Optical and Quantum Sensing and Precision Metrology II

A new type of atom-photon interface

Nathan Cooper, David Johnson, Daniele Baldolini, Matthew Overton, Elisa Da Ros, Lucia Hackermüller

Published Mar 9, 2022• 0 citations

Abstract

Hybrid quantum devices, incorporating both atoms and photons, are able to exploit the benefits of both systems. Compact, robust atom-photon interfaces will enable scalable architectures for quantum computing and quantum communication, as well as chip-scale sensors and single-photon sources. We demonstrate a new type of interface and show the interaction of cold cesium atoms with resonant photons. For this atoms are cooled in a magneto-optical trap, transferred to an optical dipole trap and positioned inside a transverse, 30 µm diameter through-hole in an optical fibre, created via laser micromachining. The intersection is orthogonal to the propagation direction of the light mode. We trap about 300 atoms at a temperature of 120µK. When the guided light is on resonance with the caesium D2 line, up to 87% of it is absorbed by the atoms. Our technique can be applied in 2-dimensional systems, i.e. in optical waveguide chips and other existing photonic systems. We also discuss the influence of hole shapes on transmission and prospects of adding a micro-cavity.

DOI: 10.1117/12.2619375

Related papers

Integrating cold caesium atoms into optical waveguides

Elisa Da Ros

This project focuses on a novel experimental method for interfacing cold atoms with optical waveguides. This relies on the introduction of cold atoms into microscopic laser-drilled holes that are perpendicular to the propagation axis of the waveguide. Direct interfacing of cold atoms with the guided mode of a waveguide is an attractive mechanism by which to create atom-photon interfaces, as the small mode area increases the interaction rate. Unlike many previous approaches, this technique can be applied in almost any existing waveguide system, including chip-based waveguide arrays and other complex environments. It therefore has great promise as a way of creating hybrid atom-photon quantum devices. Using this method, we demonstrate coupling between cold atoms and the light propagating in the core of an untapered single-mode optical fibre. This was achieved by laser-drilling a cylindrical, transverse hole (30 μm diameter) through the core of the fibre. Ensembles of cold caesium atoms can be tightly confined through an optical dipole trap within the microscopic void. Probe light, resonant with the Cs D2 line, is then coupled into the fibre. By measuring the transmitted optical power through the interface, it was determined that up to 87% of the probe power could be absorbed by the atoms. The corresponding optical depth per unit length of the atom cloud is over 700 cm^(-1), higher than any value reported to date for a comparable system. This will be a key parameter for the miniaturisation of atom-optical systems as well as for enhancing spatial resolution in sensing applications. The dependence of this absorption on several experimental parameters was also characterised and found to be in line with theoretical expectations. The atomic transition is not noticeably broadened by the presence of the fibre. We have also carried out numerical simulations of light transmission across wave-guide junctions of this type, proving that tailored hole geometries can enable enhanced optical transmission. The achievable degree of improvement is such that it is conceivable to place the void within an optical resonator, for example using laser-written Bragg gratings, and to achieve the strong coupling between the atoms and the guided light. Altogether this work demonstrates the potential of this technique to interface atoms with tightly confined light, allowing for integration in otherwise purely photonic circuits. In such environment the interaction between the atomic ensemble and the light can act as a node for the storage and processing of quantum information.

Dec 31, 20200 citations

Cold atoms in micromachined waveguides: a new platform for atom-photon interaction

Lucia Hackermüller

We use atoms in micro-machined waveguides to demonstrate a new platform for atom-photon interactions. Such hybrid quantum devices are able to exploit the benefits of both, atoms and photons. Compact, robust atom-photon interfaces enable scalable architectures for quantum computing and quantum communication, as well as chip-scale sensors and single-photon sources.

IEEE/LEOS Summer Topical MeetingsJul 1, 20231 citation

Optical Trapping and Cooling of Single Atoms

D.A. van der Flier

Single atoms are a promising candidate for the creation of a scalable quantum computer. Neutral atoms trapped by optical fields are especially encouraging due to the full controllability of the trap potential. Single neutral atoms trapped within a fibre-fibre cavity allow us to strongly couple atoms and photons. This creates an efficient atom-photon interface which can compensate for the short state transfer distance inherent of neutral atoms. A spatial light modulator allows for the creation and manipulation of an array of these single atom traps.\n\nIn this research we create a setup to cool and trap neutral rubidium-87 atoms by a combination of a magneto-optical trap (MOT) and a dipole trap. The dipole trap uses a strongly focused, far red-detuned laser, which enables us to trap single atoms via the collisional blockade regime. These traps are realised within a novel glass cell, allowing for great optical access.\n\nThe MOT in this setup is able to trap (4.27 +/- 0.10) * 10^3 atoms with a density of (7.89 +/- 0.56) * 10^9 atoms cm^-3 . The MOT temperature is in the order of 100 μK. We also show the manipulation of these properties, allowing us to tailor the MOT. The dipole trap is created with a trap waist of 37 μm, allowing us to trap a cloud of atoms. With the dipole trap we achieve a lifetime of atoms of (34.8 +/- 2.0) ms.

Jan 1, 20170 citations

Cold atoms in micromachined waveguides: A new platform for atom-photon interactions

E. Da Ros, N. Cooper, J. Nute +1 more

The authors demonstrate insertion of laser-cooled atoms into a microscopic, transverse through-hole in an optical fiber, where they overlap directly with the guided light. This is a proof-of-principle prototype for the efficient combination of cold atomic ensembles with chip-based photonic circuits.

arXiv:1906.06236Physical Review ResearchJul 17, 202011 citations

Optical Interface Created by Laser-Cooled Atoms Trapped in the Evanescent Field Surrounding an Optical Nanofiber

E. Vetsch, D. Reitz, G. Sagué +3 more

Trapping and optically interfacing laser-cooled neutral atoms are essential requirements for their use in advanced quantum technologies. Here we simultaneously realize both of these tasks with cesium atoms interacting with a multicolor evanescent field surrounding an optical nanofiber. The atoms are localized in a one-dimensional optical lattice about 200 nm above the nanofiber surface and can be efficiently interrogated with a resonant light field sent through the nanofiber. Our technique opens the route towards the direct integration of laser-cooled atomic ensembles within fiber networks, an important prerequisite for large scale quantum communication schemes. Moreover, it is ideally suited to the realization of hybrid quantum systems that combine atoms with, e.g., solid state quantum devices.

arXiv:0912.1179Physical Review LettersMay 20, 2010812 citations

Nano-Photonic Platform for Atom-Light Interaction

Su‐Peng Yu

Development of technology can allow access to new regimes in science and creation of new fields of research. The development of ultra-high finesse mirror technology enabled the development of the field of cavity quantum electrodynamics, and an abundance of wonderful physics experiments soon followed. The sophistication of the field of nano-fabrication and nano-photonics would allow unprecedented capability to mold the shape and flow of light, and provide a novel platform for efficient and hopefully integrable quantum systems. In this project, we hope to interface cold atoms, perhaps the most quintessential of quantum systems, to the engineering power of nano-photonics. We believe this field of study will not only lead to the demonstration of new physics in the quantum regime, but work toward building a network with quantum capabilities mediated by optical channels. In this project, we develop a nano-fabricated platform capable of interfacing nano-photonic devices with cold Cesium atoms in free-space. Nano-photonic waveguide devices are fabricated in a Silicon Nitride device layer on Silicon substrate. The fabrication is compatible with conventional semiconductor fabrication processes, and the chip design has been adapted to allow incorporation with free-space optics to support cold Cesium atom cloud around the waveguides. An ultra-high vacuum system that is compatible to the chip and its supporting structures was constructed to perform experiments. With our system, we were able to fabricate and characterize nano-photonic structures, including 1D photonic crystal waveguides, cavities, and 2D photonic crystal slabs. For the 1D photonic crystal waveguide devices, enhanced atom-light coupling between localized Cesium atoms in the vicinity of the devices, and also atom-atom interaction between Cesium atoms mediated by the guided mode of the photonic crystal waveguide, has been observed. The 2D photonic devices allow us many capabilities beyond that of the 1D waveguide. Demonstration of exotic optical properties including natural decay rate suppression and circular polarization engineering, should be within reach in the near future.

Jun 5, 20175 citations