Analog quantum algorithms are formulated in terms of Hamiltonians rather than unitary gates and include quantum adiabatic computing, quantum annealing, and the quantum approximate optimization algorithm (QAOA). These algorithms are promising candidates for near-term quantum applications, but they often require fine tuning via the annealing schedule or variational parameters. In this work, we explore connections between these analog algorithms, as well as limits in which they become approximations of the optimal procedure.Notably, we explore how the optimal procedure approaches a smooth adiabatic procedure but with a superposed oscillatory pattern that can be explained in terms of the interactions between the ground state and first excited state that effect the coherent error cancellation of diabatic transitions. Furthermore, we provide numeric and analytic evidence that QAOA emulates this optimal procedure with the length of each QAOA layer equal to the period of the oscillatory pattern. Additionally, the ratios of the QAOA bangs are determined by the smooth, non-oscillatory part of the optimal procedure. We provide arguments for these phenomena in terms of the product formula expansion of the optimal procedure. With these arguments, we conclude that different analog algorithms can emulate the optimal protocol under different limits and approximations. Finally, we present a new algorithm for better approximating the optimal protocol using the analytic and numeric insights from the rest of the paper. In practice, numerically, we find that this algorithm outperforms standard QAOA and naive quantum annealing procedures.

1 aBrady, Lucas, T.1 aKocia, Lucas1 aBienias, Przemyslaw1 aBapat, Aniruddha1 aKharkov, Yaroslav1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2107.0121801867nas a2200157 4500008004100000245010800041210006900149260001400218520132800232100002401560700002001584700001901604700002401623700002501647856003701672 2021 eng d00aCircuit Quantum Electrodynamics in Hyperbolic Space: From Photon Bound States to Frustrated Spin Models0 aCircuit Quantum Electrodynamics in Hyperbolic Space From Photon c5/13/20213 aCircuit quantum electrodynamics is one of the most promising platforms for efficient quantum simulation and computation. In recent groundbreaking experiments, the immense flexibility of superconducting microwave resonators was utilized to realize hyperbolic lattices that emulate quantum physics in negatively curved space. Here we investigate experimentally feasible settings in which a few superconducting qubits are coupled to a bath of photons evolving on the hyperbolic lattice. We compare our numerical results for finite lattices with analytical results for continuous hyperbolic space on the Poincaré disk. We find good agreement between the two descriptions in the long-wavelength regime. We show that photon-qubit bound states have a curvature-limited size. We propose to use a qubit as a local probe of the hyperbolic bath, for example by measuring the relaxation dynamics of the qubit. We find that, although the boundary effects strongly impact the photonic density of states, the spectral density is well described by the continuum theory. We show that interactions between qubits are mediated by photons propagating along geodesics. We demonstrate that the photonic bath can give rise to geometrically-frustrated hyperbolic quantum spin models with finite-range or exponentially-decaying interaction.

1 aBienias, Przemyslaw1 aBoettcher, Igor1 aBelyansky, Ron1 aKollár, Alicia, J.1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2105.0649001944nas a2200181 4500008004100000245006800041210006700109260001400176520137900190100002201569700001801591700001801609700002401627700002801651700002101679700002501700856003701725 2021 eng d00aDiscovering hydrodynamic equations of many-body quantum systems0 aDiscovering hydrodynamic equations of manybody quantum systems c11/3/20213 aSimulating and predicting dynamics of quantum many-body systems is extremely challenging, even for state-of-the-art computational methods, due to the spread of entanglement across the system. However, in the long-wavelength limit, quantum systems often admit a simplified description, which involves a small set of physical observables and requires only a few parameters such as sound velocity or viscosity. Unveiling the relationship between these hydrodynamic equations and the underlying microscopic theory usually requires a great effort by condensed matter theorists. In the present paper, we develop a new machine-learning framework for automated discovery of effective equations from a limited set of available data, thus bypassing complicated analytical derivations. The data can be generated from numerical simulations or come from experimental quantum simulator platforms. Using integrable models, where direct comparisons can be made, we reproduce previously known hydrodynamic equations, strikingly discover novel equations and provide their derivation whenever possible. We discover new hydrodynamic equations describing dynamics of interacting systems, for which the derivation remains an outstanding challenge. Our approach provides a new interpretable method to study properties of quantum materials and quantum simulators in non-perturbative regimes.

1 aKharkov, Yaroslav1 aShtanko, Oles1 aSeif, Alireza1 aBienias, Przemyslaw1 aVan Regemortel, Mathias1 aHafezi, Mohammad1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2111.0238501631nas a2200169 4500008004100000245009500041210006900136260001400205520107500219100001901294700002401313700002101337700002201358700001901380700002501399856003701424 2021 eng d00aLinear and continuous variable spin-wave processing using a cavity-coupled atomic ensemble0 aLinear and continuous variable spinwave processing using a cavit c9/30/20213 aSpin-wave excitations in ensembles of atoms are gaining attention as a quantum information resource. However, current techniques with atomic spin waves do not achieve universal quantum information processing. We conduct a theoretical analysis of methods to create a high-capacity universal quantum processor and network node using an ensemble of laser-cooled atoms, trapped in a one-dimensional periodic potential and coupled to a ring cavity. We describe how to establish linear quantum processing using a lambda-scheme in a rubidium-atom system, calculate the expected experimental operational fidelities. Second, we derive an efficient method to achieve linear controllability with a single ensemble of atoms, rather than two-ensembles as proposed in [K. C. Cox et al. Spin-Wave Quantum Computing with Atoms in a Single-Mode Cavity, preprint 2021]. Finally, we propose to use the spin-wave processor for continuous-variable quantum information processing and present a scheme to generate large dual-rail cluster states useful for deterministic computing.

1 aCox, Kevin, C.1 aBienias, Przemyslaw1 aMeyer, David, H.1 aFahey, Donald, P.1 aKunz, Paul, D.1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2109.1524601402nas a2200133 4500008004100000245003000041210003000071260001300101520105400114100002401168700001801192700002101210856003701231 2021 eng d00aMeta Hamiltonian Learning0 aMeta Hamiltonian Learning c4/9/20213 aEfficient characterization of quantum devices is a significant challenge critical for the development of large scale quantum computers. We consider an experimentally motivated situation, in which we have a decent estimate of the Hamiltonian, and its parameters need to be characterized and fine-tuned frequently to combat drifting experimental variables. We use a machine learning technique known as meta-learning to learn a more efficient optimizer for this task. We consider training with the nearest-neighbor Ising model and study the trained model's generalizability to other Hamiltonian models and larger system sizes. We observe that the meta-optimizer outperforms other optimization methods in average loss over test samples. This advantage follows from the meta-optimizer being less likely to get stuck in local minima, which highly skews the distribution of the final loss of the other optimizers. In general, meta-learning decreases the number of calls to the experiment and reduces the needed classical computational resources.

1 aBienias, Przemyslaw1 aSeif, Alireza1 aHafezi, Mohammad uhttps://arxiv.org/abs/2104.0445301512nas a2200217 4500008004100000245007100041210006900112260001400181490000700195520085300202100002801055700002301083700001901106700001901125700002201144700002401166700002501190700002101215700002101236856003701257 2021 eng d00aQuench Dynamics of a Fermi Gas with Strong Long-Range Interactions0 aQuench Dynamics of a Fermi Gas with Strong LongRange Interaction c5/24/20210 v113 aWe induce strong non-local interactions in a 2D Fermi gas in an optical lattice using Rydberg dressing. The system is approximately described by a t−V model on a square lattice where the fermions experience isotropic nearest-neighbor interactions and are free to hop only along one direction. We measure the interactions using many-body Ramsey interferometry and study the lifetime of the gas in the presence of tunneling, finding that tunneling does not reduce the lifetime. To probe the interplay of non-local interactions with tunneling, we investigate the short-time relaxation dynamics of charge density waves in the gas. We find that strong nearest-neighbor interactions slow down the relaxation. Our work opens the door for quantum simulations of systems with strong non-local interactions such as extended Fermi-Hubbard models.

1 aGuardado-Sanchez, Elmer1 aSpar, Benjamin, M.1 aSchauss, Peter1 aBelyansky, Ron1 aYoung, Jeremy, T.1 aBienias, Przemyslaw1 aGorshkov, Alexey, V.1 aIadecola, Thomas1 aBakr, Waseem, S. uhttps://arxiv.org/abs/2010.0587101130nas a2200169 4500008004100000245006700041210006500108260001400173520060600187100001900793700002400812700002100836700001900857700002200876700002500898856003700923 2021 eng d00aSpin-Wave Quantum Computing with Atoms in a Single-Mode Cavity0 aSpinWave Quantum Computing with Atoms in a SingleMode Cavity c9/30/20213 aWe present a method for network-capable quantum computing that relies on holographic spin-wave excitations stored collectively in ensembles of qubits. We construct an orthogonal basis of spin waves in a one-dimensional array and show that high-fidelity universal linear controllability can be achieved using only phase shifts, applied in both momentum and position space. Neither single-site addressability nor high single-qubit cooperativity is required, and the spin waves can be read out with high efficiency into a single cavity mode for quantum computing and networking applications.

1 aCox, Kevin, C.1 aBienias, Przemyslaw1 aMeyer, David, H.1 aKunz, Paul, D.1 aFahey, Donald, P.1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2109.1525201587nas a2200217 4500008004100000245005800041210005700099260001400156520092600170100003001096700002401126700002801150700002101178700002401199700002301223700001901246700002501265700002401290700001801314856003701332 2021 eng d00aTunable three-body loss in a nonlinear Rydberg medium0 aTunable threebody loss in a nonlinear Rydberg medium c9/28/20203 aLong-range Rydberg interactions, in combination with electromagnetically induced transparency (EIT), give rise to strongly interacting photons where the strength, sign, and form of the interactions are widely tunable and controllable. Such control can be applied to both coherent and dissipative interactions, which provides the potential to generate novel few-photon states. Recently it has been shown that Rydberg-EIT is a rare system in which three-body interactions can be as strong or stronger than two-body interactions. In this work, we study a three-body scattering loss for Rydberg-EIT in a wide regime of single and two-photon detunings. Our numerical simulations of the full three-body wavefunction and analytical estimates based on Fermi's Golden Rule strongly suggest that the observed features in the outgoing photonic correlations are caused by the resonant enhancement of the three-body losses.

1 aHuerta, Dalia, P. Ornelas1 aBienias, Przemyslaw1 aCraddock, Alexander, N.1 aGullans, Michael1 aHachtel, Andrew, J.1 aKalinowski, Marcin1 aLyon, Mary, E.1 aGorshkov, Alexey, V.1 aRolston, Steven, L.1 aPorto, J., V. uhttps://arxiv.org/abs/2009.1359901276nas a2200157 4500008004100000245007700041210006900118260001300187520076900200100002200969700002400991700001901015700002201034700002501056856003701081 2020 eng d00aAsymmetric blockade and multi-qubit gates via dipole-dipole interactions0 aAsymmetric blockade and multiqubit gates via dipoledipole intera c6/3/20203 aDue to their strong and tunable interactions, Rydberg atoms can be used to realize fast two-qubit entangling gates. We propose a generalization of a generic two-qubit Rydberg-blockade gate to multi-qubit Rydberg-blockade gates which involve both many control qubits and many target qubits simultaneously. This is achieved by using strong microwave fields to dress nearby Rydberg states, leading to asymmetric blockade in which control-target interactions are much stronger than control-control and target-target interactions. The implementation of these multi-qubit gates can drastically simplify both quantum algorithms and state preparation. To illustrate this, we show that a 25-atom GHZ state can be created using only three gates with an error of 7.8%.

1 aYoung, Jeremy, T.1 aBienias, Przemyslaw1 aBelyansky, Ron1 aKaufman, Adam, M.1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2006.0248601709nas a2200205 4500008004100000245006400041210006200105260001400167490000800181520108400189100002401273700002101297700002301318700002801341700003001369700002401399700001801423700002501441856003701466 2020 eng d00aExotic photonic molecules via Lennard-Jones-like potentials0 aExotic photonic molecules via LennardJoneslike potentials c9/19/20200 v1253 aUltracold systems offer an unprecedented level of control of interactions between atoms. An important challenge is to achieve a similar level of control of the interactions between photons. Towards this goal, we propose a realization of a novel Lennard-Jones-like potential between photons coupled to the Rydberg states via electromagnetically induced transparency (EIT). This potential is achieved by tuning Rydberg states to a F{ö}rster resonance with other Rydberg states. We consider few-body problems in 1D and 2D geometries and show the existence of self-bound clusters ("molecules") of photons. We demonstrate that for a few-body problem, the multi-body interactions have a significant impact on the geometry of the molecular ground state. This leads to phenomena without counterparts in conventional systems: For example, three photons in 2D preferentially arrange themselves in a line-configuration rather than in an equilateral-triangle configuration. Our result opens a new avenue for studies of many-body phenomena with strongly interacting photons.

1 aBienias, Przemyslaw1 aGullans, Michael1 aKalinowski, Marcin1 aCraddock, Alexander, N.1 aOrnelas-Huerta, Dalia, P.1 aRolston, Steven, L.1 aPorto, J., V.1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2003.0786401931nas a2200205 4500008004100000245008300041210006900124260001300193520129200206100002001498700002301518700001701541700002201558700002401580700002301604700001301627700002301640700002501663856003701688 2020 eng d00aImplementing a Fast Unbounded Quantum Fanout Gate Using Power-Law Interactions0 aImplementing a Fast Unbounded Quantum Fanout Gate Using PowerLaw c7/1/20203 aThe standard circuit model for quantum computation presumes the ability to directly perform gates between arbitrary pairs of qubits, which is unlikely to be practical for large-scale experiments. Power-law interactions with strength decaying as 1/rα in the distance r provide an experimentally realizable resource for information processing, whilst still retaining long-range connectivity. We leverage the power of these interactions to implement a fast quantum fanout gate with an arbitrary number of targets. Our implementation allows the quantum Fourier transform (QFT) and Shor's algorithm to be performed on a D-dimensional lattice in time logarithmic in the number of qubits for interactions with α≤D. As a corollary, we show that power-law systems with α≤D are difficult to simulate classically even for short times, under a standard assumption that factoring is classically intractable. Complementarily, we develop a new technique to give a general lower bound, linear in the size of the system, on the time required to implement the QFT and the fanout gate in systems that are constrained by a linear light cone. This allows us to prove an asymptotically tighter lower bound for long-range systems than is possible with previously available techniques.

1 aGuo, Andrew, Y.1 aDeshpande, Abhinav1 aChu, Su-Kuan1 aEldredge, Zachary1 aBienias, Przemyslaw1 aDevulapalli, Dhruv1 aSu, Yuan1 aChilds, Andrew, M.1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2007.0066201427nas a2200157 4500008004100000245007300041210006900114260001400183520092900197100001601126700002001142700002401162700002101186700002501207856003701232 2020 eng d00aLocalization and criticality in antiblockaded 2D Rydberg atom arrays0 aLocalization and criticality in antiblockaded 2D Rydberg atom ar c12/7/20203 aControllable Rydberg atom arrays have provided new insights into fundamental properties of quantum matter both in and out of equilibrium. In this work, we study the effect of experimentally relevant positional disorder on Rydberg atoms trapped in a 2D square lattice under anti-blockade (facilitation) conditions. We show that the facilitation conditions lead the connectivity graph of a particular subspace of the full Hilbert space to form a 2D Lieb lattice, which features a singular flat band. Remarkably, we find three distinct regimes as the disorder strength is varied: a critical regime, a delocalized but nonergodic regime, and a regime with a disorder-induced flat band. The critical regime's existence depends crucially upon the singular flat band in our model, and is absent in any 1D array or ladder system. We propose to use quench dynamics to probe the three different regimes experimentally.

1 aLiu, Fangli1 aYang, Zhi-Cheng1 aBienias, Przemyslaw1 aIadecola, Thomas1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2012.0394601309nas a2200169 4500008004100000245003800041210003800079260001400117490000800131520085000139100001900989700002401008700002601032700002501058700001901083856003701102 2020 eng d00aMinimal model for fast scrambling0 aMinimal model for fast scrambling c9/22/20200 v1253 aWe study quantum information scrambling in spin models with both long-range all-to-all and short-range interactions. We argue that a simple global, spatially homogeneous interaction together with local chaotic dynamics is sufficient to give rise to fast scrambling, which describes the spread of quantum information over the entire system in a time that is logarithmic in the system size. This is illustrated in two exactly solvable models: (1) a random circuit with Haar random local unitaries and a global interaction and (2) a classical model of globally coupled non-linear oscillators. We use exact numerics to provide further evidence by studying the time evolution of an out-of-time-order correlator and entanglement entropy in spin chains of intermediate sizes. Our results can be verified with state-of-the-art quantum simulators.

1 aBelyansky, Ron1 aBienias, Przemyslaw1 aKharkov, Yaroslav, A.1 aGorshkov, Alexey, V.1 aSwingle, Brian uhttps://arxiv.org/abs/2005.0536201302nas a2200157 4500008004100000245007300041210006900114260001400183520080100197100001800998700002201016700002001038700002401058700002501082856003701107 2020 eng d00aOptimal Measurement of Field Properties with Quantum Sensor Networks0 aOptimal Measurement of Field Properties with Quantum Sensor Netw c11/2/20203 aWe consider a quantum sensor network of qubit sensors coupled to a field f(x⃗ ;θ⃗ ) analytically parameterized by the vector of parameters θ⃗ . The qubit sensors are fixed at positions x⃗ 1,…,x⃗ d. While the functional form of f(x⃗ ;θ⃗ ) is known, the parameters θ⃗ are not. We derive saturable bounds on the precision of measuring an arbitrary analytic function q(θ⃗ ) of these parameters and construct the optimal protocols that achieve these bounds. Our results are obtained from a combination of techniques from quantum information theory and duality theorems for linear programming. They can be applied to many problems, including optimal placement of quantum sensors, field interpolation, and the measurement of functionals of parametrized fields.

1 aQian, Timothy1 aBringewatt, Jacob1 aBoettcher, Igor1 aBienias, Przemyslaw1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2011.0125901783nas a2200169 4500008004100000245010500041210006900146260001400215490000800229520122700237100002001464700002401484700001901508700002401527700002501551856003701576 2020 eng d00aQuantum Simulation of Hyperbolic Space with Circuit Quantum Electrodynamics: From Graphs to Geometry0 aQuantum Simulation of Hyperbolic Space with Circuit Quantum Elec c9/11/20200 v1023 aWe show how quantum many-body systems on hyperbolic lattices with nearest-neighbor hopping and local interactions can be mapped onto quantum field theories in continuous negatively curved space. The underlying lattices have recently been realized experimentally with superconducting resonators and therefore allow for a table-top quantum simulation of quantum physics in curved background. Our mapping provides a computational tool to determine observables of the discrete system even for large lattices, where exact diagonalization fails. As an application and proof of principle we quantitatively reproduce the ground state energy, spectral gap, and correlation functions of the noninteracting lattice system by means of analytic formulas on the Poincaré disk, and show how conformal symmetry emerges for large lattices. This sets the stage for studying interactions and disorder on hyperbolic graphs in the future. Our analysis also reveals in which sense discrete hyperbolic lattices emulate the continuous geometry of negatively curved space and thus can be used to resolve fundamental open problems at the interface of interacting many-body systems, quantum field theory in curved space, and quantum gravity.

1 aBoettcher, Igor1 aBienias, Przemyslaw1 aBelyansky, Ron1 aKollár, Alicia, J.1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/1910.1231801634nas a2200157 4500008004100000245007000041210006900111260001400180520114300194100001601337700001901353700002401372700001801396700002501414856003701439 2020 eng d00aRealizing and Probing Baryonic Excitations in Rydberg Atom Arrays0 aRealizing and Probing Baryonic Excitations in Rydberg Atom Array c7/14/20203 aWe propose a realization of mesonic and baryonic quasiparticle excitations in Rydberg atom arrays with programmable interactions. Recent experiments have shown that such systems possess a Z3-ordered crystalline phase whose low-energy quasiparticles are defects in the crystalline order. By engineering a Z3-translational-symmetry breaking field on top of the Rydberg-blockaded Hamiltonian, we show that different types of defects experience confinement, and as a consequence form mesonic or baryonic quasiparticle excitations. We illustrate the formation of these quasiparticles by studying a quantum chiral clock model related to the Rydberg Hamiltonian. We then propose an experimental protocol involving out-of-equilibrium dynamics to directly probe the spectrum of the confined excitations. We show that the confined quasiparticle spectrum can limit quantum information spreading in this system. This proposal is readily applicable to current Rydberg experiments, and the method can be easily generalized to more complex confined excitations (e.g. `tetraquarks', `pentaquarks') in phases with Zq order for q>3.

1 aLiu, Fangli1 aWhitsitt, Seth1 aBienias, Przemyslaw1 aLundgren, Rex1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2007.0725801558nas a2200217 4500008004100000245008100041210006900122260001500191520086200206100002301068700001601091700002401107700002101131700003001152700002801182700002401210700001801234700002601252700002501278856003701303 2020 eng d00aResonant enhancement of three-body loss between strongly interacting photons0 aResonant enhancement of threebody loss between strongly interact c10/19/20203 aRydberg polaritons provide an example of a rare type of system where three-body interactions can be as strong or even stronger than two-body interactions. The three-body interactions can be either dispersive or dissipative, with both types possibly giving rise to exotic, strongly-interacting, and topological phases of matter. Despite past theoretical and experimental studies of the regime with dispersive interaction, the dissipative regime is still mostly unexplored. Using a renormalization group technique to solve the three-body Schrödinger equation, we show how the shape and strength of dissipative three-body forces can be universally enhanced for Rydberg polaritons. We demonstrate how these interactions relate to the transmission through a single-mode cavity, which can be used as a probe of the three-body physics in current experiment

1 aKalinowski, Marcin1 aWang, Yidan1 aBienias, Przemyslaw1 aGullans, Michael1 aOrnelas-Huerta, Dalia, P.1 aCraddock, Alexander, N.1 aRolston, Steven, L.1 aPorto, J., V.1 aBüchler, Hans, Peter1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/2010.0977201475nas a2200181 4500008004100000245010000041210006900141260001400210520088000224100001901104700002201123700002401145700002201169700002201191700001801213700002501231856003701256 2019 eng d00aNondestructive cooling of an atomic quantum register via state-insensitive Rydberg interactions0 aNondestructive cooling of an atomic quantum register via statein c7/28/20193 aWe propose a protocol for sympathetically cooling neutral atoms without destroying the quantum information stored in their internal states. This is achieved by designing state-insensitive Rydberg interactions between the data-carrying atoms and cold auxiliary atoms. The resulting interactions give rise to an effective phonon coupling, which leads to the transfer of heat from the data atoms to the auxiliary atoms, where the latter can be cooled by conventional methods. This can be used to extend the lifetime of quantum storage based on neutral atoms and can have applications for long quantum computations. The protocol can also be modified to realize state-insensitive interactions between the data and the auxiliary atoms but tunable and non-trivial interactions among the data atoms, allowing one to simultaneously cool and simulate a quantum spin-model.

1 aBelyansky, Ron1 aYoung, Jeremy, T.1 aBienias, Przemyslaw1 aEldredge, Zachary1 aKaufman, Adam, M.1 aZoller, Peter1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/1907.1115601611nas a2200205 4500008004100000245008100041210006900122260001500191490000800206520098000214100001701194700001601211700002401227700002201251700002501273700002401298700002101322700002501343856003701368 2019 eng d00aScale-Invariant Continuous Entanglement Renormalization of a Chern Insulator0 aScaleInvariant Continuous Entanglement Renormalization of a Cher c03/27/20190 v1223 aThe multi-scale entanglement renormalization ansatz (MERA) postulates the existence of quantum circuits that renormalize entanglement in real space at different length scales. Chern insulators, however, cannot have scale-invariant discrete MERA circuits with finite bond dimension. In this Letter, we show that the continuous MERA (cMERA), a modified version of MERA adapted for field theories, possesses a fixed point wavefunction with nonzero Chern number. Additionally, it is well known that reversed MERA circuits can be used to prepare quantum states efficiently in time that scales logarithmically with the size of the system. However, state preparation via MERA typically requires the advent of a full-fledged universal quantum computer. In this Letter, we demonstrate that our cMERA circuit can potentially be realized in existing analog quantum computers, i.e., an ultracold atomic Fermi gas in an optical lattice with light-induced spin-orbit coupling.

1 aChu, Su-Kuan1 aZhu, Guanyu1 aGarrison, James, R.1 aEldredge, Zachary1 aCuriel, Ana, Valdés1 aBienias, Przemyslaw1 aSpielman, I., B.1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/1807.1148604213nas a2200241 4500008004100000245006900041210006800110260001500178300001100193490000800204520348600212100001503698700002303713700002403736700001903760700001903779700002503798700002503823700001803848700002103866700002403887856006003911 2018 eng d00aDark state optical lattice with sub-wavelength spatial structure0 aDark state optical lattice with subwavelength spatial structure c2018/02/20 a0836010 v1203 aWe report on the experimental realization of a conservative optical lattice for cold atoms with a subwavelength spatial structure. The potential is based on the nonlinear optical response of three-level atoms in laser-dressed dark states, which is not constrained by the diffraction limit of the light generating the potential. The lattice consists of a one-dimensional array of ultranarrow barriers with widths less than 10 nm, well below the wavelength of the lattice light, physically realizing a Kronig-Penney potential. We study the band structure and dissipation of this lattice and find good agreement with theoretical predictions. Even on resonance, the observed lifetimes of atoms trapped in the lattice are as long as 44 ms, nearly 105times the excited state lifetime, and could be further improved with more laser intensity. The potential is readily generalizable to higher dimensions and different geometries, allowing, for example, nearly perfect box traps, narrow tunnel junctions for atomtronics applications, and dynamically generated lattices with subwavelength spacings.

1 aWang, Yang1 aSubhankar, Sarthak1 aBienias, Przemyslaw1 aLacki, Mateusz1 aTsui, Tsz-Chun1 aBaranov, Mikhail, A.1 aGorshkov, Alexey, V.1 aZoller, Peter1 aPorto, James, V.1 aRolston, Steven, L. uhttps://link.aps.org/doi/10.1103/PhysRevLett.120.08360101617nas a2200157 4500008004100000245012800041210006900169520105700238100001801295700002401313700002101337700001801358700002101376700002501397856003701422 2018 eng d00aFractional quantum Hall phases of bosons with tunable interactions: From the Laughlin liquid to a fractional Wigner crystal0 aFractional quantum Hall phases of bosons with tunable interactio3 aHighly tunable platforms for realizing topological phases of matter are emerging from atomic and photonic systems, and offer the prospect of designing interactions between particles. The shape of the potential, besides playing an important role in the competition between different fractional quantum Hall phases, can also trigger the transition to symmetry-broken phases, or even to phases where topological and symmetry-breaking order coexist. Here, we explore the phase diagram of an interacting bosonic model in the lowest Landau level at half-filling as two-body interactions are tuned. Apart from the well-known Laughlin liquid, Wigner crystal phase, stripe, and bubble phases, we also find evidence of a phase that exhibits crystalline order at fractional filling per crystal site. The Laughlin liquid transits into this phase when pairs of bosons strongly repel each other at relative angular momentum 4ℏ. We show that such interactions can be achieved by dressing ground-state cold atoms with multiple different-parity Rydberg states.

1 aGraß, Tobias1 aBienias, Przemyslaw1 aGullans, Michael1 aLundgren, Rex1 aMaciejko, Joseph1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/1809.0449302076nas a2200229 4500008004100000245007800041210006900119520136400188100002401552700001901576700002401595700001701619700002301636700002101659700001801680700002101698700001901719700002701738700001901765700002501784856003701809 2018 eng d00aPhoton propagation through dissipative Rydberg media at large input rates0 aPhoton propagation through dissipative Rydberg media at large in3 aWe study the dissipative propagation of quantized light in interacting Rydberg media under the conditions of electromagnetically induced transparency (EIT). Rydberg blockade physics in optically dense atomic media leads to strong dissipative interactions between single photons. The regime of high incoming photon flux constitutes a challenging many-body dissipative problem. We experimentally study in detail for the first time the pulse shapes and the second-order correlation function of the outgoing field and compare our data with simulations based on two novel theoretical approaches well-suited to treat this many-photon limit. At low incoming flux, we report good agreement between both theories and the experiment. For higher input flux, the intensity of the outgoing light is lower than that obtained from theoretical predictions. We explain this discrepancy using a simple phenomenological model taking into account pollutants, which are nearly-stationary Rydberg excitations coming from the reabsorption of scattered probe photons. At high incoming photon rates, the blockade physics results in unconventional shapes of measured correlation functions.

1 aBienias, Przemyslaw1 aDouglas, James1 aParis-Mandoki, Asaf1 aTitum, Paraj1 aMirgorodskiy, Ivan1 aTresp, Christoph1 aZeuthen, Emil1 aGullans, Michael1 aManzoni, Marco1 aHofferberth, Sebastian1 aChang, Darrick1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/1807.07586