The presence of noise or the interaction with an environment can radically change the dynamics of observables of an otherwise isolated quantum system. We derive a bound on the speed with which observables of open quantum systems evolve. This speed limit is divided into Mandelstam and Tamm{\textquoteright}s original time-energy uncertainty relation and a time-information uncertainty relation recently derived for classical systems, and both are generalized to open quantum systems. By isolating the coherent and incoherent contributions to the system dynamics, we derive both lower and upper bounds on the speed of evolution. We prove that the latter provide tighter limits on the speed of observables than previously known quantum speed limits and that a preferred basis of speed operators serves to completely characterize the observables that saturate the speed limits. We use this construction to bound the effect of incoherent dynamics on the evolution of an observable and to find the Hamiltonian that gives the maximum coherent speedup to the evolution of an observable.

}, keywords = {limits, Observables}, doi = {10.1103/PhysRevX.12.011038}, url = {https://link.aps.org/doi/10.1103/PhysRevX.12.011038}, author = {Garcia-Pintos, Luis Pedro and Nicholson, Schuyler B. and Green, Jason R. and del Campo, Adolfo and Gorshkov, Alexey V.} } @article { WOS:000730391400013, title = {Ultra-broadband Kerr microcomb through soliton spectral translation}, journal = {Nat. Commun.}, volume = {12}, number = {1}, year = {2021}, month = {DEC 14}, publisher = {NATURE PORTFOLIO}, type = {Article}, abstract = {Broadband and low-noise microresonator frequency combs (microcombs) are critical for deployable optical frequency measurements. Here we expand the bandwidth of a microcomb far beyond its anomalous dispersion region on both sides of its spectrum through spectral translation mediated by mixing of a dissipative Kerr soliton and a secondary pump. We introduce the concept of synthetic dispersion to qualitatively capture the system{\textquoteright}s key physical behavior, in which the second pump enables spectral translation through four-wave mixing Bragg scattering. Experimentally, we pump a silicon nitride microring at 1063 nm and 1557 nm to enable soliton spectral translation, resulting in a total bandwidth of 1.6 octaves (137-407 THz). We examine the comb{\textquoteright}s low-noise characteristics, through heterodyne beat note measurements across its spectrum, measurements of the comb tooth spacing in its primary and spectrally translated portions, and their relative noise. These ultra-broadband microcombs provide new opportunities for optical frequency synthesis, optical atomic clocks, and reaching previously unattainable wavelengths. Integrated optical frequency measurements, benefit from broadband on-chip frequency combs. Here the authors present a low-noise microcomb whose span extends from telecom to near-visible wavelengths. Here the authors present a dissipative Kerr soliton formation approximated by introducing the concept of synthetic dispersion.}, doi = {10.1038/s41467-021-27469-0}, author = {Moille, Gregory and Perez, Edgar F. and Stone, Jordan R. and Rao, Ashutosh and Lu, Xiyuan and Rahman, Tahmid Sami and Chembo, Yanne K. and Srinivasan, Kartik} } @article {carney_ultralight_2021, title = {Ultralight dark matter detection with mechanical quantum sensors}, journal = {New J. Phys.}, volume = {23}, number = {2}, year = {2021}, note = {Place: TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND Publisher: IOP PUBLISHING LTD Type: Article}, month = {feb}, abstract = {We consider the use of quantum-limited mechanical force sensors to detect ultralight (sub-meV) dark matter (DM) candidates which are weakly coupled to the standard model. We show that mechanical sensors with masses around or below the milligram scale, operating around the standard quantum limit, would enable novel searches for DM with natural frequencies around the kHz scale. This would complement existing strategies based on torsion balances, atom interferometers, and atomic clock systems.}, keywords = {dark matter, Optomechanics, quantum sensing}, issn = {1367-2630}, doi = {10.1088/1367-2630/abd9e7}, author = {Carney, Daniel and Hook, Anson and Liu, Zhen and Taylor, Jacob M. and Zhao, Yue} } @article { WOS:000665117900005, title = {Universal stereodynamics of cold atom-molecule collisions in electric fields}, journal = {Phys. Rev. A}, volume = {103}, number = {6}, year = {2021}, month = {JUN 23}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {We use numerically exact quantum dynamics calculations to demonstrate universal stereoselectivity of cold collisions of (2)Pi molecules with S-1-state atoms in an external electric field. We show that cold collisions of OH molecules in their low-field-seeking f-states, whose dipole moments are oriented against the field direction, are much more likely to lead to inelastic scattering than those of molecules oriented along the field direction, causing nearly perfect steric asymmetry in the inelastic collision cross sections. The universal nature of this effect is due to the threshold suppression of inelastic scattering between the degenerate +/- M Stark sublevels of the high-field-seeking e-state, where M is the projection of the total angular momentum of the molecule on the field axis. Above the Lambda-doublet threshold, the stereodynamics of inelastic atom-molecule collisions can be tuned via electric-field-induced resonances, which enable effective control of Ne + OH scattering over the range of collision energies achievable in current merged beam experiments.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.103.062810}, author = {Tscherbul, V, Timur and Klos, Jacek} } @article { WOS:000686926200001, title = {Using an Atom Interferometer to Infer Gravitational Entanglement Generation}, journal = {PRX Quantum}, volume = {2}, number = {3}, year = {2021}, month = {AUG 18}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {If gravitational perturbations are quantized into gravitons in analogy with the electromagnetic field and photons, the resulting graviton interactions should lead to an entangling interaction between massive objects. We suggest a test of this prediction. To do this, we introduce the concept of interactive quantum information sensing. This novel sensing protocol is tailored to provable verification of weak dynamical entanglement generation between a pair of systems. We show that this protocol is highly robust to typical thermal noise sources. Moreover, the sensitivity can be increased both using an initial thermal state and/or an initial phase of entangling via a nongravitational interaction. We outline a concrete implementation testing the ability of the gravitational field to generate entanglement between an atomic interferometer and a mechanical oscillator. Preliminary numerical estimates suggest that near-term devices could feasibly be used to perform the experiment.}, doi = {10.1103/PRXQuantum.2.030330}, author = {Carney, Daniel and Muller, Holger and Taylor, Jacob M.} } @article { ISI:000560967100009, title = {Unitary Subharmonic Response and Floquet Majorana Modes}, journal = {Phys. Rev. Lett.}, volume = {125}, number = {8}, year = {2020}, month = {AUG 20}, pages = {086804}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Detection and manipulation of excitations with non-Abelian statistics, such as Majorana fermions, are essential for creating topological quantum computers. To this end, we show the connection between the existence of such localized particles and the phenomenon of unitary subharmonic response (SR) in periodically driven systems. In particular, starting from highly nonequilibrium initial states, the unpaired Majorana modes exhibit spin oscillations with twice the driving period, are localized, and can have exponentially long lifetimes in clean systems. While the lifetime of SR is limited in translationally invariant systems, we show that disorder can be engineered to stabilize the subharmonic response of Majorana modes. A viable observation of this phenomenon can be achieved using modern multiqubit hardware, such as superconducting circuits and cold atomic systems.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.125.086804}, author = {Shtanko, Oles and Movassagh, Ramis} } @article {lu_universal_2020, title = {Universal frequency engineering tool for microcavity nonlinear optics: multiple selective mode splitting of whispering-gallery resonances}, journal = {Photonics Res.}, volume = {8}, number = {11}, year = {2020}, note = {Place: PO BOX 800-211, SHANGHAI, 201800, PEOPLES R CHINA Publisher: CHINESE LASER PRESS Type: Article}, month = {nov}, pages = {1676{\textendash}1686}, abstract = {Whispering-gallery microcavities have been used to realize a variety of efficient parametric nonlinear optical processes through the enhanced light-matter interaction brought about by supporting multiple high quality factor and small modal volume resonances. Critical to such studies is the ability to control the relative frequencies of the cavity modes, so that frequency matching is achieved to satisfy energy conservation. Typically this is done by tailoring the resonator cross section. Doing so modifies the frequencies of all of the cavity modes, that is, the global dispersion profile, which may be undesired, for example, in introducing competing nonlinear processes. Here, we demonstrate a frequency engineering tool, termed multiple selective mode splitting (MSMS), that is independent of the global dispersion and instead allows targeted and independent control of the frequencies of multiple cavity modes. In particular, we show controllable frequency shifts up to 0.8 nm, independent control of the splitting of up to five cavity modes with optical quality factors {\textgreater}= 10(5), and strongly suppressed frequency shifts for untargeted modes. The MSMS technique can be broadly applied to a wide variety of nonlinear optical processes across different material platforms and can be used to both selectively enhance processes of interest and suppress competing unwanted processes.}, issn = {2327-9125}, doi = {10.1364/PRJ.401755}, author = {Lu, Xiyuan and Rao, Ashutosh and Moille, Gregory and Westly, Daron A. and Srinivasan, Kartik} } @article {16951, title = {Universal Logical Gates on Topologically Encoded Qubits via Constant-Depth Unitary Circuits}, journal = {Phys. Rev. Lett.}, volume = {125}, year = {2020}, month = {Jul}, pages = {050502}, doi = {10.1103/PhysRevLett.125.050502}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.125.050502}, author = {Zhu, Guanyu and Lavasani, Ali and Barkeshli, Maissam} } @article { ISI:000563710400004, title = {Universal nonequilibrium I-V curve near the two-channel Kondo-Luttinger quantum critical point}, journal = {Phys. Rev. B}, volume = {102}, number = {7}, year = {2020}, month = {AUG 28}, pages = {075145}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {Over recent decades, a growing number of systems, many of them quantum critical, have been shown to exhibit non-Fermi-liquid behavior, but a full analytic understanding of such systems out of equilibrium is still lacking. In this paper, we provide a distinct example with broad applications in correlated mesoscopic systems to two-channel Kondo-Luttinger model where a Kondo impurity couples to two voltage-biased interacting electron leads, experimentally realizable in a dissipative quantum dot. Therein, an exotic quantum phase transition has been known to exist since the 1990s from the one-channel to two-channel Kondo ground states by enhancing electron interactions in the leads, but a controlled analytic approach to this quantum critical point has not yet been established due to the breakdown of weak-coupling perturbation theory near this strong-coupling critical point. We present a controlled method to this long-standing problem by mapping the system in the strong-coupling regime to an effective spin-boson-fermion Hamiltonian. Another type of non-Fermi-liquid quantum critical point is discovered with a distinct logarithmic-in-temperature and -voltage dependence in transport. We further obtain an analytical form for the universal differential conductance out of equilibrium near the transition. Our approach can be further generalized to study nonequilibrium physics of other strong-coupling low-dimensional non-Fermi-liquid fixed points. The relevance of our results for recent experiments is discussed.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.102.075145}, author = {Lin, C-Y and Chang, Y-Y and Rylands, C. and Andrei, N. and Chung, C-H} } @article {ISI:000475499200001, title = {Universal level statistics of the out-of-time-ordered operator}, journal = {Phys. Rev. B}, volume = {100}, number = {3}, year = {2019}, month = {JUL 15}, pages = {035112}, publisher = {AMER PHYSICAL SOC}, type = {Article}, abstract = {The out-of-time-ordered correlator has been proposed as an indicator of chaos in quantum systems due to its simple interpretation in the semiclassical limit. In particular, its rate of possible exponential growth at h -> 0 is closely related to the classical Lyapunov exponent. Here we explore how this approach to quantum chaos relates to the random-matrix theoretical description. To do so, we introduce and study the level statistics of the logarithm of the out-of-time-ordered operator, (Lambda) over cap (t) = In (-{[}(x) over cap (t),(p) over cap (x)(0)](2) )/(2t), that we dub the {\textquoteleft}{\textquoteleft}Lyapunovian{{\textquoteright}{\textquoteright}} or {\textquoteleft}{\textquoteleft}Lyapunov operator{{\textquoteright}{\textquoteright}} for brevity. The Lyapunovian{\textquoteright}s level statistics is calculated explicitly for the quantum stadium billiard. It is shown that in the bulk of the filtered spectrum, this statistics perfectly aligns with the Wigner-Dyson distribution. One of the advantages of looking at the spectral statistics of this operator is that it has a well-defined semiclassical limit where it reduces to the matrix of uncorrelated classical finite-time Lyapunov exponents in a partitioned phase space. We provide a heuristic picture interpolating these two limits using Moyal quantum mechanics. Our results show that the Lyapunov operator may serve as a useful tool to characterize quantum chaos and in particular quantum-to-classical correspondence in chaotic systems by connecting the semiclassical Lyapunov growth at early times, when the quantum effects are weak, to universal level repulsion that hinges on strong quantum interference effects.}, issn = {2469-9950}, doi = {10.1103/PhysRevB.100.035112}, author = {Rozenbaum, Efim B. and Ganeshan, Sriram and Galitski, Victor} } @article {ISI:000482956700001, title = {Universal logical gates with constant overhead: instantaneous Dehn twists for hyperbolic quantum codes}, journal = {Quantum}, volume = {3}, year = {2019}, month = {JUL 26}, publisher = {VEREIN FORDERUNG OPEN ACCESS PUBLIZIERENS QUANTENWISSENSCHAF}, type = {Article}, abstract = {A basic question in the theory of fault-tolerant quantum computation is to understand the fundamental resource costs for performing a universal logical set of gates on encoded qubits to arbitrary accuracy. Here we consider qubits encoded with constant space overhead (i.e. finite encoding rate) in the limit of arbitrarily large code distance d through the use of topological codes associated to triangulations of hyperbolic surfaces. We introduce explicit protocols to demonstrate how Dehn twists of the hyperbolic surface can be implemented on the code through constant depth unitary circuits, without increasing the space overhead. The circuit for a given Dehn twist consists of a permutation of physical qubits, followed by a constant depth local unitary circuit, where locality here is defined with respect to a hyperbolic metric that defines the code. Applying our results to the hyperbolic Fibonacci Turaev-Viro code implies the possibility of applying universal logical gate sets on encoded qubits through constant depth unitary circuits and with constant space overhead. Our circuits are inherently protected from errors as they map local operators to local operators while changing the size of their support by at most a constant factor; in the presence of noisy syndrome measurements, our results suggest the possibility of universal fault tolerant quantum computation with constant space overhead and time overhead of O(d/log d). For quantum circuits that allow parallel gate operations, this yields the optimal scaling of space-time overhead known to date.}, issn = {2521-327X}, author = {Lavasani, Ali and Zhu, Guanyu and Barkeshli, Maissam} } @article {ISI:000464281100001, title = {Universal Scattering of Ultracold Atoms and Molecules in Optical Potentials}, journal = {Atoms}, volume = {7}, number = {1}, year = {2019}, month = {MAR 15}, pages = {36}, publisher = {MDPI}, type = {Article}, abstract = {Universal collisions describe the reaction of molecules and atoms as dominated by long-range interparticle interactions. Here, we calculate the universal inelastic rate coefficients for a large group of ultracold polar molecules in their lower ro-vibrational states colliding with one of their constituent atoms. The rate coefficients are solely determined by values of the dispersion coefficient and reduced mass of the collisional system. We use the ab initio coupled-cluster linear response method to compute dynamic molecular polarizabilities and obtain the dispersion coefficients for some of the collisional partners and use values from the literature for others. Our polarizability calculations agree well with available experimental measurements. Comparison of our inelastic rate coefficients with results of numerically exact quantum-mechanical calculations leads us to conjecture that collisions with heavier atoms can be expected to be more universal.}, keywords = {chemical reactions, dispersion interaction, dynamic polorizability, ultracold atom-molecule collisions, universal model, van der Waals coefficients}, issn = {2218-2004}, doi = {10.3390/atoms7010036}, author = {Li, Hui and Li, Ming and Makrides, Constantinos and Petrov, Alexander and Kotochigova, Svetlana} } @article {ISI:000459572900004, title = {The US National Quantum Initiative}, journal = {Quantum Sci. Technol.}, volume = {4}, number = {2}, year = {2019}, month = {APR}, pages = {020504}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {Quantum technology exploits the unique quantum features of superposition, entanglement, and fundamental metrology metrics in order to create new opportunities in secure communication, high-precision sensing, and revolutionary computers. Quantum technology may eventually underlie a whole new technological infrastructure, much as the semiconductor revolution changed everything in last half of the 20th century. This paper summarizes the motivations and goals for the National Quantum Initiative (NQI) in the United States, and describes some of the processes that led to the introduction and passage of legislation in the US Congress to create the NQI.}, issn = {2058-9565}, doi = {10.1088/2058-9565/ab0441}, author = {Raymer, Michael G. and Monroe, Christopher} } @article { ISI:000515524300011, title = {Use of quantum effects as potential qualifying metrics for "quantum grade silicon"}, journal = {AIP Adv.}, volume = {9}, number = {12}, year = {2019}, month = {DEC 1}, pages = {125153}, publisher = {AMER INST PHYSICS}, type = {Article}, abstract = {Across solid state quantum information, material deficiencies limit performance through enhanced relaxation, charge defect motion, or isotopic spin noise. While classical measurements of device performance provide cursory guidance, specific qualifying metrics and measurements applicable to quantum devices are needed. For quantum applications, new material metrics, e.g., enrichment, are needed, while existing classical metrics such as mobility might be relaxed compared to conventional electronics. In this work, we examine locally grown silicon that is superior in enrichment, but inferior in chemical purity compared to commercial-silicon, as part of an effort to underpin the material standards needed for quantum grade silicon and establish a standard approach for the intercomparison of these materials. We use a custom, mass-selected ion beam deposition technique, which has produced isotopic enrichment levels up to 99.999 98\% Si-28, to isotopically enrich Si-28, but with chemical purity \>99.97\% due to the molecular beam epitaxy techniques used. From this epitaxial silicon, we fabricate top-gated Hall bar devices simultaneously on Si-28 and on the adjacent natural abundance Si substrate for intercomparison. Using standard-methods, we measure maximum mobilities of approximate to(1740 +/- 2) cm(2)/(V s) at an electron density of (2.7 x 10(12) +/- 3 x 10(8)) cm(-2) and approximate to(6040 +/- 3) cm(2)/(V s) at an electron density of (1.2 x 10(12) +/- 5 x 10(8)) cm(-2) at T = 1.9 K for devices fabricated on Si-28 and Si-nat, respectively. For magnetic fields B \> 2 T, both devices demonstrate well developed Shubnikov-de Haas oscillations in the longitudinal magnetoresistance. This provides the transport characteristics of isotopically enriched Si-28 and will serve as a benchmark for the classical transport of Si-28 at its current state and low temperature, epitaxially grown Si for quantum devices more generally. (C) 2019 Author(s).

}, doi = {10.1063/1.5128098}, author = {Ramanayaka, A. N. and Tang, Ke and Hagmann, J. A. and Kim, Hyun-Soo and Simons, D. S. and Richter, C. A. and Pomeroy, J. M.} } @article { ISI:000428507500006, title = {Ultracold Anions for High-Precision Antihydrogen Experiments}, journal = {PHYSICAL REVIEW LETTERS}, volume = {120}, number = {13}, year = {2018}, month = {MAR 28}, pages = {133205}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.120.133205}, author = {Cerchiari, G. and Kellerbauer, A. and Safronova, M. S. and Safronova, U. I. and Yzombard, P.} } @article { ISI:000423107800027, title = {Ultracold atoms in multiple radio-frequency dressed adiabatic potentials}, journal = {PHYSICAL REVIEW A}, volume = {97}, number = {1}, year = {2018}, month = {JAN 16}, pages = {013616}, issn = {2469-9926}, doi = {10.1103/PhysRevA.97.013616}, author = {Harte, T. L. and Bentine, E. and Luksch, K. and Barker, A. J. and Trypogeorgos, D. and Yuen, B. and Foot, C. J.} } @conference { ISI:000450231900294, title = {Uncertainty of the Ohm Using Cryogenic and Non-Cryogenic Bridges}, booktitle = {2018 CONFERENCE ON PRECISION ELECTROMAGNETIC MEASUREMENTS (CPEM 2018)}, year = {2018}, note = {Conference on Precision Electromagnetic Measurements (CPEM), Paris, FRANCE, JUL 08-13, 2018}, keywords = {cryogenic current comparator, direct current comparator, quantized Hall resistance, standard resistor, traceability}, isbn = {978-1-5386-0974-3}, author = {Panna, Alireza R. and Kraft, Marlin E. and Rigosi, Albert F. and Jones, George R. and Payagala, Shamith U. and Kruskopf, Mattias and Jarrett, Dean G. and Elmquist, Randolph E.} } @article { ISI:000454419500004, title = {Unitary entanglement construction in hierarchical networks}, journal = {PHYSICAL REVIEW A}, volume = {98}, number = {6}, year = {2018}, month = {DEC 26}, pages = {062328}, abstract = {The construction of large-scale quantum computers will require modular architectures that allow physical resources to be localized in easy-to-manage packages. In this work we examine the impact of different graph structures on the preparation of entangled states. We begin by explaining a formal framework, the hierarchical product, in which modular graphs can be easily constructed. This framework naturally leads us to suggest a class of graphs, which we dub hierarchies. We argue that such graphs have favorable properties for quantum information processing, such as a small diameter and small total edge weight, and use the concept of Pareto efficiency to identify promising quantum graph architectures. We present numerical and analytical results on the speed at which large entangled states can be created on nearest-neighbor grids and hierarchy graphs. We also present a scheme for performing circuit placement-the translation from circuit diagrams to machine qubits-on quantum systems whose connectivity is described by hierarchies.}, issn = {2469-9926}, doi = {10.1103/PhysRevA.98.062328}, author = {Bapat, Aniruddha and Eldredge, Zachary and Garrison, James R. and Deshpande, Abhinav and Chong, Frederic T. and Gorshkov, Alexey V.} } @article { ISI:000419468200001, title = {Universal many-body response of heavy impurities coupled to a Fermi sea: a review of recent progress}, journal = {REPORTS ON PROGRESS IN PHYSICS}, volume = {81}, number = {2}, year = {2018}, month = {FEB}, pages = {024401}, keywords = {Fermi gas, Feshbach resonances, functional determinants, non-equilibrium dynamics, orthogonality catastrophe, quantum impurities}, issn = {0034-4885}, doi = {10.1088/1361-6633/aa9593}, author = {Schmidt, Richard and Knap, Michael and Ivanov, Dmitri A. and You, Jhih-Shih and Cetina, Marko and Demler, Eugene} } @article {10436, title = {Unscrambling the physics of out-of-time-order correlators}, journal = {Nature Physics}, volume = {14}, year = {2018}, pages = {988{\textendash}990}, abstract = {Quantitative tools for measuring the propagation of information through quantum many-body systems, originally developed to study quantum chaos, have recently found many new applications from black holes to disordered spin systems.

}, isbn = {1745-2481}, doi = {10.1038/s41567-018-0295-5}, url = {https://doi.org/10.1038/s41567-018-0295-5}, author = {Swingle, Brian} } @article { ISI:000449675500001, title = {Unsupervised phase mapping of X-ray diffraction data by nonnegative matrix factorization integrated with custom clustering}, journal = {NPJ COMPUTATIONAL MATERIALS}, volume = {4}, year = {2018}, month = {AUG 6}, pages = {UNSP 43}, issn = {2057-3960}, doi = {10.1038/s41524-018-0099-2}, author = {Stanev, Valentin and Vesselinov, Velimir V. and Kusne, A. Gilad and Antoszewski, Graham and Takeuchi, Ichiro and Alexandrov, Boian S.} } @article {7641, title = {Ultrafast creation of large Schr{\"o}dinger cat states of an atom}, journal = {Nature Communications}, volume = {8}, year = {2017}, pages = {697}, abstract = {Mesoscopic quantum superpositions, or Schr{\"o}dinger cat states, are widely studied for fundamental investigations of quantum measurement and decoherence as well as applications in sensing and quantum information science. The generation and maintenance of such states relies upon a balance between efficient external coherent control of the system and sufficient isolation from the environment. Here we create a variety of cat states of a single trapped atom{\textquoteright}s motion in a harmonic oscillator using ultrafast laser pulses. These pulses produce high fidelity impulsive forces that separate the atom into widely separated positions, without restrictions that typically limit the speed of the interaction or the size and complexity of the resulting motional superposition. This allows us to quickly generate and measure cat states larger than previously achieved in a harmonic oscillator, and create complex multi-component superposition states in atoms.

}, isbn = {2041-1723}, doi = {10.1038/s41467-017-00682-6}, url = {https://doi.org/10.1038/s41467-017-00682-6}, author = {Johnson, K. G. and Wong-Campos, J. D. and Neyenhuis, B. and Mizrahi, J. and Monroe, C.} } @article {ISI:000392096800044, title = {An ultra-low noise, high-voltage piezo-driver}, journal = {REVIEW OF SCIENTIFIC INSTRUMENTS}, volume = {87}, number = {12}, year = {2016}, month = {DEC}, pages = {124702}, abstract = {We present an ultra-low noise, high-voltage driver suited for use with piezoelectric actuators and other low-current applications. The architecture uses a flyback switching regulator to generate up to 250 V in our current design, with an output of 1 kV or more possible with small modifications. A high slew-rate op-amp suppresses the residual switching noise, yielding a total root-mean-square noise of approximate to 100 mu V (1 Hz-100 kHz). A low-voltage (+/- 10 V), high bandwidth signal can be summed with unity gain directly onto the output, making the driver well-suited for closed-loop feedback applications. Digital control enables both repeatable setpoints and sophisticated control logic, and the circuit consumes less than 150 mA at +/- 15 V.}, issn = {0034-6748}, doi = {10.1063/1.4969059}, author = {Pisenti, N. C. and Restelli, A. and Reschovsky, B. J. and Barker, D. S. and Campbell, G. K.} } @article { ISI:000383238600001, title = {Uncovering the hidden quantum critical point in disordered massless Dirac and Weyl semimetals}, journal = {PHYSICAL REVIEW B}, volume = {94}, number = {12}, year = {2016}, month = {SEP 8}, pages = {121107}, issn = {2469-9950}, doi = {10.1103/PhysRevB.94.121107}, author = {Pixley, J. H. and Huse, David A. and S. Das Sarma} } @article {ISI:000371389100004, title = {Understanding analog quantum simulation dynamics in coupled ion-trap qubits}, journal = {PHYSICAL REVIEW A}, volume = {93}, number = {2}, year = {2016}, month = {FEB 29}, pages = {022332}, issn = {2469-9926}, doi = {10.1103/PhysRevA.93.022332}, author = {Wu, Yang-Le and S. Das Sarma} } @article {ISI:000391982700001, title = {Universal optical conductivity of a disordered Weyl semimetal}, journal = {SCIENTIFIC REPORTS}, volume = {6}, year = {2016}, month = {AUG 30}, pages = {32446}, abstract = {Topological Weyl semimetals, besides manifesting chiral anomaly, can also accommodate a disorder-driven unconventional quantum phase transition into a metallic phase. A fundamentally and practically important question in this regard concerns an experimentally measurable quantity that can clearly distinguish these two phases. We show that the optical conductivity while serving this purpose can also play the role of a bonafide order parameter across such disorder-driven semimetal-metal quantum phase transition by virtue of displaying distinct scaling behavior in the semimetallic and metallic phases, as well as inside the quantum critical fan supporting a non-Fermi liquid. We demonstrate that the correction to the dielectric constant and optical conductivity in a dirty Weyl semimetal due to weak disorder is independent of the actual nature of point-like impurity scatterers. Therefore, optical conductivity can be used as an experimentally measurable quantity to study the critical properties and to pin the universality class of the disorder-driven quantum phase transition in Weyl semimetals.}, issn = {2045-2322}, doi = {10.1038/srep32446}, author = {Roy, Bitan and Juricic, Vladimir and S. Das Sarma} } @article { ISI:000352163100008, title = {ULTRACOLD ATOMS The quantum distillery}, journal = {NATURE PHYSICS}, volume = {11}, number = {4}, year = {2015}, month = {APR}, pages = {301-302}, issn = {1745-2473}, doi = {10.1038/nphys3268}, author = {Porto, Trey} } @article { ISI:000358599300004, title = {Universal spin-triplet superconducting correlations of Majorana fermions}, journal = {PHYSICAL REVIEW B}, volume = {92}, number = {1}, year = {2015}, month = {JUL 27}, pages = {014513}, issn = {1098-0121}, doi = {10.1103/PhysRevB.92.014513}, author = {Liu, Xin and Sau, Jay D. and S. Das Sarma} } @article { ISI:000338995700025, title = {Ultrahigh transmission optical nanofibers}, journal = {AIP ADVANCES}, volume = {4}, number = {6}, year = {2014}, month = {JUN}, issn = {2158-3226}, doi = {10.1063/1.4879799}, author = {Hoffman, J. E. and Ravets, S. and Grover, J. A. and Solano, P. and Kordell, P. R. and Wong-Campos, J. D. and Orozco, L. A. and Rolston, S. L.} } @article { ISI:000332518100093, title = {Ultra-sensitive chip-based photonic temperature sensor using ring resonator structures}, journal = {OPTICS EXPRESS}, volume = {22}, number = {3}, year = {2014}, month = {FEB 10}, pages = {3098-3104}, issn = {1094-4087}, doi = {10.1364/OE.22.003098}, author = {Xu, Haitan and Mohammad Hafezi and Jingyun Fan and Jacob M Taylor and G F Strouse and Ahmed, Zeeshan} } @conference { ISI:000343107600003, title = {Ultra-short gates improve the performance of high-speed gated single-photon avalanche diodes}, booktitle = {ADVANCED PHOTON COUNTING TECHNIQUES VIII}, series = {Proceedings of SPIE}, volume = {9114}, year = {2014}, note = {Conference on Advanced Photon Counting Techniques VIII, Baltimore, MD, MAY 07-08, 2014}, isbn = {978-1-62841-051-8}, issn = {0277-786X}, doi = {10.1117/12.2050808}, author = {Restelli, Alessandro and Bienfang, Joshua C. and Migdall, Alan L.}, editor = {Itzler, MA and Campbell, JC} } @article {2685, title = {Universal and nonuniversal effective N-body interactions for ultracold harmonically trapped few-atom systems}, journal = {Phys. Rev. A}, volume = {90}, year = {2014}, month = {Oct}, pages = {043631}, doi = {10.1103/PhysRevA.90.043631}, url = {http://link.aps.org/doi/10.1103/PhysRevA.90.043631}, author = {Yin, X. Y. and Blume, D. and Johnson, P. R. and E. Tiesinga} } @article {2628, title = {Universal van der Waals physics for three cold atoms near Feshbach resonances}, journal = {Nature Physics}, year = {2014}, month = {8/2014}, doi = {10.1038/nphys3071}, author = {Wang, Yujun and Paul S Julienne} } @inbook { ISI:000323088400002, title = {Ultracold Few-Body Systems}, booktitle = {ADVANCES IN ATOMIC, MOLECULAR, AND OPTICAL PHYSICS, VOL 62}, series = {Advances In Atomic Molecular and Optical Physics}, volume = {62}, year = {2013}, pages = {1-115}, isbn = {978-0-12-408090-4}, issn = {1049-250X}, doi = {10.1016/B978-0-12-408090-4.00001-3}, author = {Wang, Yujun and D{\textquoteright}Incao, Jose P. and Esry, Brett D.}, editor = {Arimondo, E and Berman, PR and Lin, CC} } @article { ISI:000313029200002, title = {Ultracold mixtures of atomic Li-6 and Cs-133 with tunable interactions}, journal = {Phys. Rev. A}, volume = {87}, number = {1}, year = {2013}, month = {JAN 3}, issn = {1050-2947}, doi = {10.1103/PhysRevA.87.010702}, author = {Tung, Shih-Kuang and Parker, Colin and Johansen, Jacob and Chin, Cheng and Wang, Yujun and Paul S Julienne} } @article {1909, title = {Ultrafast Spin-Motion Entanglement and Interferometry with a Single Atom}, journal = {Phys. Rev. Lett.}, volume = {103}, year = {2013}, month = {05/13/2013}, pages = {203001}, doi = {10.1103/PhysRevLett.110.203001}, url = {http://prl.aps.org/abstract/PRL/v110/i20/e203001}, author = {J Mizrahi and Crystal Senko and B Neyenhuis and K G Johnson and W C Campbell and C W S Conover and Christopher Monroe} } @article { ISI:000317193400004, title = {Unconventional spin-density waves in dipolar Fermi gases}, journal = {Phys. Rev. A}, volume = {87}, number = {4}, year = {2013}, month = {APR 5}, pages = {043604}, issn = {1050-2947}, doi = {10.1103/PhysRevA.87.043604}, author = {S G Bhongale and Ludwig Mathey and Tsai, Shan-Wen and Charles W Clark and Zhao, Erhai} } @article { ISI:000322216000003, title = {Universal density scaling of disorder-limited low-temperature conductivity in high-mobility two-dimensional systems}, journal = {Phys. Rev. B}, volume = {88}, number = {3}, year = {2013}, month = {JUL 24}, pages = {035439}, issn = {1098-0121}, doi = {10.1103/PhysRevB.88.035439}, author = {S. Das Sarma and E H Hwang} } @article { ISI:000313421800001, title = {Universal Impurity-Induced Bound State in Topological Superfluids}, journal = {PHYSICAL REVIEW LETTERS}, volume = {110}, number = {2}, year = {2013}, month = {JAN 10}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.110.020401}, author = {Hu, Hui and Jiang, Lei and Pu, Han and Chen, Yan and Liu, Xia-Ji} } @article { ISI:000327093100005, title = {Unruh effect under non-equilibrium conditions: oscillatory motion of an Unruh-DeWitt detector}, journal = {JOURNAL OF HIGH ENERGY PHYSICS}, number = {11}, year = {2013}, month = {NOV 14}, issn = {1029-8479}, doi = {10.1007/JHEP11(2013)119}, author = {Doukas, Jason and Lin, Shih-Yuin and Lu, B. L. and Mann, Robert B.} } @article { ISI:000308575500007, title = {Ultracold Molecules under Control!}, journal = {CHEMICAL REVIEWS}, volume = {112}, number = {9, SI}, year = {2012}, month = {SEP}, pages = {4949-5011}, issn = {0009-2665}, doi = {10.1021/cr300092g}, author = {Quemener, Goulven and Julienne, Paul S.} } @article { ISI:000308015500021, title = {Universal Conductance Fluctuations in Dirac Materials in the Presence of Long-range Disorder}, journal = {PHYSICAL REVIEW LETTERS}, volume = {109}, number = {9}, year = {2012}, month = {AUG 27}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.109.096801}, author = {Rossi, E. and Bardarson, J. H. and Fuhrer, M. S. and S. Das Sarma} } @article {PhysRevLett.109.065701, title = {Universal Monopole Scaling near Transitions from the Coulomb Phase}, journal = {Phys. Rev. Lett.}, volume = {109}, number = {6}, year = {2012}, pages = {65701}, publisher = {American Physical Society}, doi = {10.1103/PhysRevLett.109.065701}, url = {http://link.aps.org/doi/10.1103/PhysRevLett.109.065701}, author = {Powell, Stephen} } @article {2551, title = {Unified approach to topological quantum computation with anyons: From qubit encoding to Toffoli gate}, journal = {PHYSICAL REVIEW A}, volume = {84}, year = {2011}, month = {JUL 26}, pages = {012332}, issn = {1050-2947}, doi = {10.1103/PhysRevA.84.012332}, author = {Xu, Haitan and Taylor, J. M.} } @article {Zhou2011b, title = {Universal Thermometry for Quantum Simulation}, journal = {Phys. Rev. Lett.}, volume = {106}, number = {22}, year = {2011}, month = {may}, pages = {225301}, keywords = {2011, No Fellows}, issn = {0031-9007}, url = {http://prl.aps.org/abstract/PRL/v106/i22/e225301}, author = {Zhou, Qi and Ho, Tin-Lun} } @article {Berninger2011, title = {Universality of the Three-Body Parameter for Efimov States in Ultracold Cesium}, journal = {Phys. Rev. Lett.}, volume = {107}, number = {12}, year = {2011}, month = {sep}, pages = {120401}, keywords = {2011}, issn = {0031-9007}, url = {http://prl.aps.org/abstract/PRL/v107/i12/e120401}, author = {Martin Berninger and Alessandro Zenesini and Bo Huang and Walter Harm and N{\"a}gerl, H.-C. and Francesca Ferlaino and Rudolf Grimm and Paul S Julienne and Jeremy M Hutson} } @article {Artuso2011, title = {Using local fields to tailor hybrid quantum-dot/metal nanoparticle systems}, journal = {Phys. Rev. B}, volume = {83}, number = {23}, year = {2011}, month = {jun}, pages = {235406}, keywords = {2011}, issn = {1098-0121}, url = {http://prb.aps.org/abstract/PRB/v83/i23/e235406}, author = {Ryan D Artuso and Garnett W Bryant and Garcia-Etxarri, Aitzol and Javier Aizpurua} } @article {2455, title = {Ultracold neutral plasmas}, journal = {Physics Today}, volume = {63}, year = {2010}, month = {3/2010}, doi = {10.1063/1.3366240}, author = {Thomas C. Killian and Steven L Rolston} } @article {Campbell2010, title = {Ultrafast Gates for Single Atomic Qubits}, journal = {Phys. Rev. Lett.}, volume = {105}, number = {9}, year = {2010}, month = {aug}, pages = {090502}, abstract = {We demonstrate the use of an optical frequency comb to coherently control and entangle atomic qubits. A train of off-resonant ultrafast laser pulses is used to efficiently and coherently transfer population between electronic and vibrational states of trapped atomic ions and implement an entangling quantum logic gate with high fidelity. This technique can be extended to the high field regime where operations can be performed faster than the trap frequency. This general approach can be applied to more complex quantum systems, such as large collections of interacting atoms or molecules.

}, keywords = {2010, Single Fellow}, issn = {0031-9007}, url = {http://prl.aps.org/abstract/PRL/v105/i9/e090502}, author = {W C Campbell and J Mizrahi and Q Quraishi and Crystal Senko and David Hayes and D Hucul and D N Matsukevich and P Maunz and Christopher Monroe and Steven Olmschenk} } @article {Muller2010, title = {Ultrahigh-finesse, low-mode-volume Fabry{\textendash}Perot microcavity}, journal = {Optics Letters}, volume = {35}, number = {13}, year = {2010}, month = {jun}, pages = {2293}, publisher = {OSA}, abstract = {Ultralow-loss concave micromirrors with radius of curvature below 60$μ$m were fabricated by laser ablation and reflective coatings. A 10-$μ$m-long microcavity with a mode volume of 40$μ$m3 was set up with two such mirrors, and the cavity linewidth was measured both spectrally and temporally. The smallest linewidth obtained was 96MHz, corresponding to a quality factor of 3.3{\texttimes}106 and a finesse in excess of 1.5{\texttimes}105. With these parameters, we estimate that a variety of solid-state quantum emitters coupled to the cavity may enter the strong coupling regime.}, keywords = {2010, Fabry-Perot, Multiple JQI Affil., Quantum optics, Single Fellow}, issn = {0146-9592}, url = {http://ol.osa.org/abstract.cfm?URI=ol-35-13-2293}, author = {Andreas Muller and Flagg, Edward B. and John R Lawall and Glenn S Solomon} } @article {Sau2010a, title = {Universal quantum computation in a semiconductor quantum wire network}, journal = {Phys. Rev. A}, volume = {82}, number = {5}, year = {2010}, month = {nov}, keywords = {2010, Single Fellow}, issn = {1050-2947}, url = {http://pra.aps.org/abstract/PRA/v82/i5/e052322}, author = {Jay D Sau and Tewari, Sumanta and S. Das Sarma} } @article {Idziaszek2009a, title = {Universal rate constants for reactive collisions of ultracold molecules}, journal = {Phys. Rev. Lett.}, volume = {104}, year = {2010}, month = {3/2010}, pages = {113202}, abstract = {A simple quantum defect model gives analytic expressions for the complex scattering length and threshold collision rates of ultracold molecules. If the probability of reaction in the short-range part of the collision is high, the model gives universal rate constants for s- and p-wave collisions that are independent of short-range dynamics. This model explains the magnitudes of the recently measured rate constants for collisions of two ultracold 40K87Rb molecules, or an ultracold 40K atom with the 40K87Rb molecule [Ospelkaus et al., Science 327, 853 (2010)].

}, keywords = {2009}, doi = {10.1103/PhysRevLett.104.113202}, author = {Idziaszek, Zbigniew and Paul S Julienne} } @article {Julienne2009, title = {Ultracold molecules from ultracold atoms: a case study with the KRb molecule}, journal = {Faraday Discussions}, volume = {142}, year = {2009}, pages = {361}, keywords = {2009}, issn = {1359-6640}, url = {http://adsabs.harvard.edu/abs/2009FaDi..142..361J}, author = {Paul S Julienne} } @article {Ospelkaus2009, title = {Ultracold polar molecules near quantum degeneracy}, journal = {Faraday Discussions}, volume = {142}, year = {2009}, month = {aug}, pages = {351}, publisher = {The Royal Society of Chemistry}, keywords = {2009}, issn = {1359-6640}, url = {http://pubs.rsc.org/en/content/articlehtml/2009/fd/b821298h}, author = {Ospelkaus, S. and Ni, K.-K. and de Miranda, M. H. G. and B Neyenhuis and Wang, D. and Svetlana Kotochigova and Paul S Julienne and D S Jin and Jun Ye} } @article {Lee2008, title = {Universal Pulse Sequence to Minimize Spin Dephasing in the Central Spin Decoherence Problem}, journal = {Phys. Rev. Lett.}, volume = {100}, number = {16}, year = {2008}, month = {apr}, abstract = {We present a remarkable finding that a recently discovered [G. S. Uhrig, Phys. Rev. Lett. 98, 100504 (2007)] series of pulse sequences, designed to optimally restore coherence to a qubit in the spin-boson model of decoherence, is in fact completely model-independent and generically valid for arbitrary dephasing Hamiltonians given sufficiently short delay times between pulses. The series maximizes qubit fidelity versus number of applied pulses for sufficiently short delay times because the series, with each additional pulse, cancels successive orders of a time expansion for the fidelity decay. The "magical" universality of this property, which was not appreciated earlier, requires that a linearly growing set of "unknowns" (the delay times) must simultaneously satisfy an exponentially growing set of nonlinear equations that involve arbitrary dephasing Hamiltonian operators.}, keywords = {2008, Single Fellow}, issn = {0031-9007}, url = {http://arxiv.org/abs/arXiv:0710.1416}, author = {Lee, B. and Wayne M Witzel and S. Das Sarma} } @article {Boyer2007, title = {Ultraslow Propagation of Matched Pulses by Four-Wave Mixing in an Atomic Vapor}, journal = {Phys. Rev. Lett.}, volume = {99}, number = {14}, year = {2007}, month = {oct}, keywords = {2007, Single Fellow}, issn = {0031-9007}, url = {http://prl.aps.org/abstract/PRL/v99/i14/e143601}, author = {Vincent Boyer and C F McCormick and Arimondo, E. and Paul D Lett} } @article {Jones2006, title = {Ultracold photoassociation spectroscopy: Long-range molecules and atomic scattering}, journal = {Rev. Mod. Phys.}, volume = {78}, number = {2}, year = {2006}, month = {may}, pages = {483{\textendash}535}, keywords = {2006, Multiple Fellows}, issn = {0034-6861}, url = {http://rmp.aps.org/abstract/RMP/v78/i2/p483\_1}, author = {Kevin M Jones and Eite Tiesinga and Paul D Lett and Paul S Julienne} }