CAREER: Quantum Coherence, Optical Readout, and Quantum Transduction for Spin Qubits from First-Principles Calculations

University Of California-Santa Cruz, Santa Cruz CA

Investigators

Abstract

NONTECHNICAL SUMMARY This award supports research and education to develop computational methods to investigate properties of smallest computation units – quantum bits that are important for storing and manipulating data in quantum computers. These quantum bits (qubits) have a spin state, an angular momentum that is a quantum mechanical property of an elementary particle, such as an electron, as their basic element. Characterizations and study of these building blocks help in determining how to make quantum computers dependable and scalable. The PI will develop computational tools to understand critical properties of different materials and their qubits. These properties include their ability to support complex computer applications (quantum coherence), to read high-fidelity information (quantum readout) and to transfer information efficiently (quantum transduction). Modelling these properties of different materials will help in predicting how they will behave in different conditions (for example, different temperatures) before performing experiments to observe their behavior. Methods developed in this project will accelerate discovery of materials that show promise for scalable quantum computing. The education and outreach plan includes strengthening undergraduate education on physical chemistry through summer bootcamp and developing computational materials research through new courses and REU programs, and supporting women and underrepresented groups through organizing coffee hours and seminars through UCSC WiSE program. TECHNICAL SUMMARY The overarching goal of this project is to develop first-principles computational platforms to study critical physics processes in quantum information science (QIS) - quantum coherence, readout, and transduction of spin qubits. Understanding kinetics of excited states and spin qubit relaxation and decoherence is the core issue of spin-based QIS. Quantum coherence determines how long the spin state will last or the information will be intact; qubit readout efficiency determines if one can extract information from qubit with high fidelity; quantum transduction determines if quantum information can be transferred and communicated among qubits over a long range. All these properties are materials-specific, and have been mostly computed by simplified models which require prior inputs from experiments. In this project the PI aims to develop a fully first-principles computational platform to tackle these issues for spin qubits, which do not require prior input parameters. The general approach is to leverage the ab-initio density-matrix dynamics framework for open quantum systems that the PI has developed to resolve environmental couplings, have predictive capabilities for quantum relaxation and coherence time of spin qubit, as well as spin qubit initialization and readout efficiency through spin-photon interface. The latter will incorporate inputs of radiative, nonradiative and intersystem-crossing rates including many-body interactions. Accurate predictions of these physical parameters from first-principles will eliminate the need for prior input parameters or simplified models for general systems and open the path for designing novel quantum materials, such as new spin-defects and qubit network, which will create unprecedented performance for applications in quantum information science. The education and outreach plan include strengthening undergraduate education on physical chemistry through summer bootcamp and developing computational materials research through new courses and REU programs, and supporting women and underrepresented groups through organizing coffee hours and seminars through UCSC WiSE program. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.