Probing electron-phonon interactions in the charge-photon dynamics of cavity-coupled double quantum dots

Electron-phonon coupling is known to play an important role in the charge dynamics of semiconductor quantum dots. Here we explore its role in the combined charge-photon dynamics of cavity-coupled double quantum dots. Previous work on these systems has shown that strong electron-phonon coupling leads to a large contribution to photoemission and gain from phonon-assisted emission and absorption processes. We compare the effects of this phonon sideband in three commonly investigated gate-defined quantum dot material systems: InAs nanowires and GaAs and Si two-dimensional electron gases (2DEGs). We compare our theory with existing experimental data from cavity-coupled InAs nanowire and GaAs 2DEG double quantum dots and find quantitative agreement only when the phonon sideband and photoemission processes during lead tunneling are taken into account. Finally, we show that the phonon sideband also leads to a sizable renormalization of the cavity frequency, which allows for direct spectroscopic probes of the electron-phonon coupling in these systems

The challenge we face The latest cancer statistics

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On-Chip Quantum-Dot Light Source for Quantum-Device Readout

We use microwave radiation generated by a semiconductor double-quantum-dot (DQD) micromaser for charge-state detection. A cavity is populated with n(c) similar to 6000 photons by driving a current through an emitter DQD. These photons are used to sense the charge state of a target DQD that is located at the opposite end of the cavity. The charge dynamics in the target DQD influences the output power and emission frequency of the maser. Three different readout mechanisms are compared. The detection scheme requires no cavity input field and may potentially be used to improve the scalability of semiconductor and superconducting qubit readout technologies

On-Chip Quantum-Dot Light Source for Quantum-Device Readout

We use microwave radiation generated by a semiconductor double-quantum-dot (DQD) micromaser for charge-state detection. A cavity is populated with n(c) similar to 6000 photons by driving a current through an emitter DQD. These photons are used to sense the charge state of a target DQD that is located at the opposite end of the cavity. The charge dynamics in the target DQD influences the output power and emission frequency of the maser. Three different readout mechanisms are compared. The detection scheme requires no cavity input field and may potentially be used to improve the scalability of semiconductor and superconducting qubit readout technologies

Regional proton nuclear magnetic resonance spectroscopy differentiates cortex and medulla in the isolated perfused rat kidney

Volume-localized proton nuclear magnetic resonance spectroscopy was used as an assay of regional biochemistry in the isolated perfused rat kidney. This model eliminated artifacts caused by respiratory and cardiac motion experienced in vivo. Immersion of the kidney under its venous effluent reduced the susceptibility artifacts evoked by tissue-air interfaces. The rapid acquisition with relaxation enhancement imaging sequence was used for scout imaging. This gave excellent spatial resolution of the cortex, outer medulla, and inner medulla. Spectra were then acquired in 10 minutes using the volume-selective multipulse spectroscopy sequence from voxels with a volume of approximately 24 mu L located within the cortical or medullary regions. Spectral peaks were assigned by the addition of known compounds to the perfusion medium and by comparison with spectra of protein-free extracts of cortex and medulla. The medullary region spectra were characterized by signals from the osmolytes betaine, glycerophosphorylcholine, and inositol. The spectra from the cortex were more complex and contained lesser contributions from osmolytes