Texas’ Decision to Close Physics Programs Jeopardizes Nation’s Future September 14, 2011

Why does Africa need the Square Kilometre Array? August 16, 2011

2009 Address by Dr Adrian Tiplady, Manager, Site Characterization, SKA Africa Project Office

Honourable Minister, distinguished guests, ladies and gentleman

Why does Africa need the Square Kilometre Array? It is a question often posed by a public that is cognisant of the many high priorities that South Africa, and Africa as a whole, faces. We are currently engaged in an international race, competing to host a multi‐billion dollar, cutting edge astronomical facility that, in my view, may very well be mankind’s last great astronomical adventure still bound on earth. Do we, as South Africans, have the skills and expertise to compete within the world’s scientific community, to produce scientists and engineers of the highest calibre that will compete in the global knowledge economy? (answer at the end)

Today, during the International Year of Astronomy, the world faces economic recession and a financial crisis like never before. Uncertainties in food, water and energy supply loom, whilst climate change has become an ever present maxim in the implementation of global policies. Africa suffers from the unrelenting scourge of preventable diseases such as Aids and malaria. Why, then, has South Africa, and Africa, announced to the international community that “we have the desire to become the international hub for astronomy”?

In the US, President Barak Obama has committed to significantly increasing investment into science, as one of the most important parts of stimulating the economy. In his address to the US National Academy of Science, President Obama said:

“At such a difficult moment, there are those who say we cannot afford to invest in science, that support for research is somehow a luxury at moments defined by necessities. I fundamentally disagree. Science is more important for our prosperity, our security, our health, our environment and our quality of life than ever before”.

He went on to say:

“The pursuit of discovery half a century ago fueled our prosperity … in the half century that followed. The commitment I am making today will fuel our success for another fifty years. That’s how we will ensure that our children and their children will look back on this generation’s work as that which defined the progress and delivered the prosperity of the 21st century. …. The fact is that an investigation into a particular physical, chemical or biological process may not pay off for a year or two, or a decade, or not at all. But when it does, the rewards are often broadly shared……..And that’s why …… the public sector must invest in this kind of research – because while the risks may be large, so are the rewards for our economy and our society. ….. It was basic research in … the photoelectric effect that would one day lead to solar panels. It was basic research in physics that would eventually produce the CAT scan. The calculations of today’s GPS satellites are based on the equations that Einstein put on paper more than a century ago”.

Even with the wealth disparity between the USA and South Africa, science and technology on the African continent is still seen as key to our ability to solve the problems of development that will determine the future of Africa and South Africa. Investment in mega‐science facilities has never been as important as it is today, where the brain drain, ill equipped school leavers and the lack of funding for higher education facilities to pursue areas of basic research have a directly detrimental effect on our ability to participate in the global knowledge economy, where we become innovators as opposed to consumers of technology.. And to retain these people, to stem the flow of skilled people leaving these shores, we need to provide flagship projects, such as those in astronomy that places cutting edge development in a variety of scientific and engineering disciplines at its core competency.

In 2003, the Department of Science and Technology and the National Research Foundation decided to enter into a race with four competing countries to host the world’s largest radio telescope. The Square Kilometre Array, as it is known, began as an international project in 1991, and currently involves 55 institutions across 19 countries. At a capital cost of more than $2 billion USD, the international consortium aims to have the SKA up and running by 2022, spending a further $150 million USD per year for the next 50 years in running costs. Much of this expenditure will be spent in the host country. The instrument is projected to be between 50 and 100 times more powerful than any radio astronomy facility ever built, an array of some 4,500 radio telescopes distributed over an area 3,000 km in extent. Combining the signals from each of these telescopes using a supercomputer 100 times more powerful than anything that exists today will create a virtual telescope, spanning 3000km in diameter, with a total collecting area of 1 square kilometre ‐ the equivalent of over 1,000,000 DSTV satellite dishes. This will result in an instrument with unparalleled sensitivity and resolution.

In this International Year of Astronomy, we believe we understand just 4% of all the matter and energy in the universe. The world’s astronomical community are striving to answer some of the great fundamental questions that face the world’s scientific community, and also raise new questions ‐ not just in astronomy but indeed in fundamental physics. Instruments such as the recently launched Herschel and Planck telescopes are being put into orbit 1.5 million km away from earth, collecting the kind of data that is possible now because of technological innovations in the last 10 years. Data that could help us answer the very mysteries of the universe. Plans are afoot to venture outside of the earth, and even place telescopes onto the dark side of the moon.

The SKA is part of this frontier of new instruments. Some of the many questions to be answered are :

What is the nature of dark energy – a mysterious force that acts in opposition to gravity on very large distances, repelling massive objects from each other with ever increasing force?

How did the universe and all that is contained within it evolve – radio signals have been travelling through the universe for 13 billion years, and we are only receiving some of them today as we take “pictures” of the big bang and the first stars and galaxies. We will be able to make snapshots of the universe through time.

Mankind has long striven to answer the question of whether there is life on other planets? The detection of biomolecules, or even artificial radio transmissions, may answer this. These questions and more, however, probably do not approach the rich rewards that will come from not what we plan to investigate, but rather what we haven’t planned for. Radio telescopes today are not remembered for what they were built, but instead for what they serendipitously discovered.

When South Africa, with a rather small human capital base in radio astronomy at the time, submitted its bid in 2005, we took the international community by surprise. Any degree of afro‐pessimism was dismissed, however, when South Africa was shortlisted along with radio astronomy international heavyweight ‐ Australia. Why? Because we have something that no amount of financial investment could ever buy. We have one of the best locations in the world to build and operate astronomical facilities, and a very committed Department of Science and Technology and National Treasury.

The Southern African Large Telescope in Sutherland has some of the darkest skies in the world – and the proposed SKA core site, just 80km northwest of the town of Carnarvon in the Northern Cape, has one of the best radio frequency environments in the world, free from a majority of the interfering radio signals that plague most of the world’s radio astronomy facilities. Furthermore, because of our geographic location on the planet, the very best astronomical sources to observe pass right overhead – we literally have the best window on the planet out of which to gaze upon the universe, and explore the centre of the Milky Way Galaxy.

Protection of this site is of the utmost importance – not only to protect South Africa’s geographical advantage, but to preserve the site for the world’s astronomical community. To meet this requirement, the Department of Science and Technology has promulgated the Astronomy Geographic Advantage Act, which allows for the establishment of an astronomy reserve in the Northern Cape Province. A reserve in which astronomy facilities are protected from sources of optical and radio interference.

The Australian Minister of Science has described winning the SKA bid as being like winning the Olympic site bid every day for 50 years. If the right to host the SKA were to be awarded to South Africa, and its 7 African partner countries, we would become a premier centre for research in astronomy and fundamental physics – going hand in hand with cutting edge development in the engineering technologies that co‐exist with this field of research.

As many of the technologies do not yet exist, to build the SKA will require a significant international effort in the fields of information and communication technology, supercomputing, mechanical, radio frequency, software and electronic engineering, physics, mathematics and, of course, astronomy. All fields that provide a basis for a strong knowledge economy. In 2004 the DST, together with the NRF, decided that simply competing to host the SKA would not meet the aims of building a knowledge economy – what was needed was a flagship project that would provide an opportunity to increase the skills base of our young scientists and engineers. We needed to participate in the technology development for the SKA, to grow a substantial base of scientists and engineers in South Africa that would be able to use, operate and maintain the SKA. And so was born the Karoo Array Telescope – an SKA science and technology pathfinder.

MeerKAT, as it is now known, will be the first radio interferometer built for astronomical purposes in South Africa. It will consist of 80 dishes, and once completed in 2013 will be one of the world’s premier radio astronomy facilities that will have not only South Africa scientists, but the world’s astronomical community, clamouring to use – 9 years before the SKA is scheduled to be commissioned.

Over the course of the last 5 years, we have built up a team of some 60 young scientists and engineers who are working on the technologies and algorithms required for the MeerKAT, which will in turn test the technologies for the SKA. Many of these people would have most probably left these shores already, looking for more exciting projects to work on in Silicon Valley, or other technology clusters. However, the lure and attraction of such a project as MeerKAT, and the larger SKA, has kept them here. Although none had any radio astronomy training, the team has quickly become an international leader in the development of technologies for radio astronomy facilities, which in fact are the generic technologies upon which the digital age depends, and are highly likely over many years to generate spin‐off technologies, innovations and patents. They have managed to do this through international collaboration with institutions such as Oxford, Cambridge, Manchester, Caltech, Cornell and Berkeley, as well as the national radio astronomy observatories in the USA, India, Italy and The Netherlands. We are also working closely with several South African universities and companies.

Amongst other things, the team has developed the first every radio telescope made from composite materials, and is playing a leading role in the international development of digital hardware for real time data processing. The first 7 MeerKAT dishes are being constructed as I speak.

In a recent editorial in the local WattNow magazine, Paddy Hartdegen says the following of the SKA and MeerKAT projects : “In my view, gee whiz projects such as the SKA and the MeerKAT go a long way to encouraging youngsters to take science and engineering disciplines more seriously. And if there is some thrill attached to science, astronomy or mathematics, then the students will apply themselves more diligently at primary and secondary schools, to ensure that they will have the necessary qualification to enter a university”. He goes on to say “I believe that projects such as the SKA can actually foster the sort of compelling interest that is reserved for sports stars and pop musicians“

So, is Paddy Hartdegen right? Do the SKA and MeerKAT projects have the qualities that will attract students into science, engineering and technology? In 2005, we initiated a Youth into Science and Engineering program, to rapidly grow the human capital base in astronomy and engineering in South Africa. To date, we have awarded 142 post‐doctoral fellowships, PhD, masters degree, honours degree and undergraduate degree bursaries. We are currently awarding approximately 45 bursaries per year. We are assisting universities to increase their astronomy research capacity, and to develop additional capacity to supervise students through international supervisory programs. The question is, can these students stand on their own two feet within the international astronomical community?

For the last 3 years, we have held a post‐graduate student conference for our bursary holders, where each student presents the results of his or her research. We invite a number of international experts to attend. To date, none have declined the invitation – not due to the opportunity for a holiday in Cape Town, but instead because of the astounding reputation this conference has grown internationally due to the quality of students and research. Professor Steve Rawlings, Head of Astrophysics at Oxford University, said on his departure “I am awfully impressed by what I have seen at this conference and how things have exploded on the science and engineering side on such a short timescale. South Africa is doing all the right things for the SKA”.

So, what has the establishment of a flagship project resulted in? People. Skilled people. The new measure of financial prosperity. Skilled people who are helping to change South Africa’s reputation as a place of high technology investment, research and development. These students, who cross the race and gender lines, may never stay within the field. However, they will carry the skills they have learnt into new areas, and their impact will be felt through a variety of socio‐economic lines.

The SKA, and the MeerKAT, has matured into a project of which we, as the South African scientific community, can be proud. It is a project that should capture the South African public’s imagination, young and old alike.

Do we, as South Africans, have the skills and expertise to compete within the world’s scientific community, to produce scientists and engineers of the highest calibre that will compete in the global knowledge economy?

We have in the past, and we will continue to do so. The answer, therefore, is a resounding yes.

Morgan State University Student Spends Summer at CERN July 24, 2011

Eric Michael Seabron, a junior physics major and Morgan honor student with a 3.66 grade point average was selected to join an exclusive 18-member U.S. physics team for a 10-week summer internship at CERN (European Organization for Nuclear Research) in Geneva, Switzerland. 

 

“This internship is one of the most competitive internships an undergraduate student of physics can compete for in the United States.  Mr. Seabron will benefit from this experience by expanding both his knowledge of physics and participating in the greatest scientific experiment ever proposed, the Large Hadron Collider (LHC). Participation in this internship increases his visibility as a up-and-coming young physicist, and his opportunities for getting into a Tier-1 physics graduate program with schools like Michigan, Harvard, Stanford and Princeton to name a few,” says Dr. Keith Jackson, chair of Morgan’s physics department.

Mr. Seabron is a member of the University of Michigan’s ATLAS team sponsored by a National Science Foundation research grant for undergraduates to work on a valuable piece of equipment (Large Hadron Collider) on the ATLAS experiment. ATLAS (A Toroidal LHC ApparatuS) is one of the six particle detector experiments constructed at the LHC. He and other student colleagues will assist in the commissioning of ATLAS EE detectors, analyze event data to create R-T curves and Muon Spectrometer graphs.

Since 2009, more than 2900 scientists and engineers from 172 institutions in 37 countries have worked on the ATLAS experiment. 

The ATLAS experiment’s primary objective is to detect particles created after high-energy proton on proton collisions.  ATLAS will allow us to learn about the basic forces that have shaped our Universe since the beginning of time (if time has a beginning) and that will determine its fate. Research at ATLAS will provide answers to some of the most basic questions in physics such as the origin of mass, proof of existence of multiple dimensions, unification of fundamental forces, and evidence for dark matter candidates in the Universe. ATLAS brings experimental physics into new territory. Most exciting is the completely unknown surprise – new processes and particles that would change our understanding of energy and matter.

 

“Students who are successful strive to do more than meet the minimum level of academic performance. If they take this attitude toward their undergraduate education they will find a plethora of new experiences, challenges and opportunities waiting for them, like Mr. Seabron,” says Dr. Jackson.  

 

Eric is standing holding ladder with Michigan teammate Kareem Hegazy (on ladder) in front of 20 ft. battery cells.

NSBP and sister societies respond to National Science Board regarding broader impacts criteria July 20, 2011

Merit Review Task Force
National Science Board
Room: 1225N
4201 Wilson Boulevard
Arlington, Virginia 22230, USA

Dear Merit Review Task Force,

Thank you for the opportunity to comment on the proposed revised text for the Intellectual Merit and Broader Impacts evaluation criteria.

Members of the National Technical Association and other minority professional organizations are very concerned about the potential negative impact of the proposed changes to the Merit Review Criteria. We are particularly, concerned about the reduced visibility to the importance of STEM diversification.

Firstly, the proposed changes to the broader impacts text can lead one to infer that diversity is an option and not required since one of the national goals addresses it explicitly. It appears to allow PIs to choose other goals and be evaluated without addressing diversity. Diversity appears to become an option rather than central to all programs and projects and activities, as stated in the existing criteria.

Secondly, utilizing the broad base national goals as the core principles makes it very difficult to develop a clear framework to benchmark or measure the creativity, educational impacts and potential benefits to society of the programs, projects, reviewed. Each national goal embodies a multiplicity of challenges that are interrelated and dependent on other goals. Several goals address education, while others address workforce which are essential to the development of global competitiveness, yet another goal. Measuring impact at the goal level can become problematic. It is easier to identify underlying issues/causes that should be addressed to advance national goal(s) rather than focus on the goals themselves.

We recommend that NSF make it clear that its commitment to diversity is unchanged and indicate how diversity will be factored into the evaluation of all programs, projects and activities regardless of which national goals are addressed.

To advance the frontier of knowledge and achieve global competitiveness, a well trained American born workforce is imperative. Given the projected population demographics, the eligible workforce will shift more to people of color who are underrepresented in STEM. It is more critical than ever that NSF support programs that address workforce development and STEM education improvements to ensure America realizes its STEM related national goals. Whereas, linking programs to national goals is important, it is crucial to first define the national problems that need to be resolved to realize national goals and support research/models that resolve these issues.

Based on these facts, we urge the Merit Review Task Force to focus on criteria changes that identify categories of problem/ issues it will support to advance national goals and at the same time support its commitment to diversity.

Sincerely,

National Organization of Black Chemists and Chemical Engineers
National Society of Black Physicists
National Technical Association

US SKA Consortium votes to dissolve itself in light of decadal survey and budget realities June 15, 2011

Southern Africa’s SKA Bid: A Worthwhile Investment June 14, 2011

By Congressman Bobby Rush

Southern Africa is quickly establishing itself as a hub for astronomy, scientific expertise and in doing so, is creating an unrivalled opportunity for the development of skills and expertise that will allow Africa and its people to be significant contributors to the global knowledge economy.

In 2012, a consortium of major international science funding agencies will select a location to house the world’s most powerful radio telescope, The Square Kilometre Array (SKA). The SKA promises to revolutionize science by answering some of the most fundamental questions that remain about the origin, nature and evolution of the universe. With about 3 000 receptors linked together and a total collecting area of one square kilometre, the SKA will have 50 times the sensitivity and 10,000 times the survey speed of the best current-day radio telescopes. The SKA will enable scientists to gain insight into the origins of the universe and provide answers to fundamental questions in astronomy and physics.

Currently, two locations are under consideration: Africa, under the leadership of South Africa, and Australia/New Zealand, under the leadership of Australia. South Africa’s SKA bid proposes that the core of the telescope be located in the Northern Cape Province, with additional antenna stations in Namibia, Botswana, Kenya, Mozambique, Madagascar, Mauritius, Ghana and Zambia.

South Africa has already demonstrated its excellent science and engineering skills by designing and starting to build the MeerKAT telescope, an SKA precursor telescope. Five years before MeerKAT becomes operational, more than 43,000 hours of observing time have already been allocated to radio astronomers from Africa and around the world, who have applied for time to do research with this unique and world-leading instrument. US astronomers are leading some of these research teams.

There is already active collaboration between the South Africans and UC Berkeley, the National Radio Astronomy Observatory and Caltech on the PAPER and CBASS telescopes respectively, which are currently hosted on the South African radio astronomy reserve. Collaboration is also taking place between these US research institutions and the MeerKAT team on the development of technologies for the MeerKAT and US telescopes.

The SKA in Southern Africa represents an unrivalled opportunity to transform Africa through science and technology by driving the world’s best and brightest to the region, and providing the continent’s youth with a world-class incentive to study science and provide the world answers to the planet’s oldest questions.

The SKA in Southern Africa will create a critical mass of young people in Africa with world-class expertise in technologies that will be paramount in the global economy in the coming years. New technologies, scientific discoveries and infrastructure development taking place in Africa will contribute to the creation of entirely new industries and spur development in many fields of human endeavor, while transforming Africa as a major hub for science in the world and creating a new continent of opportunity for American business to cultivate and develop partnerships throughout Africa.

The construction of major science infrastructure in Southern Africa, such as the $2 billion SKA project, will also represents an important opportunity for U.S. business to cultivate and develop partnerships in the region that can lead to new technologies, new industries and economic development both here in the USA and throughout Africa.

The SKA represents a unique opportunity to accelerate the development of skills and expertise that will allow Africa and its people to be significant contributors to the global knowledge economy. We should support southern Africa in its quest to become contributors to global science and equal partners in the knowledge economy.

Bobby Rush is the U.S. Representative for Illinois’s 1st congressional district, serving since 1993. He is a member of the Democratic Party. A long-time advocate of increased trade with Africa, he has introduced H.R. 656, the African Investment and Diaspora Act, to advance the mutual interests of the United States and Africa with respect to the promotion of trade and investment and the advancement of socioeconomic development and opportunity.

The US remains supportive of the Square Kilometer Array project April 7, 2011

Though the United States did not officially join the Founding Board of the Square Kilometer Array (SKA), the US does remain supportive of the project. In large part, the decision not to join the Founding Board is based on the recommendations of the most recent astronomy decadal survey performed by the National Research Council, “New Worlds, New Horizons in Astronomy and Astrophysics,” released in August 2010. This report concluded that the combination of technical readiness and high cost risk made it unfeasible for the National Science Foundation (NSF) to invest in SKA construction during the 2010-2020 decade. NSF has accepted that conclusion and is setting a priority for SKA construction that is consistent with this conclusion and the other recommendations of the decadal survey.

NSF has invested in SKA technology development and in several radio telescopes that serve as scientific and technical pathfinders for the SKA, as well as pursuing some of the science goals envisioned for the international SKA, and will continue to make such investments as funds and independent reviews permit.

The SKA is an exciting project for astronomy. It was originally conceived as a focused project to study the end of the “Dark Ages” – the time when the first stars, black holes, quasars, and other high energy objects formed, ionizing the almost 100% neutral hydrogen gas left around from the Big Bang. You can imagine the universe at say z=20 being dark and transparent. But as the ultraviolet light begins to come from the first sources, the light ionizes larger and larger regions of the Universe – sort of like Swiss Cheese until redshift around z=6 where most of the hydrogen is ionized as it is today.

The SKA will slice through this redshift range giving us an accurate tomographic image of the Universe as it begins to form the elements of the periodic table, and begins to form the seeds of what we now see are galaxies and massive black holes. Its science case has expanded since then, but the main focus of the science is the tomography of the early Universe.

But the final SKA design is far from certain. Technology is still in development, and the final cost of the SKA is quite unknown. It may turn out actually that the SKA evolves to be three very large telescope arrays that are not co-located. A major factor of the SKA to site in a region free from FM carrier frequencies, and there are remarkably few in the world. Among them are sites selected in Africa and in Australia.

No definitive scientific rationale has emerged to favor the African site over the Australian or vice versa. Each project is pursuing pathfinder telescopes as pre-cursors to the SKA, and each is molded better to different capabilities.

But there may be international policy issues that would motivate the US to help fund the project now. The US presently supports, and will build, new major telescopes in Chile, including the LSST, CCAT, and ALMA the latter being an international collaboration. Chile has benefited greatly by hosting these telescopes, not only in building astronomy programs, but through other spill-over effects, e.g., broadband connectivity, service sector jobs and growth in the knowledge-based innovation economy. During President Obama’s recent trip to Chile, he and President Pinera issued a joint communique that they recognized the close historical collaboration in astronomy between the two countries and looked forward to future projects.

There are scientists and policy makers that would like to see an astronomy-catalyzed economic transformation in Africa. South Africa already has a long and distinguished history in astronomy research. Astronomers are developing academic programs and research telescopes in Botswana, Burkina Faso, Ethiopia, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Namibia, Nigeria, Zambia, and others. Last December African astronomers organized the African Astronomical Society to be the voice of the astronomy profession on the continent and to be the continental interlocutor with other astronomy professional societies around the world. The SKA is a tremendous opportunity to help develop astronomy in Africa. If the Chilean example is a guide, the SKA would help develop high-tech industry and build a larger community of African astronomers, physicists, and engineers.

But the results of the decadal survey stunts the rationale for large-scale US investment (and for the US that means NSF funding) in the SKA, at least for this decade. This is probably the right choice. There are other projects, e.g., WFIRST, LSST, where the technology is more mature and thus closer to fruition. As the US faces limited fiscal options the decadal survey is the accepted process for the field to make hard decisions. Without a determined technology for SKA there is no way to make any firm cost determinations. So the question of whether to support the SKA long-term remains open.

But all is not lost for this decade. The South African MeerKAT and Australian ASKAP, both of which will be completed in this decade, will be extremely powerful telescopes. The MeerKAT in particular will be well-suited for pulsar timing studies that can reveal much about relativity, gravitational lensing, and nuclear physics.

Maybe this decade will see investments from other functions of the federal budget, e.g., foreign assistance through the State Department. Maybe the foreign assistance budgets of other donor countries can be brought to bear on the SKA project. After all, the total budget for the SKA construction is actually quite small compared to the total amount pledged by the G20 nations for development in Africa. Maybe the US Commerce Department, other nations’ ministries of industry, and private corporations will view the SKA as a technology incubator and thus find funds to help with technology development. And maybe philanthropists will find the SKA worthy of their donor dollars.

What remains true is that in Africa the SKA project has a full head of steam. South African science minister, Naledi Pandor, has said, “I am intent on ensuring that South Africa wins the bid to host the Square Kilometer Array radio telescope” and “…[I am] …not going to entertain any matter that might distract me from achieving that goal.” The Heads of State of the African Union have endorsed the African bid for the SKA telescope, signaling multilateral cooperation at the highest levels for this project.

The African SKA project team has already achieved impressive results with their KAT-7 precursor telescope, as well as in electronic design, manufacturing and logistics. And the SKA Project Office has conceived and developed the extremely clever idea of an African VLBI network that would use decommissioned communications dishes across the continent. Five years before South Africa’s MeerKAT telescope becomes operational, more than 43,000 hours of observing time (adding up to about five years) have already been allocated to radio astronomers from Africa and around the world.

The SKA human capacity development program is already an unqualified success. The challenge is to keep the steam chest full and to build on all these successes. The National Society of Black Physicists will of course maintain its collaborations with the African astronomy community. In addition to producing outstanding astronomy research results, we believe the African SKA will lead to the creation of an African scientific technological base that will in turn act as the engine of African economic development and will transform the African economy to one that is more based on knowledge, connectivity, technology and innovation. As an international research center located in Africa, the SKA will help unbridle the imaginations of young Africans and inspire them to pursue math and science at school, and to follow careers in science and engineering. This would create a critical mass of problem solving thinkers, able to find solutions to the water, food, health, energy and environmental challenges of the continent.

Cuprate Superconductors: Puzzle of the Pseudogap April 7, 2011

by Philip Phillips, University of Illinois Urbana-Champaign

It has now been 25 years since superconductivity was discovered in the copper-oxide ceramics (hereafter cuprates). One thing we have learned since then is that these materials defy explanation within the standard paradigms of solid state physics. In metals such as mercury, superconductivity emerges from a normal state in which the interactions between the electrons can be ignored. The only interaction which is relevant is that arising from the ions. When two ions move closer together, the electrons experience a net attraction which gives rise to charge charge carriers.

In the cuprates, superconductivity emerges from the pseudogap state in which there is a depression of the single particle density of states in the absence of superconductivity. Straightforward application of the standard superconducting paradigm to a state of matter with no states at the chemical potential yields a vanishing superconducting transition temperature.

However, the transition temperature in the cuprates can be as high as 140K. Hence, something else must be going on in these materials. The experiments by He, et al [1] are designed to unlock the secrets of this mysterious pseudogap phase which sets in at a temperature as shown in the figure below.

Phase diagram and anomalous transport in the cuprate high-temperature superconductors. Heuristic phase diagram as a function of holes doped into the copper-oxide plane. The pseudogap and strange metal are characterized by a depletion of the density of states and a -linear resistivity, respectively. The pseudogap terminates at a zero-temperature critical point or quantum critical point (QCP). To the right is a Fermi liquid (conventional theory of metals) where weak-coupling accounts become valid. We currently have no theory of superconductivity in a state of matter that is a non-Fermi liquid. Even the most recent constructions of superconductivity using tools from string theory that are designed to get at strong correlations in quantum systems yield superconductivity [2] only from the Fermi liquid state. This is truly unfortunate and points to how rudimentary our understanding of superconductivity really is.

The phenomena surrounding the pseudogap in the cuprates used to be fairly simple. In zero magnetic field, lightly doped cuprates possess an incomplete Fermi surface, termed a Fermi arc, in the normal state. That is, the Fermi surface which is present in the overdoped, more conventional Fermi liquid regime is destroyed on underdoping leaving behind only a Fermi arc.

In actuality, the situation is much worse. That the Fermi arc does not represent a collection of well-defined quasiparticle excitations has been clarified by Kanigel, et al. [3] who showed that in BiSrCaCuO, the length of the Fermi arc shrinks to zero as tends to zero. Consequently, the only remnant of the arc at is a quasiparticle in the vicinity of and hence the consistency with nodal metal phenomenology.

Recently, however, new ingredients have been added to the pseudogap story in the underdoped regime which, on the surface, are difficult to reconcile with Fermi arcs. At high magnetic fields, quantum oscillations, indicative of a closed 2 Fermi surface, have been observed [4] in Y123 and Tl-2201 through measurements of the Hall resistivity, Shubnikovde Haas effect, and the magnetization in a de Haas-van Alphen experiment. Also attracting much attention is the recent experimental evidence for nematic order [5, 6] ( a state with broken translational symmetry but still possessing translational symmetry) at the onset of the pseudogap onset temperature, .

The paper by He, et al. [1] reports a series of measurements (as others have previously [7]) which point to the pseudogap regime being driven by a phase transition. The most puzzling of these experiments is the Kerr effect which requires the breaking of time-reversal symmetry. The authors claim, however, that the magnitude of this effect is too small for it to be the dominant cause of the pseudogap. If this is so, then perhaps the order which is seen is really an epiphenomenon having no causal connection to the pseudogap. What then of the transport anisotropies which have been attributed to nematic order?

Interestingly, the models [8, 9] proposed to explain the Kerr effect do not result in transport anisotropies. It might turn out that the transport anisotropies observed in the Nernst signal are a red-herring, afterall since the orthorhombic lattice symmetry of the cuprates already has asymmetric and axes.

While trying to understand the origin of competing order in the pseudogap state is important, it is entirely likely that order has nothing to do with the efficient cause of the pseudogap, the suppression of the single-particle density of states at the chemical potential. Such a claim has been made recently by Yazdani and collaborators [10] who also observed electronic inhomogeneities at the onset of the pseudogap state. They state explicitly, “While demonstrating that the fluctuating stripes emerge with the onset of the pseudogap state and occur over a large part of the cuprate phase diagram, our experiments indicate that they are a consequence of pseudogap behavior rather than its cause.” [10]

I think it is in this context that the He, et al. [1] experiments must be placed. The disassociation of order from the origin of the pseudogap is not entirely surprising. After all, the phase diagram of the cuprates does tell us that the single theory of these systems must above the superconducting dome explain the pseudogap and at higher temperatures the strange metal. Hence, focusing on the pseudogap independent of the strange metal amounts to not facing up to the nature of the charge vacuum of the high-temperature phase.

It is in this regime that the strong correlations conspire to produce the anomalous properties of the normal state. As neither the pseudogap nor the strange metal appear necessarily as states of matter in the cuprate phase diagram, the standard guiding principle of model building in which only states are relevant fails in this problem.

Nonetheless, the relevant physics should emerge from correct implementation of the Wilsonian program. As Wilson has taught us, high and low-energy physics are linked through a series of recursion equations that arise once the high-energy degrees of freedom are integrated out. In weakly interacting systems (Hg for example), such an integration simply renormalizes the coupling constants in the low-energy sector. However, in strongly interacting systems, new degrees of freedom can be generated [11].

The theoretical resolution of the normal state of the cuprates rests in demonstrating how the degrees of freedom that are generated upon integrating out the high-energy scale mediate the strange metal and at lower temperatures the pseudogap regime. While significant progress has been made on this problem recently [11], the associated phenomena found by He, et al.[1] relating to the origin of time-reversal symmetry breaking have not been addressed. This stands as an open problem.

[1] R. He, et al., Science 331, 1579 (2011)
[2] T. Hartman and S. A. Hartnoll, arXiv:1003.1918
[3] A. Kanigel, et al. Nat. Phys. 2, 447 (2006)
[4] L. Taillefer, arxiv:0901.2313
[5] R. Daou, et al. arxiv:0909.4330
[6] D. Haug, et al., Phys. Rev. Lett. 103, 017001 (2009)
[7] B. Fauque, Phys. Rev. Lett. 96, 197001 (2006)
[8] Aji, V., et al., Phys. Rev. B 81, 064515 (2010)
[9] S. Chakravarty, et al., Phys. Rev. B 63, 094503 (2001)
[10] C. V. Parker, et al., Nature 468, 677 (2010)
[11] P. Phillips, Rev. Mod. Phys. 82, 1719 (2010)

Industrial Masters and Internship Program at University of Oregon February 26, 2011

You can earn a Masters degree and a salary one year through the University of Oregon’s Masters Industrial Internship Program. This program provides students with the real-world knowledge and skills necessary to be successful in an industrial environment.

The best way to judge the success of the Industrial Masters Program may be its history and its list of corporate partners. Over the last 13 years, approximately 90% of the students that have completed internships through this program have received offers for regular employment from their host company. We also have an impressive group of corporate partners such as Nike, Intel, IBM, Fairchild Semiconductor, Hewlett Packard, the Army Research Lab, ESI, Nanometrics, FEI Company, nLight, DataLogic and SolarWorld.

Through this program students have the opportunity to earn a degree from a leading research university and also learn what is required to be successful after graduation. We focus on the science and help you develop professional business skills that will allow you to be successful throughout your career.

The course work and labs are designed to help students become more effective problem solvers and will assist in developing your communication, collaboration and leadership skills. The labs are built to give students an opportunity to have experiences that closely mirror those they’ll find in industry.

The UO’s Masters Industrial Internship Program awards MS degrees in Chemistry or Applied Physics. Students entering the program typically have bachelor degrees in one of the following areas: Chemistry, Biochemistry, Physics, Chemical Engineering, Mechanical Engineering, or Electrical Engineering.

You can choose to focus in one of four core areas:

• Photovoltaic & Semiconductor Device Processing

• Optical Materials & Devices

• Polymers & Coatings

• Organic Synthesis & Organometallics

Internships/co-ops typically pay from $2,400 – $5,400 per month. Though internships are not guaranteed, the program has historically placed 98% of its students in internships and the program staff assists in every way to ensure you are a very competitive candidate for available opportunities.

To find out more please visit: internship.uoregon.edu

We are excited to talk to you about the program and life in Oregon–and to help you plan a visit to campus. The University of Oregon is located in Eugene in Oregon’s Willamette Valley. We’re a short drive from the Pacific Ocean, the Cascade Mountains and a two hour drive from Portland – the second largest city in the Pacific Northwest.

For more information:

Lynde Ritzow, Associate Director Masters Industrial Internship Program

T: (541) 346-6835

E: lynde@uoregon.edu

W: internship.uoregon.edu

Aspen Center for Physics – 2011 Summer Program January 27, 2011

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