Bulletin of the American Physical Society
APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010; Portland, Oregon
Session J31: Focus Session: Hybrid AMO-condensed Matter Systems for Quantum Information Science |
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Sponsoring Units: DAMOP GQI Chair: Luis Orozco, U Maryland Room: E141 |
Tuesday, March 16, 2010 11:15AM - 11:51AM |
J31.00001: Hybrid systems: from atoms on squids to diamond on wires Invited Speaker: Jacob Taylor Controlling and understanding the coupling between different objects lies at the heart of modern quantum mechanics. Limits in our ability to couple and decouple certain object, such as spins in solid-state devices, inevitably translate into fundamental constraints for application of these systems to quantum information science and metrology. However, one can conceive a scenario in which different, disparate objects--hybrid systems--can be used together to overcome these limitations. I will discuss how entangling spins with photons or phonons provides the fundamental building block for any such hybrid system, and enables both quantum communication and quantum computation. Specific examples illustrating this key point and demonstrating some of the difficulties we face in integrating heterogeneous quantum bits will be considered. [Preview Abstract] |
Tuesday, March 16, 2010 11:51AM - 12:03PM |
J31.00002: Switching Induced by Poisson Radio-Frequency Pulses in Nonlinear Micromechanical Oscillators Jie Zou , Sanal Buvaev , H.B. Chan We study switching induced by Poisson radio-frequency (RF) pulses in nonlinear micromechanical oscillators. Under sufficiently large periodic excitation, nonlinear micromechanical oscillators possess multiple oscillation states with different amplitudes. The presence of noise enables the system to switch between these states. We find that in the vicinity of the bifurcation point the activation barrier, which is given by the logarithm of the switching rate, has a logarithmic dependence on the mean rate of Poisson RF pulses. Moreover, the measured dependence of the activation barrier on the distance to the saddle-node bifurcation $\eta$ is consistent with predicted universal scaling relationships. While for white Gaussian noise the activation barrier shows a clean $3/2$ power-law dependence on $\eta$, for modulated Poisson pulses the power-law has a different power of $1/2$ with an additional logarithmic factor. Our measured critical exponents are in accordance with theoretical predictions. [Preview Abstract] |
Tuesday, March 16, 2010 12:03PM - 12:15PM |
J31.00003: Switching exponent scaling near bifurcation points for non-Gaussian noise Mark Dykman , L. Billings , M. McCrary , A.N. Korotkov , I.B. Schwartz We study noise-induced switching of a system close to bifurcation parameter values where the number of stable states changes, the phenomenon that underlies the operation of bifurcation amplifiers. For non-Gaussian noise, the switching exponent Q, which gives the logarithm of the switching rate, displays a non-power-law dependence on the distance to the bifurcation point in the parameter space. For Poisson noise, Q is proportional to the square root of this distance and contains a large distance-dependent logarithmic factor that has also a characteristic dependence on the area and mean frequency of the noise pulses. Even weak additional Gaussian noise dominates switching sufficiently close to the bifurcation point, leading to a crossover in the behavior of the switching exponent to the familiar power-law scaling. Explicit results are obtained for the saddle-node and pitchfork bifurcations and are compared with numerical simulations. [Preview Abstract] |
Tuesday, March 16, 2010 12:15PM - 12:27PM |
J31.00004: Sideband eraser of ``which-path'' information for entangled photons on demand Bill Coish , Jay Gambetta The biexciton cascade in a quantum dot can be used to generate entangled-photon pairs rapidly and deterministically (on demand). However, due to a large fine-structure splitting between intermediate exciton energy levels, which-path information encoded in the frequencies of emitted photon pairs leads to a small degree of entanglement. Here we show that this information can be efficiently erased by modulating the exciton and biexciton energy levels [1], giving rise to new decay paths through additional sidebands. The resulting degree of entanglement is substantial, and can be made maximal through spectral filtering, with only a nominal reduction in collection efficiency.\\[4pt] [1] W. A. Coish and J. M. Gambetta, arXiv:0907.0437 [Preview Abstract] |
Tuesday, March 16, 2010 12:27PM - 12:39PM |
J31.00005: Breaking time-reversal symmetry in interacting photon lattices using a superconducting on-chip circulator Jens Koch , A.A. Houck , S.M. Girvin , Karyn Le Hur Recently, theoretical studies have advertised EM resonator arrays, coherently coupled to artificial atoms (e.g., superconducting qubits) as a new venue for constructing quantum simulators for strongly correlated states of matter [1]. Here, we explore the possibilities of breaking time-reversal symmetry in such interacting photon systems by coupling transmission line resonators via a superconducting circuit. We demonstrate that, given an external magnetic field and a mechanism for breaking particle-hole symmetry, such a circuit can produce complex phases in the hopping amplitudes for photons. Finally, we address the prospects of this scheme for studying new quantum phase transitions in interacting photon systems, and the realization of novel 2D lattices for photons, such as the Kagome lattice. \\[4pt] [1] M. J. Hartmann, F. G. S. L. Brand{\~a}o, and M. B. Plenio, Laser \& Photonics Review 2, 527 (2008), and references therein. [Preview Abstract] |
Tuesday, March 16, 2010 12:39PM - 12:51PM |
J31.00006: Towards hybrid quantum information in weak-coupling solid-state cavity QED systems Jan Gudat , Dapeng Ding , Cristian Bonato , Sumant Oemrawsingh , Susanna Thon , Hyochul Kim , Martin van Exter , Dirk Bouwmeester Quantum dots in oxide-apertured micropillar cavities are robust high-Q structures to implement solid-state cavity quantum electrodynamics (QED) and quantum information schemes involving single photons and the spin of a single confined electron. The electron spin interacts with the optical field through the trion state (two electrons-one hole). We discuss spin-selective photon reflection in the weak coupling cavity-QED regime and hybrid photon-electron spin schemes for implementing quantum gates. We discuss the practical implementation of the proposed schemes. In particular we show experimentally that the oxide-apertured micropillar cavities exhibit high-quality Hermite-Gaussian modes and that such modes can be permanently tuned, up to 150GHz, by introducing strain via optically induced surface deformations. [Preview Abstract] |
Tuesday, March 16, 2010 12:51PM - 1:03PM |
J31.00007: Fabricating Micro-Optomechanical Systems for Quantum Optics Dustin Kleckner , Susanna Thon , Brian Pepper , Dirk Bouwmeester Micro-optomechanical systems have attracted significant interest as a platform for observing quantum effects in mesoscopic objects. However, making a system with the required optical and mechanical characteristics is extremely challenging. We discuss the fabrication of monolithic devices made from dieletric mirrors on Si$_{3}$N$_{4}$ resonators as well as preliminary data on optomechanical systems made from these devices. [Preview Abstract] |
Tuesday, March 16, 2010 1:03PM - 1:15PM |
J31.00008: Nonlinear Optomechanics: Two-phonon cooling and squeezing Andreas Nunnenkamp , Kjetil B\O rkje , Jack Harris , Steven Girvin Motivated by recent optomechanics experiments using the membrane-in-the-middle geometry [Thompson \textit{et al.}, Nature \textbf{452}, 06715 (2008)] we explore the physics of optomechanical systems where the mechanical oscillator is coupled quadratically rather than linearly to one mode of the optical cavity field. We derive an expression for the minimal phonon number achievable by two-phonon cooling, explain how to achieve mechanical squeezing by driving the cavity on both sidebands and calculate the squeezing spectrum of the output cavity field. [Preview Abstract] |
Tuesday, March 16, 2010 1:15PM - 1:27PM |
J31.00009: Micro-resonators coupled to atoms in an optical lattice Andrew Geraci , John Kitching Recently there has been a convergence of ideas between the fields of solid-state and atomic physics -- examples range from using atoms for quantum simulation of condensed-matter Hamiltonians to physically coupling atoms with solid-state devices such as micro-resonators. In this talk, we discuss an experimental proposal involving an array of cooled microcantilevers coupled to a sample of ultracold atoms trapped near a microfabricated surface [1]. The cantilevers allow individual lattice site addressing for atomic state control and readout, and potentially may be useful in optical lattice quantum computation schemes. Assuming resonators can be cooled to their vibrational ground state, we describe the implementation of a two-qubit controlled-NOT gate with atomic internal states and the motional states of the resonators, along with a protocol for entangling two or more cantilevers on the atom chip using the trapped atoms as an intermediary. Although similar experiments could be carried out with magnetic microchip traps, the optical confinement scheme we consider may exhibit reduced near-field magnetic noise and decoherence. Prospects for using this system for tests of quantum mechanics at macroscopic scales or quantum information processing will be discussed. \\[4pt] [1] A. Geraci and J. Kitching, Phys. Rev. A 80, 032317 (2009) [Preview Abstract] |
Tuesday, March 16, 2010 1:27PM - 1:39PM |
J31.00010: Two-Qubit Atomic Entanglement in Metallic Carbon Nanotubes Misty Green , Igor Bondarev Recent progress in the growth techniques of centimeter-long single-walled carbon nanotubes (CNs) [1], as well as the experiments on the controlled encapsulation of single atoms into CNs [2], stimulate theoretical studies of the potential applications of hybrid atomically doped CN systems in quantum information science. We analyze the conditions for two spatially separated atomic qubits (two-level atoms, or ions) encapsulated in a CN, or located close to the CN surface, to be strongly coupled to a common high-finesse surface photonic mode of the nanotube, and thus to be entangled via the virtual surface photon exchange [3]. We show that metallic CNs of $\sim $1 nm diameter can be very efficient, even at room temperatures, to entangle a pair of the spatially separated atomic qubits. We discuss how to employ the rear-earth Eu3+ ions to test our predictions as they are known to be excellent probes to study quantum optical effects in spatially confined systems [4], owing to the dominant 5D0--$>$7F2 electric dipole transition that essentially creates a qubit system.\\[4pt][1] L.X.Zheng, et al., Nature Mat. 3, 673 (2004). [2] G.-H.Jeong, et al., Phys. Rev. B. 68, 075410 (2003). [3] I.V.Bondarev, J. Electron. Mat. 36, 1579 (2007). [4] S.V.Gaponenko, et al., J. Lightwave Technol. 17, 2128 (1999). [Preview Abstract] |
Tuesday, March 16, 2010 1:39PM - 1:51PM |
J31.00011: Protocol for Hybrid Entanglement Between a Trapped Atom and a Quantum Dot Edo Waks , Christopher Monroe We propose a quantum optical interface between an atomic and solid state system. We show that quantum states in a single trapped atom can be entangled with the states of a semiconductor quantum dot through their common interaction with a classical laser field. The interference and detection of the resulting scattered photons can then herald the entanglement of the disparate atomic and solid-state quantum bits. We develop a protocol that can succeed despite a significant mismatch in the radiative characteristics of the two matter-based qubits. We study in detail a particular case of this interface applied to a single trapped $^{171}$Yb ion and a cavity-coupled InGaAs semiconductor quantum dot. Entanglement fidelity and success rates are found to be robust to a broad range of experimental nonideal effects such as dispersion mismatch, atom recoil, and multi-photon scattering. We conclude that it should be possible to produce highly entangled states of these complementary qubit systems under realistic experimental conditions. [Preview Abstract] |
Tuesday, March 16, 2010 1:51PM - 2:03PM |
J31.00012: Optically generated 2-dimensional photonic cluster state from coupled quantum dots Sophia Economou , Netanel Lindner , Terry Rudolph We propose a method to generate a two-dimensional cluster state of polarization encoded photonic qubits from two coupled quantum dot emitters. We combine the recent proposal [Phys. Rev. Lett. 103, 113602 (2009)] for generating 1-dimensional cluster state strings from a single dot, with a new proposal for an optically controlled conditional phase (CZ) gate between the two quantum dots. The entanglement between the two quantum dots translates to entanglement between the two photonic cluster state strings. Further inter-pair coupling of the quantum dots using cavities and waveguides can lead to a 2-dimensional cluster sheet. Detailed analysis of errors indicates that our proposal is feasible with current tech- nology. Crucially, the emitted photons need not have identical frequencies, and so there are no constraints on the resonance energies for the quantum dots, a standard problem for such sources. [Preview Abstract] |
Tuesday, March 16, 2010 2:03PM - 2:15PM |
J31.00013: The photon shuttle Florian Marquardt , Georg Heinrich , Jack Harris Optomechanics deals with the interaction between localized optical and vibrational modes in micro- and nanomechanical setups. We show how a partially transparent membrane, placed inside an optical cavity, can shuttle photons between the two halves of the cavity when it is made to vibrate. The resulting dynamics induces mechanically driven Rabi oscillations in the photonic two-state system and shows the rich interference effects known as Landau-Zener-Stueckelberg oscillations. A wealth of other phenomena known from strongly driven atomic systems could be implemented as well in mechanically driven optomechanical circuits. [Preview Abstract] |
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