Gokhale Vikrant J, Downey Brian P, Katzer D Scott, Nepal Neeraj, Lang Andrew C, Stroud Rhonda M, Meyer David J
National Research Council Fellow residing at the US Naval Research Laboratory, Washington, DC, USA.
US Naval Research Laboratory, Washington, DC, USA.
Nat Commun. 2020 May 8;11(1):2314. doi: 10.1038/s41467-020-15472-w.
Solid-state quantum acoustodynamic (QAD) systems provide a compact platform for quantum information storage and processing by coupling acoustic phonon sources with superconducting or spin qubits. The multi-mode composite high-overtone bulk acoustic wave resonator (HBAR) is a popular phonon source well suited for QAD. However, scattering from defects, grain boundaries, and interfacial/surface roughness in the composite transducer severely limits the phonon relaxation time in sputter-deposited devices. Here, we grow an epitaxial-HBAR, consisting of a metallic NbN bottom electrode and a piezoelectric GaN film on a SiC substrate. The acoustic impedance-matched epi-HBAR has a power injection efficiency >99% from transducer to phonon cavity. The smooth interfaces and low defect density reduce phonon losses, yielding (f × Q) and phonon lifetimes up to 1.36 × 10 Hz and 500 µs respectively. The GaN/NbN/SiC epi-HBAR is an electrically actuated, multi-mode phonon source that can be directly interfaced with NbN-based superconducting qubits or SiC-based spin qubits.
固态量子声动力学（QAD）系统通过将声子源与超导或自旋量子比特耦合，为量子信息存储和处理提供了一个紧凑的平台。多模复合高音体声波谐振器（HBAR）是一种适用于QAD的常用声子源。然而，复合换能器中缺陷、晶界以及界面/表面粗糙度引起的散射严重限制了溅射沉积器件中的声子弛豫时间。在此，我们在碳化硅衬底上生长了一种外延HBAR，它由金属氮化铌（NbN）底部电极和压电氮化镓（GaN）薄膜组成。声阻抗匹配的外延HBAR从换能器到声子腔的功率注入效率大于99%。光滑的界面和低缺陷密度减少了声子损耗，分别产生高达1.36×10赫兹的（频率×品质因数）和500微秒的声子寿命。氮化镓/氮化铌/碳化硅外延HBAR是一种电驱动的多模声子源，可直接与基于氮化铌的超导量子比特或基于碳化硅的自旋量子比特连接。
