Quantum Physics Commons^™

Quality Infrastructure Empowering Collaborative Innovation In Quantum Information Industry: Mechanism, Demand, And Path, Leilei Zhang, Jian Kang, Zhou He

Bulletin of Chinese Academy of Sciences (Chinese Version)

Against the backdrop of intensified global competition in quantum information, the synergistic effectiveness of quality infrastructure, as a basic system supporting industrial innovation, is directly related to the industrialization process of quantum technology. At present, subdivided industries such as quantum computing, quantum communication, and quantum precision measurement have begun to take shape, and key technologies and core products have entered a critical period of transition from scientific and technological innovation results to industrialization, and the demand for quality infrastructure is becoming increasingly prominent. This study explores the co-evolution mechanism of quality infrastructure driven by industrial innovation and analyzes the coupling …

Super-Resolution Magnetic Microscopy And Earth’S Field Magnetometry With Color Centers In Diamond, Nazanin Mosavian

Optical Science and Engineering ETDs

In recent years, the negatively charged nitrogen- vacancy (NV) center has emerged as a promising solid-state color center capable of measuring magnetic fields with high sensi- tivity and spatial resolution under ambient conditions. In this thesis I will discuss how we perform super resolution magnetic microscopy and acquire magnetic field images of nanoparticle samples at 100 nm resolution. I will explain how 3D flux concentrators increase magnetic field amplitude and allows us to measure vector component magnetic fields as low as 50 µT with a diamond magnetometer, without the use of an additional bias magnetic field. I also describe how …

An Introduction To The Time-Independent Schrödinger Equation And Methods To Solve It, Vu Giang, Alex Gnech

OUR Journal: ODU Undergraduate Research Journal

The Time-Independent Schrödinger Equation is a linear elliptic PDE that describes quantum-mechanical systems. Its significance in the science of submicroscopic phenomena, particularly quantum mechanics, is as central as Newton’s laws of motion are to classical mechanics. This study uses various methods, including novel neural networks and finite difference schemes, to solve the one-dimensional two-body equation.

Long-Distance Photon-Mediated And Short-Distance Entangling Gates In Three-Qubit Quantum Dot Spin Systems, Nooshin M. Estakhri, Ada Warren, Sophia E. Economou, Edwin Barnes

Engineering Faculty Articles and Research

Superconducting resonator couplers will likely become an essential component in modular semiconductor quantum dot (QD) spin qubit processors, as they help alleviate crosstalk and wiring issues as the number of qubits increases. Here, we focus on a three-qubit system composed of two modules: a two-electron triple QD resonator coupled to a single-electron double QD. Using a combination of analytical techniques and numerical results, we derive an effective Hamiltonian that describes the three-qubit logical subspace and show that it accurately captures the dynamics of the system. We examine the performance of short-range and long-range entangling gates, revealing the effect of a …

Optimal Radar Ranging Pulse To Resolve Two Reflectors, Andrew N. Jordan, John C. Howell, Achim Kempf, Shunxing Zhang, Derek White

Mathematics, Physics, and Computer Science Faculty Articles and Research

Previous work established fundamental bounds on subwavelength resolution for the radar range resolution problem, called superradar [Phys. Rev. Appl. 20, 064046 (2023)]. In this work, we identify the optimal waveforms for distinguishing the range resolution between two reflectors of identical strength, leveraging results in quantum metrology. We discuss both the unnormalized optimal waveform as well as the best square-integrable pulse and their variants. Using orthogonal function theory, we give an explicit algorithm to optimize the wave pulse in finite time to have the best performance. We also explore range resolution estimation with unnormalized waveforms with multiparameter methods to …

Design, Characterization, And Simulation Of A 2d Dual-Rail Quantum Processor, Diego Barrutia

Dartmouth College Master’s Theses

Bosonic systems, such as three-dimensional (3D) λ/4 coaxial cavities and two-dimensional (2D) λ/2 coplanar waveguide (CPW) resonators, are quantum harmonic oscillators that encode information in phase space, offering a hardware-efficient route toward quantum error correction and simulation in superconducting circuits. In this thesis, we present the design, characterization, and simulation of a dual-rail processor constructed with a 2D λ/2 coplanar waveguide resonators, demonstrating a percent error between experimental and analytical results within a range of 3.31% - 13.16%. The analytical results exhibit high precision but lower accuracy relative to experimental measurements. By integrating both closed-source and open-source software tools, we …

Shear Viscosity Of Quasi One-Dimensional Bec Tubes And Entanglement Negativity Conditions, Camilla Polvara

Dissertations, Theses, and Capstone Projects

Shear Viscosity of Quasi One-dimensional BEC Tubes

We consider layered Bose-Einstein condensates interacting via contact intra-condensate interacions and dipolar inter-condensate potentials, both of which dominate intercondensate tunneling (which we neglect for simplicity). For this system, we compute the normal modes, we study its localization properties by numerically computing the inverse participation ratio, and we compute the inter-tube shear viscosity.

Entanglement Negativity Conditions

This project explores bounds on entanglement negativity using operator inequalities, building on the results of [1]. We are looking for a way to quantify entanglement, as an alternative to calculating the full negativity, which would otherwise require the …

Thermal Phase Fluctuations In Narrow Superfluid Rings, Parth Sabharwal

Dartmouth College Ph.D Dissertations

Remarkable advances have been made in the past decade in the ability to control superfluids in circuit-like configurations. Especially notable are the improvements in the initialization, stabilization and measurement of the circulation of superfluids in geometries with periodic boundary conditions, such as rings. This has significant implications for applications as rotation sensors, magnetometers, and in the emerging field of atomtronics. As the push towards studying supercurrents in lower dimensions and higher aspect ratios continues, in order to realize idealized experimental conditions and explore unusual quantum phases, phase fluctuations become increasingly pronounced, with the potential to destroy long-range order. In this …

Quantum Field Theory And The Limits Of Reductionism, Emily Adlam

Mathematics, Physics, and Computer Science Faculty Articles and Research

I suggest that the current situation in quantum field theory (QFT) provides some reason to question the universal validity of ontological reductionism. I argue that the renormalization group flow is reversible except at fixed points, which makes the relation between large and small distance scales quite symmetric in QFT, opening up at least the technical possibility of a non-reductionist approach to QFT. I suggest that some conceptual problems encountered within QFT may potentially be mitigated by moving to an alternative picture in which it is no longer the case that the large supervenes on the small. Finally, I explore some …

Questioning Reality: The Progressive Development Of Modern Physics, Joshua Lancman

STEM Month

Humanity has a tendency to divide time. The past is distinct from the present which is entirely separate from the future. In supposedly 20-20 vision history is neatly divided into different sections, distinct eras with sharp lines between them. What is present and in the future is always modern. What is past is something else with another name.

Yet time is not divided so neatly. We know this living through it: years and decades blend into one another in a non-uniform progression. To divide human history into separate eras is a necessary simplification, as it helps to ascribe order onto …

Madelung Mechanics And Superoscillations, Mordecai Waegell

Mathematics, Physics, and Computer Science Faculty Articles and Research

In single-particle Madelung mechanics, the single-particle quantum state Ψ(⃗x, t) = R(⃗x, t)eiS(⃗x,t)/h is interpreted as comprising an entire conserved fluid of classical point particles, with local density R(⃗x, t)2 and local momentum ⃗∇S(⃗x, t) (where R and S are real). The Schrödinger equation gives rise to the continuity equation for the fluid, and the Hamilton–Jacobi equation for particles of the fluid, which includes an additional density-dependent quantum potential energy term Q(⃗x, t) = − ¯h2 2m ⃗∇R(⃗x,t) R(⃗x,t) , which is all that makes the fluid behavior nonclassical. In particular, the quantum potential can become negative and create a …

Quantum Circuit Optimization Leveraging Multi-Qubit Exchange Interactions In Spin Qubits, Miguel Gonzalo Rodriguez

Open Access Theses & Dissertations

This thesis looks into how multi-qubit exchange interactions can be used to improve quantumcircuits in semiconductor quantum devices. Pairwise interactions between qubits are a common tenet of traditional quantum computing paradigms, although they can impose complexity and depth constraints on circuits. In order to improve the efficiency and scalability of quantum circuits, this research explores the theoretical underpinnings and practical uses of multi-qubit interactions. A thorough theoretical framework is formulated, outlining the mathematical equivalence of a unitary matrix representing interactions between multiple qubits. We obtain the timeevolution operator by analyzing the Hamiltonian of three spin-1/2 particles. A number of quantum …

Quantum Classical Algorithm For Solving The Hubbard Model Via Dynamical Mean-Field Theory, Anshumitra Baul

LSU Doctoral Dissertations

Modeling many-body quantum systems is widely regarded as one of the most promising applications for near-term noisy quantum computers. However, in the near term, system size limitation will remain a severe barrier for applications in materials science or strongly correlated systems. A promising avenue of research is to combine many-body physics with machine learning for the classification of distinct phases. I present a workflow that synergizes quantum computing, many-body theory, and quantum machine learning (QML) for studying strongly correlated systems. In particular, it can capture a putative quantum phase transition of the stereotypical strongly correlated system, the Hubbard model. Following …

Topics In Photonic Quantum Technology: Polarization Entanglement Dynamics In Optical Fibers And Low-Light Imaging., Pratik J. Barge

LSU Doctoral Dissertations

Recent advances in quantum photonics promise transformative impacts on computing, communication, sensing, and imaging. This thesis explores two areas in photonic quantum technology: polarization entanglement dynamics in optical fibers and low-light imaging. Optical fibers are the most suitable medium for photonic qubits and long-distance entanglement distribution is a critical requirement to realize quantum technologies. We study the decay of polarization-entanglement of the Bell state photons propagating through imperfect optical fibers with spatially fluctuating refractive index. Furthermore, to extend the distribution distance, we propose the use of dynamical decoupling in the optical fiber using half waveplates and show that significant improvement …

Structural Factors Of An Electron As The Spinning Tetrahedral Structure Composed Of Fractional Charges, Polievkt Perov

College of Arts & Sciences Faculty Works

Abstract

As suggested in our papers [1,2], the elementary particles of the 1^st generation such as an electron, quarks, and neutral particles, are all spinning composite structures made of basic elementary particles of fractional charges +- e/3. The tetrahedral structure of an electron was suggested as one of the possible composite structures of that particle. The structure consists of one positive and four negative charges of magnitude e/3, with one positive and one negative charge located on the axis of rotation and three negative charges revolving about the axis. In this paper, the form factors such as the angles …

Superphenomena For Arbitrary Quantum Observables, Andrew N. Jordan, Yakir Aharonov, Daniele C. Struppa, Fabrizio Colombo, Irene Sabadini, Tomer Shushi, Jeff Tollaksen, John C. Howell, A. Nick Vamivakas

Mathematics, Physics, and Computer Science Faculty Articles and Research

Superoscillations occur when a globally band-limited function locally oscillates faster than its highest Fourier component. We generalize this effect to arbitrary quantum-mechanical operators as a weak value, where the preselected state is a superposition of eigenstates of the operator with eigenvalues bounded to a range, and the postselection state is a local position. Superbehavior of this operator occurs whenever the operator's weak value exceeds its eigenvalue bound. We give illustrative examples of this effect for total angular momentum and energy. In the latter case, we demonstrate a sequence of harmonic oscillator potentials where a finite-energy state converges everywhere on the …

Design Of Long-Distance Entanglement Distribution Protocols For Quantum Networks, Stav Haldar

LSU Doctoral Dissertations

Future quantum technologies such as quantum communication, quantum sensing, and distributed quantum computation, will rely on networks of shared entanglement between spatially separated nodes. Distributing entanglement between these nodes, especially over long distances, currently remains a challenge, due to limitations resulting from the fragility of quantum systems, such as photon losses, non-ideal measurements, and quantum memories with short coherence times. In the absence of full-scale fault-tolerant quantum error correction, which can in principle overcome these limitations, we should understand the extent to which we can circumvent these limitations. In this work, we provide improved protocols and policies for entanglement distribution …

Generation Of Kochen-Specker Contextual Sets In Higher Dimensions By Dimensional Upscaling Whose Complexity Does Not Scale With Dimension And Their Applications, Mladen Pavičić, Mordecai Waegell

Mathematics, Physics, and Computer Science Faculty Articles and Research

Recently, handling of contextual sets, in particular Kochen-Specker (KS) sets, in higher dimensions has been given an increasing attention, both theoretically and experimentally. However, methods of their generation are diverse, not generally applicable in every dimension, and of exponential complexity. Therefore, we design a dimensional upscaling method, whose complexity does not scale with dimension. As a proof of principle we generate manageable-sized KS master sets in up to 27 dimensional spaces and show that well over 32 dimensions can be reached. From these master sets we obtain an ample number of smaller KS sets. We discuss three kinds of applications …

How Are Entanglement Entropies Related To Entropy Bounds?, Emily Adlam

Philosophy Faculty Articles and Research

In this paper we seek to understand what current knowledge of entanglement entropies suggests about the appropriate way to interpret the covariant entropy bound. We first begin by arguing that just as in the classical case, a universal bound on the von Neumann entropy could have either an epistemic or ontological origin. We then consider several possible ways of explaining the bound as a consequence of features of the entanglement entropy. We discuss consider area laws in condensed matter and quantum field theory, arguing that they suggest an epistemic reading of the bound. We also discuss the ‘spacetime from entanglement’ …

The Chemistry Of Heavy Elements: Probing Relativistic Chemical Bonding, Barbara Maria Teixeira Costa Peluzo

Chemistry Theses and Dissertations

The bottommost part of the periodic table has a unique chemistry, where the high velocities of the inner-shell electrons prevent their description by the usual Schrödinger equation. The resulting so-called relativistic effects have numerous chemical implications, on both macro and microscale, ranging from physical properties to reactivity. However, experimental probes on these intriguing atoms are limited by their natural availability and, more importantly, the danger associated with their radioactivity. Quantum chemical calculations, on the other hand, face the challenge of far more complex algebra, which demands substantial computational resources. Relativistic Hamiltonians, which act over all electrons in the system, are …