Abstract We propose a marginally stable optical resonator suitable for atom interferometry. The resonator geometry is based on two flat mirrors at the focal planes of a lens that produces the large beam waist required to coherently manipulate cold atomic ensembles. Optical gains of about 100 are achievable using optics with part-per-thousand losses. The resulting power build-up will allow for enhanced coherent manipulation of the atomic wavepackets such as large separation beamsplitters. We study the effect of longitudinal misalignments and assess the robustness of the resonator in terms of intensity and phase profiles of the intra-cavity field. We also study how to implement atom interferometry based on large momentum transfer Bragg diffraction in such a cavity.
Abstract We propose a marginally stable optical resonator suitable for atom interferometry. The resonator geometry is based on two flat mirrors at the focal planes of a lens that produces the large beam waist required to coherently manipulate cold atomic ensembles. Optical gains of about 100 are achievable using optics with part-per-thousand losses. The resulting power build-up will allow for enhanced coherent manipulation of the atomic wavepackets such as large separation beamsplitters. We study the effect of longitudinal misalignments and assess the robustness of the resonator in terms of intensity and phase profiles of the intra-cavity field. We also study how to implement atom interferometry based on large momentum transfer Bragg diffraction in such a cavity.
Summary form only given. The development of atom interferometry in the last few decades has led to high precision measurements of inertial effects and tests of fundamental physics [1]. New methods for higher sensitivity atom interferometers (AIs) are being explored, in particular the interrogation of atoms with optical cavities. The benefits of optical cavities would be higher optical power allowing large momentum transfer beam splitters, and possibly cleaner and controlled phase profiles [2]. However high sensitivity AIs require long interrogation times, which, combined with cold atom cloud expansion, bring the challenges of large centimetric waists in cavities. We propose an optical resonator composed of a convergent lens with two flat mirrors at its focal planes as shown on figure 1 [3]. When perfectly aligned any input field can be resonating inside. Especially, when a Gaussian beam, with waist w0' on the first mirror, is inputted to the cavity, the lens conjugates it to the second mirror with waist w0= λf/πw0'. This cavity is marginally stable and exhibits a half degenerate behaviour: all modes resonate at the same frequencies, odd and even modes being separated by half a free spectral range. Thus it does not have strong mode cleaning properties but it is able to magnify any input field. When misaligned, this cavity goes out of its degenerate behaviour and the circulating field begins to degrade due to mode filtering. A numerical study of the cavity behaviour, using an ABCD transfer matrix formalism, showed that typical controllable misalignments of a few micrometres would not be critical for atom interrogation. Further degradations due to surface defects and tilts are being investigated.
We present the analysis of a half degenerate optical resonator consisting of a lens located between two plane mirrors. This resonator was designed to support a large waist (cm) Gaussian beam for applications to precision inertial measurements based on large momentum transfer atom interferometry. We investigate the spatial profile of the resonating beam, and the optical gain for different beam size, and the influence of misalignments on the degeneracy of the cavity. FFT simulations show that aberrations and surface imperfections of the optics are the main contributors to spatial inhomogeneities of the resonating beam, which supports our experimental results. We also report the stability of this resonator locked to an ultra-stable optical reference.
We present a novel atom interferometer configuration that combines large momentum transfer with the enhancement of an optical resonator for the purpose of measuring gravitational strain in the horizontal directions. Using Bragg diffraction and taking advantage of the optical gain provided by the resonator, we achieve momentum transfer up to 8ℏk with mW level optical power in a cm-sized resonating waist. Importantly, our experiment uses an original resonator design that allows for a large resonating beam waist and eliminates the need to trap atoms in cavity modes. We demonstrate inertial sensitivity in the horizontal direction by measuring the change in tilt of our resonator. This result paves the way for future hybrid atom or optical gravitational wave detectors. Furthermore, the versatility of our method extends to a wide range of measurement geometries and atomic sources, opening up new avenues for the realization of highly sensitive inertial atom sensors.
The development of atom interferometry in the last few decades has led to high precision measurements of inertial effects and tests of fundamental physics. New methods for higher sensitivity atom interferometers (AIs) are being explored, particularly the interrogation of atoms with optical cavities [1]. Its benefits would be higher optical power allowing large momentum transfer beam splitters, and possibly cleaner and controlled phase profiles. However high sensitivity AIs require long interrogation times, which combined with cold atom expansion, bring the challenges of large waists in cavities.
Atom interferometers are among the most sensitive instruments for precision measurements and tests of fundamental physics. Their performance, however, is ultimately limited by quantum projection noise when uncorrelated atomic ensembles are employed. Cavity-assisted generation of entangled states has proven to be a promising route toward quantum-enhanced interferometry beyond the standard quantum limit. In this work, we present the realization and characterization of a monolithic bow-tie cavity developed to achieve a strong collective atom-light coupling with strontium atoms. Unlike conventional standing-wave Fabry-Pérot resonators, the traveling-wave geometry of the bow-tie cavity provides homogeneous atom-light coupling over the entire atomic ensemble, making it particularly suitable for entanglement-enhanced atom interferometry with freely falling atoms. The monolithic cavity architecture presents several scientifically relevant features such as high mechanical stability, high finesse, robustness against mirror misalignment, optical and atomic access and the option of generating squeezed states through different strategies. The cavity was realized for operation on the strontium (5s2)1S0−(5s5p)3P1 transition at 689 nm and achieves a finesse of F=5.7×104 while keeping the transmission of a single mirror sufficiently large to allow for efficient atomic information extraction. In this geometry, the cavity supports two foci with waists of 164 μm and 31 μm which gives access to different regimes of atom-cavity coupling. For ensembles containing up to 105 atoms, the cavity is expected to enable a Wineland squeezing parameter ξ2 of 24 dB through cavity-feedback squeezing, and 28 dB through quantum non-demolition measurements, demonstrating its potential as a platform for next-generation quantum-enhanced atom interferometers.
We propose and demonstrate a new scheme for atom interferometry, using light pulses inside an optical cavity as matter wave beam splitters. The cavity provides power enhancement, spatial filtering, and a precise beam geometry, enabling new techniques such as low power beam splitters (<100 μW), large momentum transfer beam splitters with modest power, or new self-aligned interferometer geometries utilizing the transverse modes of the optical cavity. As a first demonstration, we obtain Ramsey-Raman fringes with >75% contrast and measure the acceleration due to gravity, g, to 60 μg/sqrt[Hz] resolution in a Mach-Zehnder geometry. We use >10(7) cesium atoms in the compact mode volume (600 μm 1/e(2) waist) of the cavity and show trapping of atoms in higher transverse modes. This work paves the way toward compact, high sensitivity, multiaxis interferometry.