As an important candidate for non-volatile memory, ferroelectric tunnel junctions (FTJs) have attracted extensive research interests in recent years. The FTJs are usually a three-layer structure, with metal electrodes on the left and right sides, and ferroelectric materials as the tunnel barriers. When the polarization direction of the intermediate ferroelectric material is reversed, it usually causes a large change in the conductance of the FTJs, resulting in two different states with high and low conductance, which can be used as the ON and OFF states in binary memory units. The degree of the conductance change between the two polarization states is characterized by the tunneling electroresistance (TER) ratio, which is defined as TER=(G_ON-G_OFF )/G_OFF 100%, where G_ON and G_OFF represent the conductances of the ON and OFF states, respectively. How to develop new methods and obtain higher TER is always one of the key problems in the research of FTJs. In regard of this, based on the analysis of current quantum transport theory, the team lead by Prof. Xiaohong Zheng in Nanjing Forestry University and Prof. Lei Zhang in Shanxi University, proposed that the double barrier design could be introduced into the FTJs to greatly enhance the TER ratio, and the idea is verified by first principles calculations. They designed the Pt/BaTiO3/LaAlO3/Pt/BaTiO3/LaAlO3/Pt double barrier ferroelectric tunnel junction (DB-FTJ)[Fig. 1a] and performed density functional theory calculations to simulate its transport properties. It is found that, the switching between the ferroelectric left and right polarization states produces a huge tunneling electroresistance of 2.210 108% in the DB-FTJ proposed (which indicates that there is a huge difference in transmission coefficient between the two polarization states, as shown in Fig. 1b), which is at least three orders of magnitude larger than that of the Pt/BaTiO3/LaAlO3/Pt single barrier ferroelectric tunnel junction (SB-FTJ). The basic idea is rooted in two facts: 1) The transmission coefficient of a double barrier structure composed by two barriers in series is closely related to the product of the transmission coefficients of the two single barriers; 2) The square of positive numbers larger than 1 will increase exponentially. This idea is perfectly revealed in the DB-FTJ. The authors also proposed that two extra polarization states with head-to-head and tail-to-tail ferroelectric polarizations can be achieved by separately controlling the polarization direction of each barrier, which leads to multiple resistance states (Fig. 2). This study demonstrates that, in the design of FTJs, the double barrier structure can greatly enhance the TER ratio of FTJs and make them promising for multi-state data storage.