Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session Y52: Atomic Physics: New Frontiers II 
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Sponsoring Units: DAMOP Chair: Seth Aubin, College of William and Mary Room: Hilton Baltimore Holiday Ballroom 3 
(Author Not Attending)

Y52.00001: A fully controllable Kondo system: Coupling a flux qubit and an ultracold Fermi gas Kelly Patton We show that a composite spin1/2 Kondo system can be formed by coupling a superconducting quantum interference device (SQUID) to the internal hyperfine states of a trapped ultracold atomic Fermi gas. Here, the SQUID, or flux qubit, acts as an effective magnetic impurity that induces spinflip scattering near the Fermi energies of the trapped gas. Although the ultracold gas and SQUID are at vastly different temperatures, the formation of a strongly correlated Kondo state between the two systems is found when the gas is cooled below the Kondo temperature. We find that the Kondo temperature of this hybrid system is within current experimental limits. Furthermore, the momentum distribution of the trapped fermions is calculated. We find that it clearly contains an experimental signature of this correlated state and the associated Kondo screening length. In addition to probing Kondo physics, the con trollability of this system can be used to systematically explore the relaxation and equilibration of a strongly correlated system that has been initially prepared in a selected nonequilibrium state. [Preview Abstract] 
(Author Not Attending)

Y52.00002: Broken selection rule in the quantum Rabi model Guillermo Romero, Pol FornD\'iaz, C. J. P. M Harmans, Enrique Solano, Hans Mooij We report the spectroscopic observation of a resonant transition that breaks a selection rule in the quantum Rabi model, implemented using an $LC$ resonator and a superconducting qubit. The eigenstates of the system consist of a superposition of bare qubitoscillator states with a relative sign. In the limit of low qubitoscillator coupling strength, the matrix element between excited eigenstates of different sign is very small in presence of an oscillator drive, establishing a signpreserving selection rule. Here, our qubitresonator system operates in the ultrastrong coupling regime, where the coupling strength is 10\% of the resonator frequency, allowing signchanging transitions to be activated and, therefore, detected. This work shows that signchanging transitions are an unambiguous, distinctive signature of systems operating in the ultrastrong coupling regime of the quantum Rabi model. These results pave the way to further studies of signpreserving selection rules in multiqubit and multiphoton models. [Preview Abstract] 
Friday, March 18, 2016 11:39AM  11:51AM 
Y52.00003: "Magnetic" refrigeration in synthetic quantum magnets Michael Zaletel, Norman Yao The advent of ultracold atomic systems has promised to expand upon our understanding of strongly correlated quantum ground states; by contrast to their material cousins, cold atomic experiments benefit from unique tools such as direct optical imaging and tunable short and longrange interactions. However, despite advances in coherent quantum control, ultracold atoms remain much too hot. Although subnanokelvin temperatures are the norm in experiments, the entropy of the system remains extensively far above the ground state. One strategy to combat this is to shift the entropy elsewhere – for example, placing a gapless system near a gapped system can effectively "cool" the latter. In this talk, we will demonstrate that typical atomic systems can act as their own coolant. As an example, we consider a 1D optical lattice geometry where spin1 atoms interact via a generic AKLTtype Hamiltonian. We will discuss why decreasing the density of atoms in one region is sufficient cool the complementary portion of the system to the ground state, wherein coherent edge dynamics are observed. [Preview Abstract] 
Friday, March 18, 2016 11:51AM  12:03PM 
Y52.00004: Dissipative topological insulator with fractional winding number and single edge state Tony Lee Photonic experiments offer an opportunity to find novel topological states. We consider a onedimensional tightbinding model in the presence of gain and loss as well as longrange hopping. The system is described by a nonHermitian Hamiltonian with PT symmetry and exceptional points. The unique feature of the model is that the Hamiltonian encircles an exceptional point in momentum space, leading to novel topological features. The winding number has a fractional value 1/2 because the Brillouin zone has a periodicity of 4pi instead of 2pi. There is only one edge state due to the coalescence of eigenvectors. The edge state is topologically protected by a chiral symmetry but disappears when the bulk gap closes. We also discuss experimental realization with optical waveguides. [Preview Abstract] 
Friday, March 18, 2016 12:03PM  12:15PM 
Y52.00005: Simulating the Generalized Gibbs Ensemble (GGE): A Hilbert space Monte Carlo approach Vincenzo Alba By combining classical Monte Carlo and Bethe ansatz techniques we devise a numerical method to construct the Truncated Generalized Gibbs Ensemble (TGGE) for the spin1/2 isotropic Heisenberg (XXX) chain. The key idea is to sample the Hilbert space of the model with the appropriate GGE probability measure. The method can be extended to other integrable systems, such as the LiebLiniger model. We benchmark the approach focusing on GGE expectation values of several local observables. As finitesize effects decay exponentially with system size, moderately large chains are sufficient to extract thermodynamic quantities. The Monte Carlo results are in agreement with both the Thermodynamic Bethe Ansatz (TBA) and the Quantum Transfer Matrix approach (QTM). Remarkably, it is possible to extract in a simple way the steadystate BetheGaudinTakahashi (BGT) roots distributions, which encode complete information about the GGE expectation values in the thermodynamic limit. Finally, it is straightforward to simulate extensions of the GGE, in which, besides the local integral of motion (local charges), one includes arbitrary functions of the BGT roots. As an example, we include in the GGE the first nontrivial quasilocal integral of motion. [Preview Abstract] 
Friday, March 18, 2016 12:15PM  12:27PM 
Y52.00006: Minimally entangled typical thermal states versus matrix product purifications for the simulation of equilibrium states and time evolution Moritz Binder, Thomas Barthel We compare matrix product purifications and minimally entangled typical thermal states (METTS) for the simulation of equilibrium states and finitetemperature response functions of strongly correlated quantum manybody systems. For METTS, we highlight the interplay of statistical and DMRG truncation errors, discuss the use of selfaveraging effects, and describe schemes for the computation of response functions. We assess the computation costs and accuracies of the two methods for critical and gapped spin chains and the BoseHubbard model. For the same computation cost, purifications yield more accurate results than METTS except for temperatures well below the system’s energy gap. (Phys. Rev. B 92, 125119 (2015)) [Preview Abstract] 
Friday, March 18, 2016 12:27PM  12:39PM 
Y52.00007: Interacting Bose gas confined in a KronigPenney potential O. A. RODR\'IGUEZ, M. A. SOL\'IS We analyze the effect of the 1D periodic KronigPenney potential, composed of barriers of width $b$ and separated a distance $a$, over an interacting Bose gas. At $T=0$, the GrossPitaevskii equation is solved analytically in terms of the Jacobi elliptic functions for repulsive or attractive interaction between bosons. By applying the boundary conditions for periodic solutions as well as the normalization of the wave function, we arrive to a set of nonlinear equations from which we obtain the density profile and the chemical potential of the condensate as a function of the particle momentum. The profiles for attractive and repulsive interactions are compared with that of the noninteracting case. For attractive interaction we are able to observe a pronounced spatial localization in the middle of every two barriers. We reproduce the well known results when the KronigPenney potential becomes a Dirac Comb. [Preview Abstract] 
Friday, March 18, 2016 12:39PM  12:51PM 
Y52.00008: Concept of contact spectrum and its applications in atomic quantum Hall states Mingyuan He, ShaoLiang Zhang, HonMing Chan, Qi Zhou A unique feature of ultracold atoms is the separation of length scales, $r_0\ll k_F^{1}$, where $k_F$ and $r_0$ are the Fermi momentum characterizing the average particle distance and the range of interaction between atoms respectively. For $s$wave scattering, Shina Tan discovered that such diluteness leads to universal relations, all of which are governed by contact, among a wide range of thermodynamic quantities. In this talk, I will show that the concept of contact can be generalized to an arbitrary partialwave scattering. Contact of all partialwave scatterings form a contact spectrum, which establishes universal thermodynamic relations with notable differences from those in the presence of $s$wave scattering alone. Moreover, such a contact spectrum has an interesting connection with a special bipartite entanglement spectrum of atomic quantum Hall states, and enables an intrinsic probe of these highly correlated states using twobody shortranged correlations. [Preview Abstract] 
Friday, March 18, 2016 12:51PM  1:03PM 
Y52.00009: Energy transfer in mesoscopic vibrational systems enabled by eigenfrequency fluctuations Juan Atalaya Energy transfer between lowfrequency vibrational modes can be achieved by means of nonlinear coupling if their eigenfrequencies fulfill certain nonlinear resonance conditions. Because of the discreteness of the vibrational spectrum at low frequencies, such conditions may be difficult to satisfy for most lowfrequency modes in typical mesoscopic vibrational systems. Fluctuations of the vibrational eigenfrequencies can also be relatively strong in such systems. We show that energy transfer between modes can occur in the absence of nonlinear resonance if frequency fluctuations are allowed. The case of three modes with cubic nonlinear coupling and no damping is particularly interesting. It is found that the system has a nonthermal equilibrium state which depends only on the initial conditions. The rate at which the system approaches to such state is determined by the parameters such as the noise strength and correlation time, the nonlinearity strength and the detuning from exact nonlinear resonance. We also discuss the case of many weakly coupled modes. Our results shed light on the problem of energy relaxation of lowfrequency vibrational modes into the continuum of highfrequency vibrational modes. The results have been obtained with Mark Dykman. [Preview Abstract] 
Friday, March 18, 2016 1:03PM  1:15PM 
Y52.00010: Quantum memory and phase gate in Optical cavities based on EIT Halyne Borges, Celso VillasB\^{o}as In this work we investigate theoretically the implementation of an optical quantum memory in a system composed by a single atom, trapped in a high finesse optical cavity. In order to analyse the feasibility of implementing a quantum memory in the atomcavity system based on the EIT phenomenon, we investigated in detail which parameter configuration the memory efficiency is optimized considering the two different setups. Our results shows that for a asymmetric onesided cavity, which is the experimental setup commonly used to observe the EIT effect, the memory efficiency value saturates at about $8.5\%$. Meanwhile, for an onesided cavity, we observe for a sufficiently high value of the coupling constant $g$, the efficiency has its maximum value increased considerably, close to $100\%$. However, this experimental setup is not suitable to observe cavityEIT in the transmission spectrum, being necessary another kind of experiment, such as measurements phase difference field that leaves the cavity induced by the control field. Considering this configuration we also showed the implementation of a quantum phase gate based on the same nonlinear effect, where the pulse probe can experience a phase shift on the order of $\pi$, due to the presence or absence of a control pulse. [Preview Abstract] 
Friday, March 18, 2016 1:15PM  1:27PM 
Y52.00011: Beyond quantumclassical analogies: high time for agreement? Michele Marrocco Lately, many quantumclassical analogies have been investigated and published in many acknowledged journals. Such a surge of research on conceptual connections between quantum and classical physics forces us to ask whether the correspondence between the quantum and classical interpretation of the reality is deeper than the correspondence principle stated by Bohr. Here, after a short introduction to quantumclassical analogies from the recent literature, we try to examine the question from the perspective of a possible agreement between quantum and classical laws. A paradigmatic example is given in the striking equivalence between the classical Mie theory of electromagnetic scattering from spherical scatterers and the corresponding quantummechanical wave scattering analyzed in terms of partial waves. The key features that make the correspondence possible are examined and finally employed to deal with the fundamental blackbody problem that marks the initial separation between classical and quantum physics. The procedure allows us to recover the blackbody spectrum in classical terms and the proof is rich in consequences. Among them, the strong analogy between the quantum vacuum and its classical counterpart. [Preview Abstract] 
Friday, March 18, 2016 1:27PM  1:39PM 
Y52.00012: Application of axiomatic formal theory to the AbrahamMinkowski controversy Michael Crenshaw Continuum electrodynamics is an axiomatic formal theory whose axioms are the macroscopic Maxwell equations. We demonstrate that valid theorems of the formal theory are inconsistent with conservation laws and with special relativity because continuum electrodynamics allows transformations of the Maxwell equations that constitute an improper tensor transformation that changes the conservation properties, the relativity properties, and the spacetime embedding of the coupled equations of motion. The inconsistencies are resolved by a reformulation of physical principles in a flat nonMinkowski material spacetime in which the timelike coordinate corresponds to \textit{ct/n}. Applying Lagrangian field theory, we derive equations of motion for the macroscopic electric and magnetic fields in a simple dielectric medium. We construct a new formal theory of continuum electrodynamics and we derive a tensor energymomentum continuity theorem that trivially resolves the centuryold AbrahamMinkowski momentum controversy. We derive the theory of special relativity in a dielectric, including the material Lorentz factor and the material Lorentz transformation. We derive the momentum of a polariton in the context of material special relativity to confirm the resolution of the AbrahamMinkowski debate. [Preview Abstract] 
Friday, March 18, 2016 1:39PM  1:51PM 
Y52.00013: Particle beams carrying orbital angular momentum, charge, mass and spin Teuntje Tijssen, Armen Hayrapetyan, Joerg Goette, Mark Dennis Electron beams carrying vortices and angular momentum have been of much experimental and theoretical interest in recent years. In addition, optical vortex beams are a wellestablished field in optics and photonics. In both cases, the orbital angular momentum associated with the beam’s axial vortex has effects on the overall spin of the beam, due to spinorbit interactions. A simple model of these systems are Bessel beam solutions (of either the Dirac equation or Maxwell equations) with a nonzero azimuthal quantum number, which are found by separation in cylindrical coordinates. Here, we generalize this approach, considering the classical field theory of Bessel beams for particles which are either massive or massless, uncharged or charged and of a variety of different spins (0, $\frac{1}{2}$, 1, $\dots$). We regard the spin and helicity states and different forms of spinorbit terms that arise. Moreover, we analyse the induced electromagnetic field when the particles carry charge. Most importantly, this unified field theory approach leads to the prediction of effects for vortex beams of neutrons, mesons and neutrinos. [Preview Abstract] 
Friday, March 18, 2016 1:51PM  2:03PM 
Y52.00014: Harmonic Fractions and an Integer Power Law to Demonstrate a Relationship of the Neutron to the Properties of Hydrogen and Cosmic Observables D. W. Chakeres, R. Vento, D. I. Panchenko, J. A. Tobar, S. S. Moses, V. M. Andrianarijaona Power laws and harmonic oscillator systems represent a ubiquitous relationship among many physical phenomena. This study demonstrates a close power law relationship of the annihilation frequency of the neutron, approximately 2.27 \texttimes 10$^{\mathrm{23}}$ Hz, when used as a dimensionless base, to fundamental quantum properties of hydrogen and presentday cosmic observables. The following set of the three smallest integers: \textbraceleft 1, 0, 1\textbraceright , and the set of partial harmonic fractions: \textbraceleft 3/2, \textpm 1/2, \textpm 2/3, 3/4, \textpm 4/5\textbraceright , are associated with each physical entity investigated as a frequency equivalent. They are listed as follows: twice the maximum energy of a cosmic ray, 3/2; the base identity of the neutron, 1; the Bohr radius, 4/5; Rydberg's constant, 2/3; twice the peak spectral radiance of cosmic microwave background radiation, 1/2; Planck's constant, 0; the Sun's galactic radius, 1/2; the Sun's galactic period, 2/3; Hubble's constant, 3/4; the dimension of the observable universe, 4/5; and twice the gravitational binding energy of the electron in hydrogen, 1. When viewed in the physically equivalent frequency domain, the neutron partitions an abundance of physical constants from the very small to the very large. [Preview Abstract] 
Friday, March 18, 2016 2:03PM  2:15PM 
Y52.00015: Branching ratio, transition frequency and lifetime measurements in $^{88}$Sr$^+$ with trapped ions Helena Zhang, Michael Gutierrez, Guang Hao Low, Isaac Chuang Precise measurements of atomic properties, such as branching ratios and transition frequencies and lifetimes, are important in the study of astrophysical objects as well as verification of relativistic manybody theories. We report on a new measurement of the branching ratio of the $5P_{1/2}$ and $5P_{3/2}$ states in $^{88}$Sr$^+$ to $10^{4}$ fractional uncertainty, a $10^3$ times improvement over current results, using ions confined in a Paul trap. Using a fiber frequency comb and pulsed spectroscopy, we measure the absolute frequencies of the $5S_{1/2}5P_{1/2}$ and $5S_{1/2}5P_{3/2}$ transitions to within 200 kHz, previously only known to tens of MHz. By fitting the fluorescence curve of the ion with optical Bloch equations, we obtain a new measurement for the lifetime of the $5P_{1/2}$ and $5P_{3/2}$ states without using a pulsed laser source. [Preview Abstract] 
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