Abstract

When matter falls past the horizon of a large black hole, the expectation from string theory is that the configuration thermalizes and the information in the probe is rather quickly scrambled away. The traditional view of a classical unique spacetime near a black hole horizon conflicts with this picture. The question then arises as to what spacetime does the probe actually see as it crosses a horizon, and how does the background geometry imprint its signature onto the thermal properties of the probe. In this work, we explore these questions through an extensive series of numerical simulations of D0 branes. We determine that the D0 branes quickly settle into an incompressible symmetric state—thermalized within a few oscillations through a process driven entirely by internal nonlinear dynamics. Surprisingly, thermal background fluctuations play no role in this mechanism. Signatures of the background fields in this thermal state arise either through fluxes, i.e. black hole hair; or if the probe expands to the size of the horizon—which we see evidence of. We determine simple scaling relations for the D0 branes’ equilibrium size, time to thermalize, lifetime, and temperature in terms of their number, initial energy, and the background fields. Our results are consistent with the conjecture that black holes are the fastest scramblers as seen by matrix theory.

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

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.

Abstract

Measuring an entangled state of two particles is crucial to many quantum communication protocols. Yet Bell- state distinguishability using a finite apparatus obeying linear evolution and local measurement is theoretically limited. We extend known bounds for Bell-state distinguishability in one and two variables to the general case of entanglement in *n* two-state variables. We show that at most :mil:`2^{n+1} - 1` classes out of :mil:`4^{n}` hyper-Bell states can be distinguished with one copy of the input state. With two copies, complete distinguishability is possible. We present optimal schemes in each case.

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 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 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.

From the Cover…

.. epigraph:: “Helliwell achieves a rare clarity. For instance, the derivation of the standard kinematic results starting from Einstein's postulates is outstandingly clear. Throughout he shows an unusual and sympathetic appreciation of the problems that are faced by the beginning student.” -- John Taylor, University of Colorado .. epigraph:: “*Special Relativity* is definitely much better than the books I have read on this topic, and I would recommend it to any instructor who plans to teach a course on this topic. For anyone teaching special relativity as a part of a Modern Physics course, this book offers valuable supplementary reading.” -- Shirvel Stanislaus, Valparaiso University

Abstract

We demonstrate the operation of a device that can produce chitosan nanoparticles in a tunable size range from 50–300 nm with small size dispersion. A piezoelectric oscillator operated at megahertz frequencies is used to aerosolize a solution containing dissolved chitosan. The solvent is then evaporated from the aerosolized droplets in a heat pipe, leaving monodisperse nanoparticles to be collected. The nanoparticle size is controlled both by the concentration of the dissolved polymer and by the size of the aerosol droplets that are created. Our device can be used with any polymer or polymer/therapeutic combination that can be prepared in a homogeneous solution and vaporized.

From the Cover…

.. epigraph:: “Townsend has written an excellent book that someone needed to write for the modern physics textbook market. He has given it the same care that he gave to his excellent quantum mechanics book.” -- Jeff Dunham, Middlebury College .. epigraph:: “When I read this book I immediately adopted it for my sophomore modern physics class. This is the best introduction to quantum mechanics available.” -- B. Paul Padley, Rice University

Recent Publications

Student authorFaculty author

11. Paul Riggins and Vatche Sahakian, “Black hole thermalization, D0 brane dynamics, and emergent spacetime”, Phys. Rev. D 86 (2012) 046005.
12. J. L. Silverberg, R. N. Noar, M. Packer, M. Harrison, I. Cohen, C. Henley, and Sharon J. Gerbode, “3D Imaging and mechanical modeling of helical buckling in Medicago truncatula plant roots”, PNAS 109 (2012) 16794.
13. David Berryrieser, Peter Scherpelz, R. Resch, and Theresa W. Lynn, “Entanglement-secured single-qubit quantum secret sharing”, Phys. Rev. A 84 (2011) 032303.
14. N. Pisenti, Carl Philipp Emanuel Gaebler, and Theresa W. Lynn, “Distinguishability of hyperentangled Bell states by linear evolution and local projective measurement”, Phys. Rev. A 84 (2011) 022340.
15. 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.
16. J. T. Merrill, C. Volin, D. W. Landgren, J. M. Amini, K. Wright, S. C. 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 J. Phys. 13 (2011) 103005.
17. Andrew Higginbotham, Andrew J. Bernoff, Aaron Guillen, Thomas D. Donnelly, and Nathan Jones, “Evidence of the harmonic Faraday instability in ultrasonic atomization experiments with a deep, inviscid fluid”, J. Acoust. Soc. Am. 130 (2011) 2694-2699.
18. Thomas M. Helliwell, Special Relativity, University Science Books, Sausalito (2010).
19. Andrew Higginbotham, Thomas D. Donnelly, Shenda M. Baker, and Ian K. Wright, “Generation of Nanoparticles of Controlled Size Using Ultrasonic Piezoelectric Oscillators in Solution”, ACS Appl. Mat. and Int. 2 (2010) 2360-2364.
20. John S. Townsend, Quantum Physics: a Fundamental Approach to Modern Physics, University Science Books, Sausalito (2010).