Harvey-Collard Patrick, Jacobson N Tobias, Bureau-Oxton Chloé, Jock Ryan M, Srinivasa Vanita, Mounce Andrew M, Ward Daniel R, Anderson John M, Manginell Ronald P, Wendt Joel R, Pluym Tammy, Lilly Michael P, Luhman Dwight R, Pioro-Ladrière Michel, Carroll Malcolm S
Département de physique et Institut quantique, Université de Sherbrooke, Sherbrooke (Québec) J1K 2R1, Canada.
Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
Phys Rev Lett. 2019 May 31;122(21):217702. doi: 10.1103/PhysRevLett.122.217702.
Spin-orbit coupling is relatively weak for electrons in bulk silicon, but enhanced interactions are reported in nanostructures such as the quantum dots used for spin qubits. These interactions have been attributed to various dissimilar interface effects, including disorder or broken crystal symmetries. In this Letter, we use a double-quantum-dot qubit to probe these interactions by comparing the spins of separated singlet-triplet electron pairs. We observe both intravalley and intervalley mechanisms, each dominant for [110] and [100] magnetic field orientations, respectively, that are consistent with a broken crystal symmetry model. We also observe a third spin-flip mechanism caused by tunneling between the quantum dots. This improved understanding is important for qubit uniformity, spin control and decoherence, and two-qubit gates.
对于体硅中的电子而言，自旋轨道耦合相对较弱，但据报道，在诸如用于自旋量子比特的量子点等纳米结构中，相互作用会增强。这些相互作用被归因于各种不同的界面效应，包括无序或晶体对称性的破坏。在本信函中，我们使用双量子点量子比特，通过比较分离的单重态 - 三重态电子对的自旋来探测这些相互作用。我们观察到了谷内和谷间机制，它们分别在[110]和[100]磁场取向中占主导地位，这与晶体对称性破坏模型一致。我们还观察到了由量子点之间的隧穿引起的第三种自旋翻转机制。这种更深入的理解对于量子比特的均匀性、自旋控制和退相干以及双量子比特门而言至关重要。
