QCBRIEF
Counterdiabatic driving — a shortcut that lets a quantum system change state without the usual slowdown — has dropped its Hamiltonian requirement (the math describing how a system evolves) and now extends to gate based circuits (the gate by gate
Quantum engineers have a "fast-forward" trick for steering quantum systems between states without slowing down. The technique, called counterdiabatic driving, adds a corrective nudge that cancels shortcuts taken along the way. It normally requires a Hamiltonian, the math that describes how a quantum system evolves. A new preprint drops that prerequisite.
The authors build the corrective nudge around the adiabatic gauge potential, the math object that supplies the counterdiabatic term, without first writing down a Hamiltonian. The result is a linear system with cost comparable to the Lanczos method, a standard iterative algorithm, and no heavy matrix operations like diagonalization or matrix logarithms.
They test the approach on two model systems: a kicked top, a periodically pulsed quantum rotor, and a brickwork circuit built from a simple two-qubit gate. On both, a truncated Krylov approximation, a standard iterative shortcut, converges rapidly. The brickwork case matters because no local Hamiltonian exists there, so previous recipes could not be applied at all.
The work is theoretical: fast convergence on two model systems, not a benchmark on real quantum hardware, and the preprint has not yet been peer reviewed. It widens access to the same shortcut for gate-based circuits and periodically driven systems that previously lacked a local Hamiltonian.
The full paper is on arXiv.