Neutral-Atom Wavelength-Compatible 780 nm Single Photons from a Trapped Ion via Quantum Frequency Conversion

Abstract

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...

Optimizing repeater schemes for the quantum internet

“…The number of quantum states that can be stored and processed is presently limited. Experimental information processing platforms that have demonstrated excellent control over storage qubits include NV centers in diamond [19,30,45,[50][51][52][53], neutral atoms [31,32], non-NV color centers in diamond [54,55], quantum dots [56][57][58], and trapped ions [26][27][28].…”

“…However, the number of quantum states that can be processed at the same time is presently limited to a small number. Examples of information processing implementations include systems such as trapped ions [26][27][28], nitrogen-vacancy (NV) centers in diamond [29,30], neutral atoms [31][32][33], and quantum dots [34,35].…”

Target-wavelength-trimmed second harmonic generation with gallium phosphide-on-nitride ring resonators

“…Moreover, applications are emerging in which an absolute frequency of one or more interacting fields is required. Examples of this include PDC entangled photon sources for optical quantum computing [1][2][3][4] and frequency conversion of single visible or NIR photons, emitted by ions or solid-state defects, for long-distance fiber transmission [5][6][7][8][9]. Toward this latter application, multi-resonant frequency conversion of photons to/from the telecom band has been demonstrated in nanophotonic structures fabricated from non-linear materials such as gallium phosphide (GaP) [10], aluminum nitride [11], lithium niobate [12,13] and silicon nitride [14,15].…”

C-band single photons from a trapped ion via two-stage frequency conversion

“…This reduces the range of ion quantum networks and prevents the integration of these networks into existing telecommunications infrastructure. Of particular interest are photons produced via S-P dipole transitions, enabling direct entanglement between the photons and commonly used ground state qubits of ions such as Yb + [1,3,5,7,8,12], Ba + [3,11,12,[16][17][18], and Ca + [6,9,10]. Ground-state qubits currently demonstrate the longest coherence times in trapped ions [8], as well as the highest two-qubit gate fidelities [10].…”