Bulletin of the American Physical Society
51st Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 65, Number 4
Monday–Friday, June 1–5, 2020; Portland, Oregon
Session G02: Quantum Networks and Quantum MemoriesLive
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Chair: Alberto Marino, Univ. Oklahoma Room: D133-134 |
Wednesday, June 3, 2020 8:00AM - 8:12AM Live |
G02.00001: Ultra-broadband On-Resonance Quantum Storage in Hot Atomic Barium Vapor Kai Shinbrough, Benjamin Hunt, Virginia Lorenz Quantum memories are of critical importance to the scalability of quantum information processing and quantum technologies in communication, measurement, and computation. Here we present numerical simulation of the storage of ultra-broadband photons in hot atomic barium vapor, which allows for quantum memory operation at telecom wavelengths. We numerically calculate the optimal control field profiles for the storage process both through direct Nedler-Mead simplex search and by singular value decomposition of the storage kernel, where the latter guarantees optimality. We provide a physical interpretation of our numerical results related in part to recent work on Autler-Townes-Splitting (ATS) based quantum memory, and show saturation of the protocol-independent bound on storage efficiency imposed by the optical depth for pulses of duration 200 fs to 17.5 ps. In conclusion we provide an outlook for implementing these results experimentally. [Preview Abstract] |
Wednesday, June 3, 2020 8:12AM - 8:24AM Live |
G02.00002: Benchmarking a Trapped-Ion Quantum Memory with a Cryogenic Sapphire Oscillator Ting Rei Tan, Claire Edmunds, Alistair Milne, Cornelius Hempel, Michael Biercuk Individual qubits encoded in the hyperfine ground states of trapped ions can be a robust quantum memory [1]. Their coherence, however, is not just limited by the atomic system, but rather by the phase noise of the reference local oscillator [2] used to generate the control fields. Upconversion by a factor of $N$ from a reference at 10 MHz to the qubit frequency at several GHz leads to multiplicative phase noise of 20 log$_{10}(N)$ dB, reducing achievable fidelities. Local oscillators at GHz frequencies provide a way to circumvent this problem. Here, we report progress on the benchmarking of an ytterbium ion qubit at 12.6 GHz using a 10.6 GHz cryogenic sapphire oscillator [3] as a reference clock. Citation: [1] M. Sepiol, et al. Probing Qubit Memory Errors at the Part-per-Million Level. Physical Review Letters 123(11), 110503 (2019). [2] H. Ball, et al. The role of master clock stability in quantum information processing npj Quantum Information 2(1), 16033 (2016). [3] N. Nand, et al. Ultra-Stable Very-Low Phase-Noise Signal Source for Very Long Baseline Interferometry Using a Cryocooled Sapphire Oscillator. IEEE Transactions on Microwave Theory and Techniques 59(11), 2978-2986 (2011). [Preview Abstract] |
Wednesday, June 3, 2020 8:24AM - 8:36AM Live |
G02.00003: Enhancing the absorption of an ultrashort light pulse by a narrowband atomic medium Daniel Felinto, Alyson J. A. Carvalho, Raoni S. N. Moreira, Jose Ferraz, Sandra S. Vianna, Lucio H. Acioli The storage of broadband single photons from a parametric-down-conversion source is a capability with the potential to foster new applications in quantum information. A particular challenge to this problem, however, is the bandwidth mismatch between the short-lived photon and the long-lived memories. Ultimately, this difficulty can be mapped into the problem of how a narrowband medium can efficiently absorb a broadband pulse of light. Here we present a detailed approach to this problem focusing on the absorption of photons at 800 nm by hot vapors of Rubidium atoms. For this, we employ a stronger control field to drive a sequential two-photon transition on the atoms, together with a weak signal field consisting of a femtosecond pulse of light. We describe then how to measure small absorptions of the signal pulse and how to improve this absorption through the various parameters of the problem. Our results are modeled by a perturbative theory suitable to our present weak-absorption regime. We provide then a roadmap with different strategies to achieve larger absorptions. [Preview Abstract] |
Wednesday, June 3, 2020 8:36AM - 8:48AM Live |
G02.00004: On direct geneation of ion-photon entanglement at telecom wavelengths in 171Yb+ Wance Wang, Connor Goham, Andrew Laugharn, Joseph W Britton Entanglement between small-scale quantum processors and flying qubits is the building block of quantum networking. Leading ion-photon entanglement demonstrations at telecom wavelengths achieve high-fidelity over distances up to 50 km [0,1]. These demonstrations used quantum frequency conversion and 40Ca+ ions. Here, we explore entanglement between 171Yb+ ions and photon polarization states at 1350 nm (P3/2-D3/2) and 1650 nm (P3/2-D5/2). A cavity-mediated Raman interaction increases IR photon generation and collection efficiency. Driving the S-D quadrupole transition can map D-state coherences to the long-lived HF qubit. We also consider photon frequency qubits as an approach that decreases sensitivity to birefringence. Relative to two-species proposals, our approach avoids QFC, secondary ion species and swap gates [2]. [0] M. Bock, et al, Nature Communications (2018)9:1998 [1] V. Krutyanskiy, et al, NPJ Quantum Information (2019)5:72 [2] C. Crocker, et al, Optics Express(2019)27:20:28143 [Preview Abstract] |
Wednesday, June 3, 2020 8:48AM - 9:00AM Live |
G02.00005: Development of light-matter entanglement between trapped Ba+ ion and 780 nm photons John Hannegan, James Siverns, Qudsia Quraishi Entanglement between matter and flying qubits is essential to long-distance entanglement distribution. However, trapped ion-generated flying qubits typically have restricted propagation distances due to their blue photon wavelengths. Here, I will present our work aimed at the generation of 780 nm photons which are polarization entangled with a single 138Ba+ qubit. To ensure high-fidelity single shot state detection [1], we will shelve one of the Ba+ ion qubit states in a long-lived low lying D-state. We will discuss projected rates and entanglement fidelity using a configuration for optical frequency conversion of photons produced by the ion for both horizontal and vertical polarizations. With this setup, it is possible to generate matter-qubit entangled photons at 780 nm that extend networking distances by orders of magnitude and are compatible with neutral Rb systems [2,3]. [1] T. Noel et al., PRA, 85, 023401 (2012) [2] A. N. Craddock, J. Hannegan, D.P. Ornelas-Huerta, et. al, PRL, 123, 213601 (2019) [3] J. D. Siverns, J. Hannegan, Q. Quraishi Sc. Adv. 5 (10), eaav4651 (2019) [Preview Abstract] |
Wednesday, June 3, 2020 9:00AM - 9:12AM Live |
G02.00006: Multiplexed Photonic Qubit Memory with Individual Atoms in an Optical Cavity Stefan Langenfeld, Olivier Morin, Matthias Koerber, Gerhard Rempe A future quantum internet is likely to rely on multi-purpose nodes that can store, route and compute on photonic qubits. To this end, one needs to combine a light-matter qubit interface for communication with a multi-qubit register for computation. After recently demonstrating a qubit memory featuring a coherence time compatible with global scale communication [1], we now implement multi-qubit memory capabilities in a setup which has already been shown to support elementary computations [2]. Our system consists of two Rb87 atoms trapped in a high-finesse optical resonator. We use an atom-selective single-photon stimulated Raman adiabatic passage (STIRAP) to store and retrieve photonic qubits [3]. I will discuss how we achieve close to negligible cross-talk between the atoms, maintain a high efficiency and near-unity fidelity with a coherence time approaching 1ms. These results promote individually addressable neutral atoms in optical cavities to a scalable architecture and make them a prime candidate for realizing quantum network nodes. [1] M. K\"{o}rber et al., Nat. Photonics 12, 18-21 (2018). [2] S. Welte et al., Phys. Rev. X 8, 011018 (2018). [3] O. Morin et al., Phys. Rev. Lett. 123, 133602 (2019). [Preview Abstract] |
Wednesday, June 3, 2020 9:12AM - 9:24AM Live |
G02.00007: A passive, heralded, quantum memory with crossed fiber cavities Dominik Niemietz, Manuel Brekenfeld, Joseph Dale Christesen, Gerhard Rempe Quantum memories have been implemented in various physical systems ranging from atoms to solids, and from ensembles to single emitters. Despite progress, a large challenge concerns the always present photon loss and the always finite efficiency. Both limitations can be remedied with a herald that signals successful operation of the quantum memory. We have set up a new experiment with single neutral atoms trapped at the center of two crossed Fabry-Perot fiber cavities. Exploiting the possibilities given by the new system, we have realized a quantum memory for photonic polarization qubits which provides a herald that signals successful storage without destruction of the employed qubit \footnote{Brekenfeld et al, accepted in \textbf{Nat. Phys.} (2020)}. In addition, the memory couples to two spatially and spectrally distinct cavity modes. One mode is used for sending in and reading out the photonic qubit. The second mode replaces amplitude- and phase-critical control fields including no need for feedback-loops, rendering this memory fully passive. Our memory is robust and fits naturally into a fiber-based network. Therefore it is an important step towards the goal of realizing a practical quantum repeater \footnote{Uphoff et al, \textbf{Appl. Phys. B} 122, 46 (2016)}. [Preview Abstract] |
Wednesday, June 3, 2020 9:24AM - 9:36AM On Demand |
G02.00008: Multiplexed Spin Waves in the Strong Coupling Regime Paul Kunz, Zachary Castillo, David Meyer, Kevin Cox A broad challenge faced among all quantum technologies is: how to scale up usable entanglement, the critical resource underpinning quantum enhancement. We have developed an atom-cavity interface in which hundreds of spin waves can be individually created, stored, and readout with high efficiency through a strongly coupled single-mode cavity. An ensemble of one million laser-cooled atoms trapped within a ring cavity yields strong collective coupling (cooperativity of 300) with the TEM00 mode despite the moderate finesse (~110). The atomic ensemble has large intrinsic memory capacity as excitations can be stored as spatially distributed phase patterns (spin waves), which can be read out efficiently thanks to collective constructive interference. We have completed an initial demonstration with four independent modes read out superradiantly through the cavity showing less than 10\% crosstalk between the modes. This system could be well suited as a high capacity quantum repeater, or even a quantum simulator in which spin wave interactions are mediated via the cavity. [Preview Abstract] |
Wednesday, June 3, 2020 9:36AM - 9:48AM Not Participating |
G02.00009: Heralding Entanglement Between Imperfect Qubits Hyeongrak Choi, Dirk Englund Color centers in diamond have emerged as excellent candidates for quantum networks. However, despite their stable optical properties, residual imperfections in optical properties still limit the achievable fidelity of heralded entanglement. Here, we address this problem through a new single-photon entanglement protocol. Our calculations include entanglement distillation. Estimates based on present-day technology indicate that this protocol enables entanglement fidelity in excess of 99\% for leading diamond color centers. [Preview Abstract] |
Wednesday, June 3, 2020 9:48AM - 10:00AM Not Participating |
G02.00010: Remote entanglement of $^{138}$Ba$^{+}$ ions in separate traps using photons George Toh, Allison Carter, Ksenia Sosnova, Jameson O'Reilly, Drew Risinger, Sophia Scarano, Leeza Moldavchuk, Christopher Monroe Trapped atomic ions are one of the leading platforms for quantum computing systems and quantum networks. Here we combine these application areas by using multiple ion trap modules connected via photonic links. We report progress on one building block of a trapped ion quantum network, the remote entanglement of ions in two separate vacuum chambers. Single photons at 493~nm are to be collected from a $^{138}$Ba$^{+}$ ion in each node using high numerical aperture (NA=0.6) optics, and a Bell state measurement heralds the entanglement of the two remote qubits. We can demonstrate entanglement by measuring the correlations of the ion states in multiple bases. We will present preliminary results for entanglement generation rate and fidelity and also speculate how this system will scale to larger modules and also with more qubits per module. [Preview Abstract] |
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