Featured Research

from universities, journals, and other organizations

Quantum computer calculates exact energy of molecular hydrogen

Date:
January 14, 2010
Source:
Harvard University
Summary:
In an important first for a promising new technology, scientists have used a quantum computer to calculate the precise energy of molecular hydrogen. This groundbreaking approach to molecular simulations could have profound implications not just for quantum chemistry, but also for a range of fields from cryptography to materials science.

In an important first for a promising new technology, scientists have used a quantum computer to calculate the precise energy of molecular hydrogen. This groundbreaking approach to molecular simulations could have profound implications not just for quantum chemistry, but also for a range of fields from cryptography to materials science.

"One of the most important problems for many theoretical chemists is how to execute exact simulations of chemical systems," says author Alαn Aspuru-Guzik, assistant professor of chemistry and chemical biology at Harvard University. "This is the first time that a quantum computer has been built to provide these precise calculations."

The work, described January 10 in Nature Chemistry, comes from a partnership between Aspuru-Guzik's team of theoretical chemists at Harvard and a group of experimental physicists led by Andrew White at the University of Queensland in Brisbane, Australia. Aspuru-Guzik's team coordinated experimental design and performed key calculations, while his partners in Australia assembled the physical "computer" and ran the experiments.

"We were the software guys," says Aspuru-Guzik, "and they were the hardware guys."

While modern supercomputers can perform approximate simulations of simple molecular systems, increasing the size of the system results in an exponential increase in computation time. Quantum computing has been heralded for its potential to solve certain types of problems that are impossible for conventional computers to crack.

Rather than using binary bits labeled as "zero" and "one" to encode data, as in a conventional computer, quantum computing stores information in qubits, which can represent both "zero" and "one" simultaneously. When a quantum computer is put to work on a problem, it considers all possible answers by simultaneously arranging its qubits into every combination of "zeroes" and "ones."

Since one sequence of qubits can represent many different numbers, a quantum computer would make far fewer computations than a conventional one in solving some problems. After the computer's work is done, a measurement of its qubits provides the answer.

"Because classical computers don't scale efficiently, if you simulate anything larger than four or five atoms -- for example, a chemical reaction, or even a moderately complex molecule -- it becomes an intractable problem very quickly," says author James Whitfield, research assistant in chemistry and chemical biology at Harvard. "Approximate computations of such systems are usually the best chemists can do."

Aspuru-Guzik and his colleagues confronted this problem with a conceptually elegant idea.

"If it is computationally too complex to simulate a quantum system using a classical computer," he says, "why not simulate quantum systems with another quantum system?"

Such an approach could, in theory, result in highly precise calculations while using a fraction the resources of conventional computing.

While a number of other physical systems could serve as a computer framework, Aspuru-Guzik's colleagues in Australia used the information encoded in two entangled photons to conduct their hydrogen molecule simulations. Each calculated energy level was the result of 20 such quantum measurements, resulting in a highly precise measurement of each geometric state of molecular hydrogen.

"This approach to computation represents an entirely new way of providing exact solutions to a range of problems for which the conventional wisdom is that approximation is the only possibility," says Aspuru-Guzik.

Ultimately, the same quantum computer that could transform Internet cryptography could also calculate the lowest energy conformations of molecules as complex as cholesterol.

Aspuru-Guzik and Whitfield's Harvard co-authors on the Nature Chemistry paper are Ivan Kassal, Jacob D. Biamonte, and Masoud Mohseni. Financial support was provided by the US Army Research Office and the Australian Research Council Federation Fellow and Centre of Excellence programs. Aspuru-Guzik recently received support from the DARPA Young Investigator Program, the Alfred P. Sloan Foundation, and the Camille and Henry Dreyfus Foundation to pursue research towards practical quantum simulators.


Story Source:

The above story is based on materials provided by Harvard University. Note: Materials may be edited for content and length.


Journal Reference:

  1. B. P. Lanyon, J. D. Whitfield, G. G. Gillett, M. E. Goggin, M. P. Almeida, I. Kassal, J. D. Biamonte, M. Mohseni, B. J. Powell, M. Barbieri, A. Aspuru-Guzik & A. G. White. Towards quantum chemistry on a quantum computer. Nature Chemistry, 2010; DOI: 10.1038/nchem.483

Cite This Page:

Harvard University. "Quantum computer calculates exact energy of molecular hydrogen." ScienceDaily. ScienceDaily, 14 January 2010. <www.sciencedaily.com/releases/2010/01/100110151331.htm>.
Harvard University. (2010, January 14). Quantum computer calculates exact energy of molecular hydrogen. ScienceDaily. Retrieved August 21, 2014 from www.sciencedaily.com/releases/2010/01/100110151331.htm
Harvard University. "Quantum computer calculates exact energy of molecular hydrogen." ScienceDaily. www.sciencedaily.com/releases/2010/01/100110151331.htm (accessed August 21, 2014).

Share This




More Computers & Math News

Thursday, August 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Families Can Now Ask Twitter To Remove Photos Of Deceased

Families Can Now Ask Twitter To Remove Photos Of Deceased

Newsy (Aug. 20, 2014) — In the wake of a high-profile harassment case, Twitter says family members can ask for photos of dying or dead relatives to be taken down. Video provided by Newsy
Powered by NewsLook.com
Ballmer Leaves Microsoft's Board, Has Advice For Nadella

Ballmer Leaves Microsoft's Board, Has Advice For Nadella

Newsy (Aug. 19, 2014) — In a letter to Microsoft CEO Satya Nadella, Ballmer said he's leaving the board of directors and offered tips on how the company can be successful. Video provided by Newsy
Powered by NewsLook.com
What Google Can Gain From Special Accounts For Children

What Google Can Gain From Special Accounts For Children

Newsy (Aug. 19, 2014) — Google will reportedly offer official accounts for children younger than 13 years old. Video provided by Newsy
Powered by NewsLook.com
Breakingviews: Ebola's Economic Impact Could Eclipse SARS

Breakingviews: Ebola's Economic Impact Could Eclipse SARS

Reuters - Business Video Online (Aug. 18, 2014) — The virus ravaging Africa has yet to spread elsewhere. Yet Asia’s SARS crisis in 2003 showed how changes to behaviour can hurt the economy more than the actual disease, says Breakingviews' Una Galani. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins