Stacking the Deck: Tunable Trainability in Stacked LCUs
Variational quantum circuits have been central to many proposed near-term applications of quantum computing, but a growing body of evidence suggests that trainability and quantum advantage are fundamentally at odds: ansätze expressive enough to resist efficient classical simulation tend to exhibit barren plateaus, while structures that provably rule out barren plateaus typically render them classically simulable. We propose a stacked linear combination of unitaries (S-LCU) as a variational ansatz which provides a tunable trade-off between barren plateaus and classical simulability. Using a diagrammatic analysis, we bound the loss-landscape variance of the Free Fermion S-LCU, whose element...
| Authors | Nikhil Khatri, Stefan Zohren, Gabriel Matos |
|---|---|
| Primary category | quant-ph |
| Published | 27 July 2026 |
| Last updated at source | 27 July 2026 |
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