Arbitrary control of the temporal waveform of photons during spontaneous emission

TL;DR

This paper introduces a versatile method to generate photons with arbitrary temporal waveforms from quantum emitters, enhancing quantum communication and networking capabilities by controlling spontaneous emission processes.

Contribution

The authors present a broadly applicable technique for shaping photon waveforms during spontaneous emission using amplitude and phase modulation of the excitation field, applicable to various quantum emitters.

Findings

Able to generate photons with any temporal waveform within hardware timing limits.

Developed variational algorithms for optimal excitation pulse identification.

Established photon-number statistics and post-selection techniques for efficient photon generation.

Abstract

Control of the temporal waveform of photons produced during spontaneous emission from single quantum emitters provides a crucial tool in the establishment of hybrid quantum systems, optimization of quantum state transfer protocols and mitigation of effects due interferometric instability for network architectures based on flying qubits. We describe a method to generate photons of any temporal waveform from emitters of any excited state lifetime, limited only by the timing resolution of control hardware. We show how the temporal waveform of photons can be controlled by deterministically varying the population of an excited state which undergoes spontaneous emission. Our broadly applicable approach has only two requirements for a candidate quantum emitter: modulation of the (1) amplitude and (2) relative phase of a field coupling a ground state to the excited manifold. We detail how to identify optimal excitation pulses by employing variational algorithms to feed back on atomic populations. Additionally, we develop Quantum Monte Carlo based tools to determine photon-number statistics and establish techniques to identify optimal excitation strengths and post-selection thresholds for photon generation protocols. We situate our work in the context of other prior research on bespoke single photon sources and networking including post-emission pulse shaping, temporal gating and cavity-based methods. In comparison, our free-space process has greater flexibility in producing any waveform, requires less infrastructure, and can be readily applied across a wide range of quantum emitters. We discuss the applications and limits of this technique, including how increasing photon emission probabilities affects achievable temporal-mode overlap fidelities between emitted and target photon waveforms.