Source-linked AI summary
Dynamically Error-Corrected Gates for Universal Quantum Computation
Kaveh Khodjasteh, Lorenza Viola
TL;DR
Realistic quantum computation needs gates that remain accurate under decoherence and operational errors. The paper constructs dynamically corrected gates using bounded-strength Hamiltonian controls, achieving quadratically smaller error without encoding or measurements, while noting restrictions on system drift and pulse shapes.
Problem
Quantum gates must operate accurately in open systems with decoherence and operational errors, while scalable fault-tolerant architectures face implementation overhead from encoding and measurements.
Method
The paper uses analytic open-loop Hamiltonian engineering that combines dynamical-decoupling and composite-gate ideas, exploiting primitive gate sequences with matching leading-order errors.
Results
The constructed dynamically corrected gates achieve quadratic error scaling relative to the original error per gate, with first-order error cancellation for the targeted error subspace.
Takeaways & Limitations
Dynamically corrected gates provide a low-level error-control strategy for universal quantum computation using bounded-strength unitary controls without encoding or measurement overhead.
Takeaways & Limitations
The present construction assumes driftless systems and specific pulse shapes, although these restrictions may be relaxed with more complex sequence searches.
Abstract
from arXiv · showhide
Scalable quantum computation in realistic devices requires that precise control can be implemented efficiently in the presence of decoherence and operational errors. We propose a general constructive procedure for designing robust unitary gates on an open quantum system without encoding or measurement overhead. Our results allow for a low-level error correction strategy solely based on Hamiltonian engineering using realistic bounded-strength controls and may substantially reduce implementation requirements for fault-tolerant quantum computing architectures.