singularity-free-invariant-control

name	singularity-free-invariant-control
description	Singularity-free dynamical invariants-based quantum control for finite-dimensional state preparation under arbitrary noise. Use when designing invariant-based quantum control protocols, robust state preparation for NISQ hardware, non-Markovian open quantum systems, SU(2) subspace control, or noise-aware control synthesis.
metadata	{"arxiv_id":"2510.15340","published":"2025-10-17","authors":"Ritik Sareen, Akram Youssry, Alberto Peruzzo","tags":["quantum-control","invariant-based","state-preparation","non-Markovian","NISQ","robustness"]}

Core Concept

Invariant-based inverse engineering provides a principled framework for synthesizing analytic control fields, but existing parameterizations often produce experimentally infeasible singular pulses and are limited to simplified Lindblad noise models. This singularity-free framework extends invariant-based control to realistic open-system regimes with arbitrary noise conditions.

Key Technical Insights

1. SU(2) subspace reduction: Transforms finite-dimensional control problem into equivalent single-qubit problem by restricting dynamics to a designed SU(2) subspace, simplifying the control synthesis.

2. Two-stage protocol:

   • Stage 1: Construct a family of bounded pulses achieving perfect state preparation in closed systems
   • Stage 2: Identify the optimal member minimizing noise effects — produces smooth, hardware-feasible control fields

3. Dual noise handling:

   • Characterized noise: Noise-aware control synthesis using full master-equation description
   • Uncharacterized noise: Noise-agnostic variant preserves robustness without requiring master-equation description

Design Principles

• Bounded pulses over singular ones: Avoid experimentally infeasible control fields
• SU(2) reduction: Simplify high-dimensional control to single-qubit equivalent
• Noise-agnostic fallback: Maintain robustness when noise characterization is unavailable
• Hardware-feasible fields: Smooth, bounded control fields compatible with NISQ hardware

Applications

• High-fidelity state preparation on NISQ devices
• Non-Markovian open quantum system control
• Quantum state engineering with environmental memory
• Communication and sensing state preparation

Activation Keywords

singularity-free quantum control, dynamical invariants, invariant-based inverse engineering, SU(2) subspace control, non-Markovian quantum control, bounded pulses, NISQ state preparation, noise-aware control synthesis, open quantum systems