2018 Jocelyn Bell Burnell Medal and Prize

Carmen Palacios-Berraquero of the University of Cambridge for discovering and patenting a method to create single-photon emitting sites in atomically-thin materials, deterministically – and for using a 2-dimensional device to all-electrically induce quantum emission from these sites.

2018 Jocelyn Bell Burnell Medal and Prize Carmen Palacios-Berraquero

Carmen Palacios-Berraquero’s research lies at the interface between two disciplines, 2-dimensional materials and quantum optics, her PhD thesis title being: ‘Quantum-confined Excitons in 2-dimensional Materials’.

The family of 2D materials she studies are transition metal dichalcogenides (2D-TMDs), semiconductors offering many technological advantages – such as low power consumption and atomically-precise interfaces. Sites of single-photon emission were first measured in 2D-TMDs in 2015, appearing at random locations within the flakes and of unknown origin. This field of research began then, coinciding with the start of Carmen’s PhD, and she has since published two first-author papers in Nature Communications, which have been warmly received in terms of journal features, citations and conferences.

Her group has developed a method of deterministically creating the single-photon emitting sites in 2D-TMDs in large-scale arrays – referred to as quantum dots (QDs) – quantum confinement potentials that can trap single excitons. The excitons recombine radiatively to emit single photons, a crucial requirement for many quantum information technology (QIT) applications.

The QDs are formed by placing the flakes over substrates nano-patterned with protrusions that induce local strain and provoke the quantum confinement of excitons at low temperatures. Carmen designed and tested this method after preliminary studies – fabricating the samples, performing the optical measurements in several TMDs, and achieving quantum light at different wavelengths. Very few quantum confinement systems can be deterministically engineered in a scalable way.

In another experiment, 2D-QDs were embedded within 2D-heterostructures to form quantum devices. 2D-TMDs and other 2D materials – graphene and hexagonal boron nitride – were used to create quantum light-emitting diodes. Carmen’s optical measurements proved the electrically-driven light was indeed single-photons, and discovered these sites in a new material (WS2) for the first time. Very few single-photon sources can be triggered electrically – potentially a great advantage for on-chip quantum technologies.

Carmen is currently working towards using the QDs as a new, optically-addressable matter qubit – capturing single-spins inside them using field-effect type 2D devices. She is also leading the efforts to commercialise the technology as a single-photon source for satellite quantum communication and other applications.

This research represents the marriage of 2D-semiconductor technology with QIT, paving the way for 2D materials as platforms for scalable, on-chip quantum photonics.

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