Dynamical coupling between a nuclear spin ensemble and electromechanical phonons.

Dynamical coupling with high-quality factor resonators is essential in a wide variety of hybrid quantum systems such as circuit quantum electrodynamics and opto/electromechanical systems. Nuclear spins in solids have a long relaxation time and thus have the potential to be implemented into quantum memories and sensors. However, state manipulation of nuclear spins requires high-magnetic fields, which is incompatible with state-of-the-art quantum hybrid systems based on superconducting microwave resonators.

On-chip temporal focusing of elastic waves in a phononic crystal waveguide.

The ability to manipulate acoustic and elastic waveforms in continuous media has attracted significant research interest and is crucial for practical applications ranging from biological imaging to material characterization. Although several spatial focusing techniques have been developed, these systems require sophisticated resonant structures with narrow bandwidth, which limit their practical applications. Here we demonstrate temporal pulse manipulation in a dispersive one-dimensional phononic crystal waveguide, which enables the temporal control of ultrasonic wave propagation.

Drift-Induced Enhancement of Cubic Dresselhaus Spin-Orbit Interaction in a Two-Dimensional Electron Gas.

We investigated the effect of an in-plane electric field on drifting spins in a GaAs quantum well. Kerr rotation images of the drifting spins revealed that the spin precession wavelength increases with increasing drift velocity regardless of the transport direction. A model developed for drifting spins with a heated electron distribution suggests that the in-plane electric field enhances the effective magnetic field component originating from the cubic Dresselhaus spin-orbit interaction.

Broadband reconfigurable logic gates in phonon waveguides.

The high-quality-factor mechanical resonator in electromechanical systems has facilitated dynamic control of phonons via parametric nonlinear processes and paved the development of mechanical logic-elements. However, the narrow spectral bandwidth of the resonating element constrains the available nonlinear phenomena thus limiting the functionality of the device as well as the switching speeds. Here we have developed phonon waveguides, with a two-octave-wide phonon transmission band, in which mechanical four-wave-like mixing is demonstrated that enables the frequency of phonon waves to be converted over 1 MHz.

Gate-controlled electromechanical backaction induced by a quantum dot.

Semiconductor-based quantum structures integrated into mechanical resonators have emerged as a unique platform for generating entanglement between macroscopic phononic and mesocopic electronic degrees of freedom. A key challenge to realizing this is the ability to create and control the coupling between two vastly dissimilar systems. Here, such coupling is demonstrated in a hybrid device composed of a gate-defined quantum dot integrated into a piezoelectricity-based mechanical resonator enabling milli-Kelvin phonon states to be detected via charge fluctuations in the quantum dot.