Collaborative Research: Investigation of Superconducting Nanowires and Graphene Junctions Using a Coplanar Fabry-Perot Microwave Resonator as a Qubit Device

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****NON-TECHNICAL ABSTRACT****Recently, it became clear that quantum mechanics, which is traditionally used to describe individual and small groups of elementary particles (e.g., electrons and atoms), can also predict the behavior of the so-called "mesoscopic" objects, i.e. systems containing a large number of atoms like large molecules or nanodevices. The goal of this project is to investigate how the laws of quantum mechanics apply to nanowires. These nanowires are metallic cylinders having a diameter of a few billionth of a meter. The project will explore nanowires made out of superconducting metals. The scientific question to be addressed is the applicability of the Heisenberg uncertainty principle to the electrical current and electrical charge in nanodevices involving nanowires. The most advanced nanoscience and nanotechnology will be used to fabricate such wires. The measurements on nanowires will be done using a novel experimental approach, namely a nanowire will be inserted into a special type of microwave resonator called a microwave superconducting Fabry-Perot resonator. This project will explore the possibility of using the hybrid nanowire-resonator devices as qubits, the quantum mechanical analog of the classical "bit" that stores information in a computer. This project will support the education of graduate students in these advanced technologies, which will prepare them for scientific careers in academia and in our most advanced technology industries. Undergraduate students will also participate in the project, gaining training and hands-on experience in the most advanced scientific research. The project will also provide training to a postdoc.****TECHNICAL ABSTRACT****Recently, it became clear that macroscopic degrees of freedom, such as electrical current, can be described by laws of quantum mechanics for so-called mesoscopic systems: for example quantum mechanics is important for describing results of transport measurements in systems involving large molecules, nanoparticles, or superconducting nanodevices. The goal of this project is to investigate how the laws of macroscopic quantum mechanics apply to superconducting nanowires. In particular, quantum phase slips will be investigated. A novel experimental approach will be used, namely the nanowires will be coupled to a superconducting microwave Fabry-Perot resonator. Such a hybrid device will provide complementary experimental information when compared with traditional dc electrical transport measurements. The nanowires are expected to act as nonlinear kinetic inductors. This project will explore the possibility of using the hybrid nanowire-resonator devices as qubits. Such nanowire-qubits should be free of the decoherence mechanisms affecting Josephson tunnel junction so far employed for superconducting qubits. The nanowires will be fabricated and imaged by the most advanced nanotechnology. The measurements will be carried out using ultra-low-temperature refrigerators and ultra-low-noise microwave measurements. This project will support the education of graduate students in these advanced technologies, which will prepare them for scientific careers in academia and in our most advanced technology industries. Undergraduate students will also participate in the project, gaining training and hands-on experience in the most advanced scientific research. The project will also provide training to a postdoc.