论文标题
合并元素transmon
Merged-element transmon
论文作者
论文摘要
Transmon Qubits使用超导电路在追求量子计算方面无处不在。但是，它们仍然需要解决一些缺点。最重要的是，传输的可伸缩性受到减少电路损耗电容部分的参与所需的大型设备足迹的限制。在这项工作中，我们研究和评估替代设备几何形状的损失，即合并元素transmon（Mergemon）。为此，我们用约瑟夫森连接（JJ）的内在电容替换了传统跨对的大型外分流电容器，并降低了量子尺寸约100倍。我们使用溅射的NB-Amorphous-Si-nb Trilayer胶片报告了正交的实施。在低于10 MK的实验中，读出谐振器的频率与订购相结合，在低功率方案中表现出Qubit-State的依赖性变化。该设备还展示了单光子和多光子的转变，这些跃迁代表了两色调光谱中弱的抗谐波系统。通过主方程模拟很好地解释了过渡光谱。参与率分析确定了A-SI隧道屏障的介电损失及其接口是量子放松的主要来源。我们预计，使用低损坏，外上内增长和格子匹配的三层尺寸实施时，订购将在相对较小的设备尺寸中实现高相干性。
Transmon qubits are ubiquitous in the pursuit of quantum computing using superconducting circuits. However, they have some drawbacks that still need to be addressed. Most importantly, the scalability of transmons is limited by the large device footprint needed to reduce the participation of the lossy capacitive parts of the circuit. In this work, we investigate and evaluate losses in an alternative device geometry, namely, the merged-element transmon (mergemon). To this end, we replace the large external shunt capacitor of a traditional transmon with the intrinsic capacitance of a Josephson junction (JJ) and achieve an approximately 100 times reduction in qubit dimensions. We report the implementation of the mergemon using a sputtered Nb--amorphous-Si--Nb trilayer film. In an experiment below 10 mK, the frequency of the readout resonator, capacitively coupled to the mergemon, exhibits a qubit-state dependent shift in the low power regime. The device also demonstrates the single- and multi-photon transitions that represent a weakly anharmonic system in the two-tone spectroscopy. The transition spectra are explained well with master-equation simulations. A participation ratio analysis identifies the dielectric loss of the a-Si tunnel barrier and its interfaces as the dominant source for qubit relaxation. We expect the mergemon to achieve high coherence in relatively small device dimensions when implemented using a low-loss, epitaxially-grown, and lattice-matched trilayer.
