Scientists set a new record for measuring magnetic vibrations using the spin of a single atom

May 25, 2011

The lab, though it may seem quiet and insulated, can be as full of background noise as a crowded train station when we're trying to catch the announcements. Our brains can filter out the noise and focus on the message up to a certain point, but turning up the volume on the loudspeakers – improving the signal-to-noise ratio – helps as well.

Separating out the signal from the noise – increasing one while reducing the other – is so basic that much of scientific research could not take place without it. One common method, developed by the physicist Robert Dicke at Princeton University, is based on a principle similar to the one that enables radio broadcasts to pass through the noisy atmosphere. In short, one modulates electric waves (which correspond to the sound waves) one wishes to send over long distances, adding them on top of a high-frequency wave. To listen to the broadcast, one must have a receiver that is tuned to the frequency of the carrier wave (that numbered band on the FM dial), which then splits the two waves apart and amplifies the second "rider" wave – the music or talk we want to hear.

The method used by the physics labs is called "locked-in amplification." Here, too, a low-frequency, measured signal "rides" a high-frequency wave. A locked-in amplifier singles out the specific wave from the rest of the noise, "locking" onto the required signal and enabling scientists to make all sorts of accurate measurements.

To obtain good spatial resolution, one should measure with the smallest possible detector; one can't get much smaller than a single atom. The world of single , however, is governed by the laws of quantum physics, and any sort of observation in the quantum world is a complex undertaking. The Heisenberg uncertainty principle, one of the cornerstones of quantum theory, sets limits on our ability to measure with any kind of precision. But that very theory contains some clues as to how these limits can be approached.

Dr. Roee Ozeri and research students Shlomi Kotler, Nitzan Akerman, Yinnon Glickman and Anna Keselman in the Weizmann Institute's Physics of Complex Systems Department applied the rules of quantum mechanics to a single atomic-ion detector, building a quantum version of a locked-in amplifier. Using the ions' spin as a sensor, they were able to measure magnetic vibrations with a spatial resolution of a just few nanometers (a few billionths of a meter). The sensitivity of this measurement was extremely high: around 100 times better than any previous such measurement. This technique, says Ozeri, could be used in physics labs around the world to improve the sensitivity of all sorts of quantum sensors.

Explore further: Could 'Jedi Putter' be the force golfers need?

add to favorites email to friend print save as pdf

Related Stories

Researchers could herald a new era in fundamental physics

Feb 03, 2009

Cardiff University researchers who are part of a British-German team searching the depths of space to study gravitational waves, may have stumbled on one of the most important discoveries in physics according to an American ...

New Amplifier Pushes the Boundary of Quantum Physics

May 05, 2010

(PhysOrg.com) -- If powerful new quantum computers are to reach their enormous potential, they will need amplifiers capable of transmitting signals so weak they consist of a single photon. In the May 6 edition ...

Physicists move closer to the quantum limit

Apr 12, 2004

A new experiment in the US has come close to detecting quantum effects in a macroscopic object. Keith Schwab and colleagues from the National Security Agency (NSA) working at the University of Maryland have measured the vibrations ...

Probing the laws of gravity: A gravity resonance method

Apr 18, 2011

Quantum mechanical methods can now be used to study gravity: At the Vienna University of Technology (TU Vienna), a measurement method was developed, which allows to test the fundamental theories of physics.

Recommended for you

Could 'Jedi Putter' be the force golfers need?

Apr 18, 2014

Putting is arguably the most important skill in golf; in fact, it's been described as a game within a game. Now a team of Rice engineering students has devised a training putter that offers golfers audio, ...

Better thermal-imaging lens from waste sulfur

Apr 17, 2014

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...

User comments : 0

More news stories

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...