Sub-cycle control of terahertz high-harmonic generation by dynamical Bloch oscillations

TL;DR

This paper demonstrates control over high-harmonic generation in semiconductors using intense terahertz pulses, revealing quantum interference effects and paving the way for coherent THz electronics.

Contribution

It introduces a method to manipulate high-harmonic emission in semiconductors via sub-cycle THz waveform control, combining experimental results with quantum theory.

Findings

High-harmonic transients cover 0.1 to 675 THz spectrum.

Waveform-controlled quantum interference affects ionization paths.

Potential for all-coherent THz-rate electronic devices.

Abstract

Ultrafast charge transport in strongly biased semiconductors is at the heart of highspeed electronics, electro-optics, and fundamental solid-state physics. Intense light pulses in the terahertz (THz) spectral range have opened fascinating vistas: Since THz photon energies are far below typical electronic interband resonances, a stable electromagnetic waveform may serve as a precisely adjustable bias. Novel quantum phenomena have been anticipated for THz amplitudes reaching atomic field strengths. We exploit controlled THz waveforms with peak fields of 72 MV/cm to drive coherent interband polarization combined with dynamical Bloch oscillations in semiconducting gallium selenide. These dynamics entail the emission of phase-stable high-harmonic transients, covering the entire THz-to-visible spectral domain between 0.1 and 675 THz. Quantum interference of different ionization paths of accelerated charge carriers is controlled via the waveform of the driving field and explained by a quantum theory of inter- and intraband dynamics. Our results pave the way towards all-coherent THz-rate electronics.