Surface acoustic wave resonators in the quantum regime

Abstract

We present systematic measurements of the quality factors of surface acoustic wave (SAW) resonators on ST-X quartz in the gigahertz range at a temperature of $10 \, \textrm{mK}$. We demonstrate a internal quality factor $Q_\mathrm{i}$ approaching $0.5$ million at $0.5 \, \textrm{GHz}$ and show that $Q_\mathrm{i}\geq4.0\times10^4$ is achievable up to $4.4 \, \textrm{GHz}$. We show evidence for a polynomial dependence of propagation loss on frequency, as well as a weak drive power dependence of $Q_\mathrm{i}$ that saturates at low power, the latter being consistent with coupling to a bath of two-level systems. Our results indicate that SAW resonators are promising devices for integration with superconducting quantum circuits.Comment: 5 pages, 4 figure

Generation and Propagation of Superhigh-Frequency Bulk Acoustic Waves in GaAs

“…We rather assign the lower α eff to the reduced role of losses at interfaces and surfaces in the longer samples. The role of surface defects has been highlighted in recent studies of the absorption losses of acoustic resonators at low temperatures [43,44]. As an important consequence, the present results show that the acoustic absorption at low temperatures is limited by extrinsic (rather than by intrinsic) mechanisms, which can be minimized by improving the quality of the surfaces and interfaces.…”

Universal Quantum Transducers Based on Surface Acoustic Waves

“…(3) Our scheme is built upon an established technology [14,15]: Lithographic fabrication techniques provide almost arbitrary geometries with high precision as evidenced by a large range of SAW devices such as delay lines, bandpass filters, resonators, etc. In particular, the essential building blocks needed to interface qubits with SAW phonons have already been fabricated, according to design principles familiar from electromagnetic devices: (i) SAW resonators, the mechanical equivalents of Fabry-Perot cavities, with low-temperature measurements reaching quality factors of Q ∼ 10 5 even at gigahertz frequencies [22][23][24], and (ii) acoustic waveguides as analog to optical fibers [14]. (4) For a given frequency in the gigahertz range, due to the slow speed of sound of ∼10 3 m=s for typical materials, device dimensions are in the micrometer range, which is convenient for fabrication and integration with semiconductor components, and about 10 5 times smaller than corresponding electromagnetic resonators.…”

Generating synthetic magnetism via Floquet engineering auxiliary qubits in phonon-cavity-based lattice

“…For example, as shown in figure 1, we assume that two SAW cavities (confined by two phonon Bragg mirrors), are coupled to the same superconducting transmon (or charge) qubit located at the cross section [53][54][55][56]. The couplings are mediated by capacitances of the interdigitated-transducer (IDTs) type [30,33]. In our discussions, the qubit (noted as c-qubit) is employed for realizing a tunable couplings between two acoustic modes.…”

“…In the presence of synthetic magnetic flux, the time-reversal symmetry will be broken, which allows one to realize the circulator transport and analog Aharonov-Bohm effects for acoustic waves. Last, we demonstrate that our proposal can be scaled to simulate topological states of matter in quantum acoustodynamics system.In recent years, manipulating acoustic waves at a single-phonon level has drawn a lot of attention [28], and the quantum acoustodynamics (QAD) based on piezoelectric surface acoustic waves (SAW) has emerged as a versatile platform to explore quantum features of acoustic waves [29][30][31][32][33][34][35][36]. Unlike localized mechanical oscillations [37][38][39], the piezoelectric surface is much larger compared with the acoustic wavelength.…”

“…For example, choosing a strong piezoelectric material will increase the coupling significantly [40]. As discussed in [30][31][32], we assume g p /(2π)=60 MHz. By setting Δ p /(2π)=0.6 GHz, g 12 /(2π)=1 MHz, ω d /(2π)=15 MHz and λ=0.5 (corresponding the dashed line position in figure 2), one finds that K 1 ;0.25, and the effective hoping rate J 12 is about J 12 /(2π)=0.12 MHz.…”