Zero- Versus Infinite-Temperature Damping in Variational Quantum Circuits: Feature Scale, Sampling Cost, and Frame Gauge
The zero-temperature bias in amplitude damping within variational quantum circuits is primarily due to feature scale differences. A trainable output scale can largely eliminate these accuracy gaps in simulations, but this effect reappears as a cost in measurement shots. The paper compares standard amplitude damping with 'Pauli twirl' and shows the separation depth required depends on circuit depth and noise parameters.