Ions confined using a Paul trap require a stable, high voltage and low noise radio frequency (RF) potential. We present a guide for the design and construction of a helical coil resonator for a desired frequency that maximises the quality factor for a set of experimental constraints. We provide an in-depth analysis of the system formed from a shielded helical coil and an ion trap by treating the system as a lumped element model. This allows us to predict the resonant frequency and quality factor in terms of the physical parameters of the resonator and the properties of the ion trap. We also compare theoretical predictions with experimental data for different resonators, and predict the voltage applied to the ion trap as a function of the Q-factor, input power and the properties of the resonant circuit.

This version is available from Sussex Research Online: http://sro.sussex.ac.uk/38820/ This document is made available in accordance with publisher policies and may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the URL above for details on accessing the published version. Copyright and reuse:Sussex Research Online is a digital repository of the research output of the University.Copyright and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable, the material made available in SRO has been checked for eligibility before being made available.Copies of full text items generally can be reproduced, displayed or performed and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. We present the design and operation of an ytterbium ion trap experiment with a setup offering versatile optical access and 90 electrical interconnects that can host advanced surface and multilayer ion trap chips mounted on chip carriers. We operate a macroscopic ion trap compatible with this chip carrier design and characterize its performance, demonstrating secular frequencies >1 MHz, and trap and cool nearly all of the stable isotopes, including 171 Yb + ions, as well as ion crystals. For this particular trap we measure the motional heating rate ṅ and observe an ṅ ∝1/ω 2 behavior for different secular frequencies ω. We also determine a spectral noise density S E (1 MHz) = 3.6(9) × 10 −11 V 2 m −2 Hz −1 at an ion electrode spacing of 310(10) µm. We describe the experimental setup for trapping and cooling Yb + ions and provide frequency measurements of the 2 S 1/2 ↔ 2 P 1/2 and 2 D 3/2 ↔ 3 D[3/2] 1/2 transitions for the stable 170 Yb + , 171 Yb + , 172 Yb + , 174 Yb + ,a n d 176 Yb + isotopes which are more precise than previously published work.

Trapped ions are excellent candidates for quantum nodes, as they possess many desirable features of a network node including long-lifetimes, on-site processing capability and produce photonic flying qubits. However, unlike classical networks in which data may be transmitted in optical fibers and the range of communication readily extended with amplifiers, quantum systems often emit photons that have limited propagation range in optical fibers and, by virtue of the nature of a quantum state, cannot be noiselessly amplified. Here, we first describe a method to extract flying qubits from a Ba + trapped ion via shelving to a long lived, low-lying D-state with higher entanglement probabilities compared with current strong and weak excitation methods. We show a projected fidelity of ≈89% of the ion-photon entanglement. We compare several methods of ion-photon entanglement generation and show how the fidelity and entanglement probability varies as a function of the photon collection optic's numerical aperture. We then outline an approach for quantum frequency conversion of the photons emitted by the Ba + ion to the telecom range for long-distance networking and to 780 nm, for potential entanglement with Rubidium based quantum memories. Our approach is significant for extending the range of quantum networks and for development of hybrid quantum networks compromised of different types of quantum memories.

Quantum networks consisting of quantum memories and photonic interconnects can be used for entanglement distribution [1,2], quantum teleportation [3] and distributed quantum computing [4]. Remotely connected two-node networks have been demonstrated using memories of the same type: trapped ion systems [5], quantum dots [6] and nitrogen vacancy centers [6,7]. Hybrid systems constrained by the need to use photons with the native emission wavelength of the memory, have been demonstrated between a trapped ion and quantum dot [8] and between a single neutral atom and a Bose-Einstein Condensate [9]. Most quantum systems operate at disparate and incompatible wavelengths to each other so such two-node systems have never been demonstrated. Here, we use a trapped 138Ba + ion and a periodically poled lithium niobate (PPLN) waveguide, with a fiber coupled output, to demonstrate 19% end-to-end efficient quantum frequency conversion (QFC) of single photons from 493 nm to 780 nm. At the optimal signal-to-noise operational parameter, we use fluorescence of the ion to produce light resonant with the 87 Rb D 2 transition. To demonstrate the quantum nature of both the unconverted 493 nm photons and the converted photons near 780 nm, we observe strong quantum statics in their respective second order intensity correlations. This work extends the range of intra-lab networking between ions and networking and communication between disparate quantum memories.A quantum network may be established by interfering photons emitted by quantum memories. Connecting different types of quantum memories for hybrid networking requires overcoming the disparate photon wavelengths emitted by each quantum memory. Given advances in modularity in trapped ion and neutral atom architectures, a hybrid system with modular inter-connectivity is advantageous. In the case of photons emitted from trapped ions (with fiber attenuations of 70 dB/km at 369 nm for Yb + and 50 dB/km at 493 nm for Ba + ) generating photons in, or converting photons to, the near-infra-red range (with a fiber attenuation of 3.5 dB/km) would sig-nificantly extend the networking range between trapped ions and provide the ability to match the wavelength of another quantum memory.Trapped ions [10] are an excellent candidate for elementary logical units [11] of a network as many prerequisite components have been shown, including: modularity for photon generation and detection [5,11,12], quantum computation [13,14] and excellent single photon emission properties [15]. In this work, we overcome a challenge to extending the networking range of trapped ions by frequency converting the ion light. We demonstrate the conversion of 493 nm photons, emitted from a single barium ion, to a 780 nm wavelength resonant with the D 2 transition in neutral 87 Rb. This conversion provides the two-fold benefit of paving the way for neutralion hybrid networking and communication as well as extending the networking capability of barium ions from 100s of meters to several kilometres allowing for both an ion-ion and ne...

Advances in the distribution of quantum information will likely require entanglement shared across a hybrid quantum network [1][2][3]. Many entanglement protocols require the generation of indistinguishable photons between the various nodes of the network [4,5]. This is challenging in a hybrid environment due to typically large differences in the spectral and temporal characteristics of single photons generated in different systems [1]. Here we show, for the first time, quantum interference between photons generated from a single atomic ion and an atomic ensemble, located in different buildings and linked via optical fibre. Trapped ions are leading candidates for quantum computation and simulation with good matter-to-photon conversion [6][7][8][9][10][11][12][13]. Rydberg excitations in neutral-atom ensembles show great promise as interfaces for the storage and manipulation of photonic qubits with excellent efficiencies [14][15][16][17]. Our measurement of high-visibility interference between photons generated by these two, disparate systems is an important building block for the establishment of a hybrid quantum network.Recently, Rydberg atoms have proven to be a useful tool in the field of quantum information. The strong optical nonlinearity exhibited by neutral-atom Rydberg ensembles enables the construction of single-photon sources [15], gates [16], and transistors [17]. Strong light-matter interactions make them well suited as quantum memories [14], and for implementing quantum repeaters [18,19]. Furthermore, arrays of Rydberg atoms are a powerful new platform for quantum simulation [20, 21]. The continued success of trapped-ion systems in quantum computation [6,7], simulation [8, 9], and communication [12] owes to their long coherence and trapping lifetimes [10], high fidelity operations [11], and ease of generating ion-photon entanglement [12, 13].Given the wide-ranging applications of both platforms, future efforts in quantum information will benefit from the construction of remote hybrid atomic-ensemble-ion networks. Flying photonic qubits provide an excellent means arXiv:1907.04387v1 [quant-ph]

Fiber-based quantum networks require photons at telecommunications wavelengths to interconnect qubits separated by long distances. Trapped ions are leading candidates for quantum networking with high-fidelity two-qubit gates, long coherence times, and the ability to readily emit photons entangled with the ion's internal qubit states. However, trapped ions typically emit photons at wavelengths incompatible with telecommunications fiber. Here, we demonstrate frequency conversion of visible photons, emitted from the S–P dipole transition of a trapped Ba+ ion into the telecommunications C-band. These results are an important step toward enabling a long-distance trapped ion quantum internet.

Practical implementation of quantum networks is likely to interface different types of quantum systems. Photonically linked hybrid systems, combining unique properties of each constituent system, have typically required sources with the same photon emission wavelength. Trapped ions and neutral atoms both have compelling properties as nodes and memories in a quantum network but have never been photonically linked because of vastly different operating wavelengths. Here, we demonstrate the first interaction between neutral atoms and photons emitted from a single trapped ion. We use slow light in 87Rb vapor to delay photons originating from a trapped 138Ba+ ion by up to 13.5 ± 0.5 ns, using quantum frequency conversion to overcome the frequency difference between the ion and neutral atoms. The delay is tunable and preserves the temporal profile of the photons. This result showcases a hybrid photonic interface usable as a synchronization tool—a critical component in any future large-scale quantum network.

The optimization of two-dimensional (2D) lattice ion trap geometries for trapped ion quantum simulation is investigated. The geometry is optimized for the highest ratio of ion-ion interaction rate to decoherence rate. To calculate the electric field of such array geometries a numerical simulation based on a 'Biot-Savart like law' method is used. In this article we will focus on square, hexagonal and centre rectangular lattices for optimization. A method for maximizing the homogeneity of trapping site properties over an array is presented for arrays of a range of sizes. We show how both the polygon radii and separations scale to optimize the ratio between the interaction and decoherence rate. The optimal polygon radius and separation for a 2D lattice is found to be a function of the ratio between radio-frequency (rf) voltage and drive frequency applied to the array. We then provide a case study for 171 Yb + ions to show how a 2D quantum simulator array could be designed.