Tunable-barrier dynamic quantum dots are known to generate very accurate single-electron-based currents and can be used as a source of single-electron wave packets for use in quantum metrology, sensing, or information processing. To realize their full technological potential, it is desirable to maximize their frequency of operation to increase the current; however, it has been observed that the mechanism of electron transfer across the quantum dot consistently breaks down for gigahertz frequencies, and this remains unexplained. Here, we present an analysis technique, combined with detailed modeling, to present a mechanism of high-frequency breakdown in this class of quantum dots as a rapidly imparted momentum impulse. Such understanding aids future design and operation protocols, allowing their use in high-frequency and real-time quantum measurements and technologies.

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• Acoustic phonons
• Charge dynamics
• Quantum metrology
• Quantum transport
• Transport phenomena
• Elemental semiconductors
• Quantum dots
• Single-electron devices