From the Cover…

.. epigraph:: “Townsend is the best book I know for advanced undergraduate quantum mechanics. It is clear, contemporary, and compact. My students used it as a wonderful springboard to graduate school.” -- Ralph D. Amado, University of Pennsylvania .. epigraph:: “With this second edition, Townsend has succeeded in making a clear and pedagogical textbook on undergraduate quantum mechanics even better.” -- Charles Gale, McGill University

Abstract

Recent advances in quantum information processing with trapped ions have demonstrated the need for new ion trap architectures capable of holding and manipulating chains of many (>10) ions. Here we present the design and detailed characterization of a new linear trap, microfabricated with scalable complementary metal-oxide-semiconductor (CMOS) techniques, that is well-suited to this challenge. Forty-four individually controlled dc electrodes provide the many degrees of freedom required to construct anharmonic potential wells, shuttle ions, merge and split ion chains, precisely tune secular mode frequencies, and adjust the orientation of trap axes. Microfabricated capacitors on dc electrodes suppress radio-frequency pickup and excess micromotion, while a top-level ground layer simplifies modeling of electric fields and protects trap structures underneath. A localized aperture in the substrate provides access to the trapping region from an oven below, permitting deterministic loading of particular isotopic/elemental sequences via species-selective photoionization. The shapes of the aperture and radio-frequency electrodes are optimized to minimize perturbation of the trapping pseudopotential. Laboratory experiments verify simulated potentials and characterize trapping lifetimes, stray electric fields, and ion heating rates, while measurement and cancellation of spatially-varying stray electric fields permits the formation of nearly-equally spaced ion chains

Abstract

We study the primary root growth of wild-type Medicago truncatula plants in heterogeneous environments using 3D time-lapse imaging. The growth medium is a transparent hydrogel consisting of a stiff lower layer and a compliant upper layer. We find that the roots deform into a helical shape just above the gel layer interface before penetrating into the lower layer. This geometry is interpreted as a combination of growth-induced mechanical buckling modulated by the growth medium and a simultaneous twisting near the root tip. We study the helical morphology as the modulus of the upper gel layer is varied and demonstrate that the size of the deformation varies with gel stiffness as expected by a mathematical model based on the theory of buckled rods. Moreover, we show that plant-to-plant variations can be accounted for by biomechanically plausible values of the model parameters.

Abstract

The helical coiling of plant tendrils has fascinated scientists for centuries, yet the underlying mechanism remains elusive. Moreover, despite Darwin’s widely accepted interpretation of coiled tendrils as soft springs, their mechanical behavior remains unknown. Our experiments on cucumber tendrils demonstrate that tendril coiling occurs via asymmetric contraction of an internal fiber ribbon of specialized cells. Under tension, both extracted fiber ribbons and old tendrils exhibit twistless overwinding rather than unwinding, with an initially soft response followed by strong strain-stiffening at large extensions. We explain this behavior using physical models of prestrained rubber strips, geometric arguments, and mathematical models of elastic filaments. Collectively, our study illuminates the origin of tendril coiling, quantifies Darwin’s original proposal, and suggests designs for biomimetic twistless springs with tunable mechanical responses.

Abstract

A popular method for generating micron-sized aerosols is to submerge ultrasonic ( *ω* ~ MHz) piezoelectric oscillators in a water bath. The submerged oscillator atomizes the fluid, creating droplets with radii proportional to the wavelength of the standing wave at the fluid surface. Classical theory for the Faraday instability predicts a parametric instability driving a capillary wave at the subharmonic (*ω*/2) frequency. For many applications it is desirable to reduce the size of the droplets; however, using higher frequency oscillators becomes impractical beyond a few MHz. Observations are presented that demonstrate that smaller droplets may also be created by increasing the driving amplitude of the oscillator, and that this effect becomes more pronounced for large driving frequencies. It is shown that these observations are consistent with a transition from droplets associated with subharmonic ( *ω*/2) capillary waves to harmonic (*ω*) capillary waves induced by larger driving frequencies and amplitudes, as predicted by a stability analysis of the capillary waves.

Abstract

In ion trap quantum information processing, efficient fluorescence collection is critical for fast, high-fidelity qubit detection and ion–photon entanglement. The expected size of future many-ion processors requires scalable light collection systems. We report on the development and testing of a microfabricated surface-electrode ion trap with an integrated high-numerical aperture (NA) micromirror for fluorescence collection. When coupled to a low-NA lens, the optical system is inherently scalable to large arrays of mirrors in a single device. We demonstrate the stable trapping and transport of 40Ca+ ions over a 0.63 NA micromirror and observe a factor of 1.9 enhancement of photon collection compared to the planar region of the trap.

Abstract

A new method of direct, rapid nano- to micro-scale patterning of high purity cobalt is presented. The method utilizes a combination of electron beam induced deposition (EBID) and seeded growth at elevated temperatures below the temperature of spontaneous thermal decomposition. Dicobalt octacarbonyl \( \mathrm{Co_{2}(CO)_{8}}\) is used as the precursor and carbon as a seed layer. Seeded deposition is carried out in the substrate temperature range from 55 to 75°C. Deposition yield is significantly higher than conventional EBID and magnetotransport measurements indicate that resistivity, \( 22~\mu\Omega~\mathrm{cm} \), and saturation magnetization, 1.55 T, are much closer to the corresponding values for bulk Co than those for standard EBID.

Abstract

In single-qubit quantum secret sharing, a secret is shared between *N* parties via manipulation and measurement of one qubit at a time. Each qubit is sent to all *N* parties in sequence; the secret is encoded in the first participant’s preparation of the qubit state and the subsequent participants’ choices of state rotation or measurement basis. We present a protocol for single-qubit quantum secret sharing using polarization entanglement of photon pairs produced in type-I spontaneous parametric downconversion. We investigate the protocol’s security against eavesdropping attack under common experimental conditions: a lossy channel for photon transmission, and imperfect preparation of the initial qubit state. A protocol which exploits *entanglement* between photons, rather than simply polarization *correlation*, is more robustly secure. We implement the entanglement-based secret-sharing protocol with 87% secret-sharing fidelity, limited by the purity of the entangled state produced by our present apparatus. We demonstrate a photon-number splitting eavesdropping attack, which achieves no success against the entanglement-based protocol while showing the predicted rate of success against a correlation-based protocol.

Recent Publications

Student authorFaculty author

51.

John S. Townsend

A Modern Approach to Quantum Mechanics, Second Edition

University Science Books, Sausalito, 2012.
townsend_junior.jpg
52.

Charlie Doret, J. M. Amini, K. Wright, C. Volin, T. Killian, A. Ozakin, D. Denison, H. Hayden, C. -S. Pai, R. E. Slusher, and A. W. Harter

Controlling trapping potentials and stray electric fields in a microfabricated ion trap through design and compensation

New Journal of Physics 14 (2012) 073012.
PDF document
2012/Doret_NJP_14_073012
53.

J. L. Silverberg, R. N. Noar, M. Packer, M. Harrison, I. Cohen, C. Henley, and Sharon Gerbode

3D Imaging and mechanical modeling of helical buckling in Medicago truncatula plant roots

Proceedings of the National Academy of Sciences 109 (2012) 16794.
PDF document
3DSJG.jpg
54.

Sharon Gerbode, Joshua R. Puzey, A. G. McCormick, and L. Mahadevan

How the cucumber tendril coils and overwinds

Science 337 (2012) 1087.
PDF document
Gerbode1223304CoverArt1.jpg
55.

Andrew P. Higginbotham, Andrew J. Bernoff, Aaron M. Guillen, Thomas D. Donnelly, and Nathan Jones

Evidence of the harmonic Faraday instability in ultrasonic atomization experiments with a deep, inviscid fluid

Journal of the Acoustical Society of America 130 (2011) 2694-2699.
PDF document
donnelly_paper.png
56.

Jason Gallicchio and Matthew D Schwartz

Pure samples of quark and gluon jets at the LHC

Journal of High Energy Physics 2011 (2011) .
57.

Donna Phu, Lindsay S. Wray, Robert V. Warren, Richard C. Haskell, and Elizabeth Orwin

Effect of Substrate Composition and Alignment on Corneal Cell Phenotype

Tissue Engineering A 17 (2011) 799–807.
58.

J. T. Merrill, C. Volin, D. W. Landgren, J. M. Amini, K. Wright, Charlie Doret, C. -S. Pai, H. Hayden, T. Killian, D. L. Faircloth, K. R. Brown, A. W. Harter, and R. E. Slusher

Demonstration of integrated microscale optics in surface-electrode ion traps

New Journal of Physics 13 (2011) 103005.
PDF document
2011/Doret_NJP_13_103005
59.

L. M. Belova, James C. Eckert, J. J. L. Mulders, C. Christophersen, E. D. Dahlberg, and A. Riazanova

Rapid electron beam assisted patterning of pure cobalt at elevated temperatures via seeded growth

Nanotechnology 22 (2011) 145305.
eckert_nano110303.jpg
60.

David A. Berryrieser, Peter J. Scherpelz, Rudolph W. Resch, and Theresa W. Lynn

Entanglement-secured single-qubit quantum secret sharing

Physical Review A 84 (2011) 032303.
lynn_scherpelz.png