The electric-field effect control of two-dimensional electron gases (2-DEGs) has allowed nanoscale electron quantum transport to be explored in semiconductors. Structures based on transition metal oxides have electronic states that favour the emergence of novel quantum orders that are absent in conventional semiconductors and the 2-DEG formed at a LaAlO₃/SrTiO₃ interface—a structure in which superconductivity and spin–orbit coupling can coexist—is a promising platform to develop devices for spintronics and topological electronics. However, field-effect control of the properties of this interface at the nanoscale remains challenging. Here we show that a quantum point contact can be formed in a LaAlO₃/SrTiO₃ interface through electrostatic confinement of the 2-DEG using a split gate. Our device exhibits a quantized conductance due to ballistic transport in a controllable number of one-dimensional conducting channels. Under a magnetic field, the direct observation of the Zeeman splitting between spin-polarized bands allows the determination of the Landé g-factor, whose value differs strongly from that of the free electrons. Through source–drain voltage measurements, we also performed a spectroscopic investigation of the 3d energy levels inside the quantum point contact. The LaAlO₃/SrTiO₃ quantum point contact could potentially be used as a spectrometer to probe Majorana states in an oxide 2-DEG.

二维电子气（2-DEG）的电场效应控制已允许在半导体中探索纳米级电子量子传输。基于过渡金属氧化物的结构具有有利于出现常规半导体中不存在的新型量子级和在LaAlO ₃ / SrTiO ₃界面处形成的2-DEG的电子态-超导性和自旋轨道耦合可以共存的结构是开发自旋电子器件和拓扑电子器件的有前途的平台。然而，在纳米尺度上对该界面的性质进行场效应控制仍然具有挑战性。在这里，我们表明可以在LaAlO ₃ / SrTiO _3中形成量子点接触通过使用分裂门对2-DEG进行静电限制来实现界面连接。由于可控数量的一维传导通道中的弹道运输，我们的设备显示出量化的电导。下一个磁场，自旋极化的带之间的塞曼分裂的直接观察允许朗德的判断克-因子，其值强烈从自由电子的不同。通过源漏电压测量，我们还对量子点触点内部的3 d能级进行了光谱研究。LaAlO ₃ / SrTiO ₃量子点接触可潜在地用作光谱仪，以探测氧化物2-DEG中的马约拉纳态。