21 research outputs found
Double-sided coaxial circuit QED with out-of-plane wiring
Superconducting circuits are well established as a strong candidate platform
for the development of quantum computing. In order to advance to a practically
useful level, architectures are needed which combine arrays of many qubits with
selective qubit control and readout, without compromising on coherence. Here we
present a coaxial circuit QED architecture in which qubit and resonator are
fabricated on opposing sides of a single chip, and control and readout wiring
are provided by coaxial wiring running perpendicular to the chip plane. We
present characterisation measurements of a fabricated device in good agreement
with simulated parameters and demonstrating energy relaxation and dephasing
times of s and s respectively. The architecture
allows for scaling to large arrays of selectively controlled and measured
qubits with the advantage of all wiring being out of the plane.Comment: 4 pages, 3 figures, 1 tabl
Circuit quantum acoustodynamics with surface acoustic waves
The experimental investigation of quantum devices incorporating mechanical
resonators has opened up new frontiers in the study of quantum mechanics at a
macroscopic level. Superconducting microwave circuits have proven to be
a powerful platform for the realisation of such quantum devices, both in cavity
optomechanics, and circuit quantum electro-dynamics (QED).
While most experiments to date have involved localised nanomechanical
resonators, it has recently been shown that propagating surface acoustic waves
(SAWs) can be piezoelectrically coupled to superconducting qubits, and
confined in high-quality Fabry-Perot cavities up to microwave frequencies in
the quantum regime, indicating the possibility of realising coherent
exchange of quantum information between the two systems. Here we present
measurements of a device in which a superconducting qubit is embedded in, and
interacts with, the acoustic field of a Fabry-Perot SAW cavity on quartz,
realising a surface acoustic version of cavity quantum electrodynamics. This
quantum acoustodynamics (QAD) architecture may be used to develop new quantum
acoustic devices in which quantum information is stored in trapped on-chip
surface acoustic wavepackets, and manipulated in ways that are impossible with
purely electromagnetic signals, due to the times slower speed of
travel of the mechanical waves.Comment: 12 pages, 9 figures, 1 tabl
A phonon laser in the quantum regime
We demonstrate a trapped-ion system with two competing dissipation channels,
implemented independently on two ion species co-trapped in a Paul trap. By
controlling coherent spin-oscillator couplings and optical pumping rates we
explore the phase diagram of this system, which exhibits a regime analogous to
that of a (phonon) laser but operates close to the quantum ground state with an
average phonon number of . We demonstrate phase locking of the
oscillator to an additional resonant drive, and also observe the phase
diffusion of the resulting state under dissipation by reconstructing the
quantum state from a measurement of the characteristic function