Fabrication of ultrahigh-precision hemispherical mirrors for quantum-optics applications

Daniel B Higginbottom,Geoff T Campbell,Yves Colombe,Fengzhou Fang,Ping Koy Lam,Ben C Buchler,Gabriel Araneda

doi:10.1038/s41598-017-18637-8

Abstract

High precision, high numerical aperture mirrors are desirable for mediating strong atom-light coupling in quantum optics applications and can also serve as important reference surfaces for optical metrology. In this work we demonstrate the fabrication of highly-precise hemispheric mirrors with numerical aperture NA = 0.996. The mirrors were fabricated from aluminum by single-point diamond turning using a stable ultra-precision lathe calibrated with an in-situ white-light interferometer. Our mirrors have a diameter of 25 mm and were characterized using a combination of wide-angle single-shot and small-angle stitched multi-shot interferometry. The measurements show root-mean-square (RMS) form errors consistently below 25 nm. The smoothest of our mirrors has a RMS error of 14 nm and a peak-to-valley (PV) error of 88 nm, which corresponds to a form accuracy of λ/50 for visible optics.

Highlights

The controlled interaction of optical fields with material quantum systems is an essential engineering requirement of quantum networks and sensors
A single hemispheric mirror may enhance atom-light interactions by shaping the vacuum mode density around an emitter, but unlike an optical resonator the hemisphere-mediated atom-light interaction is single-pass. It has been predicted[13] that the spontaneous emission rate of an atomic electron at the center of curvature (CoC) of a spherical mirror may be suppressed or enhanced depending on the radius of the mirror, even when the mirror radius is much larger than the atomic wavelength
State-of-the-art diamond turning can produce low-numerical aperture (NA) optical surfaces 50 mm in diameter with peak-to-valley surface deviations of 150 nm[10] and local surface roughness below 0.4 nm[22]. This sub-wavelength precision has been utilized in quantum optics applications such as laser mode converters[23,24,25], monolithic microcavities[26], and other resonators[27]

Summary

Introduction

The controlled interaction of optical fields with material quantum systems is an essential engineering requirement of quantum networks and sensors. For a point source emitting spherical waves the ideal mode converter is a deep parabolic mirror[8,9] This single-pass approach requires high numerical aperture (NA) reflectors with sub-wavelength surface precision. A single hemispheric mirror may enhance atom-light interactions by shaping the vacuum mode density around an emitter, but unlike an optical resonator the hemisphere-mediated atom-light interaction is single-pass It has been predicted[13] that the spontaneous emission rate of an atomic electron at the center of curvature (CoC) of a spherical mirror may be suppressed or enhanced depending on the radius of the mirror, even when the mirror radius is much larger than the atomic wavelength. We demonstrate the capacity to cut concave hemispheres that surpass the requirements for single-pass QED experiments, and characterize five consecutively manufactured mirrors as a test of consistency and reproduceability

Methods

Results

Conclusion