TY - JOUR

T1 - Integrated fiber-mirror ion trap for strong ion-cavity coupling

AU - Brandstätter, Birgit

AU - McClung, A.

AU - Schüppert, K.

AU - Casabone, B.

AU - Friebe, K.

AU - Stute, A.

AU - Schmidt, Piet Oliver

AU - Deutsch, C.

AU - Reichel, J.

AU - Blatt, R.

AU - Northup, T. E.

N1 - Funding information: The authors would like to thank Ramin Lalezari from ATFilms for valuable discussions on mirror coatings; Frederik Klauser from the Institute of Physical Chemistry of the University of Innsbruck for his aid with the XPS measurements; Stefan Haslwantler, Johannes Ghetta, Ben Ames, and Jasleen Lugani for valuable discussions and aid in the construction of the FFPCs and the experimental apparatus; and the mechanical workshop of the Institute of Experimental Physics at the University of Innsbruck. We gratefully acknowledge support from the Austrian Science Fund (FWF): Project Nos. F4003 and F4019, the European Research Council through the CRYTERION Project, the European Commission via the Atomic QUantum TEchnologies (AQUTE) Integrating Project, and the Institut für Quanteninformation GmbH.

PY - 2013/12/11

Y1 - 2013/12/11

N2 - We present and characterize fiber mirrors and a miniaturized ion-trap design developed to integrate a fiber-based Fabry-Perot cavity (FFPC) with a linear Paul trap for use in cavity-QED experiments with trapped ions. Our fiber-mirror fabrication process not only enables the construction of FFPCs with small mode volumes, but also allows us to minimize the influence of the dielectric fiber mirrors on the trapped-ion pseudopotential. We discuss the effect of clipping losses for long FFPCs and the effect of angular and lateral displacements on the coupling efficiencies between cavity and fiber. Optical profilometry allows us to determine the radii of curvature and ellipticities of the fiber mirrors. From finesse measurements, we infer a single-atom cooperativity of up to 12 for FFPCs longer than 200 μm in length; comparison to cavities constructed with reference substrate mirrors produced in the same coating run indicates that our FFPCs have similar scattering losses. We characterize the birefringence of our fiber mirrors, finding that careful fiber-mirror selection enables us to construct FFPCs with degenerate polarization modes. As FFPCs are novel devices, we describe procedures developed for handling, aligning, and cleaning them. We discuss experiments to anneal fiber mirrors and explore the influence of the atmosphere under which annealing occurs on coating losses, finding that annealing under vacuum increases the losses for our reference substrate mirrors. X-ray photoelectron spectroscopy measurements indicate that these losses may be attributable to oxygen depletion in the mirror coating. Special design considerations enable us to introduce a FFPC into a trapped ion setup. Our unique linear Paul trap design provides clearance for such a cavity and is miniaturized to shield trapped ions from the dielectric fiber mirrors. We numerically calculate the trap potential in the absence of fibers. In the experiment additional electrodes can be used to compensate distortions of the potential due to the fibers. Home-built fiber feedthroughs connect the FFPC to external optics, and an integrated nanopositioning system affords the possibility of retracting or realigning the cavity without breaking vacuum.

AB - We present and characterize fiber mirrors and a miniaturized ion-trap design developed to integrate a fiber-based Fabry-Perot cavity (FFPC) with a linear Paul trap for use in cavity-QED experiments with trapped ions. Our fiber-mirror fabrication process not only enables the construction of FFPCs with small mode volumes, but also allows us to minimize the influence of the dielectric fiber mirrors on the trapped-ion pseudopotential. We discuss the effect of clipping losses for long FFPCs and the effect of angular and lateral displacements on the coupling efficiencies between cavity and fiber. Optical profilometry allows us to determine the radii of curvature and ellipticities of the fiber mirrors. From finesse measurements, we infer a single-atom cooperativity of up to 12 for FFPCs longer than 200 μm in length; comparison to cavities constructed with reference substrate mirrors produced in the same coating run indicates that our FFPCs have similar scattering losses. We characterize the birefringence of our fiber mirrors, finding that careful fiber-mirror selection enables us to construct FFPCs with degenerate polarization modes. As FFPCs are novel devices, we describe procedures developed for handling, aligning, and cleaning them. We discuss experiments to anneal fiber mirrors and explore the influence of the atmosphere under which annealing occurs on coating losses, finding that annealing under vacuum increases the losses for our reference substrate mirrors. X-ray photoelectron spectroscopy measurements indicate that these losses may be attributable to oxygen depletion in the mirror coating. Special design considerations enable us to introduce a FFPC into a trapped ion setup. Our unique linear Paul trap design provides clearance for such a cavity and is miniaturized to shield trapped ions from the dielectric fiber mirrors. We numerically calculate the trap potential in the absence of fibers. In the experiment additional electrodes can be used to compensate distortions of the potential due to the fibers. Home-built fiber feedthroughs connect the FFPC to external optics, and an integrated nanopositioning system affords the possibility of retracting or realigning the cavity without breaking vacuum.

UR - http://www.scopus.com/inward/record.url?scp=84891678175&partnerID=8YFLogxK

U2 - 10.1063/1.4838696

DO - 10.1063/1.4838696

M3 - Article

AN - SCOPUS:84891678175

VL - 84

JO - Review of Scientific Instruments

JF - Review of Scientific Instruments

SN - 0034-6748

IS - 12

M1 - 123104

ER -