Bulletin of the American Physical Society
48th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 62, Number 8
Monday–Friday, June 5–9, 2017; Sacramento, California
Session B8: Fundamental Quantum Science |
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Chair: Jacob Taylor, QuICS, University of Maryland, JQI, NIST Room: 314 |
Tuesday, June 6, 2017 10:30AM - 10:42AM |
B8.00001: Retrodiction of a sequence of measurements in a qubit interferometer Mark Hillery, Daniel Koch Alice gains information about the trajectory of a particle going through a series of interferometers by making measurements to obtain information about the path the particle took through each interferometer. Bob obtains the particle after it has passed through all of the interferometers, and he wants to determine the results of Alice's measurements. That is, he wants to determine the record of the particle's trajectory by making a further measurement on the particle. What can he find out? We model this process by a qubit going through a series of Hadamard gates, with Alice measuring the particle between each pair of gates. We examine several kinds of measurements that Bob can make, including one to determine the entire trajectory and one that rules out a trajectory. The first of these can make an error, that is, give the wrong trajectory, while the second will not give a wrong answer. The measurement that excludes a trajectory is useful in that Bob can use it to be sure of getting at least one of the results of Alice's measurements correct. Reference: M. Hillery and D. Koch, Phys. Rev. A 94, 032118 (2016). [Preview Abstract] |
Tuesday, June 6, 2017 10:42AM - 10:54AM |
B8.00002: Observation of a Discrete Time Crystal A. Kyprianidis, J. Zhang, P. Hess, P. Becker, A. Lee, J. Smith, G. Pagano, A. Potter, A. Vishwanath, I.-D. Potirniche, N. Yao, C. Monroe Spontaneous symmetry breaking is a key concept in the understanding of many physical phenomena, such as the formation of spatial crystals and the phase transition from paramagnetism to magnetic order. While the breaking of time translation symmetry is forbidden in equilibrium systems, it is possible for non-equilibrium Floquet driven systems to break a discrete time translation symmetry, and we present clear signatures of the formation of such a discrete time crystal. We apply a time periodic Hamiltonian to a chain of interacting spins under many-body localization conditions and observe the system's sub-harmonic response at twice that period. This spontaneous doubling of the periodicity is robust to external perturbations. We represent the spins with a linear chain of trapped $^{\mathrm{171}}$Yb$^{\mathrm{+}}$ ions in an rf Paul trap, generate spin-spin interactions through spin-dependent optical dipole forces, and measure each spin using state-dependent fluorescence. [Preview Abstract] |
Tuesday, June 6, 2017 10:54AM - 11:06AM |
B8.00003: Hamiltonian identifiability assisted by single-probe measurement Akira Sone, Paola Cappellaro We study the Hamiltonian identifiability of a many-body spin-$1/2$ system assisted by the measurement on a single quantum probe based on the eigensystem realization algorithm (ERA) approach employed in [Phys. Rev. Lett. \textbf{113}, 080401 (2014)]. We demonstrate a potential application of Gr\"obner basis to the identifiability test of the Hamiltonian, and provide the necessary experimental resources, such as the lower bound in the number of the required sampling points, the upper bound in total required evolution time, and thus the total measurement time. Focusing on the examples of the identifiability in the spin chain model with nearest-neighbor interaction, we classify the spin-chain Hamiltonian based on its identifiability, and provide the control protocols to engineer the non-identifiable Hamiltonian to be an identifiable Hamiltonian. [Preview Abstract] |
Tuesday, June 6, 2017 11:06AM - 11:18AM |
B8.00004: Worldline Method for Electromagnetic Casimir Energies Jonathan Mackrory, Tanmoy Bhattacharya, Daniel Steck We present our work on the worldline method for calculating electromagnetic Casimir energies. The worldline method calculates the energy by generating an ensemble of closed Brownian paths through space, and then summing up the contributions from the potential along each path. We calculate the Casimir energy due to dispersionless, dielectric bodies. We decompose the electromagnetic field into transverse electric (TE) and transverse magnetic (TM) polarizations, each of which behave as scalar fields. We will present our analytical and numerical work for both polarizations, and show agreement with prior results for both Casimir-Polder and Casimir energies for planar dielectric bodies. We will also present results showing the numerical convergence of the algorithm. [Preview Abstract] |
(Author Not Attending)
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B8.00005: Entanglement dynamics in itinerant fermionic and bosonic systems Durganandini Pillarishetty The concept of quantum entanglement of identical particles is fundamental in a wide variety of quantum information contexts involving composite quantum systems. However, the role played by particle indistinguishabilty in entanglement determination is being still debated. In this work, we study, theoretically, the entanglement dynamics in some itinerant bosonic and fermionic systems. We show that the dynamical behaviour of particle entanglement and spatial or mode entanglement are in general different. We also discuss the effect of fermionic and bosonic statistics on the dynamical behaviour. We suggest that the different dynamical behaviour can be used to distinguish between particle and mode entanglement in identical particle systems and discuss possible experimental realizations for such studies. [Preview Abstract] |
Tuesday, June 6, 2017 11:30AM - 11:42AM |
B8.00006: Abstract Withdrawn
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Tuesday, June 6, 2017 11:42AM - 11:54AM |
B8.00007: Examining an optomechanical analogy to quantum optics in an expanding universe Joseph Smiga, Jacob Taylor Unifying quantum mechanics and general relativity is a long-standing problem in physics. The simplest cosmology --- the Friedmann-Robertson-Walker-Lema\^{i}tre (FRW) model --- describes a spatially homogeneous and isotropic universe where the scale factor is the only dynamical parameter. Here we consider how quantized electromagnetic fields become entangled with the scale factor in a toy version of the FRW model. A system consisting of a photon, source, and detector is described in such a universe. We also consider a potential optomechanical analogy system that would enable experimental exploration of the effects of photon redshift detection as a quantum backaction on metric variables such as the scale factor. [Preview Abstract] |
Tuesday, June 6, 2017 11:54AM - 12:06PM |
B8.00008: Binary gas mixture in a high speed channel Dr. Sahadev Pradhan The viscous, compressible flow in a 2D wall-bounded channel, with bottom wall moving in? the positive $x-$direction, simulated using the direct simulation Monte Carlo (DSMC) method,? has been used as a test bed for examining different aspects of flow phenomenon and separation performance of a binary gas mixture at Mach number \textit{Ma }$=$\textit{ (U\textunderscore w / }$\backslash $\textit{sqrt(}$\gamma $\textit{ k\textunderscore B T\textunderscore w /m)?) }in the range\textit{0.1 \textless Ma \textless 30}, and Knudsen number \textit{Kn }$=$\textit{ 1/(}$\backslash $\textit{sqrt(2) }$\pi $\textit{ d\textasciicircum 2 n\textunderscore d H)}in the range? \textit{.1 \textless Kn \textless 10}. The generalized? analytical model is formulated which includes the fifth order differential equation for the? boundary layer at the channel wall in terms of master potential ($\chi )$, which is derived? from the equations of motion in a 2D rectangular $(x - y)$coordinate. The starting point? of the analytical model is the Navier-Stokes, mass, momentum and energy conservation? equations in the $(x - y)$coordinate, where $x$and $y$are the streamwise? and wall-normal directions, respectively. The linearization approximation is used ((Pradhan {\&} Kumaran\textit{, J. Fluid Mech -}); (Kumaran {\&} Pradhan, \textit{J. Fluid Mech -})), where the equations of motion are truncated at linear order in the velocity and pressure perturbations to the base flow, which is anisothermal compressible Couette flow. Additional assumptions in the? analytical model include high aspect ratio \textit{(L \textgreater \textgreater H)}, constant temperature in the base state (isothermal condition), and low? Reynolds number (laminar flow). The analytical solutionsare compared with direct simulation Monte Carlo (DSMC) simulations and found good agreement (with a difference of less than 10{\%}), provided the boundary conditions are accurately incorporated in the analytical solution. [Preview Abstract] |
Tuesday, June 6, 2017 12:06PM - 12:18PM |
B8.00009: Exponential gain of randomness certified by quantum contextuality Mark Um, Junhua Zhang, Ye Wang, Pengfei Wang, Kihwan Kim We demonstrate the protocol of exponential gain of randomness certified by quantum contextuality in a trapped ion system. The genuine randomness can be produced by quantum principle and certified by quantum inequalities. Recently, randomness expansion protocols based on inequality of Bell-text [1] and Kochen-Specker (KS) theorem [2], have been demonstrated. These schemes have been theoretically innovated to exponentially expand the randomness and amplify the randomness from weak initial random seed [3]. Here, we report the experimental evidence of such exponential expansion of randomness. In the experiment, we use three states of a 138Ba$+$ ion between a ground state and two quadrupole states. In the 138Ba$+$ ion system, we do not have detection loophole and we apply a methods to rule out certain hidden variable models that obey a kind of extended noncontextuality [4]. [1] S. Pironio, et al., Nature 464, 1021 (2010). [2] Mark Um, et al., Sci. Rep. 3, 1627 (2013). [3] Carl Miller and Yaoyun Shi, arxiv:1411.6608v3 (2015). [4] Otfried Guhne, et al., Phys. Rev. A 81, 022121 (2010). [Preview Abstract] |
Tuesday, June 6, 2017 12:18PM - 12:30PM |
B8.00010: Abstract Withdrawn |
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