Navigation Links
Progress in quantum computing, qubit by qubit

Cambridge, Mass. October 9, 2011 Engineers and physicists at Harvard have managed to capture light in tiny diamond pillars embedded in silver, releasing a stream of single photons at a controllable rate.

The advance represents a milestone on the road to quantum networks in which information can be encoded in spins of electrons and carried through a network via light, one photon at a time.

The finding was published in Nature Photonics, appearing online on October 9.

"We can make the emission of photons faster, which will allow us to do more processing per secondfor example, more computationsin the future quantum network," explains principal investigator Marko Lončar, Associate Professor of Electrical Engineering at the Harvard School of Engineering and Applied Sciences (SEAS).

The device Lončar's research team has built consists of parallel rows of tiny, nanofabricated diamond posts, embedded in a layer of silver, that can each act as a single photon source.

By removing the silver wrapping from their nanostructures, the team was also able to achieve a slower release of photons, which is of interest for probing the dynamics of the quantum system.

The breakthrough takes advantage of imperfections in the diamond's crystal lattice, where carbon atoms are replaced by other elements. To the naked eye, these imperfections can appear as discolorations in the diamond, turning it yellow in the case of nitrogen. Occasionally, there is also a vacancy (missing carbon atom) next to the nitrogen atom.

Each nitrogen-vacancy imperfection can serve as a nearly perfect quantum emitter, capable of emitting red photons one by one, even at room temperature. The technology is a promising candidate for realization of scalable, on-chip quantum networks.

"The color centers in diamond are very interesting as qubits for quantum information processing, where they can be used as memory to store information," says Lončar. "More importantly, they can be interrogatedthey can be written into and read outwith light."

Lončar's team fabricates diamond posts that contain negatively charged nitrogen vacancy centers, which can absorb light and hold its energy for a given amount of time, finally releasing it in the form of photons.

"The rate at which photons are emitted can be controlled by carefully nano-engineering the center's surrounding," says co-author Irfan Bulu, a research associate in the Lončar group. Attaining fine control of that release, however, has been difficult.

"One of the main challenges has been the efficiency with which you can write information into the spin of these color centers, as well as the efficiency with which you can collect photons emitted from the color centers," explains co-author Jennifer Choy, a graduate student in Lončar's lab at SEAS. "The other challenge has been the ratehow quickly you can perform these processes."

Previous work from Lončar's group solved the collection efficiency problem by using diamond nanowires to channel and direct the flow of photons. The new research manipulates the radius of diamond pillars and adds the silver coating. The diamond-silver construction acts as an optical nanoresonator, creating a strong electromagnetic field around the emitter and offering a new level of control over the rate of emission.

Moreover, the device functions at room temperaturean essential requirement for practical computing applicationsand the nanostructured chips are fully scalable.

"We've designed everything in parallel in a massive system, which allows us to make thousands or millions of devices with more or less the same properties, and we use conventional microfabrication and nanofabrication techniques, unlike what has been done in this field before," says Birgit Hausmann, a graduate student in Lončar's lab at SEAS and one of the co-authors.


Contact: Caroline Perry
Harvard University

Related biology technology :

1. Advanced Life Sciences to Host Conference Call to Update Investors on Progress of Corporate Initiatives on October 1, 2008
2. DuPont Meeting Significant 2008 Milestones in Progressing Advanced Biofuels
3. BioElectronics Announces Significant Progress in Canadian and International Distribution
4. Peregrine Pharmaceuticals Reports Progress in Its Phase II Trial of Bavituximab Plus Docetaxel in Patients With Advanced Breast Cancer
5. MedImmune Presents Data Highlighting its Progressive Inflammatory Disease Portfolio at the 72nd Annual Meeting of the American College of Rheumatology
6. Progress toward new storage media
7. Vical Reports Third Quarter 2008 Financial Results and Continued Progress in Product Development Programs
8. Genomic Health Announces Third Quarter 2008 Financial Results and Business Progress
9. New Generation Biofuels Announces Test Burn Agreement With Progress Energy Florida
10. MAP Pharmaceuticals Provides Update on Progress of Two Phase 3 Clinical Programs
11. Synvista Therapeutics Announces Progress in Phase 2 Clinical Trial Program for Alagebrium
Post Your Comments:
Related Image:
Progress in quantum computing, qubit by qubit
(Date:11/25/2015)... November 26, 2015 ... Market 2016 - 2020 report analyzes that automating ... and quality in long-term samples, minimizing manual errors, ... Automation minimizes manual errors such as mislabeling or ... Further, it plays a vital role in blood ...
(Date:11/25/2015)... -- Neurocrine Biosciences, Inc. (Nasdaq: NBIX ) announced today ... Neurocrine Biosciences, will be presenting at the 27th Annual ... . .   Listeners ... prior to the presentation to download or install any ... available on the website approximately one hour after the ...
(Date:11/25/2015)... ... November 25, 2015 , ... ... were featured on AngelList early in their initial angel funding process. Now, they ... for individuals looking to make early stage investments in the microbiome space. ...
(Date:11/24/2015)... , Nov. 24, 2015 /CNW/ - iCo Therapeutics ("iCo" ... reported financial results for the quarter ended September ... in Canadian dollars and presented under International Financial ... States ," said Andrew Rae , ... regarding iCo-008 are not only value enriching for ...
Breaking Biology Technology:
(Date:11/18/2015)... 18, 2015  As new scientific discoveries deepen our ... other healthcare providers face challenges in better using that ... In addition, as more children continue to survive pediatric ... and old age. John M. Maris, M.D ... of Philadelphia (CHOP) . --> John ...
(Date:11/17/2015)... 17, 2015  Vigilant Solutions announces today that Mr. ... of Directors. --> --> ... from the partnership at TPG Capital, one of the ... $140 Billion in revenue.  He founded and led TPG,s ... TPG companies, from 1997 to 2013.  In his first ...
(Date:11/12/2015)... 2015  Arxspan has entered into an agreement ... for use of its ArxLab cloud-based suite of ... partnership will support the institute,s efforts to electronically ... information internally and with external collaborators. The ArxLab ... the Institute,s electronic laboratory notebook, compound and assay ...
Breaking Biology News(10 mins):