Abstract: Quantum error correction can make imperfect qubits reliable, but a useful quantum computer must also manipulate the protected information. Can we encode many logical qubits with little redundancy while retaining flexible control and fast computation? In this joint presentation, we will discuss our recent work on designing quantum processors with high-rate quantum low-density parity-check (qLDPC) codes. We introduce finite-size codes that combine high encoding rates of 20–30%, practical block sizes, and sufficient error protection. By constructing a structured logical basis and leveraging code symmetries, we can build a universal logical instruction set from a few gadgets with rigorously certified fault tolerance. For instance, as few as two reusable ancillary surgery gadgets, supplemented with magic-state input, enable universal logical processing. Using fast decoders compatible with real-time operation, direct simulations support logical computation involving more than ten billion operations. These processors further support highly parallel logic: some codes can perform hundreds of logical operations simultaneously, allowing logical parallelism to compensate for a slow physical clock. We will also discuss the compatibility of these designs with reconfigurable neutral-atom arrays and superconducting circuits. Together, these results point toward architectures that combine high encoding density, computational flexibility, and speed, opening new routes toward resource-efficient quantum computers capable of executing utility-scale algorithms.
Speakers: Hsin-Yuan (Robert) Huang & Qian Xu
[Online seminar]
Format: Each talk will be 20 + 10 minutes, followed by 15 minutes of general discussion.
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