Individual atoms can act as stationary qubits and thus serve as nodes in quantum computing networks or as memories for quantum repeaters. However, to successfully use qubits based on single atoms suspended in free space, photons emitted by a single atom need to be efficiently collected. Conventionally, this can be done with high numerical aperture lenses, which can collect light from a large solid angle. Alternatively, placing the atom into a high-finesse cavity or within a sub-wavelength distance from the surface of a nano-photonic structure can affect the spatial pattern in which the atom emits photons and make the photon collection more efficient. However, these approaches remain experimentally challenging and can limit the potential for realistic scalability.
This project aims to achieve a distinctly novel way to control the emission pattern of a single atom by placing the atom at a distance of a few wavelengths from a chiral metasurface — a phased two-dimensional array of nano-scale metallic antennas or dielectric scatterers. We design and fabricate bi- and multi-layer structures with properly tuned interference between the radiation patterns of the layers. In the vicinity of such structures, the atom will emit light into a single, well defined direction without the need to place the atom at a sub-wavelength distance from a metallic or dielectric surface. The unidirectionally emitted photons can be efficiently coupled into optical fibers. Relative to current state-of-the-art, this platform simplifies and enables speed-up for certain quantum information processing tasks, such as remote entanglement between two distant atoms.
Simultaneously we will explore – through design and fabrication – the use of chiral metasurfaces for photon extraction from solid-state quantum emitters, such as colour centers in diamond. Here we hope to achieve increased photon collection efficiency from materials with high refractive index, which holds promise for improving the performance (speed and sensitivity) of electric and magnetic field sensors.
Photonic Quantum Processor
Photonic quantum processors based on integrated quantum photonic circuits require entangled photon pairs to perform quantum computations. However, current state-of-the-art technologies utilize probabilistic entangled photon sources with limited pair-extraction efficiencies, negatively affecting the computation speed. This project aims to boost the speed of on-chip quantum operations by using bright, on-demand entangled photon sources with an […]
April 24, 2023
Quantum Computational Resources in the Presence of Symmetry
Summary Fault-tolerance is essential to the performance of quantum technologies, but known schemes are extremely resource intensive. Thus, improving existing schemes or inventing new schemes is of central importance. This joint project is based on the realization that fault-tolerance schemes make use of symmetries in fundamental ways, and that studying the problem of fault tolerance […]
March 13, 2019
Novel Infrared Camera Based on Quantum Sensors for Biomedical Applications
Summary In this project we develop a novel infrared camera with low noise and high detection efficiency for biomedical applications of optical coherence tomography (OCT) using quantum materials. OCT is a technique used to image the back of the eye and allow for the diagnosis of detrimental eye conditions, for e.g., macular degeneration, diabetic retinopathy […]
March 13, 2019
Reliably operating noisy quantum computers
Summary The overall goal of the project is to develop practical methods to be able to reliably run useful applications on near-term quantum computers. This requires identifying and overcoming the ubiquitous errors that currently limit quantum computing capabilities. Traditional methods of quantifying errors in quantum computers fail to predict how errors affect the output of […]
January 22, 2020