arXiv subjects

S. Debald

Publications and source records attributed to S. Debald.

3 recordsLinked to original sources

arXiv2002

Phonon Cavity Models for Quantum Dot Based Qubits

Phonon cavities are believed to be the next step towards a control of dephasing in semiconductor quantum dot `qubits'. In this paper, we discuss two models for phonon cavities - a surface acoustic wave (SAW) inter-digitated transducer on an infinite half-space, and an elastic thin slab. The inelastic current through double quantum dots in non-perfect SAW cavities exhibits a gap at small energies and is completely suppressed in a perfect, infinite system. In the free-standing slab model, van Hove singularities evolve in the phonon spectral density. We find that these singularities cause additional side peaks in the inelastic current.

cond-mat.mes-hall↗

arXiv2002

Control of Dephasing and Phonon Emission in Coupled Quantum Dots

We predict that phonon subband quantization can be detected in the non-linear electron current through double quantum dot qubits embedded into nano-size semiconductor slabs, acting as phonon cavities. For particular values of the dot level splitting $Δ$, piezo-electric or deformation potential scattering is either drastically reduced as compared to the bulk case, or strongly enhanced due to phonon van Hove singularities. By tuning $Δ$ via gate voltages, one can either control dephasing, or strongly increase emission into phonon modes with characteristic angular distributions.

cond-mat.mes-hall↗

arXiv2000

Phonons and Phonon Confinement in Transport through Double Quantum Dots

We calculate the electron-phonon interaction coefficients for surface acoustic waves and for phonons in free standing quantum wells. These are used to derive the inelastic current through a double quantum dot caused by spontaneous emission of phonons. For the case of the free standing structure (phonon cavity), we predict a staircase-like inelastic current superimposed by van Hove singularities. Therefore, the phonon confinement can be detected by electron transport measurements.

cond-mat.mes-hall↗