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Physics

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Displaying 876 - 900 of 2574

Twist Angle-Dependent Atomic Reconstruction and Moire Patterns in Transition Metal Dichalcogenide Heterostructures

March 13, 2020
Author(s)
Matthew R. Rosenberger, Hsun-Jen Chuang, Vladimir Oleshko, Madeleine Phillips, Kathleen M. McCreary, Saujan V. Sivaram, C. Stephen Hellberg, Berend T. Jonker
Van der Waals layered materials, such as the transition metal dichalcogenides (TMDs), are an exciting class of materials with weak interlayer bonding which enables one to create so-called van der Waals heterostructures (vdWH). One promising attribute of

Certified Quantum Measurement of Majorana Fermions

March 12, 2020
Author(s)
Emanuel H. Knill, Abu Ashik Md. Irfan, Karl H. Mayer, Gerardo Ortiz
We present a quantum self-testing protocol to certify measurements of fermion parity involving Majorana fermion modes. We show that observing a set of ideal measurement statistics implies anticommutativity of the implemented Majorana fermion parity

Targeted enrichment of 28Si thin films for quantum computing

March 9, 2020
Author(s)
Ke Tang, Hyun S. Kim, Aruna N. Ramanayaka, David S. Simons, Joshua M. Pomeroy
We report on the growth of isotopically enriched 28Si epitaxial films with precisely controlled enrichment levels, ranging from natural abundance ratio of 92.2% all the way to 99.99987 % (0.832 × 10-6 mol/mol 29Si). Isotopically enriched 28Si is regarded

Direct kerr-frequency comb atomic spectroscopy

February 28, 2020
Author(s)
Liron Stern, Jordan R. Stone, Songbai Kang, Daniel C. Cole, Zachary L. Newman, Kerry Vahala
Microresonator-based soliton frequency combs- microcombs -have recently emerged to offer low- noise, photonic-chip sources for optical measurements. Owing to nonlinear-optical physics, microcombs can be built with various materials 1-3 and tuned or

Low energy cross section measurement of the 10B(a;n)13N reaction and its impact on neutron production in 1st generation stars

February 26, 2020
Author(s)
Q Liu, M Febbraro, R.J. deBoer, S. Aguilar, A Boeltzig, Y Chen, M Couder, J Gorres, Jamie Weaver, K. T. Macon, M. Wiescher, K. Manukyan, L. Morales, S Pain, W. A. Peters, C. Seymour, G. Seymour, R. Toomey, B. Vande Kolk
Nucleosynthesis in the fi rst generation of massive stars offer a unique setting to explore the creation of the fi rst heavier nuclei in an environment free of impurities from earlier stellar generations. In later generations of massive stars, hydrogen

Quasi-two-dimensional magnon identification in antiferromagnetic FePS3 via magneto-Raman spectroscopy

February 18, 2020
Author(s)
Amber D. McCreary, Jeffrey R. Simpson, Thuc T. Mai, Robert D. McMichael, Jason E. Douglas, Nicholas P. Butch, Cindi L. Dennis, Rolando Valdes Aguilar, Angela R. Hight Walker
Recently it was discovered that van der Waals-bonded magnets retain long range magnetic ordering even down to a monolayer thickness, opening many avenues in fundamental physics and potential applications of these fascinating materials. One example is FePS3

Dynamic Heterogeneity and Collective Motion in Star Polymer Melts

February 4, 2020
Author(s)
Jack F. Douglas, Jinpeng Fan, Hamed Emamy, Francis W. Starr, Alexandros Chremos
While glass formation of linear chain polymers has been widely explored, comparatively little is known about glass formation in star polymer melts. We study the segmental dynamics of star polymers via molecular dynamics simulations and contrast the

Excess Electrons Bound to H2S Trimer and Tetramer Clusters

January 24, 2020
Author(s)
Gaoxiang Liu, Manuel Diaz-Tinoco, Sandra M. Ciborowski, Chalynette Martinez-Martinez, Svetlana Lyspustina, Jay H. Hendricks, Vincent Ortiz, Kit H. Bowen
The hydrogen sulfide trimer and tetramer anions, (H2S)3– and (H2S)4–, were generated by Rydberg electron transfer and studied via a synergy between velocity-map imaging anion photoelectron spectroscopy and high-level quantum chemical calculations. The

Influence of Polymer Topology on Crystallization in Thin Films

January 22, 2020
Author(s)
Jack F. Douglas, Andrea Giuntoli, Alexandros Chremos
We investigate how varying molecular topology of polymers influences crystallization in thin polymer films. In particular, we simulate linear and star polymers having a progressively increasing number of arms (f ≤ 16) for fixed molecular mass of polymer

Isotope shifts in neutral and singly-ionized calcium

January 20, 2020
Author(s)
Alexander Kramida
All available experimental data on isotope shifts and absolute frequency measurements in the optical spectra of Ca I and Ca II are analyzed, and from them complete tables of isotope shifts and energy levels of all Ca isotopes from 36 to 52 are derived. A

Microwave-based arbitrary cphase gates for transmon qubits

January 17, 2020
Author(s)
George S. Barron, Fernando A. Calderon-Vargas, Junling Long, David P. Pappas, Sophia E. Economou
Superconducting transmon qubits are of great interest for quantum computing and quantum simulation. A key component of quantum chemistry simulation algorithms is breaking up the evolution into small steps, which naturally leads to the need for nonmaximally

Observation of an isomerizing double-well quantum system in the condensed phase

January 10, 2020
Author(s)
Varun Verma, Jascha A. Lau, Arnab Choudhury, Li Chen, Dirk Schwarzer, Alec M. Wodtke
Molecules are quantum objects; therefore, isomerization fundamentally involves quantum states bound within a molecular potential energy function with multiple minima. For isolated gas-phase molecules, eigenstates well above the isomerization saddle points

Ultranarrow linewidth photonic-atomic laser

January 8, 2020
Author(s)
Wei Zhang, Liron Stern, David R. Carlson, Douglas G. Bopp, Zachary L. Newman, Songbai Kang, John Kitching, Scott Papp
Lasers with high spectral purity can enable a diverse application space, including precision spectroscopy, coherent high-speed communications, physical sensing, and manipulation of quantum systems. Already, meticulous design and construction of bench Fabry

Efficient Randomness Certification by Quantum Probability Estimation

January 7, 2020
Author(s)
Emanuel H. Knill, Yanbao Zhang, Honghao Fu
For practical applications of quantum randomness generation, it is important to produce a fixed block of fresh random bits with as few trials as possible. Consequently, protocols with high finite-data are preferred. In this work we develop a broadly

Demonstration of 220/280 GHz Multichroic Feedhorn-Coupled TES Polarimeter

January 3, 2020
Author(s)
Samantha L. Walker, Carlos E. Sierra, Jason E. Austermann, James A. Beall, Daniel T. Becker, Bradley J. Dober, Shannon M. Duff, Gene C. Hilton, Johannes Hubmayr, Jeffrey L. Van Lanen, Jeff McMahon, Sara M. Simon, Joel N. Ullom, Michael R. Vissers
We describe the design and measurement of feedhorn-coupled, transition-edge sensor (TES) polarimeters with two passbands centered at 220 GHz and 280 GHz, intended for observations of the cosmic microwave background. Each pixel couples polarized light in

A transition-edge sensor-based x-ray spectrometer for the study of highly charged ions at the National Institute of Standards and Technology electron beam ion trap

December 16, 2019
Author(s)
Paul Szypryt, Galen C. O'Neil, Endre Takacs, Joseph N. Tan, Sean W. Buechele, Aung Naing, Douglas A. Bennett, William B. Doriese, Malcolm S. Durkin, Joseph W. Fowler, Johnathon D. Gard, Gene C. Hilton, Kelsey M. Morgan, Carl D. Reintsema, Daniel R. Schmidt, Daniel S. Swetz, Joel N. Ullom, Yuri Ralchenko
We report on the design, commissioning, and initial measurements of a Transition-Edge Sensor (TES) x-ray spectrometer for the Electron Beam Ion Trap (EBIT) at the National Institute of Standards and Technology (NIST). Over the past few decades, the NIST

Generating few-cycle pulses with integrated nonlinear photonics

December 10, 2019
Author(s)
David Carlson, Phillips Hutchison, Daniel D. Hickstein, Scott Papp
Ultrashort laser pulses that last only a few optical cycles have been transformative tools for studying and manipulating ultrafast light--matter interactions. These few-cycle pulses are typically produced from high-peak-power lasers, either directly from

Jovian Auroral Ion Precipitation: X-Ray Production from Oxygen and Sulfur Precipitation

December 9, 2019
Author(s)
Heman Gharibnejad, David Schultz, Thomas Cravens, Stephen Houston, W. R. Dunn, D. K. Haggerty, A. M. Rymer, B. H. Mauk, N. Ozak
Many attempts have been made to model X-ray emission from both bremsstrahlung and ion precipitation into Jupiter’s polar caps. Electron bremsstrahlung modeling has fallen short of producing the total overall power output observed by earth-orbit-based X-ray
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