According to quantum mechanics, small magnetic objects called nanomagnets can exist in two distinct states (i.e. north pole up and north pole down). They can switch their state through a phenomenon called quantum tunneling.

When the nanomagnet switches its poles, the abrupt change in its magnetization can be observed with low-temperature magnetometry techniques used in del Barco’s lab. The switch is called quantum tunneling because it looks like a funnel cloud tunneling from one pole to another.

A new paper in Nature shows that two almost independent halves of a new magnetic molecule can tunnel, or switch poles, at once under certain conditions. In the process, they appear to cancel out quantum tunneling.

“It’s similar to what can be observed when two rays of light run into interference,” says University of Central Florida Professor Enrique del Barco. “Once they run into the interference you can expect darkness.”

Controlling quantum tunneling shifts could help create the quantum logic gates necessary to create quantum computers. It is believed that among the different existing proposals to obtain a practical quantum computer, the spin (magnetic moment) of solid-state devices is the most promising one.

The discovery may lead to a new generation of “Quantum Computers” that will render today’s computer and credit card encryption technology obsolete.

Consumers, credit card companies and high-tech firms rely on cryptography to protect the transmission of sensitive information. The basis for current encryption systems is that computers would need thousands of years to factor a large number, making it very difficult to do.

However, if del Barco’s observation can be fully understood and applied, scientists may have the basis to create quantum computers -- which could easily break the most complicated encryption in a matter of hours.

“This is very exciting,” del Barco said. “When we first observed it, we looked at each other and said, ‘That can’t be right.’ We did it again and again and we achieved the same result every time.”

Del Barco said the observation may foster the understanding of quantum tunneling of nanoscale magnetic systems, which could revolutionize the way we understand computation.

“And this is the case of our molecular magnets,” del Barco said. “Of course, this is far from real life yet, but is an important step in the way. We still must do more research and a lot of people are already trying to figure this out, including us. It’s absolutely invigorating.”

Article: Christopher M. Ramsey, Enrique del Barc1, Stephen Hill, Sonali J. Shah, Christopher C. Beedle, David N. Hendrickson, Quantum interference of tunnel trajectories between states of different spin length in a dimeric molecular nanomagnet, Nature Physics Published online: 2 March 2008 | doi:10.1038/nphys886