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Title: Optimized coplanar waveguide resonators for a superconductor–atom interface

Abstract

We describe the design and characterization of superconducting coplanar waveguide cavities tailored to facilitate strong coupling between superconducting quantum circuits and single trapped Rydberg atoms. For initial superconductor–atom experiments at 4.2 K, we show that resonator quality factors above 10{sup 4} can be readily achieved. Furthermore, we demonstrate that the incorporation of thick-film copper electrodes at a voltage antinode of the resonator provides a route to enhance the zero-point electric fields of the resonator in a trapping region that is 40 μm above the chip surface, thereby minimizing chip heating from scattered trap light. The combination of high resonator quality factor and strong electric dipole coupling between the resonator and the atom should make it possible to achieve the strong coupling limit of cavity quantum electrodynamics with this system.

Authors:
; ; ; ; ;  [1]
  1. Department of Physics, University Of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706 (United States)
Publication Date:
OSTI Identifier:
22590467
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 109; Journal Issue: 9; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ATOMS; COPPER; ELECTRIC DIPOLES; ELECTRIC FIELDS; ELECTRIC POTENTIAL; ELECTRODES; FILMS; HEATING; QUALITY FACTOR; QUANTUM ELECTRODYNAMICS; RESONATORS; SUPERCONDUCTORS; TRAPPING; VISIBLE RADIATION; WAVEGUIDES

Citation Formats

Beck, M. A., E-mail: mabeck2@wisc.edu, Isaacs, J. A., Booth, D., Pritchard, J. D., Saffman, M., and McDermott, R. Optimized coplanar waveguide resonators for a superconductor–atom interface. United States: N. p., 2016. Web. doi:10.1063/1.4962172.
Beck, M. A., E-mail: mabeck2@wisc.edu, Isaacs, J. A., Booth, D., Pritchard, J. D., Saffman, M., & McDermott, R. Optimized coplanar waveguide resonators for a superconductor–atom interface. United States. doi:10.1063/1.4962172.
Beck, M. A., E-mail: mabeck2@wisc.edu, Isaacs, J. A., Booth, D., Pritchard, J. D., Saffman, M., and McDermott, R. 2016. "Optimized coplanar waveguide resonators for a superconductor–atom interface". United States. doi:10.1063/1.4962172.
@article{osti_22590467,
title = {Optimized coplanar waveguide resonators for a superconductor–atom interface},
author = {Beck, M. A., E-mail: mabeck2@wisc.edu and Isaacs, J. A. and Booth, D. and Pritchard, J. D. and Saffman, M. and McDermott, R.},
abstractNote = {We describe the design and characterization of superconducting coplanar waveguide cavities tailored to facilitate strong coupling between superconducting quantum circuits and single trapped Rydberg atoms. For initial superconductor–atom experiments at 4.2 K, we show that resonator quality factors above 10{sup 4} can be readily achieved. Furthermore, we demonstrate that the incorporation of thick-film copper electrodes at a voltage antinode of the resonator provides a route to enhance the zero-point electric fields of the resonator in a trapping region that is 40 μm above the chip surface, thereby minimizing chip heating from scattered trap light. The combination of high resonator quality factor and strong electric dipole coupling between the resonator and the atom should make it possible to achieve the strong coupling limit of cavity quantum electrodynamics with this system.},
doi = {10.1063/1.4962172},
journal = {Applied Physics Letters},
number = 9,
volume = 109,
place = {United States},
year = 2016,
month = 8
}
  • The authors have analyzed the propagation characteristics of wave-guiding structures with superconductors which are thin compared to the magnetic penetration depth. The complex propagation constant is evaluated within the framework of the modified spectral domain method without the need for numerical calculations in the complex plane. Good agreement is found with the results of other methods. The numerical analysis is instrumental in deducing results for the penetration depth and the surface resistance of YBa[sub 2]Cu[sub 3]O[sub 7[minus]x] thin films on sapphire with a PrBa[sub 2]Cu[sub 3]O[sub 7[minus]x] buffer layer. They confirm recent observations of a non-single-gap BCS temperature dependence.
  • We show that pairs of atoms optically excited to the Rydberg states can strongly interact with each other via effective long-range dipole-dipole or van der Waals interactions mediated by their nonresonant coupling to a common microwave field mode of a superconducting coplanar waveguide cavity. These cavity mediated interactions can be employed to generate single photons and to realize in a scalable configuration a universal phase gate between pairs of single photon pulses propagating or stored in atomic ensembles in the regime of electromagnetically induced transparency.
  • Thin films of TiN were sputter-deposited onto Si and sapphire wafers with and without SiN buffer layers. The films were fabricated into rf coplanar waveguide resonators, and internal quality factor measurements were taken at millikelvin temperatures in both the many photon and single photon limits, i.e., high and low electric field regimes, respectively. At high field, we found the highest internal quality factors ({approx}10{sup 7}) were measured for TiN with predominantly a (200)-TiN orientation. The (200)-TiN is favored for growth at high temperature on either bare Si or SiN buffer layers. However, growth on bare sapphire or Si(100) at lowmore » temperature resulted in primarily a (111)-TiN orientation. Ellipsometry and Auger measurements indicate that the (200)-TiN growth on the bare Si substrates is correlated with the formation of a thin, {approx_equal}2 nm, layer of SiN during the predeposition procedure. On these surfaces we found a significant increase of Q{sub i} for both high and low electric field regimes.« less
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