Prineha Narang

Title: Building Blocks of Scalable Quantum Information Science

Abstract: Quantum information technologies are expected to enable transformative technologies with wide-ranging global impact. Towards realizing this tremendous promise, efforts have emerged to pursue quantum architectures capable of supporting distributed quantum computing, networks and quantum sensors. Quantum architecture at scale would consist of interconnected physical systems, many operating at their individual classical or quantum limit. Such scalable quantum architecture requires modeling that accurately describes these mesoscopic hybrid phenomena. By creating predictive theoretical and computational approaches to study dynamics, decoherence and correlations in quantum matter, our work could enable such hybrid quantum technologies1,2. Capturing these dynamics poses unique theoretical and computational challenges. The simultaneous contribution of processes that occur on many time and length-scales have remained elusive for state-of-the-art calculations and model Hamiltonian approaches alike, necessitating the development of new methods in computational physics3–5. I will show selected examples of our approach in ab initio design of active defects in quantum materials6–8, and control of collective phenomena to link these active defects9,10. Building on this, in the second part of my seminar, I will present promising physical mechanisms and device architectures for coupling (transduction) to other qubit platforms via dipole-, phonon-, and  magnon-mediated  interactions9–12. In a molecular context, will discuss approaches to entangling molecules in the strong coupling regime. Being able to control molecules at a quantum level gives us access to degrees of freedom such as the vibrational or rotational degrees to the internal state structure. Entangling those degrees of freedom offers unique opportunities in quantum information processing, especially in the construction of quantum memories. In particular, we look at two identical molecules spatially separated by a variable distance within a photonic environment such as a high-Q optical cavity. By resonantly coupling the effective cavity mode to a specific vibrational frequency of both molecules, we theoretically investigate how strong light-matter coupling can be used to control the entanglement between vibrational quantum states of both molecules. Linking this with detection of entanglement and quantifying the entanglement with an appropriate entanglement measure, we use quantum tomographic techniques to reconstruct the density matrix of the underlying quantum state. Taking this further, I will present some of our recent work in capturing non-Markovian dynamics in open quantum systems (OQSs) built on the ensemble of Lindblad’s trajectories approach 13–16. Finally, I will present ideas in directly emulating quantum systems, particularly addressing the issues of model abstraction and scalability, and connect with the various quantum algorithm efforts underway.

Bio: Prineha Narang is an Assistant Professor at the John A. Paulson School of Engineering and Applied Sciences at Harvard University. Prior to joining the faculty, Prineha came to Harvard as a Ziff Environmental Fellow at the Harvard University Center for the Environment. She was also a Research Scholar in Condensed Matter Theory at the MIT Dept. of Physics, working on new theoretical methods to describe quantum interactions. Prineha’s work has been recognized by many, including the Mildred Dresselhaus Prize,  a Friedrich Wilhelm Bessel Research Award (Bessel Prize) from the Alexander von Humboldt Foundation, a Max Planck Sabbatical Award from the Max Planck Society, and the IUPAP Young Scientist Prize in Computational Physics in 2021,  a National Science Foundation CAREER Award in 2020, being named a Moore Inventor Fellow by the Gordon and Betty Moore Foundation for innovations in quantum science and technology, CIFAR Azrieli Global Scholar by the Canadian Institute for Advanced Research, a Top Innovator by MIT Tech Review (MIT TR35), and a Young Scientist by the World Economic Forum in 2018. In 2017, she was named by Forbes Magazine on their “30under30” list for her work in atom-by-atom quantum engineering.

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