arXiv subjects

Joseph Jachinowski

Publications and source records attributed to Joseph Jachinowski.

4 recordsLinked to original sources

arXiv2026

Spin-only dynamics of the multi-species nonreciprocal Dicke model

The Hepp-Lieb-Dicke model is ubiquitous in cavity quantum electrodynamics, describing spin-cavity coupling which does not conserve excitation number. Coupling the closed spin-cavity system to an environment realizes the open Dicke model, and by tuning the structure of the environment or the system-environment coupling, interesting spin-only models can be engineered. In this work, we focus on a variation of the multi-species open Dicke model which realizes mediated nonreciprocal interactions between the spin species and, consequently, a dynamical limit-cycle phase. In particular, we improve upon adiabatic elimination and, instead, employ a Redfield master equation in order to describe the effective dynamics of the spin-only system. We assess this approach at the mean-field level, comparing it both to adiabatic elimination and the full spin-cavity model, and find that the predictions are sensitive to the presence of single-particle incoherent decay. Additionally, we clarify the symmetries of the model and explore the dynamical limit-cycle phase in the case of explicit PT-symmetry breaking, finding a region of phase coexistence terminating at an codimension-two exceptional point. Lastly, we go beyond mean-field theory by exact numerical diagonalization of the master equation, appealing to permutation symmetry in order to increase the size of accessible systems. We find signatures of phase transitions even for small system sizes.

cond-mat.quant-gas↗

arXiv2025

Optical probes of coherence in two dimensional Bose gases of polaritons

Due to their photonic components, exciton-polariton systems provide a convenient platform to study the coherence properties of weakly-interacting Bose gases. In particular, optical interferometry enables the measurement of the first-order coherence function which provides information about the intrinsic correlations of the system. In this paper, we derive a universal curve for the coherent fraction of a noninteracting, equilibrium, homogeneous, two-dimensional Bose gas, with density expressed in units of the observation area, and compare to recent experimental results. Although there is a sharp transition from normal to superfluid phases in the thermodynamic limit, the coherent fraction of the gas varies continuously across this transition due to the finite system size. We find that the theory agrees nearly perfectly with the experimental data in the low-density limit with no free parameters other than the effective temperature, highly constrained by the measurements. At higher density, the experiments are consistent with standard weakly-interacting Bose gas theory. By having a theory that treats both the optical diffraction and Bose coherence, we can clearly see the effect of the quantum statistics on the coherence.

cond-mat.quant-gas↗

arXiv2024

Two dimensional arrays of Bose-Einstein condensates: interference and stochastic collapse dynamics

We demonstrate two-dimensional arrays of Bose-Einstein condensates (BECs) as a new experimental platform with parallel quantum simulation capability. A defect-free array of up to 49 BECs is formed by loading a single BEC with 50,000 atoms into 7*7 optical wells. Each BEC is prepared with independent phases, confirmed by matterwave interference. Based on BEC arrays, we realize fast determination of the phase boundary of BECs with attractive interactions. We also observe the stochastic collapse dynamics from the distribution of atom numbers in the array. We show that the collapse of a BEC can occur much faster than the averaged decay of an ensemble. The BEC arrays enable new forms of experiments to drastically increase the measurement throughput and to quantum simulate, say, large 2D Josephson-junction arrays.

cond-mat.quant-gas↗

arXiv2022

Beam Profiling with Noise Reduction From Computer Vision and Principal Component Analysis for the MAGIS-100 Experiment

MAGIS-100 is a long-baseline atom interferometer that operates as a quantum sensor. It will search for dark matter, probe fundamental quantum science, and serve as a prototype gravitational wave detector in the 0.3 to 3~Hz frequency range. The experiment uses light-pulse atom interferometry where pulses of light create the atom optics equivalents of beamsplitters and mirrors. Laser beam aberrations are a key source of systematic error for MAGIS-100, and accurately characterizing the laser beam spatial profile is therefore essential. In this paper, we describe a new and efficient beam profiling technique. We use a low-cost CMOS camera affixed to a translating and rotating optomechanical mount to image the beam, then employ computer vision and principal component analysis to minimize background noise and produce accurate beam profiles for a laser incident on a variety of aberration-inducing optical elements.

physics.ins-det↗