Research Highlights

Displaying 281 - 300 of 469
Atomic & Molecular Physics
No free lunch for entangled particles
Published: January 26, 2012

Incredibly sensitive measurements can be made using particles that are correlated in a special way (called entanglement.)  Entanglement is one of the spooky properties of quantum mechanics – two particles interact and retain a connection, even if separated by huge distances.  If you do something to one of the particles, its linked partners will also respond.

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PI(s):
Ana Maria Rey
Nanoscience
Schrödinger Cats Light the Way
Published: January 13, 2012

We can get valuable information about a material by studying how it responds to light.  But up to now, researchers have been forced to ignore how some of light’s stranger quantum behavior, such as being in a superposition of one or more intensity states, affects these measurements.  New research from the Cundiff group (with newly minted PhD Ryan Smith and graduate student Andy Hunter) has shown that it is possible to back-calculate how a semiconductor responds to light’s quantum features even though we can’t directly create light with those features.

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PI(s):
Steven Cundiff
Astrophysics
Simulating a Starquake
Published: December 28, 2011

Some stars die dramatically – the light from the supernova explosion of a distant massive star can outshine an entire galaxy. But this event isn’t the endgame for the star — the dense remnants of some of these explosions (called neutron stars) can spit out light rays over thousands of years. 

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PI(s):
Rosalba Perna
Atomic & Molecular Physics
Quantum Body Swapping
Published: October 28, 2011

Theorists Norio Takemoto (now at the Weizmann Institute of Science) and Fellow Andreas Becker figured that something was amiss when they first analyzed the details of what occurs when an ultrafast laser dislodges an electron from a “simple” molecular ion, H2+. Since H2has already lost one of its electrons, its two protons only have one electron left to play with.  How hard would it be to “see” what happened to this electron in a strong laser field? After all, a widely accepted theory said that a strong laser field would make it easier for the lone electron to escape when the ion was stretched apart (as opposed to contracted). 

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PI(s):
Andreas Becker
Chemical Physics
Chemistry in the Cosmos
Published: October 19, 2011

The Nesbitt group wants to figure out how chemistry works in outer space. In particular, the group wants to understand the “cosmo”-chemistry leading to the generation of soot, which is similar to products of combustion here on Earth.

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PI(s):
David Nesbitt
Biophysics
Cross-Cultural Spectroscopy
Published: October 19, 2011

Graduate student Jennifer Lubbeck (Jimenez Group) spent the summer of 2011 doing research in the Molecular Spectroscopy Laboratory at the RIKEN Institute in Wako, Japan (near Tokyo). Her host's group included 16 postdocs and four graduate students. The group was under the direction of Chief Scientist Tahei Tahara. However, Lubbeck actually worked directly with just five other young scientists under the supervision of Professor Kunihiko Ishi (Ishi-san).

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PI(s):
Ralph Jimenez
Astrophysics
Sculpting a Star System: The Inner Planets
Published: September 22, 2011

The Solar System has a remarkable number of planets. It includes four rocky planets (Mercury, Venus, Earth, and Mars), four giant gaseous planets, and countless smaller worlds. Early on, there may even have been a fifth rocky planet that collided with the Earth, forming the Moon. We owe the survival of so many terrestrial planets (and our own evolution as a species) to the relatively stable orbits of Jupiter, Saturn, Uranus, and Neptune during the 100 million years it took to form the inner planets of the Solar System.

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PI(s):
Phil Armitage
Atomic & Molecular Physics
Ultracold Polar Molecules to the Rescue!
Published: September 14, 2011

Physicists would very much like to understand the physics underlying high-temperature superconductors. Such an understanding may lead to the design of room temperature superconductors for use in highly efficient and much lower-cost transmission networks for electricity. A technological breakthrough like this would drastically reduce world energy costs. However, this breakthrough requires a detailed understanding of the physics of high-temperature superconductivity.

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PI(s):
Ana Maria Rey | Jun Ye
Astrophysics
Hitchhiker’s Guide into the Galaxy
Published: September 14, 2011

Long, long ago galaxies now far away formed around ravenous black holes scattered throughout the Universe. Some 12.5 billion years later, JILA scientist Gayler Harford and Fellow Andrew Hamilton have identified the superhighways that funneled gas into some of the nascent galaxies. These thruways not only routed gas to feed the monster black holes, but also supplied raw materials for the billions and billions of stars that have illuminated those galaxies ever since.

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PI(s):
Andrew Hamilton
Atomic & Molecular Physics
The Cold Case
Published: September 02, 2011

The Ye group has built a cool new system for studying cold collisions between molecules. The system is far colder than a typical chemistry experiment that takes place at room temperature or hotter (300–500 K). But, it’s also much warmer than experiments that investigate ultracold-molecule collisions conducted at hundreds of billionths of a degree above absolute zero (0 K). The new system is known as “the cold molecule experiment” and operates at temperatures of approximately 5 K (-450 °F).

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PI(s):
Jun Ye
Precision Measurement
Probing the Tell-Tale Ions
Published: August 25, 2011

JILA’s quest to determine whether the electron has an electric dipole moment (eEDM) began in 2006 with a suggestion by Fellow Eric Cornell that the molecular ion hafnium fluoride (HfF+) might be well suited for an eEDM experiment. An electric dipole moment is a measure of the separation of positive and negative charges in a system. If an electron does have an electric dipole moment, it’s a pretty darn small one. So small, in fact, that if the electron were the size of the Earth, its eEDM would only alter the planet’s roundness by less than the width of a human hair.

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PI(s):
John Bohn
Astrophysics
Everything is Illuminated
Published: August 15, 2011

Supernova 1987A is illuminating its own past. The brightest supernova to light up Earth’s night skies since the Renaissance, it appeared in the southern sky on February 23, 1987 when a blue supergiant star exploded in the Large Magellanic Cloud, a galaxy located 160,000 light years from Earth. For nearly 25 years, Fellow Dick McCray and his colleagues have studied the unfolding story of this remarkable event in the visible, ultraviolet, and x-ray wavelengths. Today, the scientists not only understand the star’s spectacular demise, but also are now learning about the blue supergiant’s chemistry prior to going supernova.

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PI(s):
Richard McCray
Laser Physics
Reactions on Demand
Published: July 16, 2011

Predrag Ranitovic dreams of controlling chemical reactions with ultrafast lasers. Now he and his colleagues in the Kapteyn/Murnane group are one step closer to bringing this dream into reality. The group recently used a femtosecond infrared (IR) laser and two extreme ultraviolet (XUV) harmonics created by the same laser to either ionize helium atoms or prevent ionization, depending on experimental conditions. The researchers adjusted experimental conditions to manipulate the electronic structure of the helium atoms as well as control the phase and amplitude of the XUV laser pulses.

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PI(s):
Henry Kapteyn | Margaret Murnane
Atomic & Molecular Physics
The Secrets of the Resonant Lattice
Published: July 15, 2011

Theoretical physicists recently combined two powerful tools for exploring ultracold atomic gases: Optical lattices and Feshbach resonances. Optical lattices are crystals of light formed by interacting laser beams. Feshbach resonances in an ultracold atom gas occur at a particular magnetic field strength and cause ultracold atoms to form very large, loosely associated molecules. However, because lattice atoms interact strongly at a Feshbach resonance, the physics of Feshbach resonances in an optical lattice is quite complicated.

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PI(s):
Ana Maria Rey
Nanoscience | Precision Measurement
Quantum CT Scans
Published: June 01, 2011

The Lehnert group and collaborators from the National Institute of Standards and Technology (NIST) recently made what was essentially a CT scan of the quantum state of a microwave field. The researchers made 100 measurements at different angles of this quantum state as it was wiggling around. Because they only viewed the quantum state from one angle at a time, they were able to circumvent quantum uncertainties to make virtually noiseless measurements of amplitude changes in their tiny microwave signals. Multiple precision measurements of the same quantum state yielded a full quantum picture of the microwave field.

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PI(s):
Konrad Lehnert
Nanoscience
JILA MONSTR and the Chamber of Secrets
Published: May 17, 2011

The semiconductor gallium arsenide (GaAs) is used to make tiny structures in electronic devices such as integrated circuits, light-emitting diodes, laser diodes, and solar cells that directly convert light into electrical energy. Because of GaAs’s importance to modern electronics, the Cundiff group seeks to understand the fundamental physics of its light-matter interactions on atomic and electronic levels.

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PI(s):
Steven Cundiff
Chemical Physics
I Sing the Body Electric
Published: May 11, 2011

The Lewandowski group recently decided to see what would happen if it could get cold molecules (1K–1mK) and ultracold (<1mK) atoms to collide. Former graduate student L. Paul Parazzoli, graduate student Noah Fitch, and Fellow Heather Lewandowski devised a novel experiment to determine the collision behavior of cold (100 mK) deuterated ammonia (ND3) molecules and ultracold (600 microK) rubidium (Rb) atoms.

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PI(s):
Heather Lewandowski
Atomic & Molecular Physics
A Flair for Lasing
Published: May 01, 2011

Triatomic hydrogen ion (H3+) has many talents. In interstellar clouds, it can be blown apart by free low-energy free electrons, which interact with the ion core (H3+), briefly forming unstable H3 molecules. The interaction of the electron with the ion core almost immediately causes the molecule to fall apart into three hydrogen atoms (3H) or a hydrogen molecule (H2) and an H atom. This reaction is known as dissociative recombination.

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PI(s):
Chris Greene
Biophysics
Upending Conventional Wisdom
Published: April 21, 2011

In science, it can be fun and interesting to upend conventional wisdom. A good example is what just happened to a widely accepted explanation for overstretching of double-stranded DNA (dsDNA). Overstretching occurs suddenly when researchers add a tiny increment of force to dsDNA that is already experiencing a pulling force of approximately 65 pN. (A piconewton is a trillionth of a newton, which is roughly equal to the gravitational force on a medium-sized apple). The small additional force causes the dsDNA to suddenly become 70% longer — as it stretches like a slinky.

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PI(s):
Thomas Perkins
Astrophysics
The World According to COS
Published: April 20, 2011

The Cosmic Origins Spectrograph, or COS, is a powerful new instrument scanning the Universe. COS was installed on the Hubble Space Telescope in 2009. Since then, it has been searching for clues about the composition of the Universe, including how galaxies like our own Milky Way formed and evolved over time. It is seeing beautiful things never before detected in the Universe because it is the lowest-noise ultraviolet (UV) spectrograph ever built for space exploration.

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PI(s):
Jeffrey Linsky