Enhanced electron-phonon coupling for a semiconductor charge qubit in a surface phonon cavity

Area of Science:

• Quantum physics
• Condensed matter physics
• Acoustics

Background:

• Electron-phonon coupling typically causes decoherence and energy loss in semiconductors.
• This coupling, however, can be exploited for strong or ultra-strong coupling regimes in acoustic cavity quantum electrodynamics.

Purpose of the Study:

• To propose and demonstrate a novel phonon cavity for surface acoustic waves.
• To investigate the potential of acoustic cavity quantum electrodynamics using surface phonons.

Main Methods:

• Fabrication of a phonon cavity using periodic metal fingers as Bragg reflectors on a GaAs/AlGaAs heterostructure.
• Characterization of the phonon cavity by measuring the piezoelectric potential to identify phonon band gaps and cavity modes.
• Utilizing tunneling spectroscopy on a double quantum dot to probe phonon-assisted transitions.

Main Results:

• Successful demonstration of a phonon cavity for surface acoustic waves.
• Identification of phonon band gaps and cavity phonon modes through frequency, time, and spatially resolved measurements.
• Observation of enhanced phonon-assisted transitions in a charge qubit, indicating strong coupling.

Conclusions:

• The developed phonon cavity effectively controls surface acoustic waves.
• This work opens avenues for exploring acoustic cavity quantum electrodynamics with surface phonons.
• The findings encourage further research into utilizing electron-phonon coupling for quantum information processing.