Bulletin of the American Physical Society
APS March Meeting 2018
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session H33: Quantum Simulation with Superconducting CircuitsFocus

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Sponsoring Units: DQI Chair: David Schuster, Univ of Chicago Room: LACC 408B 
Tuesday, March 6, 2018 2:30PM  3:06PM 
H33.00001: Manybody quantum optics with superconducting circuits Invited Speaker: Andrew Houck Superconducting circuits provide an excellent platform for the study of nonequilibrium phase transitions of light. In circuit QED, a superconducting qubit mediates very strong effective photonphoton interactions. In networks of circuit QED elements, a competition between hopping and interactions can be realized, leading to steady state phase transitions in a damped driven system. Here, we will discuss dynamical phase transitions in a circuit QED dimer and dissipative phase transitions observed in a onedimensional lattice, tunable interactions in a bandgap medium, and progress towards understanding lattices in curved space. 
Tuesday, March 6, 2018 3:06PM  3:42PM 
H33.00002: Synthetic quantum matter in superconducting circuits Invited Speaker: Ruichao Ma Superconducting circuits have emerged as a competitive platform for realizing a practical quantum computer, satisfying the challenges of controllability, long coherence and strong interactions between individual systems that are at the heart of coherent quantum computation. In this work, we apply this welldeveloped toolbox to a different problem: the exploration of strongly correlated phases of photonic quantum matter. The qubits of the quantum circuit become the sites of a Bose Hubbard lattice  their anharmonicity provides the onsite photonphoton interaction, couplings between them generates intersite tunneling, while multiplexed qubit readout provides time and site resolved microscopy of the Bose Hubbard system. We further develop a new method for dissipative preparation and stabilization of incompressible phases of matter, achieved through reservoir engineering. We characterize our BoseHubbard system through coherent lattice dynamics including quantum random walks, and then connect it to the dissipative stabilizer to realize and investigate a Mott insulator of photons. These experiments demonstrate the power of superconducting circuits for studying strongly correlated physics, and with the recently demonstrated lowloss microwave Chern insulators could point the way to topological manybody states of photons. 
Tuesday, March 6, 2018 3:42PM  3:54PM 
H33.00003: Quantum Simulation of Luttinger Liquids in Josephson Transmission Lines Roman Kuzmin , Nicholas Grabon , Nitish Mehta , Raymond Mencia , Natalia Pankratova , Moshe Goldstein , Vladimir Manucharyan Here we present the first quantum simulator for an impurityscattering in interacting 1D wires. The simulator consists of a transmission line made out of more than 30,000 Josephson junctions, serving as a highimpedance media for microwave photons, and a small phase slip Josephson junction, playing the role of a backscattering impurity. The system can be described by a boundary sineGordon model where the interaction strength is defined as g = Z/R_{Q} with Z being the transmission line impedance and R_{Q} = 6.5 kOhm the resistance quantum. By measuring scattering amplitudes and a spectrum of inelastically scattered microwave photons we can find the first and higher order correlation functions related to an AC conductance of the impurity. The ability to control the transmission line parameters and the finite size of the system allow us to fabricate lines with impedances exceeding R_{Q} while keeping the phase slip rate of the line’s junctions very low. It gives us the unique opportunity to test Luttinger liquid physics at both sides of the critical point g = 1. 
Tuesday, March 6, 2018 3:54PM  4:06PM 
H33.00004: Simulating manybody physics using Josephsonjunction arrays in circuitQED architecture Cosmic Raj , Hiroki Ikegami , Zhirong Lin , Kunihiro Inomata , Jacob Taylor , Yasunobu Nakamura Josephsonjunction arrays (JJAs) in superconducting circuits are prototypical systems which can be designed for various lattice topologies and have the ability to control the chemical potential and associated energy scales for studying the manybody phenomena in both classical and quantum regimes. Here we present microwave studies of JJAs in circuitQED architecture which have the following advantage over the usual DC transport measurement scheme: the system is only weakly perturbed by microwave excitation, enabling this particular scheme to study properties of the ground state and the excited states at the singleexcitation (photon) level. In this talk, we report the observation of lattice ordering of vortices and direct detection of plasmamode (spin wave) spectra in a 31x3 quasi1D JJA. We also present some recent results on manybody effects in a 100x100 squarelattice JJA. 
Tuesday, March 6, 2018 4:06PM  4:18PM 
H33.00005: FluxonBased Quantum Simulation in circuit QED Alexandru Petrescu , Hakan Tureci , Alexey Ustinov , IoanMihai Pop Longlived fluxon excitations can be trapped inside a superinductor ring, which is realized by a long array of Josephson junctions, one of which offers the “input/output” path for the magnetic flux [1]. The ring can be separated into smaller loops by a periodic sequence of Josephson junctions in the quantum regime, thereby allowing fluxons to tunnel between neighboring sites of this Josephson ladder. By tuning the Josephson couplings, and implicitly the fluxon tunneling probability amplitudes, a wide class of 1D tightbinding lattice models could be implemented and populated with a stable number of fluxons. We illustrate the use of this quantum simulation platform by discussing the SuSchriefferHeeger model [2] in the 1fluxon subspace, which hosts a symmetry protected topological phase with fractionally charged bound states at the edges. This pair of localized edge states could be used to implement a superconducting qubit increasingly decoupled from decoherence mechanisms. 
Tuesday, March 6, 2018 4:18PM  4:30PM 
H33.00006: Realization of Topological Maxwell Metal Bands with a Superconducting Qutrit Yang Yu , Xinsheng Tan , Danwei Zhang , Haifeng Yu , Hui Yan , ShiLiang Zhu Recently, an interesting new fermion was predicted to emerge in three or morefold degenerate points but has yet to be realized in real materials or artificial systems. Here we theoretically propose and experimentally realize a topological Maxwell metal bands with a superconducting qutrit. We do so by mapping the momentum space of condensedmatter models to the tunable parameter space of superconducting quantum circuits. We image a new band structure that consists of threefold degenerate points dubbed Maxwell points and that is effectively described by the spin1 Maxwell equations. In addition to dynamically measuring the Chern number of the simulated Maxwell point, we engineer and observe the topological phase transition from the topological Maxwell metal to a trivial insulator. Our work establishes a promising platform to explore complex and novel topological states of matter in controllable quantum systems. 
Tuesday, March 6, 2018 4:30PM  4:42PM 
H33.00007: Photonic Chern insulator in superconducting microwave lattices John Owens , Aman LaChapelle , Brendan Saxberg , Ruichao Ma , Jonathan Simon , David Schuster We present the latest progress in developing a novel architecture for exploration of topological matter. We construct photonic lattices from tunnelcoupled, timereversalbroken microwave cavities that are both low loss and compatible with Josephson junctionmediated particleparticle interactions, allowing us access to topological phenomena such as the fractional quantum Hall effect. We employ seamless 3D microwave cavities all machined from a single block of high purity superconductor, along with YttriumIronGarnet (YIG) spheres magnetically biased below the critical field so our metamaterial is scalable and directly compatible with the cQED toolbox. After demonstrating the essential properties of a timereversal broken topological insulator at room temperature in without interactions, we now push towards making a lattice cryocompatible in order to both achieve high quality factors in superconducting cavities and introduce qubits. 
Tuesday, March 6, 2018 4:42PM  4:54PM 
H33.00008: Autonomous Stabilizer for Gapped Photonic ManyBody States Brendan Saxberg , John Owens , Ruichao Ma , Jonathan Simon , David Schuster Photonic systems are a promising platform for new physics in the regime of strongly interacting and highly correlated quantum materials. We present an eightsite strongly interacting BoseHubbard lattice in the Circuit QED platform along with an autonomous scheme to stabilize the coupled qubit system into a gapped manybody state. We study the N=1 Mott insulating state of our Bose lattice and characterize the performance of our thermalizer in repumping to this manybody state. This allows us to perform several experiments including quantum random walks, repumping rates of individual lattice modes, and magnetic phases. 
Tuesday, March 6, 2018 4:54PM  5:06PM 
H33.00009: Multimode Circuit Quantum Electrodynamics with Superconducting Metamaterial Resonators Sagar Indrajeet , Haozhi Wang , Matthew Hutchings , Matthew LaHaye , Britton Plourde , Bruno Taketani , Frank Wilhelm Metamaterial resonant structures made from arrays of superconducting lumped circuit elements can be used to produce novel mode spectra, in particular, a high density of modes in the same frequency range where superconducting qubits are typically operated. Such a system could have applications in quantum simulation and multipartite entanglement. We present a series of lowtemperature measurements of such a superconducting metamaterial resonator coupled to a fluxtunable transmon qubit. We are able to track the qubit as we tune it through many of the metamaterial resonances using a separate conventional resonator to read out the qubit state. With this capability, we are able to map the frequency dependence of the qubit T1 time and observe structure that correlates with the metamaterial spectrum. In addition, we present time domain qubit measurements as a function of frequency in this multimode system as well as measurements of multiphoton twotone experiments between qubit states and metamaterial modes. 
Tuesday, March 6, 2018 5:06PM  5:18PM 
H33.00010: Characterization and performance of gmon superconducting qubits for quantum simulation Ben Chiaro , Andrew Dunsworth , Charles Neill , Zijun Chen , Brooks Foxen , James Wenner , John Martinis The gmon platform features frequency tunable superconducting qubits with tunable interqubit coupling. The current generation gmon offers 15 qubits in a 1D chain with nearestneighbor coupling and local addressability. This device realizes a BoseHubbard lattice with full experimental control of the Hamiltonian parameters. This flexibility enables the creation and investigation of manybody states of matter. In this talk, we discuss the characterization and performance of the gmon processor and the latest advances in quantum simulation with the gmon. 
Tuesday, March 6, 2018 5:18PM  5:30PM 
H33.00011: Lowering qubit requirements for quantum simulations of fermionic systems Mark Steudtner , Stephanie Wehner

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