The legacy of 40 years of cuprate superconductivity

In February 1986, Bednorz and Müller made a stunning discovery: superconductivity at a temperature of 35 K in a doped copper oxide (cuprate). Arguably, this discovery changed condensed matter physics. In April 1986, they submitted their results to Z. Phys. B. Only nineteen months later, they were awarded the Nobel Prize in Physics, the shortest time ever between a discovery and the award. A nice and short review of the history is here.

One measure of my estimate of the influence of this discovery is that it received about 5 pages of coverage in my Condensed Matter Physics: A Very Short Introduction. (See Chapter 5, Adventures in Flatland).

How things have developed over the past forty years, for better and worse, may be representative of how science advances: discovery by serendipity, hype about applications, unexpected secondary benefits, foundational questions, new concepts, unification, and incremental advances.

Hype about technological applications

On March 20, 1987, The New York Times had a front-page article, DISCOVERIES BRING A 'WOODSTOCK' FOR PHYSICS, by James Gleick. This followed the 1987 APS March meeting. It began 

"Physicists from three continents converged on the New York Hilton for a hastily scheduled special conference on a string of discoveries that seem certain to produce a rapid cascade of commercial applications in electricity, magnetism and electronics.There are many things we know and understand that we did not when they were first discovered."

This has largely been unfulfilled. There are a few niche applications, but cuprates are not used in electricity distribution or even in the superconducting magnets in hospital MRI machines, which are probably the main commercial application of superconductors. One of the significant obstacles is that it is hard to make wires from these materials, as they are ceramics. This is an example of the common gap between research laboratory science and commercially viable technology.

After 40 years, do we have a successful theory?

It depends on who you ask. But I would say there is a lot we do understand.

We have a phenomenological theory for all the macroscopic phenomena associated with the superconducting state: Ginzburg-Landau theory!

Properties of the superconducting state are well-described by a BCS wavefunction with a d-wave order parameter and the associated Bogoliubov quasiparticles. [This is somewhat puzzling, as in the metallic state quasi-particles are not well defined].

Although not everyone agrees, I think it is fair to say that the essential physics is in a one-band Hubbard model, and the key physics is:

strong electronic correlations,

a doped antiferromagnetic Mott insulator,

d-wave pairing that is "mediated"/caused from some mixture/variant of antiferromagnetic spin fluctuations or RVB spin singlets,.....

We certainly don't understand the cuprates at the same level as elemental superconductors. But we do understand the essential physics.

What is harder to describe and understand are the states adjacent to the superconducting state in the phase diagram: the pseudogap state and the strange metal.

Strongly correlated electron materials became a large, vibrant and unified field

Before 1986, there were small, disconnected communities intermittently interested in transition metal oxides, rare earths, Kondo impurities, Mott metal-insulator transitions, organic superconductors, heavy fermions, and quantum antiferromagnets.

The discovery of the cuprates brought together these communities as they found common interests, challenges, questions, concepts, and techniques.

The discovery of superconductivity in strontium ruthenate, alkali fullerides, iron pnictides and chalcogenides, twisted bilayer graphene and more cuprates, organic charge-transfer salts, and heavy fermions has shown how rich these systems are. The challenge is to understand the similarities and differences between these chemically and structurally diverse systems. In many of them, superconductivity is proximate to a Mott insulating state.

The unity and excitement were probably stimulated and enhanced by the activities and ideas of high-profile theorists such as Anderson, Schrieffer, Scalapino, Pines, Rice, and Varma. On the other hand, their acrimonious disagreements probably did not help.

Secondary theoretical benefits

The things I list below were not new ideas when the cuprate discovery happened. However, interest in the cuprates led them to become major research themes and ideas.

Importance of phase diagrams, including as a function of interaction parameters in toy models

Highlighting the limitations of electronic structure methods based on Density Functional Theory with approximate Exchange-Correlation functionals (i.e., anything computational). In the presence of strong correlations, DFT methods have spectacular failures. For example, predicting a metallic state instead of the Mott insulator.

Low dimensionality leads to qualitatively different behaviour, including the possibility of new types of order and quasiparticles. This is most dramatic in one dimension, where one has Luttinger liquids and spin-charge separation.

Spin liquids. Landau was wrong. Spontaneous symmetry breaking does not always occur in antiferromagnets.

Non-Fermi liquids. Landau was wrong. Not all metals are Fermi liquids.

Quantum criticality. Although this is a robust concept for certain toy models, whether it is relevant to the cuprates remains contentious.

Systematic improvements in approximation schemes and numerical techniques - exact diagonalisation, DMRG, DMFT, quantum Monte Carlo,...

Emergence. Chemical complexity and strong interactions can lead to new states of matter.

Secondary experimental benefits

Better probes. The desire to characterise the cuprates helped drive significant improvements in the resolution of ARPES (Angle-Resolved PhotoEmission Spectroscopy), STM (Scanning Tunnelling Microscopy), and inelastic neutron scattering. These advances have born fruit in the study of a wide range of other materials, beyond the cuprates.

Growth of single crystals. The early days of the cuprates produced a lot of junk experimental results because of the poor quality of the samples produced by "shake and bake". However, the involvement of solid-state chemists has improved things. The techniques have also led to the production of single crystals for a wide range of strongly correlated materials.

Why is there so little research on cuprates today?

Today, there is little research directly on cuprates, both theoretically and experimentally. It is hard to get funding to work on them, even though there is a lot we don't understand really well.

This is because of the problem of fashion in science. The low-lying fruit has been picked. There is a continuous new stream of materials being discovered with exotic properties, the latest being twisted bilayer van der Waals compounds.

Autobiography of John Goodenough (1922-2023)

 John Goodenough was an amazing scientist. He made important contributions to our understanding of strongly correlated electron materials, magnetism, solid state chemistry, and materials science and engineering. He developed materials that are widely used in computer RAMs and rechargeable lithium batteries. He kept working in the laboratory and writing papers into his early 90s. Goodenough was awarded the Nobel Prize in Chemistry in 2019. Here is his Nobel Lecture, including text, slides, and video.

In 2008 he published Witness to Grace, a brief autobiography that chronicles his personal, scientific, and spiritual journeys. It is a fascinating story. The book is now out of print and the publisher is out of business. I have scanned a copy. You can download it here. I thank David Purdy for bringing to my attention the need to preserve the book.

Quantum BS: piling it higher

Hans Bachor recently gave a talk at UQ, Hype and Trust in Quantum Technologies

Trust is a core value in science, trust in data, analysis, concepts, models. This is achieved in physics by open publishing, scientific discourse, testing, repeating experiments, asking critical questions and designing new tests. Fortunately, science is self-correcting in the long term. Hype includes predictions which sensationalise scientific discoveries and exaggerate the future impact. Increasing competition for funding, visibility or job security can make this more attractive. But it also erodes trust in science by the public and investors and has negative social effects on us the researchers. How can we balance them?

I think this problem more broadly reflects the way universities have become to imitate the social context they are imbedded in, rather than being a critique of those societies.

The sociologist Christian Smith eloquently described the emergence of BS in universities, several years ago.

Superconductors in Hollywood

 Recently my wife and I watched the movie, Joe Versus the Volcano, starring Tom Hanks and Meg Ryan. What I did not expect was that making superconductors commercially viable was central to the (silly but amusing) plot. 

The plot summary on Wikipedia says

a wealthy industrialist named Samuel Graynamore needs "bubaru", a mineral essential for manufacturing superconductors. There are deposits of it on the tiny Pacific island of Waponi Woo, but the resident Waponis will only let him mine it if he solves a problem for them...

Here is the relevant scene...

The movie was made in 1990, just after the discovery of cuprate superconductors and at that time there was a lot of hype about commercialisation. I wonder if the scriptwriters drew on that.

Some amazing things about the universe that make science possible

 This post takes off from the following Einstein quotes.

"The most incomprehensible thing about the universe is that it is comprehensible"

from "Physics and Reality"(1936), in Ideas and Opinions, trans. Sonja Bargmann (New York: Bonanza, 1954), p292.

"...I consider the comprehensibility of the world (to the extent that we are authorized to speak of such a comprehensibility) as a miracle or as an eternal mystery. Well, a priori, one should expect a chaotic world, which cannot be grasped by the mind in any way .. the kind of order created by Newton's theory of gravitation, for example, is wholly different." 

Letters to Solovine, New York, Philosophical Library, 1987, p 131.

There are several dimensions to the comprehensibility of the universe. The dimension highlighted by Einstein is that there is order in the world, reflected in laws that can be succinctly stated and mathematically encoded. These laws seem to hold for all time and everywhere in the universe. Here I suggest there are three other dimensions that make science possible. 

A second amazing dimension is that humans have the rational ability to do science: to reason, to understand, to communicate, and to make instruments such as telescopes and microscopes. There seems to be somewhat of a match between the rationality of the universe and human rationality. This is written in the spirit of arguments about fine-tuning, where one imagines alternative universes.

Humans could have been different. Suppose that the amount and variation of human intelligence (at least that aspect of intelligence relevant to doing science) were different, and the mean and standard deviation were lower. Suppose that intelligence was lower so that there were no brilliant humans like Darwin, Einstein, Newton, Pauling, ... In fact, suppose that even the brightest people were as good at science as I am at music and dancing. Scientific progress would be rather limited.

But it is not just human intelligence that matters. A third amazing dimension is that of manual dexterity. I am "all thumbs" and not particularly good in the lab. There are some gifted experimentalists with an outstanding ability to do things most people cannot, even with training. Such abilities allow them to fabricate precision instruments, grow crystals, see faint images, ... If some humans did not have such abilities scientific progress would have been much slower, or possibly non-existent.

A fourth crucial dimension concerns the availability and processability of certain materials that are central to scientific progress. Making instruments requires particular materials such as metals, glass, and semiconductors. Suppose we lived in a world where some of these were very rare or just could not be processed to the purity or malleability required.

Systemic flaws that are undermining good science

Everyone likes to be right. But, sometimes I really wish I was wrong, particularly about problems I see in the world. I wish I was wrong about science being broken. Some of these issues I discuss in the final chapter of Condensed Matter Physics: A Very Short Introduction, due to the relevance of these problems to the future of the field.

Similar concerns were discussed with greater clarity, way back in 2014, by four scientists who are much more experienced and distinguished than I am. 

Rescuing US biomedical research from its systemic flaws 

Bruce Alberts, Marc W. Kirschner, Shirley Tilghman, and Harold Varmus

Positions the different authors have held include President of the US Academy of Sciences, President of Princeton University, and Director of the National Institutes of Health.

Although the article focuses on biomedical research I think the three words "medicine, biomedical, and biology" could be replaced respectively with "technology, materials science, and condensed matter physics" almost everywhere in the article. 

Here are a few quotes.

The long-held but erroneous assumption of never-ending rapid growth in biomedical science has created an unsustainable hypercompetitive system that is discouraging even the most outstanding prospective students from entering our profession—and making it difficult for seasoned investigators to produce their best work. This is a recipe for long-term decline, and the problems cannot be solved with simplistic approaches. Instead, it is time to confront the dangers at hand and rethink some fundamental features of the US biomedical research ecosystem.

... the remarkable outpouring of innovative research from American laboratories—high-throughput DNA sequencing, sophisticated imaging, structural biology, designer chemistry, and computational biology—has led to impressive advances in medicine and fueled a vibrant pharmaceutical and biotechnology sector. In the context of such progress, it is remarkable that even the most successful scientists and most promising trainees are increasingly pessimistic about the future of their chosen career.

... hypercompetition for the resources and positions that are required to conduct science suppresses the creativity, cooperation, risk-taking, and original thinking required to make fundamental discoveries.

The system now favors those who can guarantee results rather than those with potentially path-breaking ideas that, by definition, cannot promise success. Young investigators are discouraged from departing too far from their postdoctoral work, when they should instead be posing new questions and inventing new approaches. Seasoned investigators are inclined to stick to their tried-and-true formulas for success rather than explore new fields. 

One manifestation of this shift to short-term thinking is the inflated value that is now accorded to studies that claim a close link to medical practice. Human biology has always been a central part of the US biomedical effort... Many surprising discoveries, powerful research tools, and important medical benefits have arisen from efforts to decipher complex biological phenomena in model organisms. In a climate that discourages such work by emphasizing short-term goals, scientific progress will inevitably be slowed, and revolutionary findings will be deferred.

As competition for jobs and promotions increases, the inflated value given to publishing in a small number of so-called “high impact” journals has put pressure on authors to rush into print, cut corners, exaggerate their findings, and overstate the significance of their work. 

The development of original ideas that lead to important scientific discoveries takes time for thinking, reading, and talking with peers. Today, time for reflection is a disappearing luxury for the scientific community. 

...administrative tasks are taking up an ever-increasing fraction of the day and present serious obstacles to concentration on the scientific mission itself. 

The following is particularly true of luxury journals. 

Professional editors are increasingly serving in roles played in the past by working scientists and can undermine the enterprise when they base judgments about publication on newsworthiness rather than scientific quality. 

Even after they have landed a research position in academia or research institutes, new investigators wait an average of 4–5 y to receive federal funding for their work compared with 1 y in 1980 (2). Two stark statistics tell much of the tale—the average age at which PhD recipients assume their first tenure-track job is 37 y, and they are approaching 42 y when they are awarded their first NIH grant.

Although it varies across fields and individuals, I get the impression that most scientists do their best work in the rough age range of 35-45. Currently, people are spending most of these years looking for a permanent job and then applying for grants, rather than actually doing science.

The graph below shows just how much the system changed in just thirty years. NIH grants became "gentrified". In different words, all the grants now go to "old farts" doing the same old thing, rather than to "young turks" who want to try new things and have a real impact.

Percentage of NIH R01 Principal Investigators aged 36 and younger and aged 66 and older, 1980–2010

The authors did make some concrete proposals and in a follow-up article, they discuss a broader meeting held to discuss the issues.

Addressing systemic problems in the biomedical research enterprise

To what extent progress has been made in the biomedical community in the past eight years I do not know.

de Gennes enthuses about Chemistry and skewers Comte

Pierre-Gilles de Gennes (1932-2007) was arguably the founder of soft matter as a research field, as recognized by the Nobel Prize in Physics in 1991. After this de Gennes gave many lectures in French high schools, which were then published as a book, Fragile Objects: Soft Matter, Hard Science, and the Thrill of Discovery. Previously, I mentioned the book with regard to whether condensed matter physics is too abstract.

 One of many fascinating sections of the book is a chapter entitled, The Imperialism of Mathematics. de Gennes sings the praises of chemistry, and rants about the weaknesses of the French system, laying the blame at the feet of his compatriot Auguste Comte (1798-1857). Comte was one of the first philosophers of modern science and a founder of sociology and of positivism.

Below I reproduce some of the relevant text. When reading it bear in mind that de Gennes was a theoretical physicist and did work that often involved quite abstract mathematics and concepts.

        THE "AUGUSTE COMTE" PREJUDICE

I now come to a prejudice typical of French culture, inherited from the positivism of Auguste Comte. This nineteenth-century philosopher achieved some degree of fame by inventing a classification system of the sciences. 

At the top of his hierarchy was mathematics; at the bottom was chemistry, which according to him "barely deserved the name of science"; in the middle were astronomy and physics. This classification dismissed out of hand geography and mineralogy, sciences which were declared concrete and descriptive, retaining only those that were theoretical, abstract, and general. The tone was set! It is ironic that this philosophical concept came from an individual who had once written in a letter "The only absolute truth is that everything is relative," and who claimed to be steeped quasi-religiously in factually observable laws, in other words, laws verifiable by experiments. 

The "Auguste Comte" prejudice corrupts to this day the teaching of the sciences, the scientific disciplines, and even the scientists themselves. It also contains the seed of contempt for manual labor, which has interfered for years by curbing every attempt at reform to revalue the manual trades and their apprenticeship... 

An example comes to mind, of some graduates of the Polytechnic School of Paris attending an advanced program at Orsay to learn solid-state physics. They would often show up convinced that they knew everything on the basis of calculations. 

... But the typical Polytechnic graduate I inherited at the time would remain stumped in front of his bare blackboard. One of them finally blurted out (I will never forget his comment): "But, sir, what Hamiltonian should I diagonalize?" He was trying to hang on to theoretical ideas which had no connection whatsoever with this practical problem. This kind of answer explains, in large part, the weakness of French industrial research.

Among all the catastrophes brought about by the positivist prejudice, none is worse than the widespread contempt for chemistry. I have already pointed out the importance of this discipline for our industrial future, the importance of chemists, these marvelously inventive sculptors of molecules, to whom the French teaching establishment does not do nearly enough justice. An undergraduate math major once told me about a teacher who, on opening day, announced: "I personally dislike chemistry, but I have to talk about it. So, I will start by giving you two hours of chemical nomenclature: what the name of an obscure and com- plex molecule is, and the like." At the conclusion of the two hours, the entire class was turned off chemistry for life!

When Lucien Monnerie, the director of studies, and I took over re- sponsibility for courses at the Institute of Physics and Chemistry, we had to wage a determined battle to overcome the antichemistry prejudice. Just before our arrival, the students had organized a strike: they all wanted to become physicists. Slowly, we climbed back up the slope with a series of measures: changing labels, opening up several new channels, turning the entire curriculum upside down, and launching a verbal propaganda campaign. It was rather easy for me to sound persuasive; being a theoretical physicist, nobody could accuse me of protecting my own turf. But it took us 10 years to restore the proper balance. 

To anyone who wants to form a more precise idea of chemistry, of the life of a typical chemical engineer, I would advise reading the magnificent collection of essays by Primo Levi, The Periodic Table. They recount real-life stories. They possess an authenticity and a vitality which give a universal impact to the account of an ordinary fact, the description of minute events. It is an excellent antidote to the poison spread by Auguste Comte's classification scheme.

Towards real materials applications

There is a chasm between finding a material that has a desirable property that is key to a technological application and producing a commercial product. In the hype about materials research, the width of this chasm is too often glossed over.

The Structure of Materials by Samuel M. Allen and Edwin L. Thomas (based on a course in Materials Science and Engineering at MIT) introduces the tetrahedron of

structure, properties, processing, and performance. In condensed matter physics the focus is largely on the relationship between structure and properties. But, for engineering, these are both also related to performance and processing (i.e. ability to make materials and devices).

 The book also emphasises the multiple length scales associated with the structure of "real" materials. The scales range from the atomic scale of Angstroms to the scale of micrometers associated with objects such as grain boundaries, topological defects, and domain walls. These longer length scales are also relevant in liquid crystals, glasses, and polymers.

Chemical fingerprints on blood diamonds

“Fortunately, the majority of gentlemen who are persuaded to steal things don’t really know a huge amount about science”

This is a choice quote in a fascinating article, New Australian technology tracks down gold thieves and blood diamonds ["New tech to trace dodgy diamonds" in the print edition] in the Australian Financial Review (AFR) Weekend.

It describes the work of John Watling, Chief Scientist at the company Source Certain. Basically by measuring the relative amounts of different trace elements [chemical impurities] in a sample of gold or diamond one can determine what mine that it has come from.

Desperately seeking tantalum

The road from materials research to commercial technology is a complex and tortuous one. It is not just a matter of what is physically possible. There are rigorous criteria that must be met along the way: financially competitive, mass production, reliability, durability, non-toxicity, ...

The materials needed don't just have to be available, cheap enough, and sufficiently abundant. One also needs supply chains that are not only reliable but also ethical.

In The Economist there is a fascinating (and disturbing) article that shows the complexities involved with the supply chains for just one of the metals used in our smart phones.

Why it’s hard for Congo’s coltan miners to abide by the law 

American rules against conflict minerals have unintended consequences.

Tantalum, a metal used in smartphone and laptop batteries, is extracted from coltan ore. In 2019 40% of the world’s coltan was produced in the Democratic Republic of Congo, according to official data. More was sneaked into Rwanda and exported from there. Locals dig for the ore by hand in Congo’s eastern provinces, where more than 100 armed groups hide in the bush. Some mines are run by warlords who work with rogue members of the Congolese army to smuggle the coltan out.

Before reading this article I had no idea what coltan is and so I read the Wikipedia page.  

On the science side, I wrongly guessed that coltan was some compound containing cobalt and tantalum. It is actually a mixture of two distinct crystals, tantalite [(Fe, Mn)Ta₂O₆] and columbite [(Fe, Mn)Nb2O6]. 

On the economic side, I found it interesting that until a few years ago Australia actually supplied most of the world's coltan.

In terms of political economy, this problem is an example of the "resource curse", a common experience of countries in The Bottom Billion.

If you are concerned about these issues and you live in Europe you might consider buying a Fairphone.

Lessons from the discovery of liquid crystals

I recently learned a little about the history of the discovery of liquid crystals, stimulated by Soft Matter: A Very Short Introduction by Tom McLeish. Besides being a fascinating story there are lessons about the importance of curiosity-driven research, interdisciplinarity, serendipity, and the long road to technology.

Friedrich Reinitzer (1857 - 1927) was a botanist and chemist who worked at the Institute of Plant Physiology in Prague. He was studying cholesterol with the aim of determining its molecular weight. He produced crystals of cholesteryl benzoate and measured their heat capacity as a function of temperature. Aside: For chemists today this measurement is known as differential scanning calorimetry (a constant source of heat is added and the temperature measured as a function of time). 

In 1888, Reinitzer observed that the crystal melted at 145.5 degrees Celsius (signified by absorption of heat), forming a milky liquid. However, at 178.5 degrees Celsius, there was a second absorption of heat, and the liquid became transparent. This suggested that there were two melting transitions. Puzzled by this Reinitzer consulted the physicist and crystallographer, Otto Lehmann, who promoted the idea that this was a new state of matter, which he dubbed a "liquid crystal" (or flowing crystal).

Today, cholesteryl benzoate is classified as a chiral nematic liquid crystal, which is also sometimes known as a cholesteric liquid crystal, in honour of the first one. A schematic of the ordering is shown below.

The milkiness was not explained until the 1960s by Pierre-Gilles de Gennes, who exploited an analogue with a superconductor in a magnetic field.

More detail is in the paper

Liquid‐Crystal Science from 1888 to 1922: Building a Revolution 

Michel Mitov 

This discovery of liquid crystals was the first of many cases where a new state of matter was discovered by a thermodynamic measurement. Others include superfluid 4He (the lambda transition) and superfluid 3He, as I have recently highlighted.

Quantum matters for the public

I have now finished my first draft of  Chapter 7 of Condensed Matter Physics: A Very Short Introduction. The main purpose of the chapter is to introduce quantum states of matter. It is arguably the most challenging of the chapters to write and to understand. But, it is potentially the most fascinating.

I welcome comments and suggestions. However, bear in mind that my target audience is not the typical reader of this blog, but rather your non-physicist friends and family.

I think it still needs a lot of work, particularly to be less technical. For example, I should probably drop Aharonov Bohm ...

The goal is for the chapter to be interesting, accessible, and bring out the excitement and importance of condensed matter physics.

The Classics matter

Some people might expect me to be enthused that the Australian government recently announced that the tuition costs for university degrees in the humanities and social sciences would increase and the costs of undergraduate degrees in mathematics and sciences has decreased. This is based on three unquestioned assumptions and values. First, university is a job-training program. Second, all these extra mathematics and science graduates will get employment in the area that they study. Third, there is no need to address the massive other problems that Australian universities are facing, further accentuated by covid-19.

The central purpose of a university education is to learn to think.

Why study the classics? Recently, I read the following letter to The Economist written by Robert Machado, a PhD student in classics at Cambridge.

As a teacher and researcher in classics, I care profoundly about the subject’s purpose (Johnson, May 2nd). Too many of my colleagues rely on the guff that it teaches grammatical rigour or fall back onto vague assertions about the origins of Western civilisation. Although it is good to have a knowledge of ancient societies, the study of classics or indeed any ancient peoples offers one important transferable skill. When studying any ancient civilisation, one quickly brushes up against the reality that 99.9% of the information one would like to have is already lost. This forces any student or researcher to reflect hard on what data can be used. We must carefully analyse and argue over every scrap, while avoiding the temptation to come to conclusions that the data do not justify. In an age where we are faced with a glut of data, knowing what they can or cannot be used to say is vital.

Rodney Stark was a well-established sociology professor at the University of Washington when he made the bold move to work on the history of early Christianity, making use of methods and concepts from sociology. In the Preface to his book, The Rise of Christianity, he notes

my effort to reconstruct the rise of Christianity has been a cherished hobby - a justification for reading books and articles that now fill an entire wall of my study. It would be impossible to express adequately how much pleasure I have gained from these authors. I am convinced that the students of antiquity are on average the most careful researchers and the most graceful writers in the world of scholarship. 

Parenthetically, I note that Stark's work and attitude provides a model of how to successfully break into a new field.

The commercial applications gap

These days too many seminars, papers, and grant applications begin with great claims about the potential commercial applications of the research being discussed.
We should be skeptical about any hype concerning technological applications of basic research in materials science.
There is a big gap between a commercial device/material and what you can do in the lab with millions of dollars worth of equipment on a milligram of a material or a single electronic device.

It does not matter whether it is a photovoltaic cell, a catalyst, or a superconducting wire. All of the following demanding criteria must be met. Furthermore, it must be better than any existing technology and any competitor on most of these counts.

Cheap to manufacture.
Scaleable to mass production.
Durable. Often on the scale of years or decades.
Reliable and reproducible. Devices, whether batteries or computer memories, must work all the time.
Healthy. Not expose the user or manufacturer to toxic materials.
Use materials available in abundance (silicon, water, ...) rather than scarce ones, such as some rare earth elements.
Environmentally friendly.

Thanks to Tanglaw Roman for emphasizing these issues to me.

This post was partly stimulated by re-reading the front page of The New York Times from March 20, 1987, which features an article Discoveries bring a `Woodstock' for physics. The article describes the famous session on cuprate superconductors at the 1987 March meeting of the American Physical Society. It is worth reading to see how so little of what was promised then has not happened (unfortunately).

Can you think of other criteria that new technologies must meet to be commercially viable?

The bloody delusions of silicon valley medicine

On a recent flight, I watched the HBO documentary The Inventor: Out for Blood in Silicon Valley. It chronicles the dramatic rise and fall of Elizabeth Holmes, founder of a start-up, Theranos, that claimed to have revolutionised blood testing.



There is a good article in the New Republic
What the Theranos Documentary Misses
Instead of examining Elizabeth Holmes’s personality, look at the people and systems that aided the company’s rise.

In spite of the weaknesses described in that article, the documentary made me think about a range of issues at the interface of science, technology, philosophy, and social justice.

The story underscores Kauzmann's maxim, ``people will often believe what they want to believe rather than what the evidence before them suggests they should believe.''

Truth matters. Eventually, we all bounce up against reality: scientific, technological, economic, legal, ...  It does not matter how much hype and BS one can get away, eventually, it will all come crashing down. It is just amazing that some people seem to get away with it for so long...
This is why transparency is so important. A bane of modern life is the proliferation of Non-Disclosure Agreements. Although, I concede they have a limited role is certain commercial situations, they seem to be now used to avoid transparency and accountability for all sorts of dubious practises in diverse social contexts.

The transition from scientific knowledge to a new technology is far from simple. A new commercial device needs to be scalable, reliable, affordable, and safe. For medicine, the bar is a lot higher than a phone app! 

Theranos had a board featuring ``big'' names in politics, business, and military, such as Henry Kissinger, George Shulz, Daniel Mattis,.. All these old men were besotted with Holmes and more than happy to take large commissions for sitting on the board. Chemistry, engineering, and medical expertise were sorely lacking. However, even the old man with relevant knowledge Channing Robertson was a true believer until the very end.

Holmes styled herself on Steve Jobs and many wanted to believe that she would revolutionise blood testing. However, the analogy is flawed. Jobs basically took existing robust technology and repackaged and marketed it in clever ways. Holmes claimed to have invented a totally new technology. What she was trying to do was a bit like trying to build a Macintosh computer in the 1960s.

Why is condensed matter physics important and interesting?

I am trying to get some momentum in writing A Very Short Introduction to Condensed Matter Physics. The intended audience is the intellectually curious person with little background in science. My goal is to convince them that CMP is important and interesting. I can think of several reasons.

1. CMP is intimately connected with everyday technology ranging from liquid crystal displays to computer chips.
2. CMP comprises the majority of physics (employees, papers, conferences, ...) and has significant interaction with areas of science and engineering.
3. CMP is a rich source of creative ideas, concepts, and techniques that represent a significant intellectual achievement and are relevant to many other intellectual endeavors.
4. CMP is full of surprises. We keep discovering new unanticipated phases of matter.
5. CMP presents significant scientific challenges: theoretical, computational, and experimental (from characterisation to sample synthesis).

I am going to focus on 3.
However, it is interesting that the traditional route is 1. Furthermore, different people (including reviewers of the book proposal) are quite divided about 1. versus 3.
[More on that later following this article].

What are the big picture ideas of condensed matter, that are significant intellectual achievements in their own right and particularly relevant to other endeavors?
Here are a few suggestions. It provides very concrete systems to address, at both the mathematical and experimental level, the following issues, which turn out to be often inter-related.

A. Qualitative distinctions are defined by discontinuities. (Different phases of matter).

B. Simple models of complex systems. (Landau theory of phase transitions; Effective Hamiltonians).

C. Universality versus particularity. (Universality classes for critical phenomena).

D. Emergence and the hierarchal nature of reality. (Effective interactions. Renormalisation.)

What do you think are the great intellectual achievements of condensed matter that people need to know about?

Hype, DNA, drugs, and emergence

Unfortunately, hype in science reflects hype in broader society, including in business. The complete DNA sequencing of the human genome was an amazing scientific achievement. Unfortunately, it was also associated with a lot of hype about what this would mean for medicine and for the pharmaceutical industry. This issue is made painfully and succinctly in a recent column in the business section of  The Guardian by Nils Pratley.

It has been almost two decades since the first bosses of the newly merged GlaxoSmithKline talked up the medical wonders that would flow from the unravelling of the human genome. GSK would become the “Microsoft of the pharmaceutical industry”, they said.  

To put it mildly, the corporate vision hasn’t been realised. GSK’s share price stood at £20 at the time of the turn-of-the-century merger and is £15.42 today. Lack of productivity in the labs has been a constant complaint. The genetics revolution is happening, but not at the pace originally promised, at least not at GSK.

These challenges could have been forseen by filtering the hype through a emergentist perspective, such as that presented beautifully by Denis Noble in a 2006 book, The Music of Life: Biology beyond the Genome.  Knowing a DNA sequence is about as useful, for better or worse, as knowing the many-body Schrodinger equation for a plutonium crystal. A great place to start, but ....

Why does transparency matter?

I feel this is post is a bit like extolling the value of motherhood. But it does need to be said again and again in a range of contexts. Transparency is relevant in science and universities in many different ways

• Provide enough information in a paper (or its supplementary material) so that others can reproduce your results.
• Be honest about the strengths and weaknesses of any method.
• Provide estimates of the uncertainty of any result.
• Faculty and institutions need to provide Ph.D students and postdocs with realistic information about their future job prospects within academia. [In particular, the prospect of a tenured faculty position at a research university is highly unlikely].
• When people are being asked to evaluate something [a job applicant, a grant application, a commercial venture, a new technology, ...] they need to be provided enough information to make a well-informed decision.
• Make minutes of committee meetings, annual reports,  freely and easily available.
• Make salaries and benefits of senior management publically available.
• If someone is affected by a decision they should be informed of the basis of that decision.

My view is it always better to provide too much information rather than little. Due to the existence of the internet it is very easy to make information available (either publically or in a password protected site) for those who are interested.

I am increasingly concerned how individuals and institutions hide behind excuses such as intellectual property, commercial-in-confidence issues, legal action, personnel matters, non-disclosure agreements, internal budgetary matters, .... to justify a lack of transparency.
I am not saying that there is no role for these considerations, just that they are invoked way too often.

When people and institutions are not transparent, it is natural for others to

• suspect something is being hidden [corruption, mismanagement, ...]
• lose confidence, respect or trust in the non-transparent parties

What do you think?
Are there areas of science and universities that justify greater transparency?

Quantum entanglement technology hype

Last month The Economist had a cover story and large section on commercial technologies based on quantum information.

To give the flavour here is a sample from one of the articles

Very few in the field think it will take less than a decade [to build a large quantum computer], and many say far longer. But the time for investment, all agree, is now—because even the smaller and less capable machines that will soon be engineered will have the potential to earn revenue. Already, startups and consulting firms are springing up to match prospective small quantum computers to problems faced in sectors including quantitative finance, drug discovery and oil and gas. .... Quantum simulators might help in the design of room-temperature superconductors allowing electricity to be transmitted without losses, or with investigating the nitrogenase reaction used to make most of the world’s fertiliser.

I know people are making advances [which are interesting from a fundamental science point of view] but it seems to me we are a very long way from doing anything cheaper [both financially and computationally] than a classical computer.

Doug Natelson noted that at the last APS March Meeting, John Martinis said that people should not believe the hype, even from him!

Normally The Economist gives a hard-headed analysis of political and economic issues. I might not agree with it [it is too neoliberal for me] but at least I trust it to give a rigorous and accurate analysis. I found this section to be quite disappointing. I hope uncritical readers don't start throwing their retirement funds into start-ups that are going to develop the "quantum internet" because they believe that this is going to be as important as the transistor (a claim the article ends with).

Maybe I am missing something.
I welcome comments on the article.

What are the biggest discoveries in solid state electronic technology?

Watching an excellent video about the invention of the transistor stimulated to me to think about other big discoveries and inventions in solid state technology.

Who would have thought that huge device would become the basis of an amazing revolution (both technological, economic, and even social...)?

In particular, which are the most ubiquitous ones?
For which devices did both theory and experiment play a role, as they did for the transistor?

I find it worthwhile to think about this for two reasons. First, this semester I am again teaching solid state physics and it is nice to motivate students with examples.
 Second, there is too much hype about basic research in materials and device physics, that glosses over the formidable technical and economic obstacles, to materials and devices becoming ubiquitous. Can history give us some insight as to what is realistic?

Here is a preliminary list of some solid state devices that are ubiquitous.

transistor

inorganic semiconductor photovoltaic cell

liquid crystal display

semiconductor laser

optical fiber

giant magnetoresistance used in hard disk drives

blue LED used in solid state lighting

lithium battery

Some of these feature in a nice brochure produced by the USA National Academy of Sciences.

Here are a few that might be on the list but I am not sure about as I think they are more niche applications with limited commercial success. Of course, that may change...

thermoelectric refrigerators

organic LEDs

superconductors (in MRI magnets and as passive filters in mobile phone relay towers )

Is graphene in any commercial device?

What would you add or subtract from the list?