Engineering conduction-band valley couplings is a key challenge for Si-based spin qubits. Recent work has shown that the most reliable method for enhancing valley couplings entails adding Ge concentration oscillations to the quantum well. However, ultrashort oscillation periods are difficult to grow, while long oscillation periods do not provide useful improvements. Here, we show that the main benefits of short-wavelength oscillations can be achieved in long-wavelength structures through a second-order coupling process involving Brillouin-zone folding induced by shear strain. We finally show that such strain can be achieved through common fabrication techniques, making this an exceptionally promising system for scalable quantum computing.

工程导带谷耦合是硅基自旋量子位的一个关键挑战。最近的研究表明，增强谷耦合的最可靠方法是在量子阱中添加 Ge 浓度振荡。然而，超短振荡周期很难增长，而长振荡周期则不能提供有用的改进。在这里，我们表明，短波长振荡的主要好处可以通过涉及剪切应变引起的布里渊区折叠的二阶耦合过程在长波长结构中实现。我们最终证明，这种应变可以通过常见的制造技术来实现，这使得它成为可扩展量子计算的一个非常有前途的系统。