Counterdiabatic Driving under Variational Frame Dressing

Conventional counterdiabatic (CD) driving is a powerful technique for accelerating adiabatic quantum protocols, but it often prescribes auxiliary control fields that are physically impossible to implement in a laboratory setting. This paper addresses the challenge of deriving CD protocols that are strictly confined to the native control operators of a given quantum system.

The authors propose a 'dressed-frame' framework. Instead of performing CD driving in the standard adiabatic frame, they introduce a time-dependent unitary transformation (the dressed frame) that reshapes the effective Hamiltonian. By defining a dressed-frame generator that is not added to the physical Hamiltonian, the authors gain the freedom to manipulate the adiabatic problem while forcing the necessary counterdiabatic correction to remain within the accessible control space. This leads to a nonlinear commutator equation that can be solved variationally without requiring the explicit construction of instantaneous eigenstates.

The researchers demonstrate the utility of this framework through three distinct applications:

• Spectator Error Suppression: In a multi-qubit chain, the method derives an X-only correction that protects spectator qubits from crosstalk, even when the conventional CD approach would require unavailable Y-control.
• Bell-State Preparation: The framework identifies an X-only protocol for preparing Bell states in a transverse-field Ising system, effectively utilizing the existing entangling interaction to bypass the need for non-native two-qubit control pulses.
• Holonomic Gates: In a tripod system, the authors show that the method can implement a fast holonomic gate while keeping all correction pulses confined to the native tripod couplings, preserving the geometric robustness of the original adiabatic protocol.