[CS] Joshua Viszlai Candidacy Exam/Feb 27, 2025

[via cs]

This is an announcement of Joshua Viszlai's Candidacy Exam.
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Candidate: Joshua Viszlai

Date: Thursday, February 27, 2025

Time: 11 am CST

Location: JCL 280 

Title: Software/Hardware Co-Design of Fault-Tolerant Quantum Systems

Abstract: Quantum computers are poised to deliver computational speedups for problems intractable classically. It is known that many of these problems, such as quantum chemistry and factoring, will require fault-tolerant systems to translate noisy physical qubits into resilient logical qubits via quantum error correcting (QEC) codes. Quantum hardware itself, however, has made broad progress in a variety of qubit modalities, indicating a need for device-tailored QEC systems.
 
In this thesis we study how co-designing fault-tolerance with the underlying hardware improves system performance. In 2D arrays of optically trapped atoms, we examine dual-species systems that exhibit long-range, asymmetric interaction strengths due to Förster resonances between atomic species. By interleaving the embeddings of QEC blocks on physical qubits we show the resulting logical qubit connectivity mitigates routing conflicts during compilation, increasing gate parallelism and decreasing program runtime. We also study how the use of structured, parallel movement in atomic systems can be matched to qLDPC codes to admit an effective implementation. We propose mapping and routing procedures to implement generalized-bicycle codes, enabling more qubit-efficient quantum memories. Finally, we study classical decoding systems that must operate in tandem with quantum hardware. We propose a novel decoding approach based on speculative decoding of windows and demonstrate its ability to reduce program latencies compared to existing decoders.
 

Advisor: Fred Chong

Committee Members: Fred Chong, Robert Rand, Hannes Bernien