Sequential Discrimination Between Non-Orthogonal Quantum States, 2019 The Graduate Center, City University of New York

#### Sequential Discrimination Between Non-Orthogonal Quantum States, Dov L. Fields

*All Dissertations, Theses, and Capstone Projects*

The problem of discriminating between non-orthogonal states is one that has generated a lot of interest. This basic formalism is useful in many areas of quantum information. It serves as a fundamental basis for many quantum key distribution schemes, it functions as an integral part of other quantum algorithms, and it is useful in experimental settings where orthogonal states are not always possible to generate. Additionally, the discrimination problem reveals important fundamental properties, and is intrinsically related to entanglement. In this thesis, the focus is on exploring the problem of sequentially discriminating between non-orthogonal states. In the simplest version these ...

Possible Schemes For A Single Photon Switch, 2019 University of Arkansas, Fayetteville

#### Possible Schemes For A Single Photon Switch, Hemlin Swaran Rag

*Theses and Dissertations*

I consider the effectiveness of a single control photon to route a target photon using two processes: the first one uses the transient excitation of a two-level system and the second one which uses the permanent population transfer in a three-level Λ-system to route the target photon. In the absence of a single control photon and when the system has additional decay channels, I find ways to optimize the success probability of routing with an increasing number of photons in the control field.

Benchmarks Of Nonclassicality For Qubit Arrays, 2019 Chapman University

#### Benchmarks Of Nonclassicality For Qubit Arrays, Mordecai Waegell, Justin Dressel

*Mathematics, Physics, and Computer Science Faculty Articles and Research*

We present a set of practical benchmarks for *N-*qubit arrays that economically test the fidelity of achieving multi-qubit nonclassicality. The benchmarks are measurable correlators similar to two-qubit Bell correlators, and are derived from a particular set of geometric structures from the *N*-qubit Pauli group. These structures prove the Greenberger–Horne–Zeilinger (GHZ) theorem, while the derived correlators witness genuine N-partite entanglement and establish a tight lower bound on the fidelity of particular stabilizer state preparations. The correlators need only *M* ≤ *N* + 1 distinct measurement settings, as opposed to the 2^{2N} − 1 settings that would normally be required ...

Stereodynamical Control Of A Quantum Scattering Resonance In Cold Molecular Collisions, 2019 Universidad de Salamanca

#### Stereodynamical Control Of A Quantum Scattering Resonance In Cold Molecular Collisions, Pablo G. Jambrina, James F.E. Croft, Hua Guo, Mark Brouard, Balakrishnan Naduvalath, F. Javier Aoiz

*Chemistry and Biochemistry Faculty Publications*

Cold collisions of light molecules are often dominated by a single partial wave resonance. For the rotational quenching of HD (v=1, j=2) by collisions with ground state para-H2, the process is dominated by a single L=2 partial wave resonance centered around 0.1 K. Here, we show that this resonance can be switched on or off simply by appropriate alignment of the HD rotational angular momentum relative to the initial velocity vector, thereby enabling complete control of the collision outcome.

Topological Nodal Line Semimetals In Graphene Network Structures, 2019 University of Chinese Academy of Sciences

#### Topological Nodal Line Semimetals In Graphene Network Structures, Jian-Tao Wang, Hongming Weng, Chengfeng Chen

*Physics & Astronomy Faculty Publications*

Topological semimetals are a fascinating class of quantum materials that possess extraordinary electronic and transport properties. These materials have attracted great interests in recent years for their fundamental significance and potential device applications. There have been intensive studies suggested that three-dimensional graphene networks support topological semimetals with two types of continuous nodal lines: one is to form closed nodal rings in Brillouin zone and the other ones traversing the whole Brillouin zone to be periodically connected. Carbon has negligible spin-orbit coupling, non-magnetism and great diversity of allotropes, which makes it very promising in realizing topological nodal line semimetals. Here we ...

Laser Cooling With Adiabatic Transfer On A Raman Transition, 2019 JILA/CU-Boulder

#### Laser Cooling With Adiabatic Transfer On A Raman Transition, Graham Greve, Baochen Wu, James K. Thompson

*JILA Faculty Contributions*

Sawtooth Wave Adiabatic Passage (SWAP) laser cooling was recently demonstrated using a narrow-linewidth single-photon optical transition in atomic strontium and may prove useful for cooling other atoms and molecules. However, many atoms and molecules lack the appropriate narrow optical transition. Here we use such an atom, ^{87}Rb, to demonstrate that two-photon Raman transitions with arbitrarily-tunable linewidths can be used to achieve 1D SWAP cooling without significantly populating the intermediate excited state. Unlike SWAP cooling on a narrow transition, Raman SWAP cooling allows for a final 1D temperature well below the Doppler cooling limit (here, 25 times lower); and the ...

Quadratic To Linear Magnetoresistance Tuning In Tmb4, 2019 Nanyang Technological University

#### Quadratic To Linear Magnetoresistance Tuning In Tmb4, Sreemanta Mitra, Jeremy Goh Swee Kang, John Shin, Jin Quan Ng, Sai Swaroop Sunku, Tai Kong, Paul C. Canfield, B. Sriram Shastry, Pinaki Sengupta, Christos Panagopoulos

*Paul C. Canfield*

The change of a material's electrical resistance (*R*) in response to an external magnetic field (*B*) provides subtle information for the characterization of its electronic properties and has found applications in sensor and storage related technologies. In good metals, Boltzmann's theory predicts a quadratic growth in magnetoresistance (MR) at low *B* and saturation at high fields. On the other hand, a number of nonmagnetic materials with weak electronic correlation and low carrier concentration for metallicity, such as inhomogeneous conductors, semimetals, narrow gap semiconductors and topological insulators, and two dimensional electron gas, show positive, nonsaturating linear magnetoresistance (LMR). However ...

Pairwise Completely Positive Matrices And Conjugate Local Diagonal Unitary Invariant Quantum States, 2019 Mount Allison University

#### Pairwise Completely Positive Matrices And Conjugate Local Diagonal Unitary Invariant Quantum States, Nathaniel Johnston, Olivia Maclean

*Electronic Journal of Linear Algebra*

A generalization of the set of completely positive matrices called pairwise completely positive (PCP) matrices is introduced. These are pairs of matrices that share a joint decomposition so that one of them is necessarily positive semidefinite while the other one is necessarily entrywise non-negative. Basic properties of these matrix pairs are explored and several testable necessary and sufficient conditions are developed to help determine whether or not a pair is PCP. A connection with quantum entanglement is established by showing that determining whether or not a pair of matrices is pairwise completely positive is equivalent to determining whether or not ...

Phantoms In Science: Nietzsche's Nonobjectivity On Planck's Quanta, 2019 Bellarmine University

#### Phantoms In Science: Nietzsche's Nonobjectivity On Planck's Quanta, Donald Richard Dickerson Iii

*Undergraduate Theses*

What does Maxwell Planck's concept of phantomness suggest about the epistemological basis of science and how might a Nietzschean critique reveal solution to the weaknesses revealed? With his solution to Kirchoff's equation, Maxwell Planck launched the paradigm of quantum physics. This same solution undermined much of current understandings of science versus pseudoscience. Using Nietzsche's perspectivism and other philosophical critiques, Planck's answer to blackbody radiation is used to highlight the troubles with phantom problems in science and how to try to direct science towards a more holistic and complete scientific approach.

Exploring Quantum Dynamics And Thermodynamics In Superconducting Qubits, 2019 Washington University in St. Louis

#### Exploring Quantum Dynamics And Thermodynamics In Superconducting Qubits, Mahdi Naghiloo

*Arts & Sciences Electronic Theses and Dissertations*

Quantum technology has been rapidly growing due to its potential revolutionary applications. In particular, superconducting qubits provide a strong light-matter interaction as required for quantum computation and in principle can be scaled up to a high level of complexity. However, obtaining the full benet of quantum mechanics in superconducting circuits requires a deep understanding of quantum physics in such systems in all aspects. One of the most crucial aspects is the concept of measurement and the dynamics of the quantum systems under the measurement process. This thesis is intended to be a pedagogical introduction to the concept of quantum measurement ...

Experimental Evidence Supportive Of The Quantum Dna Model, 2019 University of Tennessee Health Science Center

#### Experimental Evidence Supportive Of The Quantum Dna Model, F. Matthew Mihelic

*Faculty Publications*

The DNA molecule can be modeled as a quantum logic processor in which electron spin qubits are held coherently in each nucleotide in a logically and thermodynamically reversible enantiomeric symmetry, and can be coherently conducted along the pi-stacking interactions of aromatic nucleotide bases, while simultaneously being spin-filtered via the helicity of the DNA molecule. Entangled electron pairs can be separated by that spin-filtering, held coherently at biological temperatures in the topologically insulated nucleotide quantum gates, and incorporated into separate DNA strands during DNA replication. Two separate DNA strands that share quantum entangled electrons can be mitotically divided into individual cells ...

Unbounded Derivations Of C*-Algebras And The Heisenberg Commutation Relation, 2019 University of Nebraska-Lincoln

#### Unbounded Derivations Of C*-Algebras And The Heisenberg Commutation Relation, Lara M. Ismert

*Dissertations, Theses, and Student Research Papers in Mathematics*

This dissertation investigates the properties of unbounded derivations on C*-algebras, namely the density of their analytic vectors and a property we refer to as "kernel stabilization." We focus on a weakly-defined derivation δ_{D} which formalizes commutators involving unbounded self-adjoint operators on a Hilbert space. These commutators naturally arise in quantum mechanics, as we briefly describe in the introduction.

A first application of kernel stabilization for δ_{D} shows that a large class of abstract derivations on unbounded C*-algebras, defined by O. Bratteli and D. Robinson, also have kernel stabilization. A second application of kernel stabilization provides a ...

A Qubit Algorithm For Simulating The Nonlinear Schroedinger Equation, 2019 William & Mary

#### A Qubit Algorithm For Simulating The Nonlinear Schroedinger Equation, Connor Simpson

*Undergraduate Honors Theses*

Recent work in mathematical physics and nonlinear optics has shown that Hamiltonians that are non-Hermitian but still symmetric under parity and time reversal can describe eigenstates of a system with real eigenvalues. Other research has also showed that the nonlinear Schrodinger equation can be generalized to describe PT-symmetric systems, which generates novel solutions not described by its Hermitian equivalent. The Hermitian form of the nonlinear Schroedinger equation can also be extended to describe a particular case of the general PT-symmetric NLS, suggesting a connection between the two. I attempted to generate a unitary operator that will be useful for unitary ...

Free Electron Sources And Diffraction In Time, 2019 University of Nebraska-Lincoln

#### Free Electron Sources And Diffraction In Time, Eric R. Jones

*Theses, Dissertations, and Student Research: Department of Physics and Astronomy*

The quantum revolution of the last century advanced synergistically with technology, for example, with control of the temporal and spatial coherence, and the polarization state of light. Indeed, experimental confirmation of the quirks of quantum theory, as originally highlighted by Einstein, Podolsky, and Rosen, through Bohm, and then Bell, have been performed with photons, i.e., electromagnetic wave packets prepared in the same quantum states. Experimental tests of quantum mechanics with matter wave packets have been limited due to challenges in preparing all of the packets with similar quantum states. While great strides have been made for trapped atoms and ...

Implementing A Self-Corrected Chemical Potential Scheme In Determinant Quantum Monte Carlo Simulations, 2019 University of Tennessee, Knoxville

#### Implementing A Self-Corrected Chemical Potential Scheme In Determinant Quantum Monte Carlo Simulations, Kevin Gordon Kleiner

*Chancellor’s Honors Program Projects*

No abstract provided.

The Nature Of The Heisenberg-Von Neumann Cut: Enhanced Orthodox Interpretation Of Quantum Mechanics, 2019 California Institute for Integral Studies

#### The Nature Of The Heisenberg-Von Neumann Cut: Enhanced Orthodox Interpretation Of Quantum Mechanics, Ashok Narasimhan, Deepak Chopra, Menas Kafatos

*Mathematics, Physics, and Computer Science Faculty Articles and Research*

We examine the issue of the Heisenberg-von Neumann cut in light of recent interpretations of quantum eraser experiments which indicate the possibility of a universal Observer outside space-time at an information level of existence. The delayed-choice aspects of observation, measurement, the role of the observer, and information in the quantum framework of the universe are discussed. While traditional double-slit experiments are usually interpreted as indicating that the collapse of the wave function involves choices by an individual observer in space-time, the extension to quantum eraser experiments brings in some additional subtle aspects relating to the role of observation and what ...

Roadmap On Superoscillations, 2019 University of Bristol

#### Roadmap On Superoscillations, Michael Berry, Nicolay Zheludev, Yakir Aharonov, Fabrizio Colombo, Irene Sabadini, Daniele C. Struppa, Jeff Tollaksen, Edward T. F. Rogers, Fei Qin, Minghui Hong, Xiangang Luo, Roei Remez, Ady Arie, Jörg B. Götte, Mark R. Dennis, Alex M. H. Wong, George V. Eleftheriades, Yaniv Eliezer, Alon Bahabad, Gang Chen, Zhongquan Wen, Gaofeng Liang, Chenglong Hao, C-W Qiu, Achim Kempf, Eytan Katzav, Moshe Schwartz

*Mathematics, Physics, and Computer Science Faculty Articles and Research*

Superoscillations are band-limited functions with the counterintuitive property that they can vary arbitrarily faster than their fastest Fourier component, over arbitrarily long intervals. Modern studies originated in quantum theory, but there were anticipations in radar and optics. The mathematical understanding—still being explored—recognises that functions are extremely small where they superoscillate; this has implications for information theory. Applications to optical vortices, sub-wavelength microscopy and related areas of nanoscience are now moving from the theoretical and the demonstrative to the practical. This Roadmap surveys all these areas, providing background, current research, and anticipating future developments.

Improving The Readout Of Semiconducting Qubits, 2019 University of New Mexico

#### Improving The Readout Of Semiconducting Qubits, Matthew Jon Curry

*Physics & Astronomy ETDs*

Semiconducting qubits are a promising platform for quantum computers. In particular, silicon spin qubits have made a number of advancements recently including long coherence times, high-fidelity single-qubit gates, two-qubit gates, and high-fidelity readout. However, all operations likely require improvement in fidelity and speed, if possible, to realize a quantum computer.

Readout fidelity and speed, in general, are limited by circuit challenges centered on extracting low signal from a device in a dilution refrigerator connected to room temperature amplifiers by long coaxial cables with relatively high capacitance. Readout fidelity specifically is limited by the time it takes to reliably distinguish qubit ...

Reducing Quantum Uncertainty Via Spatial Optimization, 2019 William & Mary

#### Reducing Quantum Uncertainty Via Spatial Optimization, Austin T. Kalasky

*Undergraduate Honors Theses*

High precision optical detection is fundamentally limited by quantum noise. This limit can be bypassed with the use of squeezed states of light with modified quantum noise. We study squeezed states of light with a focus on optimization of squeezing generated via polarization self-rotation (PSR) in hot rubidium vapor. The goal of our research is to reduce quantum noise by optimizing cell temperature and beam shape of the input pump field. We find that computerized spatial optimization algorithms (combined with manual optimization of temperature and laser detuning) are successful in improving squeezing levels, with one spatial mask yielding over 1 ...

Investigating The Talbot Effect In Arrays Of Optical Dipole Traps For Neutral Atom Quantum Computing, 2019 California Polytechnic State University, San Luis Obispo

#### Investigating The Talbot Effect In Arrays Of Optical Dipole Traps For Neutral Atom Quantum Computing, Sergio Aguayo

*Physics*

Quantum computers are devices that are able to perform calculations not achievable for classical computers. Although there are many methods for creating a quantum computer, using neutral atoms offers the advantage of being stable when compared to other methods. The purpose of this investigation is to explore possible optical dipole trap configurations that would be useful for implementing a quantum computer with neutral atoms. Specifically, we computationally investigate arrays of pinholes, the diffraction pattern generated by them, and the onset of the Talbot effect in these traps. We manipulate the radius of the pinholes, the number of pinholes in the ...