Atomtronics...

[Credit: C. Suplee/NIST]

Topics: Atomic Physics, Bose-Einstein Condensate, Diversity in Science, Nanotechnology, Quantum Mechanics, Semiconductor Technology, Women in Science

Gretchen Campbell describes the new and emerging field of atomtronics, which seeks to make circuit-like devices with extremely cold atoms.

When Gretchen Campbell entered graduate school in 2001, Bose-Einstein condensates (BECs) were still a novelty. Today, says Campbell, an atomic physicist at the Joint Quantum Institute (JQI) of the University of Maryland and the National Institute of Standards and Technology (NIST), researchers have moved beyond exploring the properties of these extremely cold collections of atoms, which behave like giant quantum waves. Instead, they’re using BECs as tools to study other kinds of physics. In Campbell’s field of atomtronics, for example, scientists are manipulating BECs with light to engineer systems that mimic transistors and other circuit components, or function as entirely new devices. The group she leads at the JQI has fabricated and studied a tiny ring of BEC intercepted in one spot by laser light that acts as a barrier for the atoms. Rotating this spot around the ring causes the system to behave like a superconducting quantum interference device, or SQUID, a sensitive detector of magnetic fields. Campbell, who initially wanted to be a vet, spoke with Physics about what attracted her to atomic physics and the many experiments that she’d like to try with ring-shaped BECs.

Image Source: Improved Isotope Enrichment, #P4TC

How do you describe atomtronics to someone outside of physics?

One of the properties of ultracold atoms is that they behave as a superfluid. People have proposed that it’s possible that we could use this superfluid behavior to create circuits, in which the atoms take the place of electrons. There have been some proposals to create analogs of conventional electronics. Others say, hey, let’s take advantage of the qualities of ultracold atoms that are distinct from electrons and see if we can make new types of devices and sensors.

What are these distinct qualities?

Since BECs behave as a superfluid, this means that if we create currents in our atomtronic circuits, they will persist, in much the same way that a superconducting current will persist in a loop of superconducting wire. Now, with BECs you have coherence, which you wouldn’t have in, say, a conventional electronic system. We also have the advantage that we can control the internal states of the atoms.

Image Source: NASA Cold Atom Laboratory, International Space Station

I take it there aren’t any practical atomtronics devices in existence yet?

Yeah, not at all.

If you had to guess, what do you think the first one might be?

I don’t really know. We’ve demonstrated a proof-of-principle rotation sensor: In our ring-shaped device, the current of the BEC will change when the rotating laser spot reaches a critical rotation rate. The rate associated with this transition will shift if the BEC itself experiences a rotational acceleration, so measuring the shift allows us to measure rotation. But because our device is so small—the rings are only 100 micrometers—it’s perhaps best suited for measuring changes in acceleration on a very small length scale. One always hopes that down the road there will be a practical application, but right now I’d say atomtronics is completely driven by fundamental physics.

APS Physics: Things You Can Do with a Loop of Cold Atoms, Jessica Thomas