Quantum Communications

         Exciting new research opportunities in quantum communications and quantum computing are emerging. Quantum communications (my area) refers to communication systems that are based on quantum entanglement, which may be realized using electronic and photonic implementations. Complementary roles are envisioned for each in space communications (my area); entangled electron-based states (qubits) will be used for secure onboard routing and enhanced processing, while photonic qubits will be used for secure ground-satellite and satellite-satellite transmissions.

         Initial electron-based superconducting implementations show great promise but currently suffer from non-robust qubit generation and significant active cooling requirements. My research focuses on investigation of 1) quantum materials for spin qubit generation at higher temperatures and 2) scalable quantum entanglement architectures, as complimentary approaches to achieve the same goals. For both, we are actively engaged in the development of appropriate fidelity and concurrence entanglement metrics.

a. 2D Quantum Conductive Layers

         My group in collaboration with the quantum communications and magnetics groups at the NASA Goddard Space Flight center pursues a materials-by-design investigation of spin state entanglement in 2D quantum conductive layers. The objective of using a quantum conductive layer is generation of the maximum number of qubits with qubit readout based on specialty codes that can process many and possibly hyper-entangled qubits. Evidences for 2D conductive layer quantum entanglement have been reported in cuprate, ruthenate and other materials systems. Our initial selection of strontium ruthenate for investigation is based on its Sr2RuO4 form having a 2D layer structure and unconventional high Tc behavior, along with its better-known synthesis protocol.In an approach borrowed from biological investigations, we also investigate the 3D SrRuO3 form as a negative control with the hypothesis that the 2D-layer films may show evidence of entanglement while the 3D films will not. A series of 2D conductive layer versus 3D ruthenate films have been grown for our group by molecular beam epitaxy at Cornell University through an NSF-MIP Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM) award. Our goal is to develop the first fundamental understanding of how compositional changes influence specific entanglement metrics based on magnetic susceptibility as the entanglement witness. A second focus has emerged, to identify dislocation impacts on entanglement witness and how these may impact reproducibility between quantum research groups.

b. Heterostructures

         Well known double-layer heterostructure technology may offer an alternative path to robust, high-temperature spin qubit generation through utilization of magnetically controlled spin-orbit interactions (SOI) between vertically coupled quantum dots (0D). Quantum point contacts are typically used to generate 0D electron confinement; however, our group relaxes this fabrication restriction through combination of a split-gate 1D channel with the addition of surface acoustic waves (SAW) that dynamically induce 0D regions (“flying qubit”). Recently, we theoretically investigated SOI coupling and entanglement in four double-layer heterostructures with known fabrication protocols at room temperature. In0.85Al0.15Sb/InSb heterostructures were shown to be the most promising from a magnetic field requirement perspective but Al0.3Ga0.7As/GaAs heterostructures are shown to be possible and these have well developed fabrication protocols. We are exploring collaboration with a molecular beam epitaxy group for experimental realization and tests.

My group also works as part of a larger NASA/University group to implement long distance-to-onboard communication with artificial intelligence (AI) control at optoelectronic interfaces. The AI control research has twice been competitively awarded NASA Michigan Space Grant Consortium funding in FY20 and FY21.