of atoms for the first time
Yale physicists created a "squeezed state" of atoms using Bose-Einstein Condensate (BEC), a sample of rubidium atoms so cold that all of the atoms collapse into a single quantum state.
The results of their study, published in a recent issue of Science, may lead to improvements in the field of precision measurement and could improve navigational systems on planes and ships.
"Our experiments are the first to observe number-squeezed states in a sample of atoms," says Chad Orzel, postdoctoral associate in physics at Yale and first author on the study. "Combining the number-squeezed states that we make with the techniques used in atom interferometry, we hope to dramatically improve the sensitivity of detectors for rotation and acceleration, and gradients in gravity. Accelerometers and gyroscopes (rotation detectors) are currently used in navigation systems for planes and ships, and gravity gradiometers have applications in submarine navigation and in locating ore deposits for mining."
Mark Kasevich, a collaborator on the study, says creating a squeezed state of atoms is like playing a game of modified ice hockey, using a special puck and a very narrow goal. "The object of the game is to get the puck into the goal, but in this modified game, the puck diameter is initially wider than the width of the goal, making it nearly impossible to score a goal," Kasevich says. "But if the puck is made of a deformable material, it could be squeezed into a long, thin, cigar-like shape. Although the puck's length greatly exceeds its width, if the puck is shot head-on into the goal, it could now go through. At this point we don't care that the puck is elongated; so long as its width is narrower than the width of the goal, we can score."
Kasevich says many quantum-mechanical precision measurements are similar to this. "Often we can trade off a parameter we care about in one dimension, such as the number of atoms or the width of the puck, for something we don't care about in another dimension, such as the phase of the field or the length of the puck, to enable an outcome which would have not been possible with the non-squeezed state."
The "squeezing" is a metaphor that describes a way of working around the limits of the Heisenberg Uncertainty Principle, which places a limit on how accurately the value of two complementary physical quantities can be measured. The Uncertainty Principle states that it is impossible to know both the exact position and the velocity of a particle. "If we make a better measurement of the position, we lose our knowledge of how fast the particle is moving, and vice versa," says Orzel.
The Uncertainty Principle also states that there is a similar relationship between the number of particles in a given state and a quantum-mechanical property of those particles referred to as the "phase" of that state. "If we make a very precise measurement of the number of particles we have, we lose all information about the associated phase," says Orzel. "In typical real-world situations, both the phase and the number are known reasonably well, but are slightly uncertain."
Orzel and collaborators loaded a BEC into an array of atom traps created by a single laser beam. By manipulating the intensity of the trapping laser and the strength of the interactions between the atoms, they were able to reduce the quantum uncertainty in the number of atoms in a single well from ± 50 atoms to± 2 atoms.
"Quantum states of this type, with reduced uncertainty in the number of particles and increased uncertainty in the phase, are called 'squeezed states,' and have been studied extensively in light," says Orzel. "This is the first time anyone has seen number-squeezing in atoms."
The number-squeezed states produced in the laboratory have the potential to dramatically improve the sensitivity of detectors based on atom interferometry. Atom-interferometric detectors for rotation, acceleration and gravity gradients are already as good as state-of-the art detectors based on more traditional means.
"The use of squeezed states in atom interferometry could improve the sensitivity by an order of a magnitude or more," Kasevich says.
In addition to Orzel and Kasevich, other researchers on the study at Yale included Ari Tuchman, Mathew Fenselau and Masami Yasuda, who is now at Tokyo University.
-- By Karen Peart
T H I S
Bulletin Home
W E E K ' SS T O R I E S
Alcohol is beneficial for elderly hearts
Undergraduate-led ventures win Y50K business plan competition
Weekend honors '300 Years of Creativity and Discovery' at Yale
MEDICAL CENTER NEWSBlood pressure medication helps dialysis patients, study shows
Medical school administrator Merle Waxman is featured in new book . . .
Therapeutic benefits of light may be traced to body's tissues
Scientists create squeezed state of atoms for the first time
Museum's gifts aid children in scientific discovery
Symposium marks Graphic Design Program's 50th year
Juniors win awards for their scholarship, contributions
Two Eli football stars are tapped in the NFL draft
Drama school ends its season with Wilder's 'Our Town,' . . .
Pictures from a Convocation: A Photo Essay
Three engineering alumni honored with YSEA awards
Theologian to discuss 'God, the Open and the Void' in Litowitz Lecture
Dorothee Metlitzki dies; scholar played role in Israel's founding
Anita Golden Pepper, advocate for health care rights, dies
Yale affiliates honored for their community service
Lecture to look at 'Feminism & Love for the Church'
|Visiting on Campus|Calendar of Events|In the News|Bulletin Board
Yale Scoreboard|Classified Ads|Search Archives|Deadlines
Bulletin Staff|Public Affairs Home|News Releases|
E-Mail Us|Yale Home Page