arXiv subjects

Matthew B. Squires

Publications and source records attributed to Matthew B. Squires.

9 recordsLinked to original sources

arXiv2026

From MOT to BEC using a single crossed-wire pair

We demonstrate a new magneto-optical trap (MOT) configuration using a simple pair of crossed wires rotated at 45 deg and an appropriate bias field to generate a MOT of >10^8 atoms. The same pair of wires, with slightly adjusted control parameters, is then used to magnetically trap the atoms and cool them via forced evaporative cooling into a Bose-Einstein condensate (BEC) with >10^4 atoms. We present the theoretical framework for generating a quadrupole field using a pair of crossed wires with arbitrary rotation angle, along with the atom chip design and fabrication. Finally, we describe the experimental protocols required for BEC production using only a single crossed-wire atom chip.

physics.atom-ph↗

arXiv2025

Deep Learning for Absorption-Image Analysis

The quantum state of ultracold atoms is often determined through measurement of the spatial distribution of the atom cloud. Absorption imaging of the cloud is regularly used to extract this spatial information. Accurate determination of the parameters which describe the spatial distribution of the cloud is crucial to the success of many ultracold atom applications. In this work, we present modified deep learning image classification models for image regression. To overcome challenges in data collection, we train the model on simulated absorption images. We compare the performance of the deep learning models to least-squares techniques and show that the deep learning models achieve accuracy similar to least-squares, while consuming significantly less computation time. We compare the performance of models which take a single atom image against models which use an atom image plus other images that contain background information, and find that both models achieved similar accuracy. The use of single image models will enable single-exposure absorption imaging, which simplifies experiment design and eases imaging hardware requirements.

quant-ph↗

arXiv2020

Clean, Robust Alkali Sources by Intercalation within Highly-Oriented Pyrolytic Graphite

We report the fabrication, characterization, and use of rubidium vapor dispensers based on highly-oriented pyrolytic graphite (HOPG) intercalated with metallic rubidium. Compared to commercial chromate salt dispensers, these intercalated HOPG (IHOPG) dispensers hold an order of magnitude more rubidium in a similar volume, require less than one-fourth the heating power, and emit less than one-half as many impurities. Appropriate processing permits exposure of the IHOPG to atmosphere for over ninety minutes without any adverse effects. Intercalation of cesium and potassium into HOPG have also been demonstrated in the literature, which suggests that IHOPG dispensers may also be be made for those metals.

physics.atom-ph↗

arXiv2017

Tunable axial potentials for atom chip waveguides

We present a method for generating precise magnetic potentials that can be described by a polynomial series along the axis of a cold atom waveguide near the surface of an atom chip. With a single chip design consisting of several wire pairs, various axial potentials can be created by varying the ratio of the currents in the wires, including double wells, triple wells, and pure harmonic traps with suppression of higher order terms. We use this method to design and fabricate a chip with modest experimental requirements. Finally, we use the chip to demonstrate a double well potential.

physics.atom-ph↗

arXiv2016

Ex Vacuo Atom Chip Bose-Einstein Condensate (BEC)

Ex vacuo atom chips, used in conjunction with a custom thin walled vacuum chamber, have enabled the rapid replacement of atom chips for magnetically trapped cold atom experiments. Atoms were trapped in $>2$ kHz magnetic traps created using high power atom chips. The thin walled vacuum chamber allowed the atoms to be trapped $\lesssim1$ mm from the atom chip conductors which were located outside of the vacuum system. Placing the atom chip outside of the vacuum simplified the electrical connections and improved thermal management. Using a multi-lead Z-wire chip design, a Bose-Einstein condensate was produced with an external atom chip. Vacuum and optical conditions were maintained while replacing the Z-wire chip with a newly designed cross-wire chip. The atom chips were exchanged and an initial magnetic trap was achieved in less than three hours.

physics.atom-ph↗

arXiv2010

Atom chips on direct bonded copper substrates

We present the use of direct bonded copper (DBC) for the straightforward fabrication of high power atom chips. Atom chips using DBC have several benefits: excellent copper/substrate adhesion, high purity, thick (> 100 microns) copper layers, high substrate thermal conductivity, high aspect ratio wires, the potential for rapid (< 8 hr) fabrication, and three dimensional atom chip structures. Two mask options for DBC atom chip fabrication are presented, as well as two methods for etching wire patterns into the copper layer. The wire aspect ratio that optimizes the magnetic field gradient as a function of power dissipation is determined to be 0.84:1 (height:width). The optimal wire thickness as a function of magnetic trapping height is also determined. A test chip, able to support 100 A of current for 2 s without failing, is used to determine the thermal impedance of the DBC. An assembly using two DBC atom chips to provide magnetic confinement is also shown.

physics.ins-det↗

arXiv2009

A Compact, Transportable, Microchip-Based System for High Repetition Rate Production of Bose-Einstein Condensates

We present a compact, transportable system that produces Bose-Einstein condensates (BECs) near the surface of an integrated atom microchip. The system occupies a volume of 0.4 m^3 and operates at a repetition rate as high as 0.3 Hz. Evaporative cooling in a chip trap with trap frequencies of several kHz leads to nearly pure condensates containing 1.9x10^4 87Rb atoms. Partial condensates are observed at a temperature of 1.58(8) μK, close to the theoretical transition temperature of 1.1 μK.

physics.atom-ph↗

arXiv2009

Adjustable microchip ring trap for cold atoms and molecules

We describe the design and function of a circular magnetic waveguide produced from wires on a microchip for atom interferometry using deBroglie waves. The guide is a two-dimensional magnetic minimum for trapping weak-field seeking states of atoms or molecules with a magnetic dipole moment. The design consists of seven circular wires sharing a common radius. We describe the design, the time-dependent currents of the wires and show that it is possible to form a circular waveguide with adjustable height and gradient while minimizing perturbation resulting from leads or wire crossings. This maximal area geometry is suited for rotation sensing with atom interferometry via the Sagnac effect using either cold atoms, molecules and Bose-condensed systems.

physics.atom-ph↗

arXiv2008

Collisional decoherence in trapped atom interferometers that use non-degenerate sources

The coherence time, and thus sensitivity, of trapped atom interferometers that use non-degenerate gasses are limited by the collisions between the atoms. An analytic model that describes the effects of collisions between atoms in an interferometer is developed. It is then applied to an interferometer using a harmonically trapped non-degenerate atomic gas that is manipulated with a single set of standing wave laser pulses. The model is used to find the optimal operating conditions of the interferometer and direct Monte-Carlo simulation of the interferometer is used to verify the analytic model.

physics.atom-ph↗