Weak Measurements And Quantum-To-Classical Transitions In Free Electron–Photon Interactions, 2023 ShanghaiTech University

#### Weak Measurements And Quantum-To-Classical Transitions In Free Electron–Photon Interactions, Yiming Pan, Eliahu Cohen, Ebrahim Karimi, Avraham Gover, Norbert Schönenberger, Tomáš Chlouba, Kangpeng Wang, Saar Nehemia, Peter Hommelhoff, Ido Kaminer, Yakir Aharonov

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

How does the quantum-to-classical transition of measurement occur? This question is vital for both foundations and applications of quantum mechanics. Here, we develop a new measurement-based framework for characterizing the classical and quantum free electron–photon interactions and then experimentally test it. We first analyze the transition from projective to weak measurement in generic light–matter interactions and show that any classical electron-laserbeam interaction can be represented as an outcome of weak measurement. In particular, the appearance of classical point-particle acceleration is an example of an amplified weak value resulting from weak measurement. A universal factor, exp(-Γ^{2}/2) , quantifies the …

Contributions Of Tunneling In 8Π-6Π Electrocyclic Cascade Reactions Of Bicyclo[4.2.0]Octa-2,4-Diene Moieties, 2023 University of San Francisco

#### Contributions Of Tunneling In 8Π-6Π Electrocyclic Cascade Reactions Of Bicyclo[4.2.0]Octa-2,4-Diene Moieties, Ishika Jain, Claire Castro, William L. Karney

*Featured Student Work*

Six-electron electrocyclic reactions usually require relatively high temperatures; however recent research has shown that such reactions can occur at significantly lower temperatures in biosynthetic and biomimetic pathways. Pathways resulting in bicyclo[4.2.0]octa-2,4-diene moieties arise from thermally allowed 8π-6π electrocyclization cascade reactions of 1,3,5,7-octatetraenes, as in the biosynthesis of endiandric acids, elysiapyrones, and numerous other natural products. We report multidimensional tunneling calculations to explore the possible contribution of heavy-atom tunneling (e.g. by carbon) to biosynthetic pathways and biomimetic syntheses, and thus to provide a more complete picture of biochemical kinetics. M06-2X/cc-pVDZ calculations on the 8π-6π cascade cyclizations of methylated octatetraene model systems …

Electromagnetically Induced Transparency In An Ensemble Of Three-Level Lambda Systems, 2023 University of Windsor

#### Electromagnetically Induced Transparency In An Ensemble Of Three-Level Lambda Systems, Sara Moezzi

*Electronic Theses and Dissertations*

Electromagnetically induced transparency (EIT) is a technique whereby a medium otherwise opaque to radiation of a particular frequency can be made transparent at that frequency by applying radiation of an appropriate second frequency. EIT demonstrates numerous current applications, with a notable focus on its utilization within the field of quantum information. Given the absence of an established theory of EIT in atomic ensembles, my primary focus is to develop theoretical models that describe both the quantum mechanical origin of EIT as well as the effect of interatomic interactions. In this thesis, I present two theoretical models of EIT in an …

Dynamics Of Spin And Charge Of Color Centers In Diamond Under Cryogenic Conditions, 2023 The Graduate Center, City University of New York

#### Dynamics Of Spin And Charge Of Color Centers In Diamond Under Cryogenic Conditions, Richard G. Monge

*Dissertations, Theses, and Capstone Projects*

Individual quantum systems in semiconductors are currently the most sought-after platform for applications in quantum science. Most notably, the nitrogen-vacancy (NV) center in diamond features a defect deep within the electronic bandgap, making it amenable for precise manipulation to help pave the way to perform fundamental quantum physics experimentation. The NV center also offers long coherence times and versatile spin-dependent fluorescent properties, making it an ideal candidate for a nanoscale magnetometer. Furthermore, multi-color excitation offers deterministic charge state manipulation. While ambient operation has been key to their appeal, bringing NVs to cryogenic conditions opens new opportunities for alternate forms of …

Nonlinear Processes In Room Temperature Exciton-Polaritons, 2023 The Graduate Center, City University of New York

#### Nonlinear Processes In Room Temperature Exciton-Polaritons, Prathmesh Deshmukh

*Dissertations, Theses, and Capstone Projects*

Strong light-matter coupling in solid state systems is an intriguing process that allows one to exploit the advantages of both light and matter. In this context, microcavities have become essential platforms for studying the strong coupling regime, where hybrid light-matter states known as exciton-polaritons form, leading to enhanced light matter interaction, modified material properties, and novel quantum phenomena. In this thesis, we explore the phenomenology of exciton-polaritons in strained TMD microcavities, 2D perovskites, fluorescent proteins and organic dyes encompassing thermalization, polariton lasing, and the observation of nonlinear effects.

Transition metal dichalcogenides (TMDs) have emerged as a remarkable class of two- …

Aspects Of The Phenomenology Of Interference That Are Genuinely Nonclassical, 2023 Technische Universität Berlin

#### Aspects Of The Phenomenology Of Interference That Are Genuinely Nonclassical, Lorenzo Catani, Matthew Leifer, Giovanni Scala, David Schmid, Robert W. Spekkens

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

Interference phenomena are often claimed to resist classical explanation. However, such claims are undermined by the fact that the specific aspects of the phenomenology upon which they are based can in fact be reproduced in a noncontextual ontological model [Catani *et al.*, arXiv:2111.13727]. This raises the question of what *other* aspects of the phenomenology of interference *do* in fact resist classical explanation. We answer this question by demonstrating that the most basic quantum wave-particle duality relation, which expresses the precise tradeoff between path distinguishability and fringe visibility, cannot be reproduced in any noncontextual model. We do this by …

Super-Resolution Microscopy With Color Centers In Diamond, 2023 University of New Mexico

#### Super-Resolution Microscopy With Color Centers In Diamond, Forrest A. Hubert

*Optical Science and Engineering ETDs*

This dissertation explores the development and application of diamond color centers, specifically the silicon-vacancy (SiV) and nitrogen-vacancy (NV) centers, in super-resolution microscopy and magnetic imaging techniques. It demonstrates the potential of SiV centers as photostable fluorophores in stimulated emission depletion (STED) microscopy, with a resolution of approximately 90 nm. The research also presents a method for nanoscale magnetic microscopy using NV centers by combining charge state depletion (CSD) microscopy with optically detected magnetic resonance (ODMR) to image magnetic fields produced by 30 nm iron-oxide nanoparticles. The individual magnetic feature width reaches ~100 nm while resolving magnetic field patterns from nanoparticles …

Nonlinear Charge And Spin Currents In Non-Centrosymmetric Electron Systems, 2023 Clemson University

#### Nonlinear Charge And Spin Currents In Non-Centrosymmetric Electron Systems, Aniruddha Pan

*All Dissertations*

In this thesis, we discuss the existence of spin and charge currents in systems with broken spin inversion symmetry proportional to the magnitude square of the driving electric and thermal fields. This outcome is predicated on symmetry considerations in the momentum space, whereby the product between the current operator and the out-of-equilibrium distribution function has to be even.

First, we derive the second-order correction to the particle distribution function $\delta f^{(2)}$ in a semi-classical approximation, considering the local change in the equilibrium distribution function caused by external fields. Our approach departs significantly from the previous theory where $\delta f^{(2)}$ is …

Photon Counting Statistics Of Classical And Quantum Light Sources, 2023 University of Arkansas-Fayetteville

#### Photon Counting Statistics Of Classical And Quantum Light Sources, Luis Felipe Morales Bultron

*Graduate Theses and Dissertations*

Multiple sources of light, including coherent light, thermal light, light from a degenerate parametric oscillation and resonance fluorescence from a two level coherently driven atom are considered for the analysis of their wait time statistics. We include the second order normalized correlation function and Mandel's Q parameter for brief discussion. A general framework to analyze the generalized conditional and unconditional wait time distributions is also obtained in order to understand the photo-count statistics of the light sources included in this work. Average and variance of wait times with respect to both unconditional and conditional wait time distribution are also obtained …

Entangled Photon Anti-Correlations Are Evident From Classical Electromagnetism, 2023 San José State University

#### Entangled Photon Anti-Correlations Are Evident From Classical Electromagnetism, Ken Wharton, Emily Adlam

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

For any experiment with two entangled photons, some joint measurement outcomes can have zero probability for a precise choice of basis. These perfect anti-correlations would seem to be a purely quantum phenomenon. It is, therefore, surprising that these very anti-correlations are also evident when the input to the same experiment is analyzed via classical electromagnetic theory. Demonstrating this quantum–classical connection for arbitrary two-photon states and analyzing why it is successful motivates alternative perspectives concerning entanglement, the path integral, and other topics in quantum foundations.

Quantum Reality With Negative-Mass Particles, 2023 Chapman University

#### Quantum Reality With Negative-Mass Particles, Mordecai Waegell, Eliahu Cohen, Avshalom C. Elitzur, Jeff Tollaksen, Yakir Aharonov

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

Physical interpretations of the time-symmetric formulation of quantum mechanics, due to Aharonov, Bergmann, and Lebowitz are discussed in terms of weak values. The most direct, yet somewhat naive, interpretation uses the time-symmetric formulation to assign eigenvalues to unmeasured observables of a system, which results in logical paradoxes, and no clear physical picture. A top–down ontological model is introduced that treats the weak values of observables as physically real during the time between pre- and post-selection (PPS), which avoids these paradoxes. The generally delocalized rank-1 projectors of a quantum system describe its fundamental ontological elements, and the highest-rank projectors corresponding to …

Conservation Laws And The Foundations Of Quantum Mechanics, 2023 Chapman University

#### Conservation Laws And The Foundations Of Quantum Mechanics, Yakir Aharonov, Sandu Popescu, Daniel Rohrlich

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

In a recent paper, [Y. Aharonov, S. Popescu, D. Rohrlich, *Proc. Natl. Acad. Sci. U.S.A.*118 e1921529118 (2021)], it was argued that while the standard definition of conservation laws in quantum mechanics, which is of a statistical character, is perfectly valid, it misses essential features of nature and it can and must be revisited to address the issue of conservation/nonconservation in individual cases. Specifically, in the above paper, an experiment was presented in which it can be proven that in some individual cases, energy is not conserved, despite being conserved statistically. It was felt however that this is worrisome and …

Quantum Stirling Heat Engine Operating In Finite Time, 2023 University of Rochester

#### Quantum Stirling Heat Engine Operating In Finite Time, Debmalya Das, George Thomas, Andrew N. Jordan

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

In a quantum Stirling heat engine, the heat exchanged with two thermal baths is partly utilized for performing work by redistributing the energy levels of the working substance. We analyze the thermodynamics of a quantum Stirling engine operating in finite time. We develop a model in which a time-dependent potential barrier changes the energy-level structure of the working substance. The process takes place under a constant interaction with the thermal bath. We further show that in the limit of slow operation of the cycle and low temperature, the efficiency of such an engine approaches Carnot efficiency. We also show that …

Entanglement In The Hawking Effect: From Astrophysical To Optical Black Holes, 2023 Louisiana State University at Baton Rouge

#### Entanglement In The Hawking Effect: From Astrophysical To Optical Black Holes, Dimitrios Kranas

*LSU Doctoral Dissertations*

The Hawking effect is an exciting physical prediction lying at the intersection of the two most successful theories of the past century, namely, Einstein’s theory of relativity and quantum mechanics. In this dissertation, we put special emphasis on the quantum aspects of the Hawking process encoded in the entanglement shared by the emitted fluxes of created quanta. In particular, we employ sharp tools from quantum information theory to quantify the entanglement produced by the Hawking effect throughout the black hole evaporation process. Our framework allows us to extend previous calculations of entanglement to a larger set of cases, for instance, …

Adaptive Quantum Information Processing In Non-Equilibrium Environments, 2023 Louisiana State University

#### Adaptive Quantum Information Processing In Non-Equilibrium Environments, Arshag Danageozian

*LSU Doctoral Dissertations*

Solid state and condensed matter systems, such as diamond impurities, superconductors, quantum dots, and ion traps, constitute important physical platforms for various applications in quantum information processing (QIP). However, it has consistently been shown that all such modern platforms suffer from non-equilibrium behavior on timescales that are relevant for many important QIP tasks. The causes range from intrinsic non-equilibrium dynamics (e.g. in diamond) to the presence of various impurities with their own internal dynamics (e.g. in superconductors and quantum dots) or variations in the control fields used to stabilize the quantum matter (e.g. in ion traps). When reserving degrees of …

Human And Technical Factors In The Adoption Of Quantum Cryptographic Algorithms, 2023 Rose-Hulman Institute of Technology

#### Human And Technical Factors In The Adoption Of Quantum Cryptographic Algorithms, Alyssa Pinkston

*Mathematical Sciences Technical Reports (MSTR)*

The purpose of this research is to understand what factors would cause users to choose quantum key distribution (QKD) over other methods of cryptography. An Advanced Encryption Standard (AES) key can be exchanged through communication using the Rivest, Shamir, Adleman (RSA) cryptographic algorithm, QKD, or post-quantum cryptography (PQC). QKD relies on quantum physics where RSA and PQC use complex mathematics to encrypt data. The BB84 quantum cryptographic protocol involves communication over a quantum channel and a public channel. The quantum channel can be technically attacked by beamsplitting or intercept/resend. QKD, like other forms of cryptography, is vulnerable to social attacks …

Aharonov–Bohm Effect With An Effective Complex-Valued Vector Potential, 2023 University of Bristol

#### Aharonov–Bohm Effect With An Effective Complex-Valued Vector Potential, Ismael L. Paiva, Yakir Aharonov, Jeff Tollaksen, Mordecai Waegell

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

The interaction between a quantum charge and a dynamic source of a magnetic field is considered in the Aharonov–Bohm (AB) scenario. It is shown that, in weak interactions with a post-selection of the source, the effective vector potential is, generally, complex-valued. This leads to new experimental protocols to detect the AB phase before the source is fully encircled. While this does not necessarily change the nonlocal status of the AB effect, it brings new insights into it. Moreover, we discuss how these results might have consequences for the correspondence principle, making complex vector potentials relevant to the study of classical …

Effective Non-Hermiticity And Topology In Markovian Quadratic Bosonic Dynamics, 2023 Dartmouth College

#### Effective Non-Hermiticity And Topology In Markovian Quadratic Bosonic Dynamics, Vincent Paul Flynn

*Dartmouth College Ph.D Dissertations*

Recently, there has been an explosion of interest in re-imagining many-body quantum phenomena beyond equilibrium. One such effort has extended the symmetry-protected topological (SPT) phase classification of non-interacting fermions to driven and dissipative settings, uncovering novel topological phenomena that are not known to exist in equilibrium which may have wide-ranging applications in quantum science. Similar physics in non-interacting bosonic systems has remained elusive. Even at equilibrium, an "effective non-Hermiticity" intrinsic to bosonic Hamiltonians poses theoretical challenges. While this non-Hermiticity has been acknowledged, its implications have not been explored in-depth. Beyond this dynamical peculiarity, major roadblocks have arisen in the search …

Rigorous Analysis Of Markov Processes With Applications To Quantum Information, 2023 University of New Mexico

#### Rigorous Analysis Of Markov Processes With Applications To Quantum Information, Samuel Edwin Slezak

*Physics & Astronomy ETDs*

**We present a rigorous analysis of the rapid convergence of techniques based on Markov chains for the simulation of thermal quantum systems. We show that a classical computing algorithm called path integral Monte Carlo is capable of simulating thermal states of transverse field Ising models above a threshold temperature by demonstrating the existence of a rapidly mixing Markov chain. We then turn to quantum computing algorithms and show that an idealized version of quantum Metropolis sampling can efficiently simulate systems that satisfy the eigenstate thermalization hypothesis. In a related result, we find a class of stoquastic frustration free Hamiltonians that …**

Making The Transition To Post-Quantum Cryptography, 2023 Cleveland State University

#### Making The Transition To Post-Quantum Cryptography, J. Simon Richard

*The Downtown Review*

Without intervention, quantum computing could threaten the security of a large portion of our internet in the near future. However, solutions exist. This paper, which is intended for a general audience, provides a wider context for our current state of quantum-preparedness amid the transition from classical cryptosystems to post-quantum cryptosystems—cryptographic algorithms that can resist the attacks of quantum computers. It will also submit a possible way forward inspired by the actions taken around the globe to prevent the millennium (or Y2K) bug.