Circuit quantum acoustodynamics with surface acoustic waves

Abstract

The experimental investigation of quantum devices incorporating mechanical resonators has opened up new frontiers in the study of quantum mechanics at a macroscopic level. It has recently been shown that surface acoustic waves (SAWs) can be piezoelectrically coupled to superconducting qubits, and confined in high-quality Fabry–Perot cavities in the quantum regime. Here we present measurements of a device in which a superconducting qubit is coupled to a SAW cavity, realising a surface acoustic version of cavity quantum electrodynamics. We use measurements of the AC Stark shift between the two systems to determine the coupling strength, which is in agreement with a theoretical model. This quantum acoustodynamics architecture may be used to develop new quantum acoustic devices in which quantum information is stored in trapped on-chip acoustic wavepackets, and manipulated in ways that are impossible with purely electromagnetic signals, due to the 105 times slower mechanical waves.

Displacemon Electromechanics: How to Detect Quantum Interference in a Nanomechanical Resonator

“…Using device parameters based on current technology, our qubit-resonator displacemon can achieve effective ultrastrong coupling using a modulated coupling scheme. A similar interferometry scheme could also be applied to other kinds of solid-state qubits coupled to high-quality resonators, such as spin qubits coupled to nanotubes [32,33], diamond defects coupled to cantilevers [55], or piezoelectric resonators coupled to superconducting qubits [70,71]. However, the parameters estimated for the proposed device of Fig.…”

Phononic loss in superconducting resonators on piezoelectric substrates

“…Here, we find that despite well established processing and measurement techniques, CPW resonators fabricated on a piezoelectric substrate are not limited by any of the above factors. This type of substrate has recently been used for building devices that combine circuit QED with mechanical excitations at quantum level [13][14][15][16][17][18]. From a broader point of view, superconducting CPW resonators enable studies of semiconductor qubits realized on piezoelectric substrate [19,20] and even to couple them to superconducting qubits [21].…”

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

“…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.…”

“…Unlike localized mechanical oscillations [37][38][39], the piezoelectric surface is much larger compared with the acoustic wavelength. Therefore, the phonons are itinerant on the material surface and in the form of propagating waves [31]. To control the quantized motions effectively, the SAW cavities are often combined with other systems, for example, with superconducting qubits or color centers, to form as hybrid quantum systems [40].…”