# Optimal shortcut approach based on an easily obtained intermediate Hamiltonian

## TL;DR

This paper introduces a method to accelerate adiabatic quantum processes by designing an intermediate Hamiltonian, simplifying the transition to the final transitionless Hamiltonian and reducing the complexity of implementation.

## Contribution

The authors propose a novel approach to shortcut adiabatic evolution using an intermediate Hamiltonian, avoiding complex counterdiabatic driving and simplifying practical implementation.

## Key findings

- Effective speedup of adiabatic processes demonstrated in a three-level system.
- Intermediate Hamiltonian structure resembles the original with modified coefficients.
- Method simplifies the realization of transitionless quantum evolution.

## Abstract

We present a general approach to speed up the adiabatic process without adding the traditional counterdiabatic driving (CD) Hamiltonian. The strategy is to design an easy-to-get intermediate Hamiltonian to connect the original Hamiltonian and final transitionless Hamiltonian. With final transitionless Hamiltonian, the same target can be achieved as in the adiabatic process governed by the original Hamiltonian, but in a shorter time. We apply the present approach to a three-level system, and the result shows that the final transitionless Hamiltonian usually has the same structure as the original Hamiltonian but with different time-dependent coefficients, allowing speedup to be achieved in a much easier way compared to previous methods.