Introduction To The Pontryagin Maximum Principle For Quantum Optimal Control [ORIGINAL • 2027]

Thus, the costate is essentially the system’s "backward-propagated" sensitivity.

[ \frac\delta \mathcalJ\delta u_k(t) \approx \textIm \langle \chi(t) | H_k | \psi(t) \rangle ]

The PMP states that for an optimal control $u^*(t)$, there exists an adjoint variable $\lambda(t) \in \mathbbR^n$ such that: