Skip to Content
Uncategorized

Now You See It: How To Spot Quantum Behavior

Distinguishing quantum behavior from its classical counterpart is harder than it sounds. Now a group of theorists have worked out how a few simple measurements can do the trick.

Imagine you want to measure the quantum behavior of electrons in some kind of nanostructure, a quantum wire, say.

You send a few electrons through the wire and measure the current. You see a few oscillations and assume they’re the Rabi oscillations you were looking for. These oscillations occur when a quantum system rapidly switches between one state and another so they’re a pretty good indicator that you’ve got some decent quantum behavior to study in your wire. Right?

Not quite. There are plenty of ways that ordinary classical currents can oscillate too. So who’s to say you haven’t got a classical current in your wire?

And therein lies the problem: how to tell a quantum current from a classical one. It’s of more than passing interesting for physicists building nanostructures designed to work as quantum playgrounds for electrons. There must be some way to easily distinguish quantum from classical behavior, but how?

Today, Neill Lambert at the Institute of Physical and Chemical Research (RIKEN) in Japan and few buddies say they’ve solved the problem. What they’ve done is “formulate a set of inequalities that would allow an experimentalist to exclude the possibility of a classical description of transport through a nanostructure.”

All an experimentalist has to do is measure the local charge in the device as well as the current flow through it. If the results violate the Lambert team’s inequalities, then there’s definitely quantum behavior in the air.

That’s a useful trick to have up your sleeve but it may have wider application. Lambert and company say that similar inequalities can be derived to test the quantum behavior of other systems such as atom-field interactions in quantum optics and the quantum behavior of networks of quantum dots, Cooper pair boxes and even molecules.

It’s this last one that really catches the eye. Testing the quantum behavior of networks of molecules is exactly the kind of thing that quantum biologists want to do. Some have even managed it in certain systems, such as light harvesting in photosynthesis.

But the experiments are hard and the results sometimes difficult to interpret. A set of inequalities for quantum behavior could make life much easier.

Ref: arxiv.org/abs/1002.3020: Distinguishing Quantum And Classical Transport Through Nanostructures

Deep Dive

Uncategorized

Embracing CX in the metaverse

More than just meeting customers where they are, the metaverse offers opportunities to transform customer experience.

Identity protection is key to metaverse innovation

As immersive experiences in the metaverse become more sophisticated, so does the threat landscape.

The modern enterprise imaging and data value chain

For both patients and providers, intelligent, interoperable, and open workflow solutions will make all the difference.

Scientists have created synthetic mouse embryos with developed brains

The stem-cell-derived embryos could shed new light on the earliest stages of human pregnancy.

Stay connected

Illustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.