A new way to control atomic interactions

A new study shows how to manipulate atoms so they interact with an unprecedented degree of control. The researchers used light and magnetic fields to program a straight line of atoms into shapes.

The shapes were created by controlling the way atoms exchange particles andsync up certain properties. Researchers can create a wide range of geometries by manipulating interactions. They found that the far ends of the straight line could be programmed to interact just as strongly as the center of the line. The ability to program nonlocal interactions to this degree, regardless of the atoms, had never been demonstrated before.

The mathematical description of how particles move and interact on the atomic scale could be a key step forward in the development of advanced technologies for computation and simulation based on the laws of quantum mechanics.

The paper demonstrates a new level of control over the programmability of interactions in a quantum mechanical system.

The study was published in the journal Nature.

Two graduate students, Eric Cooper and Avikar Periwal, are also co-lead authors of the paper. The researchers in the lab are Cooper, Kunkel and Periwal.

The team ran the experiments, devised clever ways of analyzing and visualization the data, and developed theoretical models.

We chose some simple geometries, like rings and disconnected chains, just as proof of principle, but we also formed more complex geometries, like ladder-like structures and treelike interactions, which have applications to open problems in physics.

atoms on command

The optical tables are a pair of which dominate the floorspace in the lab. The tables have electronic components strung together by wires. A metallic cylinder studded with porthole windows is the heart of one optical table. The rubidium atoms are carefully placed inside the chamber so that no other atoms can disturb them. The rubidium atoms were trapped in this airless chamber and cooled down to within whiskers of absolute zero, the lowest temperature theoretically possible where particle movement comes to a virtual standstill. The extremely cold realm just above absolute zero is where quantum mechanical effects can dominate over classical physics, and thus where the atoms can be quantum mechanically manipulated.

It is possible to get the atoms to talk to each other by shining light through the bunches of atoms. As the light strikes each atom, it conveys information between them, generating patterns called correlations, whereby every atom shares a desired quantum mechanical property. An example of a quantum mechanical property is the spin of an atom, which can have values of 0, 1, or +2.

Until recently, only two basic kinds of atomic networks could be made, but that has changed. Every atom is part of an all-to-all network. The nearest neighbor principle is where laser-suspended atoms interact most strongly with each other.

The new study by the researchers at the university shows a method that shows information over specific distances between atoms. Spatial location does not matter, and a richer set of correlations can be programmed.

With an all-to-all network, it is like I am sending a worldwide bulletin to everyone, while in a nearest-neighbor network, it is like I am only talking to the person who lives next door.

The researchers succeeded in creating correlations by controlling the frequencies of light shone at rubidium atoms and applying a magnetic field to the optical table. Each bunch of atoms along the line spin a bit faster when the magnetic field strengthens from one end of the vacuum chamber to the other. Even though each atomic bunch had a unique rotation rate, certain bunches would occasionally arrive at the same orientation. The researchers used light to measure interactions between atomic clouds. The researchers were able to generate interactions between clouds at any set of distances along the line.

The ability to control nonlocal interactions is powerful.

Benefitting from control.

One of the many applications of the Stanford team is the crafting of optimization algorithms for quantum computers, machines that rely on the laws of quantum mechanics for crunching numbers. Artificial intelligence, machine learning, cybersecurity, financial modeling, drug development, climate change forecasting, logistics and scheduling optimization are some of the applications of quantum computing. Scheduling problems could be solved by finding the shortest possible routes for deliveries or optimal scheduling of university classes with the help of quantum computer-tailored algorithms.

Testing out theories of quantum gravity is another promising application. The treelike shapes in this study were designed to serve as basic models of space-time curved by a hypothetical new concept of gravity based on quantum mechanical principles that would remake our understanding of gravity as described in Albert Einstein's theory of relativity. Black holes can also be investigated using a similar approach.

Experiments by Schleier-Smith and colleagues show that quantum states can be correlated in a way that can be harnessed for applications ranging from ultraprecise sensors to quantum computation.

We made a lot of progress with this study and we are looking to build on it.

More information: Avikar Periwal et al, Programmable interactions and emergent geometry in an array of atom clouds, Nature (2021). DOI: 10.1038/s41586-021-04156-0 Journal information: Nature Citation: A new way to control atomic interactions (2022, February 28) retrieved 28 February 2022 from https://phys.org/news/2022-02-atomic-interactions.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.