arXiv subjects

Reed Nessler

Publications and source records attributed to Reed Nessler.

7 recordsLinked to original sources

arXiv2025

The Kerr-Induced Superradiant Tricritical Point

The interplay of interaction and dissipation in open quantum systems can forge phase transitions beyond conventional paradigms. In the canonical quantum Rabi model, we demonstrate that a photon-photon (Kerr) interaction transforms the celebrated superradiant phase transition, inducing a line that separates continuous, second-order behavior from discontinuous, first-order regimes. Strikingly, this is not a line of tricritical points. Instead, we prove that genuine tricriticality is an isolated phenomenon, emerging only at a single, mathematically exact dissipation rate: the ``sweet spot'' of $\kappa_t^2 = (\sqrt{13}-2)/3$. Our discovery pinpoints the precise and restrictive conditions for realizing a rare multicritical point in a foundational quantum optical system, identifying this critical dissipation as a unique gateway to a higher order of criticality.

quant-ph↗

arXiv2024

A Non-Terminating Game of Beggar-My-Neighbor

We demonstrate the existence of a non-terminating game of Beggar-My-Neighbor, discovered by lead author Brayden Casella. We detail the method for constructing this game and identify a cyclical structure of 62 tricks that is reached by 30 distinct starting hands. We further present a short history of the search for this solution since the problem was posed, and a record of previously found longest terminating games. The existence of this non-terminating game provides a solution to a long-standing question which John H. Conway called an `anti-Hilbert problem.'

math.CO↗

arXiv2021

Quantum Optical Immunoassay: Upconversion Nanoparticle-based Neutralizing Assay for COVID-19

In a viral pandemic, a few important tests are required for successful containment of the virus and reduction in severity of the infection. Among those tests, a test for the neutralizing ability of an antibody is crucial for assessment of population immunity gained through vaccination, and to test therapeutic value of antibodies made to counter the infections. Here, we report a sensitive technique to detect the relative neutralizing strength of various antibodies against the SARS-CoV-2 virus. We used bright, photostable, background-free, fluorescent upconversion nanoparticles conjugated with SARS-CoV-2 receptor binding domain as a phantom virion. A glass bottom plate coated with angiotensin-converting enzyme 2 (ACE-2) protein imitates the target cells. When no neutralizing IgG antibody was present in the sample, the particles would bind to the ACE-2 with high affinity. In contrast, a neutralizing antibody can prevent particle attachment to the ACE-2-coated substrate. A prototype system consisting of a custom-made confocal microscope was used to quantify particle attachment to the substrate. The sensitivity of this assay can reach 4.0 ng/ml and the dynamic range is from 1.0 ng/ml to 3.2 {\mu}g/ml. This is to be compared to 19 ng/ml sensitivity of commercially available kits.

physics.bio-ph↗

arXiv2020

Anti-interference Computational Ghost Imaging with Pink Noise Speckle Patterns

We propose a computational ghost imaging scheme using customized pink noise speckle pattern illumination. By modulating the spatial frequency amplitude of the speckles, we generate speckle patterns with a significant positive spatial correlation. We experimentally reconstruct images using our synthesized speckle patterns in the presence of a variety of noise sources and pattern distortion and shown it is robust to noise interference. The results are compared with the use of standard white noise speckle patterns. We show that our method gives good image qualities under different noise interference situations while the traditional way fails. The proposed scheme promises potential applications in underwater, dynamic, and moving target computational ghost imaging.

physics.optics↗

arXiv2019

A general method for rotational averages

The theory of nonlinear spectroscopy on randomly oriented molecules leads to the problem of averaging molecular quantities over the random rotation. We solve this problem for arbitrary tensor rank by deriving a closed-form expression for the rotationally invariant tensor of averaged direction cosine products. From it we obtain some useful new facts about this tensor. Our results serve to speed the inherently lengthy calculations of nonlinear optics.

math-ph↗

arXiv2019

On three-dimensional rotational averages of odd-rank tensors

The recent growing interest in nonlinear optical spectroscopy in optically active medium demands the three-dimensional rotational average of high-rank tensors. In the present paper, we present a new method for finding the rotational average of odd-rank tensors in an overcomplete basis of isotropic tensors. The method is successfully applied to the rotational averages of tensors of rank 5,7,9,11.

math-ph↗

arXiv2018

Magnus expansion method for two-level atom interacting with few-cycle pulse

Using the Magnus expansion to the fourth order, we obtain analytic expressions for the atomic state of a two-level system driven by a laser pulse of arbitrary shape with small pulse area. We also determine the limitation of our obtained formulas due to limited range of convergence of the Magnus series. We compare our method to the recently developed method of Rostovtsev et al. (PRA 2009, 79, 063833) for several detunings. Our analysis shows that our technique based on the Magnus expansion can be used as a complementary method to the one in PRA 2009.

quant-ph↗