Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A Quantum Pen for Single Atoms

17.03.2011
Physicists at the Max Planck Institute of Quantum Optics succeeded in manipulating atoms individually in a lattice of light and in arranging them in arbitrary patterns. These results are an important step towards large scale quantum computing and for the simulation of condensed matter systems.

Physicists around the world are searching for the best way to realize a quantum computer. Now scientists of the team around Stefan Kuhr and Immanuel Bloch at the Max Planck Institute of Quantum Optics (Garching/Munich) took a decisive step in this direction. They could address and change the spin of single atoms with laser light and arrange them in arbitrary patterns (Nature 471, p. 319 (2011), DOI: 10.1038/ nature09827).


Figure 1: With the help of a laser beam, the scientists could address single atoms in the lattice of light and change their spin state. In this way they succeeded in having total control over the single atoms and in "writing" arbitrary two-dimensional patterns. MPQ


Figure 2: With the addressing scheme arbitrary patterns of atoms in the lattice can be prepared. The atomic patterns each consist of 10 - 30 single atoms that are kept in an artificial crystal of light. (High resolution images available online at www.quantum-munich.de/media) MPQ

In this way, the physicists strung the atoms along a line and could directly observe their tunnelling dynamics in a “racing duel” of the atoms. A register of hundreds of addressable quantum particles could serve for storing and processing of quantum information in a quantum computer.

In the present experiment, the scientists load laser-cooled rubidium atoms into an artificial crystal of light. These so-called optical lattices are generated by superimposing several laser beams. The atoms are kept in the lattice of light similar to marbles in the hollows of an egg carton.

Already a few months ago, the team of Stefan Kuhr and Immanuel Bloch showed that each site of the optical lattice can be filled with exactly one atom. With the help of a microscope, the scientists visualized atom by atom and thereby verified the shell-like structure of this “Mott insulator”. Now the scientists succeeded in individually addressing the atoms in the lattice and in changing their respective energy state. Using the microscope, they focused a laser beam down to a diameter of about 600 nanometers, which is just above the lattice spacing, and directed it at individual atoms with high precision.

The laser beam slightly deforms the electron shell of the addressed atom and thereby changes the energy difference between its two spin states. Atoms with a spin – i.e. an intrinsic angular momentum – behave like little magnetic needles that can align in two opposite directions. If the atoms are irradiated with microwaves that are in resonance with the modified spin transition, only the addressed atoms absorb a microwave photon, which causes their spin to flip. All other atoms in the lattice remain unaffected by the microwave field.

The scientists demonstrated the high fidelity of this addressing scheme in a series of experiments. For this purpose, the spins of all atoms along a line were flipped one after the other, by moving the addressing laser from lattice site to lattice site. After removing all atoms with a flipped spin from the trap, the addressed atoms are visible as holes, which can easily be counted. In this way, the physicists deduced that the addressing worked in 95% of the cases. Atoms at the neighbouring sites are not influenced by the addressing laser. The method provides the possibility to generate arbitrary distributions of atoms in the lattice (see figures).

Starting from an arrangement of 16 atoms that were strung together on neighbouring lattice sites like a necklace of beads, the scientists studied what happens when the height of the lattice is ramped down so far that the particles are allowed to “tunnel” according to the rules of quantum mechanics. They move from one lattice site to the other, even if their energy is not sufficient to cross the barrier between the lattice wells. “As soon as the height of the lattice has reached the point where tunnelling is possible, the particles start running as if they took part in a horse-race”, doctoral candidate Christof Weitenberg describes. “By taking snapshots of the atoms in the lattice at different times after the "starting signal", we could directly observe the quantum mechanical tunnelling-effect of single massive particles in an optical lattice for the first time”.

The new addressing technique allows many interesting studies of the dynamics of collective quantum states, as they appear in solid state systems. It also opens new perspectives in quantum information processing. “A Mott isolator with exactly one atom per lattice site acts as a natural quantum register with a few hundred quantum bits, the ideal starting point for scalable quantum information processing” as Stefan Kuhr explains. “We have shown that we can individually address single atoms. In order for the atom to suit as a quantum bit, we need to generate coherent superpositions of its two spin states. A further step is to realize elementary logical operations between two selected atoms in the lattice, so-called quantum gates.” [Olivia Meyer-Streng]

Original Publication:
Christof Weitenberg, Manuel Endres, Jacob F. Sherson, Marc Cheneau, Peter Schauß, Takeshi Fukuhara, Immanuel Bloch, and Stefan Kuhr
“Single-Spin Addressing in an Atomic Mott Insulator”
Nature 471, 319 (2011), DOI:10.1038/nature0982
Contact:
Prof. Dr. Stefan Kuhr
Max Planck Institute of Quantum Optics
Hans-Kopfermann-Straße 1
85748 Garching b. München
Germany
Phone: +49 89 32905 738
e-mail: stefan.kuhr@mpq.mpg.de
Prof. Dr. Immanuel Bloch
Chair of Experimental Physics
LMU Munich, Schellingstr. 4
80799 München, Germany, and
Max Planck Institute of Quantum Optics
Phone: +49 89 32905 138
e-mail: immanuel.bloch@mpq.mpg.de
Dr. Olivia Meyer-Streng
Press & Public Relations
Max Planck Institute of Quantum Optics
Phone: +49 - 89 / 32905 - 213
e-mail: olivia.meyer-streng@mpq.mpg.de

Dr. Olivia Meyer-Streng | Max-Planck-Institut
Further information:
http://www.quantum-munich.de

More articles from Physics and Astronomy:

nachricht Neutron star merger directly observed for the first time
17.10.2017 | University of Maryland

nachricht Breaking: the first light from two neutron stars merging
17.10.2017 | American Association for the Advancement of Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Ocean atmosphere rife with microbes

17.10.2017 | Life Sciences

Neutrons observe vitamin B6-dependent enzyme activity useful for drug development

17.10.2017 | Life Sciences

NASA finds newly formed tropical storm lan over open waters

17.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>