cathode materials as part of the chemical cycles in rechargeable batteries, and they are functionalized to non-destructive means to monitor, control, and enhance the performance of the renewable battery systems.
Quantum enhanced atmospheric monitoring
Thomas Jennewein, a professor in the Department of Physics and Astronomy and IQC, hopes to achieve state-of-the-art performance in quantum signal receiver technology. Current free-space applications often use polarization-encoded photons, which are limited in applications where geometric reference is not constant (i.e., hand held-devices or aircraft). Time-bin encoding, which uses time windows instead of polarization, offers a more robust solution. By combining his expertise in free-space quantum receivers with Université de Sherbrooke’s new detector array technology and introducing new capabilities for time-bin encoding, Jennewein will develop a quantum receiver with a short time delay and high timing resolution. This may improve light detection and radar (LiDAR), a remote sensing method that can measure topography, vegetation, human infrastructure, landscape, and other information about the Earth.
Building upon his developed free-space communication satellite systems, Jennewein leads the Quantum Encryption and Science Satellite (QEYSSat) mission science division. The satellite provides a platform to create and demonstrate quantum sensing and metrology applications. Jennewein will explore new methods to advance spectroscopic sensing for atmospheric constituents, including methane or aerosols. After conducting a feasibility study on trace gas metrology using quantum communication channels, optical telescopes will be used to deploy the greenhouse gas monitoring technology to the field.