High Energy Physicists Set New Record for Network Data Transfer

Caltech-led high-energy physicists show how long range networks can be used to support leading edge science

PASADENA, Calif. - Building on eight years of record-breaking developments, and on the restart of the Large Hadron Collider (LHC), an international team of high-energy physicists, computer scientists, and network engineers led by the California Institute of Technology (Caltech) joined forces to capture the Bandwidth Challenge award for massive data transfers during the SuperComputing 2009 (SC09) conference held in Portland, Oregon.

Caltech's partners in the project include scientists from Michigan (UM), Fermilab, Brookhaven National Laboratory, CERN, San Diego (UCSD), Florida (UF and FIU), Brazil (Rio de Janeiro State University, UERJ, and the São Paulo State University, UNESP), Korea (Kyungpook National University, KISTI), Estonia (NICPB) and Pakistan (NUST).

Caltech's exhibit at SC09 by the High Energy Physics (HEP) group and the Center for Advanced Computing Research (CACR) demonstrated applications for globally distributed data analysis for the LHC at CERN. It also demonstrated Caltech's worldwide collaboration system, EVO (Enabling Virtual Organizations; http://evo.caltech.edu), developed with UPJS in Slovakia; its global-network and grid monitoring system MonALISA (http://monalisa.caltech.edu); and its Fast Data Transfer application (http://monalisa.caltech.edu/FDT), developed in collaboration with the Politechnica University (Bucharest). The CACR team also showed near-real-time simulations of earthquakes in the Southern California region, experiences in time-domain astronomy with Google Sky, and recent results in multiphysics multiscale modeling.
The focus of the exhibit was the HEP team's record-breaking demonstration of storage-to-storage data transfer over wide area networks from two racks of servers and a network switch-router on the exhibit floor. The high-energy physics team's demonstration, "Moving Towards Terabit/Sec Transfers of Scientific Datasets: The LHC Challenge," achieved a bidirectional peak throughput of 119 gigabits per second (Gbps) and a data flow of more than 110 Gbps that could be sustained indefinitely among clusters of servers on the show floor and at Caltech, Michigan, San Diego, Florida, Fermilab, Brookhaven, CERN, Brazil, Korea, and Estonia.
Following the Bandwidth Challenge, the team continued its tests and established a world-record data transfer between the Northern and Southern hemispheres, sustaining 8.26 Gbps in each direction on a 10 Gbps link connecting São Paulo and Miami.

By setting new records for sustained data transfer among storage systems over continental and transoceanic distances using simulated LHC datasets, the HEP team demonstrated its readiness to enter a new era in the use of state-of-the-art cyber infrastructure to enable physics discoveries at the high energy frontier, while demonstrating some of the groundbreaking tools and systems they have developed to enable a global collaboration of thousands of scientists located at 350 universities and laboratories in more than 100 countries to make the next round of physics discoveries.
"By sharing our methods and tools with scientists in many fields, we hope that the research community will be well-positioned to further enable their discoveries, taking full advantage of current networks, as well as next-generation networks with much greater capacity as soon as they become available," says Harvey Newman, Caltech professor of physics, head of the HEP team, colead of the U.S. LHCNet, and chair of the U.S. LHC Users Organization. "In particular, we hope that these developments will afford physicists and young students throughout the world the opportunity to participate directly in the LHC program, and potentially to make important discoveries."

The record-setting demonstrations were made possible through the use of fifteen 10 Gbps links to the SC09 booth provided by SCinet, together with National Lambda Rail (11 links including six dedicated links to Caltech) and CENIC, Internet2 (two links), ESnet, and Cisco. The Caltech HEP team used its dark-fiber connection to Los Angeles provided by Level3 and a pair of DWDM optical multiplexers provided by Ciena Corporation to light the fiber with a series of 10G wavelengths to and from the Caltech campus in Pasadena. Ciena also supported a portion of the Caltech traffic with a single serial 100G wavelength running into the SC09 conference from the Portland Level3 PoP, operating alongside other links into SC09 from Portland. Onward connections to the partner sites included links via Esnet and Internet2 to UCSD; FLR to University of Florida as well as FIU and Brazil; MiLR to Michigan; Starlight and USLHCNet to CERN; AMPATH, together with RNP and ANSP, to Brazil via Southern Light; GLORIAD and KREONet to Korea; and Internet2 and GEANT3 to Estonia.
The network equipment at the Caltech booth was a single heavily populated Nexus 7000 series switch-router provided by Cisco and a large number of 10 gigabit Ethernet server-interface cards provided by Myricom. The server equipment on the show floor included five widely available Supermicro 32 core servers using Xeon quad core processors with 12 Seagate SATA disks each, and 18 Sun Fire X4540 servers, each with 12 cores and 48 disks provided by Sun Microsystems.

One of the features of next-generation networks supporting the largest science programs-notably the LHC experiments-is the use of dynamic circuits with bandwidth guarantees crossing multiple network domains. The Caltech team at SC09 used Internet2's recently announced ION service-developed together with ESnet, GEANT and in collaboration with US LHCNet-to create a dynamic circuit between Portland and CERN as part of the bandwidth-challenge demonstrations.

One of the key elements in this demonstration was Fast Data Transfer (FDT), an open-source Java application developed by Caltech in close collaboration with Politechnica University in Bucharest.  FDT runs on all major platforms and uses the NIO libraries to achieve stable disk reads and writes coordinated with smooth data flow using TCP across long-range networks. The FDT application streams a large set of files across an open TCP socket, so that a large data set composed of thousands of files-as is typical in high-energy physics applications-can be sent or received at full speed, without the network transfer restarting between files. FDT can work on its own, or together with Caltech's MonALISA system, to dynamically monitor the capability of the storage systems as well as the network path in real time, and send data out to the network at a moderated rate that achieves smooth data flow across long-range networks. 

Since it was first deployed at SC06, FDT has been shown to reach sustained throughputs among storage systems at 100 percent of network capacity where needed in production use, including among systems on different continents. FDT also achieved a smooth bidirectional throughput of 191 Gbps (199.90 Gbps peak) using an optical system carrying an OTU-4 wavelength over 80 km provided by CIENA last year at SC08.

Another new aspect of the HEP demonstration was large-scale data transfers among multiple file systems widely used in production by the LHC community, with several hundred terabytes per site. This included two recently installed instances of the open-source file system Hadoop, where in excess of 9.9 Gbps was read from Caltech on one 10 Gbps link, and up to 14 Gbps was read on shared ESnet and NLR links, a level just compatible with the production traffic on the same links. The high throughput was achieved through the use of a new FDT/Hadoop adaptor-layer written by NUST in collaboration with Caltech.

The SC09 demonstration also achieved its goal of clearing the way to Terabit/sec (Tbps) data transfers. The 4-way Supermicro servers at the Caltech booth-each with four 10GE Myricom interfaces-provided 8.3Gbps of stable throughput each, reading or writing on 12 disks, using FDT. A system capable of one Tbps to or from storage could therefore be built today in just six racks at relatively low cost, while also providing 3840 processing cores and 3 Petabytes of disk space, which is comparable to the larger LHC centers in terms of computing and storage capacity.

An important ongoing theme of SC09-including at the Caltech booth, where the EVOGreen initiative (www.evogreen.org) was highlighted-was the reduction of carbon footprint through the use of energy-efficient information technologies. A particular focus is the use of systems with a high ratio of computing and I/O performance to energy consumption. In the coming year, in preparation for SC10 in New Orleans, the HEP team will be looking into the design and construction of compact systems with lower power and cost that are capable of delivering data at several hundred Gbps, aiming to reach 1 Tbps by 2011 when multiple 100 Gbps links into SC11 may be available.   

The two largest physics collaborations at the LHC-CMS and ATLAS, each encompassing more than 2,000 physicists, engineers, and technologists from 180 universities and laboratories-are about to embark on a new round of exploration at the frontier of high energies. When the LHC experiments begin to take collision data in a new energy range over the next few months, new ground will be broken in our understanding of the nature of matter and space-time, and in the search for new particles. In order to fully exploit the potential for scientific discoveries during the next year, more than 100 petabytes (1017 bytes) of data will be processed, distributed, and analyzed using a global grid of 300 computing and storage facilities located at laboratories and universities around the world, rising to the exabyte range (1018 bytes) during the following years.

The key to discovery is the analysis phase, where individual physicists and small groups located at sites around the world repeatedly access, and sometimes extract and transport, multi-terabyte data sets on demand from petabyte data stores in order to optimally select the rare "signals" of new physics from the potentially overwhelming "backgrounds" from already-understood particle interactions. The HEP team hopes that the demonstrations at SC09 will pave the way toward more effective distribution and use for discoveries of the masses of LHC data.

The demonstration and the developments leading up to the SC09 Bandwidth Challenge were made possible through the support of the partner network organizations mentioned, the National Science Foundation (NSF), the U.S. Department of Energy (DOE) Office of Science, and the funding agencies of the HEP team's international partners, as well as the U.S. LHC Research Program funded jointly by DOE and NSF.

Further information about the demonstration may be found at http://supercomputing.caltech.edu

Jon Weiner
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F. Brock Fuller, 82

F. Brock Fuller, emeritus professor of mathematics at the California Institute of Technology (Caltech), died on November 6 at the Rafael Convalescent Hospital in San Rafael, California, four years after being diagnosed with diffuse Lewy body disease. He was 82.

Fuller received his bachelor's, master's, and PhD degrees from Princeton. He came to Caltech in 1952 as a research fellow. He became assistant professor of mathematics in 1955, associate professor in 1959, and professor in 1966. In 1994, he became professor emeritus.

Much of Fuller's work revolved around what are called "writhing numbers," and the way in which these mathematical descriptions of twisting and coiling could describe supercoiled double-stranded DNA helices. (A supercoiled DNA helix is one in which the already-twisted DNA strands twist again, either in the same direction as the original helix, or in the opposite direction.)

In the early 1980s, Fuller-who was also an audiophile-was involved in analyzing digital recording technologies as they began to reach prominence in the audio-entertainment industry. Working alongside Caltech colleagues such as Gary Lorden and James Boyk, Fuller examined music piped in to Thomas Laboratory from Dabney Lounge, comparing various signals.

Fuller moved to San Rafael, in northern California, in 1996. He is survived by his wife, Alison Clark Fuller of San Rafael; his daughter, Lynn D. Fuller of San Francisco, as well as her husband, William Bivins, and their four children, Samuel, Zachary, Elizabeth, and Claire Bivins; and his sister, Cornelia Fuller of Pasadena.

Jon Weiner
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LIGO Listens for Gravitational Echoes of the Birth of the Universe

Results set new limits on gravitational waves originating from the Big Bang; constrain theories about universe formation

Pasadena, Calif.—An investigation by the LIGO (Laser Interferometer Gravitational-Wave Observatory) Scientific Collaboration and the Virgo Collaboration has significantly advanced our understanding of the early evolution of the universe.

Analysis of data taken over a two-year period, from 2005 to 2007, has set the most stringent limits yet on the amount of gravitational waves that could have come from the Big Bang in the gravitational wave frequency band where LIGO can observe. In doing so, the gravitational-wave scientists have put new constraints on the details of how the universe looked in its earliest moments.

Much like it produced the cosmic microwave background, the Big Bang is believed to have created a flood of gravitational waves—ripples in the fabric of space and time—that still fill the universe and carry information about the universe as it was immediately after the Big Bang. These waves would be observed as the "stochastic background," analogous to a superposition of many waves of different sizes and directions on the surface of a pond. The amplitude of this background is directly related to the parameters that govern the behavior of the universe during the first minute after the Big Bang.

Earlier measurements of the cosmic microwave background have placed the most stringent upper limits of the stochastic gravitational wave background at very large distance scales and low frequencies. The new measurements by LIGO directly probe the gravitational wave background in the first minute of its existence, at time scales much shorter than accessible by the cosmic microwave background.

The research, which appears in the August 20 issue of the journal Nature, also constrains models of cosmic strings, objects that are proposed to have been left over from the beginning of the universe and subsequently stretched to enormous lengths by the universe's expansion; the strings, some cosmologists say, can form loops that produce gravitational waves as they oscillate, decay, and eventually disappear.

Gravitational waves carry with them information about their violent origins and about the nature of gravity that cannot be obtained by conventional astronomical tools. The existence of the waves was predicted by Albert Einstein in 1916 in his general theory of relativity. The LIGO and GEO instruments have been actively searching for the waves since 2002; the Virgo interferometer joined the search in 2007.

The authors of the new paper report that the stochastic background of gravitational waves has not yet been discovered. But the nondiscovery of the background described in the Nature paper already offers its own brand of insight into the universe's earliest history.

The analysis used data collected from the LIGO interferometers, a 2 km and a 4 km detector in Hanford, Washington, and a 4 km instrument in Livingston, Louisiana. Each of the L-shaped interferometers uses a laser split into two beams that travel back and forth down long interferometer arms. The two beams are used to monitor the difference between the two interferometer arm lengths.

According to the general theory of relativity, one interferometer arm is slightly stretched while the other is slightly compressed when a gravitational wave passes by.

The interferometer is constructed in such a way that it can detect a change of less than a thousandth the diameter of an atomic nucleus in the lengths of the arms relative to each other.

Because of this extraordinary sensitivity, the instruments can now test some models of  the evolution of the early universe that are expected to produce the stochastic background.

"Since we have not observed the stochastic background, some of these early-universe models that predict a relatively large stochastic background have been ruled out," says Vuk Mandic, assistant professor at the University of Minnesota.

"We now know a bit more about parameters that describe the evolution of the universe when it was less than one minute old," Mandic adds. "We also know that if cosmic strings or superstrings exist, their properties must conform with the measurements we made-that is, their properties, such as string tension, are more constrained than before."

This is interesting, he says, "because such strings could also be so-called fundamental strings, appearing in string-theory models. So our measurement also offers a way of probing string-theory models, which is very rare today."

"This result was one of the long-lasting milestones that LIGO was designed to achieve," Mandic says. Once it goes online in 2014, Advanced LIGO, which will utilize the infrastructure of the LIGO observatories and be 10 times more sensitive than the current instrument, will allow scientists to detect cataclysmic events such as black-hole and neutron-star collisions at 10-times-greater distances.

"Advanced LIGO will go a long way in probing early universe models, cosmic-string models, and other models of the stochastic background. We can think of the current result as a hint of what is to come," he adds.

"With Advanced LIGO, a major upgrade to our instruments, we will be sensitive to sources of extragalactic gravitational waves in a volume of the universe 1,000 times larger than we can see at the present time. This will mean that our sensitivity to gravitational waves from the Big Bang will be improved by orders of magnitude," says Jay Marx of the California Institute of Technology, LIGO's executive director.

"Gravitational waves are the only way to directly probe the universe at the moment of its birth; they're absolutely unique in that regard. We simply can't get this information from any other type of astronomy. This is what makes this result in particular, and gravitational-wave astronomy in general, so exciting," says David Reitze, a professor of physics at the University of Florida and spokesperson for the LIGO Scientific Collaboration.

"The scientists of the LIGO Scientific Collaboration and the Virgo Collaboration have joined their efforts to make the best use of their instruments. Combining simultaneous data from the LIGO and Virgo interferometers gives information on gravitational-wave sources not accessible by other means. It is very suggestive that the first result of this alliance makes use of the unique feature of gravitational waves being able to probe the very early universe. This is very promising for the future," says Francesco Fidecaro, a professor of physics with the University of Pisa and the Istituto Nazionale di Fisica Nucleare, and spokesperson for the Virgo Collaboration.

Maria Alessandra Papa, senior scientist at the Max Planck Institute for Gravitational Physics and the head of the LSC overall data analysis effort adds, "Hundreds of scientists work very hard to produce fundamental results like this one: the instrument scientists who design, commission and operate the detectors, the teams who prepare the data for the astrophysical searches and the data analysts who develop and implement sensitive techniques to look for these very weak and elusive signals in the data."

The LIGO project, which is funded by the National Science Foundation (NSF), was designed and is operated by Caltech and the Massachusetts Institute of Technology for the purpose of detecting gravitational waves, and for the development of gravitational-wave observations as an astronomical tool.

Research is carried out by the LIGO Scientific Collaboration, a group of 700 scientists at universities around the United States and in 11 foreign countries. The LIGO Scientific Collaboration interferometer network includes the LIGO interferometers and the GEO600 interferometer, which is located near Hannover, Germany, and designed and operated by scientists from the Max Planck Institute for Gravitational Physics, along with partners in the United Kingdom funded by the Science and Technology Facilities Council (STFC).

The Virgo Collaboration designed and constructed the 3 km long Virgo interferometer located in Cascina, Italy, funded by the Centre National de la Recherche Scientifique (France) and by the Istituto Nazionale di Fisica Nucleare (Italy). The Virgo Collaboration consists of 200 scientists from five Europe countries and operates the Virgo detector. Support for the operation comes from the Dutch—French—Italian European Gravitational Observatory Consortium. The LIGO Scientific Collaboration and Virgo work together to jointly analyze data from the LIGO, Virgo, and GEO interferometers.

The next major milestone for LIGO is the Advanced LIGO Project, slated to begin operation in 2014. Advanced LIGO will incorporate advanced designs and technologies that have been developed by the LIGO Scientific Collaboration. It is supported by the NSF, with additional contributions from the U.K.'s STFC and Germany's Max Planck Society.

The paper is entitled "An Upper Limit on the Amplitude of Stochastic Gravitational-Wave Background of Cosmological Origin."

Kathy Svitil

Caltech Physicists Create First Nanoscale Mass Spectrometer

Device can instantly measure the mass of an individual molecule

PASADENA, Calif.-Using devices millionths of a meter in size, physicists at the California Institute of Technology (Caltech) have developed a technique to determine the mass of a single molecule, in real time.

The mass of molecules is traditionally measured using mass spectrometry, in which samples consisting of tens of thousands of molecules are ionized, to produce charged versions of the molecules, or ions. Those ions are then directed into an electric field, where their motion, which is choreographed by both their mass and their charge, allows the determination of their so-called mass-to-charge ratio. From this, their mass can ultimately be ascertained.

The new technique, developed over 10 years of effort by Michael L. Roukes, a professor of physics, applied physics, and bioengineering at the Caltech and codirector of Caltech's Kavli Nanoscience Institute, and his colleagues, simplifies and miniaturizes the process through the use of very tiny nanoelectromechanical system (NEMS) resonators. The bridge-like resonators, which are 2 micrometers long and 100 nanometers wide, vibrate at a high frequency and effectively serve as the "scale" of the mass spectrometer.

"The frequency at which the resonator vibrates is directly proportional to its mass," explains research physicist Askshay Naik, the first author of a paper about the work that appears in the latest issue of the journal Nature Nanotechnology. Changes in the vibration frequency, then, correspond to changes in mass.

"When a protein lands on the resonator, it causes a decrease in the frequency at which the resonator vibrates and the frequency shift is proportional to the mass of the protein," Naik says. 

As described in the paper, the researchers used the instrument to test a sample of the protein bovine serum albumin (BSA), which is known to have a mass of 66 kilodaltons (kDa; a dalton is a unit of mass used to describe atomic and molecular masses, with one dalton approximately equal to the mass of one hydrogen atom).

The BSA protein ions are produced in vapor form using an electrospray ionization (ESI) system.The ions are then sprayed on to the NEMS resonator, which vibrates at a frequency of 450 megahertz. "The flux of proteins reaching the NEMS is such that only one to two protein lands on the resonator in a minute," Naik says.

When the BSA protein molecule is dropped onto the resonator, the resonator's vibration frequency decreases by as much as 1.2 kiloHertz-a small, but readily detectable, change. In contrast, the beta-amylase protein molecule, which has a mass of about 200 kDa, or three times that of BSA, causes a maximum frequency shift of about 3.6 kHz.

Because the location where the protein lands on the resonator also affects the frequency shift-falling onto the center of the resonator causes a larger change than landing on the end or toward the sides, for example-"we can't tell the mass with a single measurement, but needed about 500 frequency jumps in the published work," Naik says. In future, the researchers will decouple measurements of the mass and the landing position of the molecules being sampled. This technique, which they have already prototyped, will soon enable mass spectra for complicated mixtures to be built up, molecule-by molecule.

Eventually, Roukes and colleagues hope to create arrays of perhaps hundreds of thousands of the NEMS mass spectrometers, working in parallel, which could determine the masses of hundreds of thousands of molecules "in an instant," Naik says.

As Roukes points out, "the next generation of instrumentation for the life sciences-especially those for systems biology, which allows us to reverse-engineer biological systems-must enable proteomic analysis with very high throughput. The potential power of our approach is that it is based on semiconductor microelectronics fabrication, which has allowed creation of perhaps mankind's most complex technology."

The paper, "Towards single-molecule nanomechanical mass spectrometry," appears in the July 4 issue of Nature Nanotechnology. The other authors of the paper are graduate student Mehmet S. Hanay and staff scientist Philip Feng, from Caltech, and Wayne K. Hiebert of the National Research Council of Canada. The work was supported by the National Institutes of Health and, indirectly, by the Defense Advanced Research Projects Agency and the Space and Naval Warfare Systems Command.

Kathy Svitil

Mechanics: Nano Meets Quantum

Caltech physicists devise new method to detect quantum mechanical effects in ordinary objects

PASADENA, Calif.—At the quantum level, the atoms that make up matter and the photons that make up light behave in a number of seemingly bizarre ways. Particles can exist in "superposition," in more than one state at the same time (as long as we don't look), a situation that permitted Schrödinger's famed cat to be simultaneously alive and dead; matter can be "entangled"—Albert Einstein called it "spooky action at a distance"—such that one thing influences another thing, regardless of how far apart the two are.

Previously, scientists have successfully measured entanglement and superposition in photons and in small collections of just a few atoms. But physicists have long wondered if larger collections of atoms—those that form objects with sizes closer to what we are familiar with in our day-to-day life—also exhibit quantum effects.

"Atoms and photons are intrinsically quantum mechanical, so it's no surprise if they behave in quantum mechanical ways. The question is, do these larger collections of atoms do this as well," says Matt LaHaye, a postdoctoral research scientist working in the laboratory of Michael L. Roukes, a professor of physics, applied physics, and bioengineering at the California Institute of Technology (Caltech) and codirector of Caltech's Kavli Nanoscience Institute.

"It'd be weird to think of ordinary matter behaving in a quantum way, but there's no reason it shouldn't," says Keith Schwab, an associate professor of applied physics at Caltech, and a collaborator of Roukes and LaHaye. "If single particles are quantum mechanical, then collections of particles should also be quantum mechanical. And if that's not the case—if the quantum mechanical behavior breaks down—that means there's some kind of new physics going on that we don't understand."

The tricky part, however is devising an experiment that can detect quantum mechanical behavior in such ordinary objects—without, for example, those effects being interfered with or even destroyed by the experiment itself.

Now, however, LaHaye, Schwab, Roukes,  and their colleagues have developed a new tool that meets such fastidious demands and that can be used to search for quantum effects in an ordinary object. The researchers describe their work in the latest issue of the journal Nature.

In their experiment, the Caltech scientists used microfabrication techniques to create a very tiny nanoelectromechanical system (NEMS) resonator, a silicon-nitride beam—just 2 micrometers long, 0.2 micrometers wide, and weighing 40 billionths of a milligram—that can resonate, or flex back and forth, at a high frequency when a voltage is applied.

A small distance (300 nanometers, or 300 billionths of a meter) from the resonator, the scientists fabricated a second nanoscale device known as a single-Cooper-pair box, or superconducting "qubit"; a qubit is the basic unit of quantum information.

The superconducting qubit is essentially an island formed between two insulating barriers across which a set of paired electrons can travel. In the Caltech experiments, the qubit has only two quantized energy states: the ground state and an excited state. This energy state can be controlled by applying microwave radiation, which creates an electric field.

Because the NEMS resonator and the qubit are fabricated so closely together, their behavior is tightly linked; this allows the NEMS resonator to be used as a probe for the energy quantization of the qubit. "When the qubit is excited, the NEMS bridge vibrates at a higher frequency than it does when the qubit is in the ground state," LaHaye says.

One of the most exciting aspects of this work is that this same coupling should also enable measurements to observe the discrete energy levels of the vibrating resonator that are predicted by quantum mechanics, the scientists say. This will require that the present experiment be turned around (so to speak), with the qubit used to probe the NEMS resonator. This could also make possible demonstrations of nanomechanical quantum superpositions and Einstein's spooky entanglement

"Quantum jumps are, perhaps, the archetypal signature of behavior governed by quantum effects," says Roukes. "To see these requires us to engineer a special kind of interaction between our measurement apparatus and the object being measured. Matt's results establish a practical and really intriguing way to make this happen."

The paper, "Nanomechanical measurements of a superconducting qubit," was published in the June 18 issue of Nature. In addition to LaHaye, Schwab, and Roukes, its coauthors were Junho Suh, a graduate student at Caltech, and Pierre M. Echternach of the Jet Propulsion Laboratory. The work was funded by the National Science Foundation, the Foundational Questions Institute, and Caltech's Center for the Physics of Information. 

Kathy Svitil

Uncertainty Principle Used to Detect Entanglement of Photon Shared Among Four Locations

PASADENA, Calif.-Scientists at the California Institute of Technology (Caltech) have developed an efficient method to detect entanglement shared among multiple parts of an optical system. They show how entanglement, in the form of beams of light simultaneously propagating along four distinct paths, can be detected with a surprisingly small number of measurements. Entanglement is an essential resource in quantum information science, which is the study of advanced computation and communication based on the laws of quantum mechanics.

In the May 8 issue of the journal Science, H. Jeff Kimble, the William L. Valentine Professor and professor of physics at Caltech, and his colleagues demonstrate for the first time that quantum uncertainty relations can be used to identify entangled states of light that are only available in the realm of quantum mechanics. Their approach builds on the famous Heisenberg uncertainty principle, which places a limit on the precision with which the momentum and position of a particle can be known simultaneously.

Entanglement, which lies at the heart of quantum physics, is a state in which the parts of a composite system are more strongly correlated than is possible for any classical counterparts, regardless of the distances separating them.

Entanglement in a system with more than two parts, or multipartite entanglement, is a critical tool for diverse applications in quantum information science, such as for quantum metrology, computation, and communication. In the future, a "quantum internet" will rely on entanglement for the teleportation of quantum states from place to place (for a recent review see H. J. Kimble, Nature 453, 1023 (2008)).

"For some time physicists have studied the entanglement of two parts-or bipartite entanglement-and techniques for classifying and detecting the entanglement between two parts of a composite system are well known," says Scott Papp, a postdoctoral scholar and one of the authors of the paper. "But that hasn't been the case for multipartite states. Since they contain more than two parts, their classification is much richer, but detecting their entanglement is extremely challenging."

In the Caltech experiment, a pulse of light was generated containing a single photon-a massless bundle, with both wave-like and particle-like properties, that is the basic unit of electromagnetic radiation. The team split the single photon to generate an entangled state of light in which the quantum amplitudes for the photon propagate among four distinct paths, all at once. This so-called W state plays an important role in quantum information science.

To enable future applications of multipartite W states, the entanglement contained in them must be detected and characterized. This task is complicated by the fact that entanglement in W states can be found not only among all the parts, but also among a subset of them.

To distinguish between these two cases in real-world experiments, coauthors Steven van Enk and Pavel Luogovski from the University of Oregon developed a novel approach to entanglement detection based on the uncertainty principle. (See also the recent theoretical article by van Enk, Lougovski, and the Caltech group, "Verifying multi-partite mode entanglement of W states" at http://xxx.lanl.gov/abs/0903.0851.)

The demonstration of the detection of entanglement in multipartite W states is the key breakthrough of the Caltech group's work.

The new approach to entanglement detection makes use of non-local measurements of a photon propagating through all four paths. The measurements indicate whether a photon is present, but give no information about which path it takes.

"The quantum uncertainty associated with these measurements has allowed us to estimate the level of correlations among the four paths through which a single photon simultaneously propagates, by comparing to the minimum uncertainty possible for any less entangled states," says Kyung Soo Choi, a Caltech graduate student and one of the authors of the paper. 

Correlations of the paths above a certain level signify entanglement among all the pathways; even partially entangled W states do not attain a similar level of correlation. A key feature of this approach is that only a relatively small number of measurements must be performed.

Due to their fundamental structure, the entanglement of W states persists even in the presence of some sources of noise. This is an important feature for real-world applications of W states in noisy environments. The Caltech experiments have directly tested this property by disturbing the underlying correlations of the entangled state. When the correlations are purposely weakened, there is a reduction in the number of paths of the optical system that are entangled. And yet, as predicted by the structure of W states, the entanglement remains amongst a subset of the paths.

"Our work introduces a new protocol for detecting an important class of entanglement with single photons," Papp explains. "It signifies the ever-increasing degree of control we have in the laboratory to study and manipulate quantum states of light and matter."

Next, the researchers plan to apply their technique to entangled states of atoms. These efforts will build upon previous advances in the Caltech Quantum Optics Group, including the mapping of photonic entanglement to and from a quantum memory (http://media.caltech.edu/press_releases/13115), and the distribution of entanglement amongst the nodes of a quantum network (http://media.caltech.edu/press_releases/12969).

The paper, "Characterization of Multipartite Entanglement for One Photon Shared Among Four Optical Modes," appears in the May 8 issue of Science. The authors are Scott B. Papp, Kyung Soo Choi (whose contributions to the work were equal to Papp's), and H. Jeff Kimble of Caltech; Hui Deng, a former Caltech postdoctoral scholar, now at the University of Michigan, Ann Arbor; and Pavel Lougovski and S. J. van Enk of the University of Oregon. Van Enk is also an associate of the Institute for Quantum Information at Caltech.

The work was funded by the Intelligence Advanced Research Projects Activity, the National Science Foundation, and Northrop Grumman Space Technology.

Kathy Svitil
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Caltech Submillimeter Observatory in Hawaii to be Decommissioned

New radio telescopes on the horizon will take over its duties; Mauna Kea site to be returned to its natural state

Hilo, HI, April 30, 2009-- The California Institute of Technology (Caltech) will begin decommissioning the Caltech Submillimeter Observatory (CSO) in Hawaii. Plans call for the dismantling of the observatory to begin in 2016, with the return of the site to its natural state by 2018.

The decommissioning of the CSO is due to the construction of the next generation of radio telescope, the Cornell Caltech Atacama Telescope (CCAT), to be located in Chile. CCAT's scheduled opening will occur prior to CSO's dismantling.

The Caltech Submillimeter Observatory is a cutting-edge facility for astronomical research and instrumentation development. Located near the summit of Mauna Kea, the CSO began operation in 1986. By 2016, the observatory will have given science 30 years of groundbreaking achievements.

"The timing of this works very nicely," says Tom Phillips, director of the CSO and Altair Professor of Physics in Caltech's Division of Physics, Mathematics and Astronomy. "The international community of astronomers that rely on CSO will have a seamless transition as CCAT comes online just as CSO is decommissioned."

Caltech operates the CSO under a contract from the National Science Foundation (NSF). Its partners include the University of Texas and University of Hawaii.
The observatory has been a host for many scientists worldwide. As part of its mission, observatory time is shared among University of Hawaii researchers, Caltech, the University of Texas, and international partners.

"Our partnerships have made the observatory tremendously productive," says Andrew Lange, chair of Caltech's Division of Physics, Mathematics and Astronomy. "Without support from the state of Hawaii, its university, and the residents of the Big Island, we would not have been able to produce such valuable scientific achievements through the years."

The CSO's 10-meter radio telescope was designed and assembled by a team led by Caltech's Robert Leighton and is considered one of the easiest telescopes to use for astronomical observations.

Work at the CSO has led to the detection of heavy water on comets, which has helped determine the composition of comets. It has also led to the observation of "dusty" planets--which optical telescopes are often unable to see--allowing astronomers a better picture of a planet's composition.

Eleven staff members currently work at the Hilo, Hawaii offices of the observatory while about eight staff members work at Caltech's Pasadena campus.

"The CSO has a distinguished history of scientific achievement in Hawaii," says Caltech president Jean-Lou Chameau. "The work done there has led to important advances in astrophysics and made future observatories, such as the CCAT, possible."

When CCAT comes online in the next decade, it will be used to address some of the fundamental questions regarding the cosmos, including the origin of galaxies and early evolution of the universe; the formation of stars; and the history of planetary systems.

CCAT is a joint project of Cornell University, Caltech and its Jet Propulsion Laboratory, the University of Colorado, a Canadian consortium including the University of British Columbia and Waterloo University, a German consortium including the University of Cologne and the University of Bonn, and the United Kingdom through its Astronomy Technology Centre at Edinburgh. More than twice the size of the CSO, the 25-meter CCAT telescope will be located in the high Andes region of northern Chile.

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CSO Scientific Achievements:

•    Development of superconducting-tunnel-junction detectors for radio astronomy, now commonly used on ground- and space-based radio observatories (ALMA, CARMA, Herschel)
•    Determination of the role of atomic carbon in the interstellar medium
•    Detection of the submillimeter "line forest," using the line-survey technique, as well as of key hydride molecules, which has led to improved understanding of the interstellar chemistry
•    Discovery of a new phase of stellar evolution, which occurs for red giant stars just before they completely lose their envelope to form planetary nebulae
•    Mapping of the molecular gas of radio galaxy Centaurus A, among others
•    Determination of the volatile composition of comets, including the first ground-based detection of HDO (heavy water) in a comet, leading to improved understanding of the origin of comets and of terrestrial water
•    Spectroscopy of distant and local galaxies using the Z-spec spectrometer--developed at CSO--which has helped us better understand the processes of galaxy formation and provides a method for measuring galaxies too dusty to be seen optically
•    Discovery of ND3, a rare type of ammonia, about 11 orders of magnitude stronger than initially presumed to exist
•    Imaging of distant, dusty galaxies close up which would be difficult to observe with optical telescopes--using tools such as the Submillimeter High Angular Resolution Camera (SHARC)
•    Spatially resolved imaging of nearby stellar debris disks, using SHARC, providing evidence for the presence of planets in these systems
•    Discovery of signs of intermittent turbulence in interstellar molecular clouds

Jon Weiner

Caltech Astrophysicist Awarded Dan David Prize

PASADENA, Calif.--Andrew Lange, the Marvin L. Goldberger Professor of Physics and chair of the Division of Physics, Mathematics and Astronomy at the California Institute of Technology (Caltech), has been awarded the 2009 Dan David Prize along with Paolo De Bernardis of the University La Sapienza in Rome and Paul Richards of the University of California, Berkeley. Lange and De Bernardis have been recognized for leading the BOOMERanG experiment, which provided the first undisputed evidence of the universe's flat geometry. Richards's MAXIMA experiment confirmed the result soon after. The experiments made the first resolved images of the cosmic microwave background radiation. Lange and colleagues were able to deduce the universe's geometry from the angular sizes of the intricate structures in the images, using theoretical tools developed by Marc Kamionkowski, the Robinson Professor of Theoretical Physics and Astrophysics at Caltech, and his colleagues.

The Dan David Prize is a joint international enterprise, endowed by the Dan David Foundation and headquartered at Tel Aviv University. The prize is awarded annually for achievements having an outstanding scientific, technological, cultural, or social impact on our world. Each year fields are chosen within three time dimensions: Past, Present, and Future. Lange, De Bernardis, and Richards are sharing the $1 million prize in the Past dimension for Astrophysics--History of the Universe. "The work recognized by this prize was a team effort," says Lange. "Many other people deserve recognition, especially Jamie Bock and his group at the Jet Propulsion Laboratory (JPL) microdevices lab, which developed the detectors that enabled both BOOMERanG and MAXIMA." Additional analysis of BOOMERanG and MAXIMA's data implied that ordinary matter constitutes a small fraction of the cosmic mass density (5 percent at the present time). These results have been subsequently confirmed and carry important implications for fundamental physics. The nature of most of the cosmic matter (known as Dark Matter) is actively being explored, and the flat geometry of the universe is believed to have originated from an early epoch of the universe's inflation, during which space curvature was erased by a prolonged period of vast expansion.

"The measurement of the large-scale geometry of the universe by Lange and his colleagues is one of the great achievements of all time in cosmology; it richly deserves this Dan David Prize," said Kip Thorne, the Richard P. Feynman Professor of Theoretical Physics at Caltech. "We at Caltech should be very proud to be associated with Andrew Lange, his BOOMERanG team, and their achievements."

Lange and his Caltech students worked closely with Bock and his group at JPL in developing the spiderweb bolometers that made possible BOOMERanG and MAXIMA, as well as several other major cosmological and astronomical projects and instruments.

"This technology is about to be launched into orbit on the Planck satellite later this spring," says Lange. "We still have much more to learn from the microwave background."

The other 2009 Dan David laureates are former British prime minister Tony Blair for Present Leadership, and Robert Gallo, director of the Institute of Human Virology at the University of Maryland School of Medicine, for Future Global Public Health. Dan David laureates donate 10 percent of their prize money to graduate students in their respective fields, thereby contributing to the community and fostering a new generation of scholars. For more information, visit http://www.dandavidprize.org/.

Deborah Williams-Hedges
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Caltech's Newest Shining Star: The Cahill Center for Astronomy and Astrophysics

PASADENA, Calif.--The California Institute of Technology (Caltech) scientists who study the outer reaches of space are about to get some space of their own with the official opening of the Cahill Center for Astronomy and Astrophysics.

The opening not only marks the beginning of a new era for Caltech astronomy, but is the Institute's kick-off for the International Year of Astronomy, a global effort initiated by the International Astronomical Union and UNESCO to mark the 400th anniversary of the first use of an astronomical telescope by Galileo Galilei. The aim of the year is to stimulate worldwide interest in astronomy and science.

The Cahill Center--located at 1216 California Boulevard--boasts 100,000 square feet of offices, laboratories, and common areas. Designed by the Los Angeles-based firm Morphosis (led by Pritzker Prize-winning architect Thom Mayne) and built by general contractor Hathaway Dinwiddie, the building is both highly functional and visually impressive.

Everything about this building has that thought-through feel--from its address (1216, in angstroms, is the wavelength of ultraviolet light emitted by hydrogen atoms) to the view from the lobby up an ever-narrowing staircase to the skylight on the third floor (which mimics the experience of peering up through a telescope) to the cut-through hallways on each floor (which connect Caltech's north and south campuses and serve to orient the building's occupants).

But what is perhaps most important about the Cahill Center is that it will allow some 300 of Caltech's top-ranked astronomy and astrophysics faculty and graduate students to work together in a building dedicated to their needs for the first time in more than 40 years, thanks to Charles H. Cahill, who provided the lead gift for the $50 million center. The building has been named for Cahill and his late wife, Anikó Dér Cahill.

"As a civil engineer myself, I'm always excited to be part of the birth of a new building, especially one that has been needed and envisioned by our faculty and administrators for so long," says Caltech president Jean-Lou Chameau. "If not for the extraordinary generosity of Charles Cahill and several other supporters, our faculty might still be waiting for this dream to become a reality."

Indeed, the Cahill Center was made possible not only by Cahill's lead gift, but by generous support from a number of Institute friends, including the Sherman Fairchild Foundation, the Ahmanson Foundation, the Kenneth & Eileen Norris Foundation, Fred & Joyce Hameetman (whose gift will name the Hameetman Auditorium), and Michael Scott.

"Taking a program like this to the next level is a team effort," says Chameau, "and our donors have been a key part of this remarkable team."

"For decades, our extraordinary astrophysics faculty have been scattered across campus, among several overcrowded buildings," says Andrew Lange, chair of Caltech's Division of Physics, Mathematics and Astronomy and the Marvin L. Goldberger Professor of Physics. "The Cahill Center will bring together 26 astrophysics faculty and their groups into a single, remarkable space. Students and faculty alike will have a much richer experience. I can safely predict that new discoveries will be spawned in the coming year by conversations in hallways and interaction spaces that would not have otherwise taken place."

Some of the key features of the building include

  • the 148-seat Hameetman auditorium and a library situated on the building's first floor to maximize their use as social and gathering spaces;
  • offices located on the building's second and third floors and the western part of the first floor, amongst which are scattered conference rooms and interactive spaces designed specifically to promote impromptu discussions and informal group meetings;
  • a single basement floor (with ample access to natural light) which houses all of the building's laboratories;
  • remote-observing rooms; and
  • a building-wide wireless system.

"The design for the Cahill Center draws on the institute's desire to maximize interaction between the astronomy and astrophysics faculty and their research groups," explains Kim Groves, principal in charge for the Morphosis team. "Visual and vertical connections between the laboratory and office levels occur via the main stair, while interaction areas and open break rooms punctuate each floor, all providing opportunities for chance and planned discussions to occur between the researchers. Views out of the building look across the campus and up into the sky, providing select moments to celebrate the study of astronomy and astrophysics on the world-renowned Caltech campus."

The Cahill Center for Astronomy and Astrophysics.
Credit: Bob Paz/Caltech

The Cahill Center is noteworthy not only for its creative design concept and execution, but also because it will be the first Caltech building to be certified under the LEED Green Building Rating System. LEED, which stands for Leadership in Energy and Environmental Design, was created by the U.S. Green Building Council, a coalition of more than 7,500 organizations from all sectors of the construction industry. LEED certifications are meant to encourage "whole-building" sustainability by recognizing structures that meet the building council's high standards.

"Conventional buildings have significant impacts on the environment over their lifetimes, considering the resources used to construct and maintain them and the generation of the energy used to operate them," notes John Onderdonk, Caltech's manager for sustainability programs. "Constructing LEED-certified buildings, which represent the state of the art in resource and energy efficient design, is critical to improving Caltech's environmental performance."

The Cahill Center will be given its gold-level LEED distinction because of the many features that allow it to reduce negative environmental and health impacts. The building's design provides for

  • reducing water use by 30 percent;
  • reducing energy use by 24.5 to 28 percent; and
  • providing access to daylight to a minimum of 75 percent of its spaces.

"Two of the most visible green features of the Cahill Center are the use of day lighting throughout the building--which reduces the need for electrical lighting--and the architectural paneling on the exterior," Onderdonk explains. "The paneling actually shades the building, thereby reducing heat gain and the need for interior air conditioning."

This focus on keeping things green extended to the construction phase of the building as well. In building the Cahill Center, the architects and construction crews focused on using materials with recycled content, as well as local and regional materials; they also used low-emitting adhesives, sealants, paints, carpets, composite woods, and laminate adhesives. In addition, they diverted more than 90 percent of the construction waste from the landfills, which significantly reduced the building's impact on the environment.

The opening of the Cahill Center for Astronomy and Astrophysics will be followed on January 27 with a full-day symposium to celebrate Caltech astrophysics. The symposium, "The Future of Astrophysics," is being held in the Hameetman Auditorium, with webcasts to the Cahill conference rooms. Speakers will include

  • Michael Turner, professor of physics, University of Chicago;
  • Jason Glenn, associate professor of astrophysics, University of Colorado;
  • Seth Shostak, senior astronomer, SETI Institute;
  • Roger Blandford, professor of physics, Stanford University;
  • Tim De Zeeuw, director general, European Southern Observatory;
  • Robert Kirshner, professor of astronomy, Harvard University;
  • Steven Beckwith, vice president for research and graduate education, University of California;
  • Andrea Ghez, professor of physics and astronomy, University of California, Los Angeles;
  • Peter Goldreich, professor in the School of Natural Sciences, Institute for Advanced Study; and
  • Jerry Nelson, professor of astronomy, University of California, Santa Cruz.

For more information about the symposium, please contact Michelle Vine at 626-395-3817 or vine@caltech.edu.

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About Caltech: Caltech is recognized for its highly select student body of 900 undergraduates and 1,200 graduate students, and for its outstanding faculty. Since 1923, Caltech faculty and alumni have garnered 32 Nobel Prizes and five Crafoord Prizes.

In addition to its prestigious on-campus research programs, Caltech operates the W. M. Keck Observatory in Mauna Kea, the Palomar Observatory, the Laser Interferometer Gravitational-Wave Observatory (LIGO), and the Jet Propulsion Laboratory. Caltech is a private university in Pasadena, California. For more information, visit http://www.caltech.edu.

Lori Oliwenstein
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About Caltech Astronomy

Astronomer Royal of the United Kingdom, Martin Rees, summed up Caltech's legacy in astronomy when he said, "The universe of astronomy has no center, but the universe of astronomers does. For years that center has been in Pasadena, California."

As part of Caltech's Division of Physics, Mathematics and Astronomy, the astronomy department's primary mission is to perform cutting-edge research in astronomy and astrophysics while educating undergraduate and graduate students to become the scientific leaders of tomorrow.

Astronomy has been a major component of Caltech's scientific identity since the early days of the Institute. George Ellery Hale, the first director of the Mount Wilson Observatory, was elected to the board of trustees of Throop Polytechnic Institute (later to be renamed the California Institute of Technology) in 1907. Hale is largely responsible for shifting the institution's focus to engineering and science, fields in which Caltech would quickly become a world leader.

Among Caltech's major contributions to the field of astronomy is the first survey of the entire sky visible from the Northern Hemisphere, the Palomar Observatory Sky Survey. Conducted in l948, it revealed thousands of new stars, galaxies, and comets. This provided astronomers the world over with an atlas of the heavens to be used for the next three decades. Today, Palomar Mountain in San Diego County is home to the 200-inch Hale Telescope, which was for four decades the largest and most powerful optical telescope in the Western Hemisphere.

In 1964, Caltech astronomer Maarten Schmidt determined that quasars--a puzzling class of cosmic objects--were the most powerful and distant objects in the universe. Since quasar light travels for billions of years to reach Earth, Schmidt's discovery gave astronomers unprecedented insight into how the universe looked billions of years before the birth of the sun and its planets.

Today, the Caltech astronomy department--led by more than 30 faculty--continues to engage in a wide variety of astronomical research projects, with topics ranging from nearby stars to the most distant galaxies in the universe. To help maintain these research efforts, the department supports an interest in worldwide astronomical observatories at locations ranging from San Diego County to Hawaii to the Chilean Andes, including

The Palomar Observatory, located in San Diego County, was dedicated in 1948 and is home to the 200-inch Hale Telescope, as well as a 60-inch instrument, the 48-inch Samuel Oschin Telescope, and an 18-inch Schmidt Telescope.

The Laser Interferometer Gravitational-Wave Observatory, or LIGO, is dedicated to the detection of cosmic gravitational waves and the harnessing of these waves for scientific research. Albert Einstein predicted the existence of these waves in 1916, and LIGO--which was designed by Caltech and MIT physicists--began its search in 2001. LIGO consists of two widely separated installations within the United States--one in Hanford, Washington, and the other in Livingston, Louisiana--which are operated in unison as a single observatory.

The Keck Observatory is perched atop the dormant volcano Mauna Kea on the island of Hawaii. Keck is a joint effort of Caltech and the University of California, and consists of twin 10-meter telescopes, Keck I and Keck II. Recently, the two telescopes have been used in combination as the Keck Interferometer, with sufficient power and resolution to detect planetary systems around nearby stars.

The Caltech Submillimeter Observatory is a 10-meter dish atop Mauna Kea in Hawaii.

The Owens Valley Radio Observatory is located some five hours north of Pasadena, near the Sierra Nevada range. The observatory is home to a variety of dishes and interferometers, and is the operations base for the CARMA millimeter-wave interferometer (see below).

The Combined Array for Research in Millimeter-wave Astronomy, or CARMA, is the merger of two university-based millimeter arrays--the Owens Valley Radio Observatory (OVRO) millimeter array and the Berkeley-Illinois-Maryland Association (BIMA) millimeter array--which together form a powerful astronomical tool for the new millennium.

The Chajnantor Observatory is located at an altitude of over 16,000 feet in the Chilean Andes. It is the site of the Cosmic Background Imager (CBI) and will be the site of the Q/U Imaging Experiment (QUIET) project. The site is accessible year-round and provides superb conditions for cosmic microwave background observations.

The Thirty Meter Telescope is a collaboration between Caltech, the University of California, and the Association of Canadian Universities for Research in Astronomy (ACURA) to build a 30-meter-diameter telescope for astronomy at visible and infrared wavelengths.

The Big Bear Solar Observatory is a world center for observations of the sun. The facility is managed by the New Jersey Institute of Technology for a university consortium that includes Caltech.

Visit http://www.astro.caltech.edu to learn more about Caltech Astronomy.

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Lori Oliwenstein
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