Quantum oscillator responds to pressure

Oct 14, 2012
Frequency spectra are plotted versus mechanical deformation in the diagram. Every atomic quantum system leaves a characteristic white line. Credit: KIT / CFN

In the far future, superconducting quantum bits might serve as components of high-performance computers. Today already do they help better understand the structure of solids, as is reported by researchers of Karlsruhe Institute of Technology in the Science magazine. By means of Josephson junctions, they measured the oscillations of individual atoms "tunneling" be-tween two positions. This means that the atoms oscillated quantum mechanically. Deformation of the specimen even changed the frequency.

"We are now able to directly control the frequencies of individual tunneling atoms in the solid," say Alexey Ustinov and Georg Weiß, Professors at the Physikalisches Institut of KIT and members of the Center for Functional Nanostructures CFN. Metaphorically speaking, the researchers so far have been confronted with a closed box. From inside, different clattering noises could be heard. Now, it is not only possible to measure the individual objects contained, but also to change their physical properties in a controlled manner.

The specimen used for this purpose consists of a superconducting ring interrupted by a nanometer-thick non-conductor, a so-called . The qubit formed in this way can be switched very precisely between two quantum states. "Interestingly, such a Josephson couples to the other atomic in the non-conductor," explains Ustinov. "And we measure their tunneling frequencies via this coupling."

At temperatures slightly above , most sources of noise in the material are switched off. The only remaining noise is produced by atoms of the material when they jump between two equivalent positions. "These frequency spectra of atom jumps can be measured very precisely with the Josephson junction," says Ustinov. "Metaphorically speaking, we have a microscope for the of individual atoms."

In the experiment performed, 41 jumping atoms were counted and their frequency spectra were measured while the specimen was bent slightly with a piezo element. Georg Weiß explains: "The atomic dis-tances are changed slightly only, while the frequencies of the tunneling atoms change strongly." So far, only the sum of all tunneling atoms could be measured. The technology to separately switch atomic tunneling systems only emerged a few years ago. The new method developed at KIT to control atomic quantum systems might provide valuable insights into how qubits can be made fit for applica-tion. However, the method is also suited for studying materials of conventional electronic components, such as transistors, and estab-lishing the basis of further miniaturization.

Explore further: Entanglement made tangible

More information: DOI: 10.1126/science.1226487

Related Stories

Scientists view a quantum jump in real time

Apr 11, 2011

(PhysOrg.com) -- For more than two decades, scientists have been "watching" electrons in atoms make the jump between energy levels in real time. "Atoms have energy levels, and when electrons 'jump' from one level to another, ...

Towards hybrid quantum systems

May 16, 2012

EU-funded scientists made advances in the development of a hybrid quantum system (HQS) by combining different quantum technologies.

Tuning in to noisy interference

Jul 29, 2011

Establishing a detailed knowledge of the noise properties of superconducting systems is an important step towards the development of quantum computers, which will enable new types of computing. However, the ...

German researchers take a look inside molecules

Aug 20, 2010

Looking at individual molecules through a microscope is part of nanotechnologists' everyday lives. However, it has so far been difficult to observe atomic structures inside organic molecules. In the renowned ...

Recommended for you

Entanglement made tangible

Sep 30, 2014

EPFL scientists have designed a first-ever experiment for demonstrating quantum entanglement in the macroscopic realm. Unlike other such proposals, the experiment is relatively easy to set up and run with existing semiconductor ...

Putting the squeeze on quantum information

Sep 25, 2014

Canadian Institute for Advanced Research researchers have shown that information stored in quantum bits can be exponentially compressed without losing information. The achievement is an important proof of principle, and could ...

Are weak values quantum? Don't bet on it

Sep 24, 2014

(Phys.org) —New work asserts that a key technique used to probe quantum systems may not be so quantum after all, according to Perimeter postdoctoral researcher Joshua Combes and his colleague Christopher ...

User comments : 0