Abrupt Transitions in Variational Quantum Circuit Training

Understand

Variational quantum algorithms dominate gate-based applications of modern quantum processors.

• The so called, {\it layer-wise trainability conjecture} appears in various works throughout the variational quantum computing literature.
• The conjecture asserts that a quantum circuit can be trained piece-wise, e.g.~that a few layers can be trained in sequence to minimize an objective function.
• Here we prove this conjecture false.