Featured Research

from universities, journals, and other organizations

Breakthrough In Quantum Mechanics: Superconducting Electronic Circuit Pumps Microwave Photons

Date:
August 5, 2008
Source:
University of California - Santa Barbara
Summary:
Researchers have recently reached what they are calling a milestone in experimental quantum mechanics. They have used a superconducting electronic circuit known as a Josephson phase qubit to controllably pump microwave photons, one at a time, into a superconducting microwave resonator.

A close-up of one of the circuits used in the quantum mechanics experiment.
Credit: UCSB photo

Researchers at UC Santa Barbara have recently reached what they are calling a milestone in experimental quantum mechanics.

In a paper published in the July 17 issue of the journal Nature, UCSB physicists Max Hofheinz, John Martinis, and Andrew Cleland documented how they used a superconducting electronic circuit known as a Josephson phase qubit, developed in Martinis's lab, to controllably pump microwave photons, one at a time, into a superconducting microwave resonator.

Up to six photons were pumped into and stored in the resonator, and their presence was then detected using the qubit, which acts like an electronic atom, as an analyzer. The photon number states, known as Fock states, have never before been controllably created, said Cleland.

"These states are ones you learn about in introductory quantum mechanics classes, but no one has been able to controllably create them before," Cleland said.

Using the same technique, the researchers also created another type of special state, known as a coherent state, in the superconducting resonator. These states are relatively easily generated, and appear to behave in a completely non-quantum mechanical fashion, but by using the same analysis technique, the UCSB researchers were able to demonstrate the expected underlying quantum behavior.

Hofheinz, a postdoctoral researcher from Germany who's been at UCSB for the past year working on this project, explained how the resonator works.

"The resonator is the electrical equivalent of a pendulum," Hofheinz said. "In quantum mechanics the energy, or amplitude of motion of this pendulum, only comes in finite steps, in quanta. We first carefully prepared the resonator in these quantum states, and showed we could do this controllably and then measure the states. Then we 'kicked' the pendulum directly, a method where the amplitude can take on any value, and appears to not be limited to these quanta. But when we look at the resonator with our qubit, we see that the amplitude does come in steps, but that the resonator is actually in several such states at the same time, so that on average it looks like it is not limited to the quantum states."

Hofheinz spent several months in the UCSB Nanofabrication cleanroom fabricating the device used for the experiment. "This resonator, once you excite it, has to 'swing' for a very long time," he explained. "The first samples I fabricated stopped oscillating very quickly. We had to work to rearrange the fabrication method to get the resonator to oscillate longer."

He then fine-tuned the microwave electronics built by Martinis's group to emit the precisely shaped signals necessary to produce these exciting results.

Martinis, Cleland, and Hofheinz say that their research could help in the quest to build a possible quantum computer, which both the government and industry have been seeking for a long time. A quantum computer could be used to break – or make – the encryption codes most heavily used for secure communication.

"Harmonic oscillators might allow us to get a quantum computer built more quickly," Cleland said.

"I think if they really build one of these quantum computers, there will definitely be resonators in them," Hofheinz said.


Story Source:

The above story is based on materials provided by University of California - Santa Barbara. Note: Materials may be edited for content and length.


Cite This Page:

University of California - Santa Barbara. "Breakthrough In Quantum Mechanics: Superconducting Electronic Circuit Pumps Microwave Photons." ScienceDaily. ScienceDaily, 5 August 2008. <www.sciencedaily.com/releases/2008/08/080805150812.htm>.
University of California - Santa Barbara. (2008, August 5). Breakthrough In Quantum Mechanics: Superconducting Electronic Circuit Pumps Microwave Photons. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2008/08/080805150812.htm
University of California - Santa Barbara. "Breakthrough In Quantum Mechanics: Superconducting Electronic Circuit Pumps Microwave Photons." ScienceDaily. www.sciencedaily.com/releases/2008/08/080805150812.htm (accessed October 21, 2014).

Share This



More Matter & Energy News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Gulfstream G500, G600 Unveiling

Gulfstream G500, G600 Unveiling

Flying (Oct. 20, 2014) Watch Gulfstream's public launch of the G500 and G600 at their headquarters in Savannah, Ga., along with a surprise unveiling of the G500, which taxied up under its own power. Video provided by Flying
Powered by NewsLook.com
Japanese Scientists Unveil Floating 3D Projection

Japanese Scientists Unveil Floating 3D Projection

Reuters - Innovations Video Online (Oct. 20, 2014) Scientists in Tokyo have demonstrated what they say is the world's first 3D projection that floats in mid air. A laser that fires a pulse up to a thousand times a second superheats molecules in the air, creating a spark which can be guided to certain points in the air to shape what the human eye perceives as an image. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com
What We Know About Microsoft's Rumored Smartwatch

What We Know About Microsoft's Rumored Smartwatch

Newsy (Oct. 20, 2014) Microsoft will reportedly release a smartwatch that works across different mobile platforms, has a two-day battery life and tracks heart rate. Video provided by Newsy
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:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

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