A Giant of Astronomy and a Quantum of Solace

Cerro Paranal, the 2600m high mountain in the Chilean Atacama Desert that hosts ESO's Very Large Telescope, will be the stage for scenes in the next James Bond movie, "Quantum of Solace".
Looking akin to Mars, with its red sand and lack of vegetation, the Atacama Desert is thought to be the driest place on Earth. Cerro Paranal is home to ESO's Very Large Telescope (VLT), which, with its array of four giant 8.2-m individual telescopes, is the world's most advanced optical observatory. The high-altitude site and extreme dryness make excellent conditions for astronomical observations.

"We needed a unique site for a unique set of telescopes, and we found it at Paranal," said Andreas Kaufer, ESO's Paranal Director. "We are very excited that the Bond production team have also chosen this location."

The excellent astronomical conditions at Paranal come at a price, however. In this forbidding desert environment, virtually nothing can grow outside. The humidity drops below 10%, there are intense ultraviolet rays from the sun, and the high altitude leaves people short of breath. Living in this extremely isolated place feels like visiting another planet.

To make it possible for people to live and work here, a hotel or "Residencia" was built in the base camp, allowing them to escape from the arid outside environment. Here, returning from long shifts at the VLT and other installations on the mountain, they can breathe moist air and relax, sheltered from the harsh conditions outside. The Residencia's award-winning design, including an enclosed tropical garden and pool under a futuristic domed roof, gives its interior a feeling of open space within the protective walls - this is a true "haven in the desert".

It is this unique building that serves as the backdrop for the James Bond filming.

QUANTUM OF SOLACE producer, Michael G. Wilson said: "The Residencia of Paranal Observatory caught the attention of our director, Marc Forster and production designer, Dennis Gassner, both for its exceptional design and its remote location in the Atacama desert. It is a true oasis and the perfect hide-out for Dominic Greene, our villain, whom 007 is tracking in our new James Bond film."

In addition to the shooting at the Residencia, further action will take place at the Paranal airstrip.

The film crew present on Paranal includes Englishman Daniel Craig, taking again the role of James Bond, French actor Mathieu Amalric, leading lady Olga Kurylenko, from the Ukraine, as well as acclaimed Mexican actors, Joaquin Cosio and Jesus Ochoa. This cast from across Europe and Latin America mirrors the international staff that works for ESO at Paranal.

After leaving Paranal at the end of the week, the film crew will shoot in other locations close to Antofagasta. Other sequences have been filmed in Panama and, following the Chilean locations, the unit will be travelling to Italy and Austria before returning to Pinewood Studios near London in May.

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Physicists discover how fundamental particles lose track of quantum mechanical properties

Science Express, the advance online publication of the journal Science, researchers report a series of experiments that mark an important step toward understanding a longstanding fundamental physics problem of quantum mechanics. The scientists presented their findings at the annual meeting of the American Physical Society here this week.

The problem the physicists addressed is how a fundamental particle in matter loses track of its quantum mechanical properties through interactions with its environment.

The research was performed by scientists at the California NanoSystems Institute at the University of California, Santa Barbara and the U. S. Department of Energy Ames Laboratory in Iowa.

At the quantum level things like particles or light waves behave in ways very different from what scientists expect in a human-scale world. In the quantum world, for example, an electron can exist in two places at the same time, what is called a "superposition" of states, or spin up and down at the same time.

Quantum mechanics in computing could lead to communication with no possible eavesdropping, lightning-fast database searches, and code-cracking ability.

The answer to the problem the researchers have tackled is key to unraveling how the classical world in which we live emerges from all the interacting quantum particles in matter. This scientific query surrounds the basic quantum dynamics of a single particle spin coupled to a collection, or bath, of random spins. This scenario describes the underlying behavior of a broad class of materials around us, ranging from quantum spin tunneling in magnetic molecules to nuclear magnetic resonance in semiconductors.

�We were stunned by these unexpected experimental results, and extremely excited by the ability to control and monitor single quantum states, especially at room temperature,� said author David Awschalom, a professor of physics at UC Santa Barbara. Awschalom is affiliated with the California NanoSystems Institute at UCSB and is the Director of the Center for Spintronics & Quantum Computation, also at the university.

Recently the issue of how fundamental particles lose track of quantum mechanical properties through interaction with the environment has gained crucial importance in the field of quantum information. In this area, robust manipulation of quantum states promises enormous speedups over classical computation. Keeping track of the quantum phase is essential for keeping the quantum information, and insight into loss of the phase will greatly help to mitigate this process.

Experimental work on this subject has thus far been hindered by the lack of high-fidelity coherent control of a single spin in nature and our inability to directly influence the bath dynamics.

In a collaboration between physicists in Awschalom�s research group at UCSB and Slava Dobrovitski, a visiting scientist from Ames Laboratory in Iowa, a series of experiments were undertaken that utilized electron spins in diamond to investigate different regimes of spin-bath interactions, and provide much information about the decoherence dynamics.

The scientists use diamond crystals to study a single electron spin tied to an adjustable collection of nearby spins. Two features of diamond that make this system viable for unprecedented investigations into the coherent dynamics are the precise optical control of a single spin that is unique to diamond, and the magnetic tunability of the spin-bath and intrabath dynamics with small permanent magnets. Their team�s observations contain a number of extraordinary discoveries, such as the time-dependent disappearance and reappearance of quantum oscillations of the spins in the diamond lattice.

�To our surprise, when looking at longer times, the oscillations disappeared then re-appeared,� said co-author Ronald Hanson, a postdoctoral student at UCSB during this period who is now a professor at the Kavli Institute of Nanoscience Delft, at Delft University of Technology, in the Netherlands. �At first it looked like an artifact, but repeated measurements reproduced this behavior.�

The problem of a single spin coupled to a bath of spins has been the subject of an intense international research effort, as this conceptual framework describes the physical behavior of a number of real systems. Among others, these include atomic and electronic spins that are prime candidates for implementing quantum information processors and coherent spintronics devices.

A series of direct experiments coupled to theoretical simulations demonstrate that spins in diamond serve as a nearly ideal, adjustable, model of central spin.

�This work demonstrates a rare level of synergy between experiment, analytical theory, and computer simulations,� said Dobrovitski. �These three constituents all agree, support, and complement each other. Together, they give a lucid qualitative picture of what happens with spin centers in diamond, and, at the same time, provide a quantitatively accurate description. This agreement is hard to anticipate in advance for such complex systems, where many nuclear and electron quantum spins interact with each other.�

Studies of the quantum dynamics of spins in diamond is an emerging topic involving several leading research groups worldwide. It may also be important in the context of recent interest in possible carbon-based electronic devices employing carbon nanotubes and/or graphene.

###

Awschalom won the APS Oliver E. Buckley Prize for fundamental contributions to experimental studies of quantum spin dynamics and spin coherence in condensed matter systems. Awschalom�s other honors include the Agilent Europhysics Prize, the AAAS Newcomb-Cleveland Prize, the Outstanding Investigator Prize from the Materials Research Society, and the Magnetism Prize of the International Union of Pure and Applied Physics. He is a member of the National Academy of Sciences.

Awschalom earned his B.S. in physics at the University of Illinois at Urbana-Champaign, and his Ph.D. in experimental physics at Cornell University. He joined the UC Santa Barbara faculty as a professor of physics in 1991. His research has been chronicled in his more than 300 scientific journal articles, and has also been featured in The New York Times, The Wall Street Journal, San Francisco Chronicle, Dallas Morning News, Discover magazine, Scientific American, Physics World, and New Scientist. His research focuses on optical and magnetic interactions in semiconductor quantum structures, spin dynamics and coherence in condensed matter systems, macroscopic quantum phenomena in nanometer-scale magnets, and quantum information processing in the solid state.

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Physicists discover how fundamental particles lose track of quantum mechanical properties

In today’s Science Express, the advance online publication of the journal Science, researchers report a series of experiments that mark an important step toward understanding a longstanding fundamental physics problem of quantum mechanics. The scientists presented their findings at the annual meeting of the American Physical Society here this week.

The problem the physicists addressed is how a fundamental particle in matter loses track of its quantum mechanical properties through interactions with its environment.

The research was performed by scientists at the California NanoSystems Institute at the University of California, Santa Barbara and the U. S. Department of Energy Ames Laboratory in Iowa.

At the quantum level things like particles or light waves behave in ways very different from what scientists expect in a human-scale world. In the quantum world, for example, an electron can exist in two places at the same time, what is called a “superposition” of states, or spin up and down at the same time.

Quantum mechanics in computing could lead to communication with no possible eavesdropping, lightning-fast database searches, and code-cracking ability.

The answer to the problem the researchers have tackled is key to unraveling how the classical world in which we live emerges from all the interacting quantum particles in matter. This scientific query surrounds the basic quantum dynamics of a single particle spin coupled to a collection, or bath, of random spins. This scenario describes the underlying behavior of a broad class of materials around us, ranging from quantum spin tunneling in magnetic molecules to nuclear magnetic resonance in semiconductors.

“We were stunned by these unexpected experimental results, and extremely excited by the ability to control and monitor single quantum states, especially at room temperature,” said author David Awschalom, a professor of physics at UC Santa Barbara. Awschalom is associate director of the California NanoSystems Institute at UCSB and is the director of the Center for Spintronics and Quantum Computation, also at the university.

Recently the issue of how fundamental particles lose track of quantum mechanical properties through interaction with the environment has gained crucial importance in the field of quantum information. In this area, robust manipulation of quantum states promises enormous speedups over classical computation. Keeping track of the quantum phase is essential for keeping the quantum information, and insight into loss of the phase will greatly help to mitigate this process.

Experimental work on this subject has thus far been hindered by the lack of high-fidelity coherent control of a single spin in nature and the inability to directly influence the bath dynamics.

In a collaboration between physicists in Awschalom’s research group at UCSB and Slava Dobrovitski, a visiting scientist from Ames Laboratory in Iowa, a series of experiments were undertaken that utilized electron spins in diamond to investigate different regimes of spin-bath interactions, and provide much information about the decoherence dynamics.

The scientists use diamond crystals to study a single electron spin tied to an adjustable collection of nearby spins. Two features of diamond that make this system viable for unprecedented investigations into the coherent dynamics are the precise optical control of a single spin that is unique to diamond, and the magnetic tunability of the spin-bath and intrabath dynamics with small permanent magnets. Their team’s observations contain a number of extraordinary discoveries, such as the time-dependent disappearance and reappearance of quantum oscillations of the spins in the diamond lattice.

“To our surprise, when looking at longer times, the oscillations disappeared then re-appeared,” said co-author Ronald Hanson, a postdoctoral student at UCSB during this period who is now a professor at the Kavli Institute of Nanoscience Delft, at Delft University of Technology, in the Netherlands. “At first it looked like an artifact, but repeated measurements reproduced this behavior.”

The problem of a single spin coupled to a bath of spins has been the subject of an intense international research effort, as this conceptual framework describes the physical behavior of a number of real systems. Among others, these include atomic and electronic spins that are prime candidates for implementing quantum information processors and coherent spintronics devices.

A series of direct experiments coupled to theoretical simulations demonstrate that spins in diamond serve as a nearly ideal, adjustable, model of central spin.

“This work demonstrates a rare level of synergy between experiment, analytical theory, and computer simulations,” said Dobrovitski. “These three constituents all agree, support, and complement each other. Together, they give a lucid qualitative picture of what happens with spin centers in diamond, and, at the same time, provide a quantitatively accurate description. This agreement is hard to anticipate in advance for such complex systems, where many nuclear and electron quantum spins interact with each other.”

Studies of the quantum dynamics of spins in diamond is an emerging topic involving several leading research groups worldwide. It may also be important in the context of recent interest in possible carbon-based electronic devices employing carbon nanotubes and/or graphene.

Awschalom won the American Physical Society’s Oliver E. Buckley Prize for fundamental contributions to experimental studies of quantum spin dynamics and spin coherence in condensed matter systems. Awschalom’s other honors include the Agilent Europhysics Prize, the AAAS Newcomb-Cleveland Prize, the Outstanding Investigator Prize from the Materials Research Society, and the International Magnetism Prize of the International Union of Pure and Applied Physics. He is a member of the National Academy of Sciences.

Awschalom earned his B.S. in physics at the University of Illinois at Urbana-Champaign, and his Ph.D. in experimental physics at Cornell University. He joined the UC Santa Barbara faculty as a professor of physics in 1991. His research has been chronicled in his more than 300 scientific journal articles, and has also been featured in The New York Times, The Wall Street Journal, San Francisco Chronicle, Dallas Morning News, Discover magazine, Scientific American, Physics World, and New Scientist. His research focuses on optical and magnetic interactions in semiconductor quantum structures, spin dynamics and coherence in condensed matter systems, macroscopic quantum phenomena in nanometer-scale magnets, and quantum information processing in the solid state.
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Sound of quantum drums

Forty years ago, mathematician Mark Kac asked the theoretical question, "Can one hear the shape of a drum?"

If drums of different shapes always produce their own unique sound spectrum, then it should be possible to identify the shape of a specific drum merely by studying its spectrum, thus "hearing" the drum's shape (a procedure analogous to spectroscopy, the way scientists detect the composition of a faraway star by studying its light spectrum).

But what if two drums of different shapes could emit exactly the same sound? If so, it would be impossible to work backward from the spectrum and uniquely surmise the physical structure of the drum, because there would be more than one correct answer to the question.

It took until the 1990s for mathematicians to prove that, in fact, two drums of different shapes could produce the same sound. In other words, you can't hear the shape of a drum. That outcome, which was physically verified in one instance with vibrations on the surface of soap bubbles, raised theoretical questions about spectroscopy.

"This revolutionized our conception of the fundamental connections between shape and sound, but also had profound implications for spectroscopy in general, because it introduced an ambiguity," according to Stanford physicist Hari Manoharan.

For Manoharan, the next step in studying this conundrum was to take the drum question to another level—a much lower level. He and his students investigated the drum question in the quantum realm, where it could have an effect on real nano-electronic systems.

Using a tunneling scanning microscope and two roomfuls of equipment to move around individual carbon monoxide molecules on a copper surface, they built tiny walls only one-molecule high and shaped them into nine-sided enclosures that could resonate like drums (because of the quantum wave/particle duality of the electrons within the enclosure).

Manoharan calls these enclosures quantum drums. Each drum has only 30 or so electrons inside. They are walled in by roughly100 carbon monoxide molecules.

The result? Just as in the normal world, two nanostructures with different shapes can resonate in the same way, a phenomenon known as isospectrality. Manoharan, along with his graduate student Chris Moon and others, published their result in the Feb 8 edition of the journal Science. To reinforce the point, they created a video, complete with two quantum drums beating with the same sound. (The real "sound" is at ultra-high frequencies in the terahertz range; in the video, the sound has been converted to the range of human hearing.)

The practical value of having two different nanostructures with identical properties may lie in the design of ever-smaller computer chip circuits, Manoharan said. Designers of nano-electronic circuits will have two ways to get the same result. "Now your design palette is twice as big," he said.

While the chip industry attempts to shrink existing circuitry, Manoharan is literally coming from the opposite direction. "My research asks, what if you start at the bottom of the ladder? We assemble structures one atom at a time," he said. The unexplored gap between bottom-up research and the industry's shrink-down effort "is where the excitement is," he said.

The work has a natural connection to the problems of quantum computing, he said.

The research may also have connections to string theory, used by cosmologists attempting to understand the structure of the universe, Manoharan said: "There is somehow embedded into the topology of our universe this bizarre spectral ambiguity." String theories describe complex surfaces that are higher-dimensional analogues of these two-dimensional quantum drums.

The drum research has another finding important to the world of quantum mechanics. While it is impossible to directly observe the quantum phase of the wave functions of the electrons inside the drum structure, Manoharan's team has devised a way to extract that information by taking measurements from two isospectral drums and then mathematically combining the information, a process called quantum transplantation.

"We discovered that this extra degree of freedom in geometry provides us with a method to 'cheat' quantum mechanics and obtain normally obscured quantum-mechanical phase information," Manoharan said.

There are other ways to experimentally determine quantum phase information from atoms or molecules in gases, or from quantum dots and rings, all of them relying on a process called interferometry. The addition of a new method, "geometry over interferometry," will benefit researchers, Manoharan said.

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Scientists propose test of string theory

Ancient light absorbed by neutral hydrogen atoms could be used to test certain predictions of string theory, say cosmologists at the University of Illinois. Making the measurements, however, would require a gigantic array of radio telescopes to be built on Earth, in space or on the moon.

String theory – a theory whose fundamental building blocks are tiny one-dimensional filaments called strings – is the leading contender for a “theory of everything.” Such a theory would unify all four fundamental forces of nature (the strong and weak nuclear forces, electromagnetism, and gravity). But finding ways to test string theory has been difficult.

Now, cosmologists at the U. of I. say absorption features in the 21-centimeter spectrum of neutral hydrogen atoms could be used for such a test.

“High-redshift, 21-centimeter observations provide a rare observational window in which to test string theory, constrain its parameters and show whether or not it makes sense to embed a type of inflation – called brane inflation – into string theory,” said Benjamin Wandelt, a professor of physics and of astronomy at the U. of I.

“If we embed brane inflation into string theory, a network of cosmic strings is predicted to form,” Wandelt said. “We can test this prediction by looking for the impact this cosmic string network would have on the density of neutral hydrogen in the universe.”

Wandelt and graduate student Rishi Khatri describe their proposed test in a paper accepted for publication in the journal Physical Review Letters.

About 400,000 years after the Big Bang, the universe consisted of a thick shell of neutral hydrogen atoms (each composed of a single proton orbited by a single electron) illuminated by what became known as the cosmic microwave background.

Because neutral hydrogen atoms readily absorb electromagnetic radiation with a wavelength of 21 centimeters, the cosmic microwave background carries a signature of density perturbations in the hydrogen shell, which should be observable today, Wandelt said.

Cosmic strings are filaments of infinite length. Their composition can be loosely compared to the boundaries of ice crystals in frozen water.

When water in a bowl begins to freeze, ice crystals will grow at different points in the bowl, with random orientations. When the ice crystals meet, they usually will not be aligned to one another. The boundary between two such misaligned crystals is called a discontinuity or a defect.

Cosmic strings are defects in space. A network of strings is predicted by string theory (and also by other supersymmetric theories known as Grand Unified Theories, which aspire to unify all known forces of nature except gravity) to have been produced in the early universe, but has not been detected so far. Cosmic strings produce characteristic fluctuations in the gas density through which they move, a signature of which will be imprinted on the 21-centimeter radiation.

The cosmic string network predicted to occur with brane inflation could be tested by looking for the corresponding fluctuations in the 21-centimeter radiation.

Like the cosmic microwave background, the cosmological 21-centimeter radiation has been stretched as the universe has expanded. Today, this relic radiation has a wavelength closer to 21 meters, putting it in the long-wavelength radio portion of the electromagnetic spectrum.

To precisely measure perturbations in the spectra would require an array of radio telescopes with a collective area of more than 1,000 square kilometers. Such an array could be built using current technology, Wandelt said, but would be prohibitively expensive.

If such an enormous array were eventually constructed, measurements of perturbations in the density of neutral hydrogen atoms could also reveal the value of string tension, a fundamental parameter in string theory, Wandelt said. “And that would tell us about the energy scale at which quantum gravity begins to become important.”

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