Adiabatic theorem revisited: the unexpectedly good performance of adiabatic passage

TL;DR

This paper explains why adiabatic passage often performs better than expected in finite time, revealing a new adiabaticity criterion and suggesting shortcut strategies for quantum state transfer.

Contribution

It provides a theoretical explanation for the improved performance of adiabatic passage and introduces a new criterion and strategies for near adiabatic quantum control.

Findings

Deviations from adiabatic eigenstates decrease significantly towards the end of the process.

A separate adiabaticity criterion for high fidelity transfer is proposed.

New shortcut strategies for near adiabatic dynamics are suggested.

Abstract

Adiabatic passage employs a slowly varying time-dependent Hamiltonian to control the evolution of a quantum system along the Hamiltonian eigenstates. For processes of finite duration, the exact time evolving state may deviate from the adiabatic eigenstate at intermediate times, but in numerous applications it is observed that this deviation reaches a maximum and then decreases significantly towards the end of the process. We provide a straightforward theoretical explanation for this welcome but often unappreciated fact. Our analysis emphasizes a separate adiabaticity criterion for high fidelity state-to-state transfer and it points to new effective shortcut strategies for near adiabatic dynamics.