Abstract
We report a demonstration of the hallmark concept of quantum optics: periodic collapse and revival of quantum coherence (QCR) in a room temperature ensemble of quantum dots (QD). Control over quantum states, inherent to QCR, together with the dynamical QD properties present an opportunity for practical room temperature building blocks of quantum information processing. The amplitude decay of QCR is dictated by the QD homogeneous linewidth, thus, enabling its extraction in a double-pulse Ramsey-type experiment. The more common photon echo technique was also invoked and yielded the same linewidth. Measured electrical bias and temperature dependencies of the transverse relaxation times enable to determine the two main decoherence mechanisms: carrier-carrier and carrier-phonon scatterings.
Highlights
Collapse and revival of wave functions lasting well beyond the classical Cummings decay [1] are hallmark quantum optics phenomena
We demonstrate the hallmark concept of periodic collapse and revival of coherence in a room-temperature ensemble of quantum dots (QDs) in the form of a 1.5-mm-long optical amplifier
The amplitude decay of coherent revival (CR) is dictated by the QD homogeneous linewidth, enabling its extraction in a double-pulse Ramsey-type experiment
Summary
Collapse and revival of wave functions lasting well beyond the classical Cummings decay [1] are hallmark quantum optics phenomena. Predicted by Eberly et al [2] for interaction of a quantized coherent field with a single atom, they were termed quantum coherent revival (QCR). For a coherent interaction with classical fields, similar revivals have been observed. The QD ensemble acts as an effective two-level system [13] where the charge carrier band-to-band ground-state transition makes up the two states of a quantum bit (qubit) which are prepared, manipulated, and measured by coherent optical excitation. The different modes have slightly different transition frequencies and accumulate different phases as they precess At specific times, their phases align and a revival event takes place. Our findings pave the way to practical elements for quantum information processing, communication, and simulations where coherent states are controlled using compact semiconductor nanostructures operating at room temperature. Unlike our room-temperature CR demonstration, all these quantum elements operate exclusively at cryogenic temperatures
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