Tag Archives: quantum mechanics

Why are jokes funny? There may be a quantum explanation

Some years ago a friend who’d attended a conference on humour told me I really shouldn’t talk about humour until I had a degree on the topic. I decided the best way to deal with that piece of advice was to avoid all mention of any theories about humour to that friend. I’m happy to say the strategy has worked well although this latest research may allow me to broach the topic once again. From a March 17, 2017 Frontiers (publishing) news release on EurekAlert (Note: A link has been removed),

Why was 6 afraid of 7? Because 789. Whether this pun makes you giggle or groan in pain, your reaction is a consequence of the ambiguity of the joke. Thus far, models have not been able to fully account for the complexity of humor or exactly why we find puns and jokes funny, but a research article recently published in Frontiers in Physics suggests a novel approach: quantum theory.

By the way, it took me forever to get the joke. I always blame these things on the fact that I learned French before English (although my English is now my strongest language). So, for anyone who may immediately grasp the pun: Why was 6 afraid of 7? Because 78 (ate) 9.

This news release was posted by Anna Sigurdsson on March 22, 2017 on the Frontiers blog,

Aiming to answer the question of what kind of formal theory is needed to model the cognitive representation of a joke, researchers suggest that a quantum theory approach might be a contender. In their paper, they outline a quantum inspired model of humor, hoping that this new approach may succeed at a more nuanced modeling of the cognition of humor than previous attempts and lead to the development of a full-fledged, formal quantum theory model of humor. This initial model was tested in a study where participants rated the funniness of verbal puns, as well as the funniness of variants of these jokes (e.g. the punchline on its own, the set-up on its own). The results indicate that apart from the delivery of information, something else is happening on a cognitive level that makes the joke as a whole funny whereas its deconstructed components are not, and which makes a quantum approach appropriate to study this phenomenon.

For decades, researchers from a range of different fields have tried to explain the phenomenon of humor and what happens on a cognitive level in the moment when we “get the joke”. Even within the field of psychology, the topic of humor has been studied using many different approaches, and although the last two decades have seen an upswing of the application of quantum models to the study of psychological phenomena, this is the first time that a quantum theory approach has been suggested as a way to better understand the complexity of humor.

Previous computational models of humor have suggested that the funny element of a joke may be explained by a word’s ability to hold two different meanings (bisociation), and the existence of multiple, but incompatible, ways of interpreting a statement or situation (incongruity). During the build-up of the joke, we interpret the situation one way, and once the punch line comes, there is a shift in our understanding of the situation, which gives it a new meaning and creates the comical effect.

However, the authors argue that it is not the shift of meaning, but rather our ability to perceive both meanings simultaneously, that makes a pun funny. This is where a quantum approach might be able to account for the complexity of humor in a way that earlier models cannot. “Quantum formalisms are highly useful for describing cognitive states that entail this form of ambiguity,” says Dr. Liane Gabora from the University of British Columbia, corresponding author of the paper. “Funniness is not a pre-existing ‘element of reality’ that can be measured; it emerges from an interaction between the underlying nature of the joke, the cognitive state of the listener, and other social and environmental factors. This makes the quantum formalism an excellent candidate for modeling humor,” says Dr. Liane Gabora.

Although much work and testing remains before the completion of a formal quantum theory model of humor to explain the cognitive aspects of reacting to a pun, these first findings provide an exciting first step and opens for the possibility of a more nuanced modeling of humor. “The cognitive process of “getting” a joke is a difficult process to model, and we consider the work in this paper to be an early first step toward an eventually more comprehensive theory of humor that includes predictive models. We believe that the approach promises an exciting step toward a formal theory of humor, and that future research will build upon this modest beginning,” concludes Dr. Liane Gabora.

Here’s a link to and a citation for the paper,

Toward a Quantum Theory of Humor by Liane Gabora and Kirsty Kitto. Front. Phys., 26 January 2017 | https://doi.org/10.3389/fphy.2016.00053

This paper has been published in an open access journal. In viewing the acknowledgements at the end of the paper I found what I found to be a surprising funding agency,

This work was supported by a grant (62R06523) from the Natural Sciences and Engineering Research Council of Canada. We are grateful to Samantha Thomson who assisted with the development of the questionnaire and the collection of the data for the study reported here.

While I’m at this, I might as well mention that Kirsty Katto is from the Queensland University of Technology (QUT) in Australia and, for those unfamiliar with the geography, the University of British Columbia is the the Canada’s province of British Columbia.

Mapping 23,000 atoms in a nanoparticle

Identification of the precise 3-D coordinates of iron, shown in red, and platinum atoms in an iron-platinum nanoparticle.. Courtesy of Colin Ophus and Florian Nickel/Berkeley Lab

The image of the iron-platinum nanoparticle (referenced in the headline) reminds of foetal ultrasound images. A Feb. 1, 2017 news item on ScienceDaily tells us more,

In the world of the very tiny, perfection is rare: virtually all materials have defects on the atomic level. These imperfections — missing atoms, atoms of one type swapped for another, and misaligned atoms — can uniquely determine a material’s properties and function. Now, UCLA [University of California at Los Angeles] physicists and collaborators have mapped the coordinates of more than 23,000 individual atoms in a tiny iron-platinum nanoparticle to reveal the material’s defects.

The results demonstrate that the positions of tens of thousands of atoms can be precisely identified and then fed into quantum mechanics calculations to correlate imperfections and defects with material properties at the single-atom level.

A Feb. 1, 2017 UCLA news release, which originated the news item, provides more detail about the work,

Jianwei “John” Miao, a UCLA professor of physics and astronomy and a member of UCLA’s California NanoSystems Institute, led the international team in mapping the atomic-level details of the bimetallic nanoparticle, more than a trillion of which could fit within a grain of sand.

“No one has seen this kind of three-dimensional structural complexity with such detail before,” said Miao, who is also a deputy director of the Science and Technology Center on Real-Time Functional Imaging. This new National Science Foundation-funded consortium consists of scientists at UCLA and five other colleges and universities who are using high-resolution imaging to address questions in the physical sciences, life sciences and engineering.

Miao and his team focused on an iron-platinum alloy, a very promising material for next-generation magnetic storage media and permanent magnet applications.

By taking multiple images of the iron-platinum nanoparticle with an advanced electron microscope at Lawrence Berkeley National Laboratory and using powerful reconstruction algorithms developed at UCLA, the researchers determined the precise three-dimensional arrangement of atoms in the nanoparticle.

“For the first time, we can see individual atoms and chemical composition in three dimensions. Everything we look at, it’s new,” Miao said.

The team identified and located more than 6,500 iron and 16,600 platinum atoms and showed how the atoms are arranged in nine grains, each of which contains different ratios of iron and platinum atoms. Miao and his colleagues showed that atoms closer to the interior of the grains are more regularly arranged than those near the surfaces. They also observed that the interfaces between grains, called grain boundaries, are more disordered.

“Understanding the three-dimensional structures of grain boundaries is a major challenge in materials science because they strongly influence the properties of materials,” Miao said. “Now we are able to address this challenge by precisely mapping out the three-dimensional atomic positions at the grain boundaries for the first time.”

The researchers then used the three-dimensional coordinates of the atoms as inputs into quantum mechanics calculations to determine the magnetic properties of the iron-platinum nanoparticle. They observed abrupt changes in magnetic properties at the grain boundaries.

“This work makes significant advances in characterization capabilities and expands our fundamental understanding of structure-property relationships, which is expected to find broad applications in physics, chemistry, materials science, nanoscience and nanotechnology,” Miao said.

In the future, as the researchers continue to determine the three-dimensional atomic coordinates of more materials, they plan to establish an online databank for the physical sciences, analogous to protein databanks for the biological and life sciences. “Researchers can use this databank to study material properties truly on the single-atom level,” Miao said.

Miao and his team also look forward to applying their method called GENFIRE (GENeralized Fourier Iterative Reconstruction) to biological and medical applications. “Our three-dimensional reconstruction algorithm might be useful for imaging like CT scans,” Miao said. Compared with conventional reconstruction methods, GENFIRE requires fewer images to compile an accurate three-dimensional structure.

That means that radiation-sensitive objects can be imaged with lower doses of radiation.

The US Dept. of Energy (DOE) Lawrence Berkeley National Laboratory issued their own Feb. 1, 2017 news release (also on EurekAlert) about the work with a focus on how their equipment made this breakthrough possible (it repeats a little of the info. from the UCLA news release),

Scientists used one of the world’s most powerful electron microscopes to map the precise location and chemical type of 23,000 atoms in an extremely small particle made of iron and platinum.

The 3-D reconstruction reveals the arrangement of atoms in unprecedented detail, enabling the scientists to measure chemical order and disorder in individual grains, which sheds light on the material’s properties at the single-atom level. Insights gained from the particle’s structure could lead to new ways to improve its magnetic performance for use in high-density, next-generation hard drives.

What’s more, the technique used to create the reconstruction, atomic electron tomography (which is like an incredibly high-resolution CT scan), lays the foundation for precisely mapping the atomic composition of other useful nanoparticles. This could reveal how to optimize the particles for more efficient catalysts, stronger materials, and disease-detecting fluorescent tags.

Microscopy data was obtained and analyzed by scientists from the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) at the Molecular Foundry, in collaboration with Foundry users from UCLA, Oak Ridge National Laboratory, and the United Kingdom’s University of Birmingham. …

Atoms are the building blocks of matter, and the patterns in which they’re arranged dictate a material’s properties. These patterns can also be exploited to greatly improve a material’s function, which is why scientists are eager to determine the 3-D structure of nanoparticles at the smallest scale possible.

“Our research is a big step in this direction. We can now take a snapshot that shows the positions of all the atoms in a nanoparticle at a specific point in its growth. This will help us learn how nanoparticles grow atom by atom, and it sets the stage for a materials-design approach starting from the smallest building blocks,” says Mary Scott, who conducted the research while she was a Foundry user, and who is now a staff scientist. Scott and fellow Foundry scientists Peter Ercius and Colin Ophus developed the method in close collaboration with Jianwei Miao, a UCLA professor of physics and astronomy.

Their nanoparticle reconstruction builds on an achievement they reported last year in which they measured the coordinates of more than 3,000 atoms in a tungsten needle to a precision of 19 trillionths of a meter (19 picometers), which is many times smaller than a hydrogen atom. Now, they’ve taken the same precision, added the ability to distinguish different elements, and scaled up the reconstruction to include tens of thousands of atoms.

Importantly, their method maps the position of each atom in a single, unique nanoparticle. In contrast, X-ray crystallography and cryo-electron microscopy plot the average position of atoms from many identical samples. These methods make assumptions about the arrangement of atoms, which isn’t a good fit for nanoparticles because no two are alike.

“We need to determine the location and type of each atom to truly understand how a nanoparticle functions at the atomic scale,” says Ercius.

A TEAM approach

The scientists’ latest accomplishment hinged on the use of one of the highest-resolution transmission electron microscopes in the world, called TEAM I. It’s located at the National Center for Electron Microscopy, which is a Molecular Foundry facility. The microscope scans a sample with a focused beam of electrons, and then measures how the electrons interact with the atoms in the sample. It also has a piezo-controlled stage that positions samples with unmatched stability and position-control accuracy.

The researchers began growing an iron-platinum nanoparticle from its constituent elements, and then stopped the particle’s growth before it was fully formed. They placed the “partially baked” particle in the TEAM I stage, obtained a 2-D projection of its atomic structure, rotated it a few degrees, obtained another projection, and so on. Each 2-D projection provides a little more information about the full 3-D structure of the nanoparticle.

They sent the projections to Miao at UCLA, who used a sophisticated computer algorithm to convert the 2-D projections into a 3-D reconstruction of the particle. The individual atomic coordinates and chemical types were then traced from the 3-D density based on the knowledge that iron atoms are lighter than platinum atoms. The resulting atomic structure contains 6,569 iron atoms and 16,627 platinum atoms, with each atom’s coordinates precisely plotted to less than the width of a hydrogen atom.

Translating the data into scientific insights

Interesting features emerged at this extreme scale after Molecular Foundry scientists used code they developed to analyze the atomic structure. For example, the analysis revealed chemical order and disorder in interlocking grains, in which the iron and platinum atoms are arranged in different patterns. This has large implications for how the particle grew and its real-world magnetic properties. The analysis also revealed single-atom defects and the width of disordered boundaries between grains, which was not previously possible in complex 3-D boundaries.

“The important materials science problem we are tackling is how this material transforms from a highly randomized structure, what we call a chemically-disordered structure, into a regular highly-ordered structure with the desired magnetic properties,” says Ophus.

To explore how the various arrangements of atoms affect the nanoparticle’s magnetic properties, scientists from DOE’s Oak Ridge National Laboratory ran computer calculations on the Titan supercomputer at ORNL–using the coordinates and chemical type of each atom–to simulate the nanoparticle’s behavior in a magnetic field. This allowed the scientists to see patterns of atoms that are very magnetic, which is ideal for hard drives. They also saw patterns with poor magnetic properties that could sap a hard drive’s performance.

“This could help scientists learn how to steer the growth of iron-platinum nanoparticles so they develop more highly magnetic patterns of atoms,” says Ercius.

Adds Scott, “More broadly, the imaging technique will shed light on the nucleation and growth of ordered phases within nanoparticles, which isn’t fully theoretically understood but is critically important to several scientific disciplines and technologies.”

The folks at the Berkeley Lab have created a video (notice where the still image from the beginning of this post appears),

The Oak Ridge National Laboratory (ORNL), not wanting to be left out, has been mentioned in a Feb. 3, 2017 news item on ScienceDaily,

… researchers working with magnetic nanoparticles at the University of California, Los Angeles (UCLA), and the US Department of Energy’s (DOE’s) Lawrence Berkeley National Laboratory (Berkeley Lab) approached computational scientists at DOE’s Oak Ridge National Laboratory (ORNL) to help solve a unique problem: to model magnetism at the atomic level using experimental data from a real nanoparticle.

“These types of calculations have been done for ideal particles with ideal crystal structures but not for real particles,” said Markus Eisenbach, a computational scientist at the Oak Ridge Leadership Computing Facility (OLCF), a DOE Office of Science User Facility located at ORNL.

A Feb. 2, 2017 ORNL news release on EurekAlert, which originated the news item, elucidates further on how their team added to the research,

Eisenbach develops quantum mechanical electronic structure simulations that predict magnetic properties in materials. Working with Paul Kent, a computational materials scientist at ORNL’s Center for Nanophase Materials Sciences, the team collaborated with researchers at UCLA and Berkeley Lab’s Molecular Foundry to combine world-class experimental data with world-class computing to do something new–simulate magnetism atom by atom in a real nanoparticle.

Using the new data from the research teams on the West Coast, Eisenbach and Kent were able to precisely model the measured atomic structure, including defects, from a unique iron-platinum (FePt) nanoparticle and simulate its magnetic properties on the 27-petaflop Titan supercomputer at the OLCF.

Electronic structure codes take atomic and chemical structure and solve for the corresponding magnetic properties. However, these structures are typically derived from many 2-D electron microscopy or x-ray crystallography images averaged together, resulting in a representative, but not true, 3-D structure.

“In this case, researchers were able to get the precise 3-D structure for a real particle,” Eisenbach said. “The UCLA group has developed a new experimental technique where they can tell where the atoms are–the coordinates–and the chemical resolution, or what they are — iron or platinum.”

The ORNL news release goes on to describe the work from the perspective of the people who ran the supercompute simulationsr,

A Supercomputing Milestone

Magnetism at the atomic level is driven by quantum mechanics — a fact that has shaken up classical physics calculations and called for increasingly complex, first-principle calculations, or calculations working forward from fundamental physics equations rather than relying on assumptions that reduce computational workload.

For magnetic recording and storage devices, researchers are particularly interested in magnetic anisotropy, or what direction magnetism favors in an atom.

“If the anisotropy is too weak, a bit written to the nanoparticle might flip at room temperature,” Kent said.

To solve for magnetic anisotropy, Eisenbach and Kent used two computational codes to compare and validate results.

To simulate a supercell of about 1,300 atoms from strongly magnetic regions of the 23,000-atom nanoparticle, they used the Linear Scaling Multiple Scattering (LSMS) code, a first-principles density functional theory code developed at ORNL.

“The LSMS code was developed for large magnetic systems and can tackle lots of atoms,” Kent said.

As principal investigator on 2017, 2016, and previous INCITE program awards, Eisenbach has scaled the LSMS code to Titan for a range of magnetic materials projects, and the in-house code has been optimized for Titan’s accelerated architecture, speeding up calculations more than 8 times on the machine’s GPUs. Exceptionally capable of crunching large magnetic systems quickly, the LSMS code received an Association for Computing Machinery Gordon Bell Prize in high-performance computing achievement in 1998 and 2009, and developments continue to enhance the code for new architectures.

Working with Renat Sabirianov at the University of Nebraska at Omaha, the team also ran VASP, a simulation package that is better suited for smaller atom counts, to simulate regions of about 32 atoms.

“With both approaches, we were able to confirm that the local VASP results were consistent with the LSMS results, so we have a high confidence in the simulations,” Eisenbach said.

Computer simulations revealed that grain boundaries have a strong effect on magnetism. “We found that the magnetic anisotropy energy suddenly transitions at the grain boundaries. These magnetic properties are very important,” Miao said.

In the future, researchers hope that advances in computing and simulation will make a full-particle simulation possible — as first-principles calculations are currently too intensive to solve small-scale magnetism for regions larger than a few thousand atoms.

Also, future simulations like these could show how different fabrication processes, such as the temperature at which nanoparticles are formed, influence magnetism and performance.

“There’s a hope going forward that one would be able to use these techniques to look at nanoparticle growth and understand how to optimize growth for performance,” Kent said.

Finally, here’s a link to and a citation for the paper,

Deciphering chemical order/disorder and material properties at the single-atom level by Yongsoo Yang, Chien-Chun Chen, M. C. Scott, Colin Ophus, Rui Xu, Alan Pryor, Li Wu, Fan Sun, Wolfgang Theis, Jihan Zhou, Markus Eisenbach, Paul R. C. Kent, Renat F. Sabirianov, Hao Zeng, Peter Ercius, & Jianwei Miao. Nature 542, 75–79 (02 February 2017) doi:10.1038/nature21042 Published online 01 February 2017

This paper is behind a paywall.

Keeping up with science is impossible: ruminations on a nanotechnology talk

I think it’s time to give this suggestion again. Always hold a little doubt about the science information you read and hear. Everybody makes mistakes.

Here’s an example of what can happen. George Tulevski who gave a talk about nanotechnology in Nov. 2016 for TED@IBM is an accomplished scientist who appears to have made an error during his TED talk. From Tulevski’s The Next Step in Nanotechnology talk transcript page,

When I was a graduate student, it was one of the most exciting times to be working in nanotechnology. There were scientific breakthroughs happening all the time. The conferences were buzzing, there was tons of money pouring in from funding agencies. And the reason is when objects get really small, they’re governed by a different set of physics that govern ordinary objects, like the ones we interact with. We call this physics quantum mechanics. [emphases mine] And what it tells you is that you can precisely tune their behavior just by making seemingly small changes to them, like adding or removing a handful of atoms, or twisting the material. It’s like this ultimate toolkit. You really felt empowered; you felt like you could make anything.

In September 2016, scientists at Cambridge University (UK) announced they had concrete proof that the physics governing materials at the nanoscale is unique, i.e., it does not follow the rules of either classical or quantum physics. From my Oct. 27, 2016 posting,

A Sept. 29, 2016 University of Cambridge press release, which originated the news item, hones in on the peculiarities of the nanoscale,

In the middle, on the order of around 10–100,000 molecules, something different is going on. Because it’s such a tiny scale, the particles have a really big surface-area-to-volume ratio. This means the energetics of what goes on at the surface become very important, much as they do on the atomic scale, where quantum mechanics is often applied.

Classical thermodynamics breaks down. But because there are so many particles, and there are many interactions between them, the quantum model doesn’t quite work either.

It is very, very easy to miss new developments no matter how tirelessly you scan for information.

Tulevski is a good, interesting, and informed speaker but I do have one other hesitation regarding his talk. He seems to think that over the last 15 years there should have been more practical applications arising from the field of nanotechnology. There are two aspects here. First, he seems to be dating the ‘nanotechnology’ effort from the beginning of the US National Nanotechnology Initiative and there are many scientists who would object to that as the starting point. Second, 15 or even 30 or more years is a brief period of time especially when you are investigating that which hasn’t been investigated before. For example, you might want to check out the book, “Leviathan and the Air-Pump: Hobbes, Boyle, and the Experimental Life” (published 1985) is a book by Steven Shapin and Simon Schaffer (Wikipedia entry for the book). The amount of time (years) spent on how to make just the glue which held the various experimental apparatuses together was a revelation to me. Of  course, it makes perfect sense that if you’re trying something new, you’re going to have figure out everything.

By the way, I include my blog as one of the sources of information that can be faulty despite efforts to make corrections and to keep up with the latest. Even the scientists at Cambridge University can run into some problems as I noted in my Jan. 28, 2016 posting.

Getting back to Tulevsk, herei’s a link to his lively, informative talk :

ETA Jan. 24, 2017: For some insight into how uncertain, tortuous, and expensive commercializing technology can be read Dexter Johnson’s Jan. 23, 2017 posting on his Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website). Here’s an excerpt (Note: Links have been removed),

The brief description of this odyssey includes US $78 million in financing over 15 years and $50 million in revenues over that period through licensing of its technology and patents. That revenue includes a back-against-the-wall sell-off of a key business unit to Lockheed Martin in 2008.  Another key moment occured back in 2012 when Belgian-based nanoelectronics powerhouse Imec took on the job of further developing Nantero’s carbon-nanotube-based memory back in 2012. Despite the money and support from major electronics players, the big commercial breakout of their NRAM technology seemed ever less likely to happen with the passage of time.

2016 thoughts and 2017 hopes from FrogHeart

This is the 4900th post on this blog and as FrogHeart moves forward to 5000, I’m thinking there will be some changes although I’m not sure what they’ll be. In the meantime, here are some random thoughts on the year that was in Canadian science and on the FrogHeart blog.

Changeover to Liberal government: year one

Hopes were high after the Trudeau government was elected. Certainly, there seems to have been a loosening where science communication policies have been concerned although it may not have been quite the open and transparent process people dreamed of. On the plus side, it’s been easier to participate in public consultations but there has been no move (perceptible to me) towards open government science or better access to government-funded science papers.

Open Science in Québec

As far as I know, la crème de la crème of open science (internationally) is the Montreal Neurological Institute (Montreal Neuro; affiliated with McGill University. They bookended the year with two announcements. In January 2016, Montreal Neuro announced it was going to be an “Open Science institution (my Jan. 22, 2016 posting),

The Montreal Neurological Institute (MNI) in Québec, Canada, known informally and widely as Montreal Neuro, has ‘opened’ its science research to the world. David Bruggeman tells the story in a Jan. 21, 2016 posting on his Pasco Phronesis blog (Note: Links have been removed),

The Montreal Neurological Institute (MNI) at McGill University announced that it will be the first academic research institute to become what it calls ‘Open Science.’  As Science is reporting, the MNI will make available all research results and research data at the time of publication.  Additionally it will not seek patents on any of the discoveries made on research at the Institute.

Will this catch on?  I have no idea if this particular combination of open access research data and results with no patents will spread to other university research institutes.  But I do believe that those elements will continue to spread.  More universities and federal agencies are pursuing open access options for research they support.  Elon Musk has opted to not pursue patent litigation for any of Tesla Motors’ patents, and has not pursued patents for SpaceX technology (though it has pursued litigation over patents in rocket technology). …

Then, there’s my Dec. 19, 2016 posting about this Montreal Neuro announcement,

It’s one heck of a Christmas present. Canadian businessmen Larry Tannenbaum and his wife Judy have given the Montreal Neurological Institute (Montreal Neuro), which is affiliated with McGill University, a $20M donation. From a Dec. 16, 2016 McGill University news release,

The Prime Minister of Canada, Justin Trudeau, was present today at the Montreal Neurological Institute and Hospital (MNI) for the announcement of an important donation of $20 million by the Larry and Judy Tanenbaum family. This transformative gift will help to establish the Tanenbaum Open Science Institute, a bold initiative that will facilitate the sharing of neuroscience findings worldwide to accelerate the discovery of leading edge therapeutics to treat patients suffering from neurological diseases.

‟Today, we take an important step forward in opening up new horizons in neuroscience research and discovery,” said Mr. Larry Tanenbaum. ‟Our digital world provides for unprecedented opportunities to leverage advances in technology to the benefit of science.  That is what we are celebrating here today: the transformation of research, the removal of barriers, the breaking of silos and, most of all, the courage of researchers to put patients and progress ahead of all other considerations.”

Neuroscience has reached a new frontier, and advances in technology now allow scientists to better understand the brain and all its complexities in ways that were previously deemed impossible. The sharing of research findings amongst scientists is critical, not only due to the sheer scale of data involved, but also because diseases of the brain and the nervous system are amongst the most compelling unmet medical needs of our time.

Neurological diseases, mental illnesses, addictions, and brain and spinal cord injuries directly impact 1 in 3 Canadians, representing approximately 11 million people across the country.

“As internationally-recognized leaders in the field of brain research, we are uniquely placed to deliver on this ambitious initiative and reinforce our reputation as an institution that drives innovation, discovery and advanced patient care,” said Dr. Guy Rouleau, Director of the Montreal Neurological Institute and Hospital and Chair of McGill University’s Department of Neurology and Neurosurgery. “Part of the Tanenbaum family’s donation will be used to incentivize other Canadian researchers and institutions to adopt an Open Science model, thus strengthening the network of like-minded institutes working in this field.”

Chief Science Advisor

Getting back to the federal government, we’re still waiting for a Chief Science Advisor. Should you be interested in the job, apply here. The job search was launched in early Dec. 2016 (see my Dec. 7, 2016 posting for details) a little over a year after the Liberal government was elected. I’m not sure why the process is taking so long. It’s not like the Canadian government is inventing a position or trailblazing in this regard. Many, many countries and jurisdictions have chief science advisors. Heck the European Union managed to find their first chief science advisor in considerably less time than we’ve spent on the project. My guess, it just wasn’t a priority.

Prime Minister Trudeau, quantum, nano, and Canada’s 150th birthday

In April 2016, Prime Minister Justin Trudeau stunned many when he was able to answer, in an articulate and informed manner, a question about quantum physics during a press conference at the Perimeter Institute in Waterloo, Ontario (my April 18, 2016 post discussing that incident and the so called ‘quantum valley’ in Ontario).

In Sept. 2016, the University of Waterloo publicized the world’s smallest Canadian flag to celebrate the country’s upcoming 150th birthday and to announce its presence in QUANTUM: The Exhibition (a show which will tour across Canada). Here’s more from my Sept. 20, 2016 posting,

The record-setting flag was unveiled at IQC’s [Institute of Quantum Computing at the University of Waterloo] open house on September 17 [2016], which attracted nearly 1,000 visitors. It will also be on display in QUANTUM: The Exhibition, a Canada 150 Fund Signature Initiative, and part of Innovation150, a consortium of five leading Canadian science-outreach organizations. QUANTUM: The Exhibition is a 4,000-square-foot, interactive, travelling exhibit IQC developed highlighting Canada’s leadership in quantum information science and technology.

“I’m delighted that IQC is celebrating Canadian innovation through QUANTUM: The Exhibition and Innovation150,” said Raymond Laflamme, executive director of IQC. “It’s an opportunity to share the transformative technologies resulting from Canadian research and bring quantum computing to fellow Canadians from coast to coast to coast.”

The first of its kind, the exhibition will open at THEMUSEUM in downtown Kitchener on October 14 [2016], and then travel to science centres across the country throughout 2017.

You can find the English language version of QUANTUM: The Exhibition website here and the French language version of QUANTUM: The Exhibition website here.

There are currently four other venues for the show once finishes its run in Waterloo. From QUANTUM’S Join the Celebration webpage,


  • Science World at TELUS World of Science, Vancouver
  • TELUS Spark, Calgary
  • Discovery Centre, Halifax
  • Canada Science and Technology Museum, Ottawa

I gather they’re still looking for other venues to host the exhibition. If interested, there’s this: Contact us.

Other than the flag which is both nanoscale and microscale, they haven’t revealed what else will be included in their 4000 square foot exhibit but it will be “bilingual, accessible, and interactive.” Also, there will be stories.

Hmm. The exhibition is opening in roughly three weeks and they have no details. Strategy or disorganization? Only time will tell.

Calgary and quantum teleportation

This is one of my favourite stories of the year. Scientists at the University of Calgary teleported photons six kilometers from the university to city hall breaking the teleportation record. What I found particularly interesting was the support for science from Calgary City Hall. Here’s more from my Sept. 21, 2016 post,

Through a collaboration between the University of Calgary, The City of Calgary and researchers in the United States, a group of physicists led by Wolfgang Tittel, professor in the Department of Physics and Astronomy at the University of Calgary have successfully demonstrated teleportation of a photon (an elementary particle of light) over a straight-line distance of six kilometres using The City of Calgary’s fibre optic cable infrastructure. The project began with an Urban Alliance seed grant in 2014.

This accomplishment, which set a new record for distance of transferring a quantum state by teleportation, has landed the researchers a spot in the prestigious Nature Photonics scientific journal. The finding was published back-to-back with a similar demonstration by a group of Chinese researchers.

The research could not be possible without access to the proper technology. One of the critical pieces of infrastructure that support quantum networking is accessible dark fibre. Dark fibre, so named because of its composition — a single optical cable with no electronics or network equipment on the alignment — doesn’t interfere with quantum technology.

The City of Calgary is building and provisioning dark fibre to enable next-generation municipal services today and for the future.

“By opening The City’s dark fibre infrastructure to the private and public sector, non-profit companies, and academia, we help enable the development of projects like quantum encryption and create opportunities for further research, innovation and economic growth in Calgary,” said Tyler Andruschak, project manager with Innovation and Collaboration at The City of Calgary.

As for the science of it (also from my post),

A Sept. 20, 2016 article by Robson Fletcher for CBC (Canadian Broadcasting News) online provides a bit more insight from the lead researcher (Note: A link has been removed),

“What is remarkable about this is that this information transfer happens in what we call a disembodied manner,” said physics professor Wolfgang Tittel, whose team’s work was published this week in the journal Nature Photonics.

“Our transfer happens without any need for an object to move between these two particles.”

A Sept. 20, 2016 University of Calgary news release by Drew Scherban, which originated the news item, provides more insight into the research,

“Such a network will enable secure communication without having to worry about eavesdropping, and allow distant quantum computers to connect,” says Tittel.

Experiment draws on ‘spooky action at a distance’

The experiment is based on the entanglement property of quantum mechanics, also known as “spooky action at a distance” — a property so mysterious that not even Einstein could come to terms with it.

“Being entangled means that the two photons that form an entangled pair have properties that are linked regardless of how far the two are separated,” explains Tittel. “When one of the photons was sent over to City Hall, it remained entangled with the photon that stayed at the University of Calgary.”

Next, the photon whose state was teleported to the university was generated in a third location in Calgary and then also travelled to City Hall where it met the photon that was part of the entangled pair.

“What happened is the instantaneous and disembodied transfer of the photon’s quantum state onto the remaining photon of the entangled pair, which is the one that remained six kilometres away at the university,” says Tittel.

Council of Canadian Academies and The State of Science and Technology and Industrial Research and Development in Canada

Preliminary data was released by the CCA’s expert panel in mid-December 2016. I reviewed that material briefly in my Dec. 15, 2016 post but am eagerly awaiting the full report due late 2017 when, hopefully, I’ll have the time to critique the material, and which I hope will have more surprises and offer greater insights than the preliminary report did.


Thank you to my online colleagues. While we don’t interact much it’s impossible to estimate how encouraging it is to know that these people continually participate and help create the nano and/or science blogosphere.

David Bruggeman at his Pasco Phronesis blog keeps me up-to-date on science policy both in the US, Canada, and internationally, as well as, keeping me abreast of the performing arts/science scene. Also, kudos to David for raising my (and his audience’s) awareness of just how much science is discussed on late night US television. Also, I don’t know how he does it but he keeps scooping me on Canadian science policy matters. Thankfully, I’m not bitter and hope he continues to scoop me which will mean that I will get the information from somewhere since it won’t be from the Canadian government.

Tim Harper of Cientifica Research keeps me on my toes as he keeps shifting his focus. Most lately, it’s been on smart textiles and wearables. You can download his latest White Paper titled, Fashion, Smart Textiles, Wearables and Disappearables, from his website. Tim consults on nanotechnology and other emerging technologies at the international level.

Dexter Johnson of the Nanoclast blog on the IEEE (Institute of Electrical and Electronics Engineers) website consistently provides informed insight into how a particular piece of research fits into the nano scene and often provides historical details that you’re not likely to get from anyone else.

Dr. Andrew Maynard is currently the founding Director of the Risk Innovation Lab at the University of Arizona. I know him through his 2020 Science blog where he posts text and videos on many topics including emerging technologies, nanotechnologies, risk, science communication, and much more. Do check out 2020 Science as it is a treasure trove.

2017 hopes and dreams

I hope Canada’s Chief Science Advisor brings some fresh thinking to science in government and that the Council of Canadian Academies’ upcoming assessment on The State of Science and Technology and Industrial Research and Development in Canada is visionary. Also, let’s send up some collective prayers for the Canada Science and Technology Museum which has been closed since 2014 (?) due to black mold (?). It would be lovely to see it open in time for Canada’s 150th anniversary.

I’d like to see the nanotechnology promise come closer to a reality, which benefits as many people as possible.

As for me and FrogHeart, I’m not sure about the future. I do know there’s one more Steep project (I’m working with Raewyn Turner on a multiple project endeavour known as Steep; this project will involve sound and gold nanoparticles).

Should anything sparkling occur to me, I will add it at a future date.

In the meantime, Happy New Year and thank you from the bottom of my heart for reading this blog!

Unbreakable encrypted message with key that’s shorter than the message

A Sept. 5, 2016 University of Rochester (NY state, US) news release (also on EurekAlert), makes an intriguing announcement,

Researchers at the University of Rochester have moved beyond the theoretical in demonstrating that an unbreakable encrypted message can be sent with a key that’s far shorter than the message—the first time that has ever been done.

Until now, unbreakable encrypted messages were transmitted via a system envisioned by American mathematician Claude Shannon, considered the “father of information theory.” Shannon combined his knowledge of algebra and electrical circuitry to come up with a binary system of transmitting messages that are secure, under three conditions: the key is random, used only once, and is at least as long as the message itself.

The findings by Daniel Lum, a graduate student in physics, and John Howell, a professor of physics, have been published in the journal Physical Review A.

“Daniel’s research amounts to an important step forward, not just for encryption, but for the field of quantum data locking,” said Howell.

Quantum data locking is a method of encryption advanced by Seth Lloyd, a professor of quantum information at Massachusetts Institute of Technology, that uses photons—the smallest particles associated with light—to carry a message. Quantum data locking was thought to have limitations for securely encrypting messages, but Lloyd figured out how to make additional assumptions—namely those involving the boundary between light and matter—to make it a more secure method of sending data.  While a binary system allows for only an on or off position with each bit of information, photon waves can be altered in many more ways: the angle of tilt can be changed, the wavelength can be made longer or shorter, and the size of the amplitude can be modified. Since a photon has more variables—and there are fundamental uncertainties when it comes to quantum measurements—the quantum key for encrypting and deciphering a message can be shorter that the message itself.

Lloyd’s system remained theoretical until this year, when Lum and his team developed a device—a quantum enigma machine—that would put the theory into practice. The device takes its name from the encryption machine used by Germany during World War II, which employed a coding method that the British and Polish intelligence agencies were secretly able to crack.

Let’s assume that Alice wants to send an encrypted message to Bob. She uses the machine to generate photons that travel through free space and into a spatial light modulator (SLM) that alters the properties of the individual photons (e.g. amplitude, tilt) to properly encode the message into flat but tilted wavefronts that can be focused to unique points dictated by the tilt. But the SLM does one more thing: it distorts the shapes of the photons into random patterns, such that the wavefront is no longer flat which means it no longer has a well-defined focus. Alice and Bob both know the keys which identify the implemented scrambling operations, so Bob is able to use his own SLM to flatten the wavefront, re-focus the photons, and translate the altered properties into the distinct elements of the message.

Along with modifying the shape of the photons, Lum and the team made use of the uncertainty principle, which states that the more we know about one property of a particle, the less we know about another of its properties. Because of that, the researchers were able to securely lock in six bits of classical information using only one bit of an encryption key—an operation called data locking.

“While our device is not 100 percent secure, due to photon loss,” said Lum, “it does show that data locking in message encryption is far more than a theory.”

The ultimate goal of the quantum enigma machine is to prevent a third party—for example, someone named Eve—from intercepting and deciphering the message. A crucial principle of quantum theory is that the mere act of measuring a quantum system changes the system. As a result, Eve has only one shot at obtaining and translating the encrypted message—something that is virtually impossible, given the nearly limitless number of patterns that exist for each photon.

The paper by Lum and Howell was one of two papers published simultaneously on the same topic. The other paper, “Quantum data locking,” was from a team led by Chinese physicist Jian-Wei Pan.

“It’s highly unlikely that our free-space implementation will be useful through atmospheric conditions,” said Lum. “Instead, we have identified the use of optic fiber as a more practical route for data locking, a path Pan’s group actually started with. Regardless, the field is still in its infancy with a great deal more research needed.”

Here’s a link to and a citation for the paper,

Quantum enigma machine: Experimentally demonstrating quantum data locking by Daniel J. Lum, John C. Howell, M. S. Allman, Thomas Gerrits, Varun B. Verma, Sae Woo Nam, Cosmo Lupo, and Seth Lloyd. Phys. Rev. A, Vol. 94, Iss. 2 — August 2016 DOI: http://dx.doi.org/10.1103/PhysRevA.94.022315

©2016 American Physical Society

This paper is behind a paywall.

There is an earlier open access version of the paper by the Chinese researchers on arXiv.org,

Experimental quantum data locking by Yang Liu, Zhu Cao, Cheng Wu, Daiji Fukuda, Lixing You, Jiaqiang Zhong, Takayuki Numata, Sijing Chen, Weijun Zhang, Sheng-Cai Shi, Chao-Yang Lu, Zhen Wang, Xiongfeng Ma, Jingyun Fan, Qiang Zhang, Jian-Wei Pan. arXiv.org > quant-ph > arXiv:1605.04030

The Chinese team’s later version of the paper is available here,

Experimental quantum data locking by Yang Liu, Zhu Cao, Cheng Wu, Daiji Fukuda, Lixing You, Jiaqiang Zhong, Takayuki Numata, Sijing Chen, Weijun Zhang, Sheng-Cai Shi, Chao-Yang Lu, Zhen Wang, Xiongfeng Ma, Jingyun Fan, Qiang Zhang, and Jian-Wei Pan. Phys. Rev. A, Vol. 94, Iss. 2 — August 2016 DOI: http://dx.doi.org/10.1103/PhysRevA.94.020301

©2016 American Physical Society

This version is behind a paywall.

Getting back to the folks at the University of Rochester, they have provided this image to illustrate their work,

The quantum enigma machine developed by researchers at the University of Rochester, MIT, and the National Institute of Standards and Technology. (Image by Daniel Lum/University of Rochester)

The quantum enigma machine developed by researchers at the University of Rochester, MIT, and the National Institute of Standards and Technology. (Image by Daniel Lum/University of Rochester)

Book announcement: Atomistic Simulation of Quantum Transport in Nanoelectronic Devices

For anyone who’s curious about where we go after creating chips at the 7nm size, this may be the book for you. Here’s more from a July 27, 2016 news item on Nanowerk,

In the year 2015, Intel, Samsung and TSMC began to mass-market the 14nm technology called FinFETs. In the same year, IBM, working with Global Foundries, Samsung, SUNY, and various equipment suppliers, announced their success in fabricating 7nm devices. A 7nm silicon channel is about 50 atomic layers and these devices are truly atomic! It is clear that we have entered an era of atomic scale transistors. How do we model the carrier transport in such atomic scale devices?

One way is to improve existing device models by including more and more parameters. This is called the top-down approach. However, as device sizes shrink, the number of parameters grows rapidly, making the top-down approach more and more sophisticated and challenging. Most importantly, to continue Moore’s law, electronic engineers are exploring new electronic materials and new operating mechanisms. These efforts are beyond the scope of well-established device models — hence significant changes are necessary to the top-down approach.

An alternative way is called the bottom-up approach. The idea is to build up nanoelectronic devices atom by atom on a computer, and predict the transport behavior from first principles. By doing so, one is allowed to go inside atomic structures and see what happens from there. The elegance of the approach comes from its unification and generality. Everything comes out naturally from the very basic principles of quantum mechanics and nonequilibrium statistics. The bottom-up approach is complementary to the top-down approach, and is extremely useful for testing innovative ideas of future technologies.

A July 27, 2016 World Scientific news release on EurekAlert, which originated the news item, delves into the topics covered by the book,

In recent decades, several device simulation tools using the bottom-up approach have been developed in universities and software companies. Some examples are McDcal, Transiesta, Atomistic Tool Kit, Smeagol, NanoDcal, NanoDsim, OpenMX, GPAW and NEMO-5. These software tools are capable of predicting electric current flowing through a nanostructure. Essentially the input is the atomic coordinates and the output is the electric current. These software tools have been applied extensively to study emerging electronic materials and devices.

However, developing such a software tool is extremely difficult. It takes years-long experiences and requires knowledge of and techniques in condensed matter physics, computer science, electronic engineering, and applied mathematics. In a library, one can find books on density functional theory, books on quantum transport, books on computer programming, books on numerical algorithms, and books on device simulation. But one can hardly find a book integrating all these fields for the purpose of nanoelectronic device simulation.

“Atomistic Simulation of Quantum Transport in Nanoelectronic Devices” (With CD-ROM) fills the chasm. Authors Yu Zhu and Lei Liu have experience in both academic research and software development. Yu Zhu is the project manager of NanoDsim, and Lei Liu is the project manager of NanoDcal. The content of the book is based Zhu and Liu’s combined R&D experiences of more than forty years.

In this book, the authors conduct an experiment and adopt a “paradigm” approach. Instead of organizing materials by fields, they focus on the development of one particular software tool called NanoDsim, and provide relevant knowledge and techniques whenever needed. The black of box of NanoDsim is opened, and the complete procedure from theoretical derivation, to numerical implementation, all the way to device simulation is illustrated. The affilicated source code of NanoDsim also provides an open platform for new researchers.

I’m not recommending the book as I haven’t read it but it does seem intriguing. For anyone who wishes to purchase it, you can do that here.

I wrote about IBM and its 7nm chip in a July 15, 2015 post.

A Moebius strip of moving energy (vibrations)

This research extends a theorem which posits that waves will adapt to slowly changing conditions and return to their original vibration to note that the waves can be manipulated to a new state. A July 25, 2016 news item on ScienceDaily makes the announcement,

Yale physicists have created something similar to a Moebius strip of moving energy between two vibrating objects, opening the door to novel forms of control over waves in acoustics, laser optics, and quantum mechanics.

The discovery also demonstrates that a century-old physics theorem offers much greater freedom than had long been believed. …

A July 25, 2016 Yale University news release (also on EurekAlert) by Jim Shelton, which originated the news item, expands on the theme,

Yale’s experiment is deceptively simple in concept. The researchers set up a pair of connected, vibrating springs and studied the acoustic waves that traveled between them as they manipulated the shape of the springs. Vibrations — as well as other types of energy waves — are able to move, or oscillate, at different frequencies. In this instance, the springs vibrate at frequencies that merge, similar to a Moebius strip that folds in on itself.

The precise spot where the vibrations merge is called an “exceptional point.”

“It’s like a guitar string,” said Jack Harris, a Yale associate professor of physics and applied physics, and the study’s principal investigator. “When you pluck it, it may vibrate in the horizontal plane or the vertical plane. As it vibrates, we turn the tuning peg in a way that reliably converts the horizontal motion into vertical motion, regardless of the details of how the peg is turned.”

Unlike a guitar, however, the experiment required an intricate laser system to precisely control the vibrations, and a cryogenic refrigeration chamber in which the vibrations could be isolated from any unwanted disturbance.

The Yale experiment is significant for two reasons, the researchers said. First, it suggests a very dependable way to control wave signals. Second, it demonstrates an important — and surprising — extension to a long-established theorem of physics, the adiabatic theorem.

The adiabatic theorem says that waves will readily adapt to changing conditions if those changes take place slowly. As a result, if the conditions are gradually returned to their initial configuration, any waves in the system should likewise return to their initial state of vibration. In the Yale experiment, this does not happen; in fact, the waves can be manipulated into a new state.

“This is a very robust and general way to control waves and vibrations that was predicted theoretically in the last decade, but which had never been demonstrated before,” Harris said. “We’ve only scratched the surface here.”

In the same edition of Nature, a team from the Vienna University of Technology also presented research on a system for wave control via exceptional points.

Here’s a link to and a citation for the paper,

Topological energy transfer in an optomechanical system with exceptional points by H. Xu, D. Mason, Luyao Jiang, & J. G. E. Harris. Nature (2016) doi:10.1038/nature18604 Published online 25 July 2016

This paper is behind a paywall.

First hologram of a single photon (light particle)

Polish scientists have created a technique for something thought to be impossible. From a July 19, 2016 news item on Nanowerk,

Until quite recently, creating a hologram of a single photon was believed to be impossible due to fundamental laws of physics. However, scientists at the Faculty of Physics, University of Warsaw, have successfully applied concepts of classical holography to the world of quantum phenomena. A new measurement technique has enabled them to register the first ever hologram of a single light particle, thereby shedding new light on the foundations of quantum mechanics.

A July 18, 2016 University of Warsaw press release on EurekAlert, which originated the news item, describes the breakthrough in more detail,

Scientists at the Faculty of Physics, University of Warsaw, have created the first ever hologram of a single light particle. The spectacular experiment, reported in the prestigious journal Nature Photonics, was conducted by Dr. Radoslaw Chrapkiewicz and Michal Jachura under the supervision of Dr. Wojciech Wasilewski and Prof. Konrad Banaszek. Their successful registering of the hologram of a single photon heralds a new era in holography: quantum holography, which promises to offer a whole new perspective on quantum phenomena.

“We performed a relatively simple experiment to measure and view something incredibly difficult to observe: the shape of wavefronts of a single photon,” says Dr. Chrapkiewicz.

In standard photography, individual points of an image register light intensity only. In classical holography, the interference phenomenon also registers the phase of the light waves (it is the phase which carries information about the depth of the image). When a hologram is created, a well-described, undisturbed light wave (reference wave) is superimposed with another wave of the same wavelength but reflected from a three-dimensional object (the peaks and troughs of the two waves are shifted to varying degrees at different points of the image). This results in interference and the phase differences between the two waves create a complex pattern of lines. Such a hologram is then illuminated with a beam of reference light to recreate the spatial structure of wavefronts of the light reflected from the object, and as such its 3D shape.

One might think that a similar mechanism would be observed when the number of photons creating the two waves were reduced to a minimum, that is to a single reference photon and a single photon reflected by the object. And yet you’d be wrong! The phase of individual photons continues to fluctuate, which makes classical interference with other photons impossible. Since the Warsaw physicists were facing a seemingly impossible task, they attempted to tackle the issue differently: rather than using classical interference of electromagnetic waves, they tried to register quantum interference in which the wave functions of photons interact.

Wave function is a fundamental concept in quantum mechanics and the core of its most important equation: the Schrödinger equation. In the hands of a skilled physicist, the function could be compared to putty in the hands of a sculptor: when expertly shaped, it can be used to ‘mould’ a model of a quantum particle system. Physicists are always trying to learn about the wave function of a particle in a given system, since the square of its modulus represents the distribution of the probability of finding the particle in a particular state, which is highly useful.

“All this may sound rather complicated, but in practice our experiment is simple at its core: instead of looking at changing light intensity, we look at the changing probability of registering pairs of photons after the quantum interference,” explains doctoral student Jachura.

Why pairs of photons? A year ago, Chrapkiewicz and Jachura used an innovative camera built at the University of Warsaw to film the behaviour of pairs of distinguishable and non-distinguishable photons entering a beam splitter. When the photons are distinguishable, their behaviour at the beam splitter is random: one or both photons can be transmitted or reflected. Non-distinguishable photons exhibit quantum interference, which alters their behaviour: they join into pairs and are always transmitted or reflected together. This is known as two-photon interference or the Hong-Ou-Mandel effect.

“Following this experiment, we were inspired to ask whether two-photon quantum interference could be used similarly to classical interference in holography in order to use known-state photons to gain further information about unknown-state photons. Our analysis led us to a surprising conclusion: it turned out that when two photons exhibit quantum interference, the course of this interference depends on the shape of their wavefronts,” says Dr. Chrapkiewicz.

Quantum interference can be observed by registering pairs of photons. The experiment needs to be repeated several times, always with two photons with identical properties. To meet these conditions, each experiment started with a pair of photons with flat wavefronts and perpendicular polarisations; this means that the electrical field of each photon vibrated in a single plane only, and these planes were perpendicular for the two photons. The different polarisation made it possible to separate the photons in a crystal and make one of them ‘unknown’ by curving their wavefronts using a cylindrical lens. Once the photons were reflected by mirrors, they were directed towards the beam splitter (a calcite crystal). The splitter didn’t change the direction of vertically-polarised photons, but it did diverge diplace horizontally-polarised photons. In order to make each direction equally probable and to make sure the crystal acted as a beam splitter, the planes of photon polarisation were bent by 45 degrees before the photons entered the splitter. The photons were registered using the state-of-the-art camera designed for the previous experiments. By repeating the measurements several times, the researchers obtained an interference image corresponding to the hologram of the unknown photon viewed from a single point in space. The image was used to fully reconstruct the amplitude and phase of the wave function of the unknown photon.

The experiment conducted by the Warsaw physicists is a major step towards improving our understanding of the fundamental principles of quantum mechanics. Until now, there has not been a simple experimental method of gaining information about the phase of a photon’s wave function. Although quantum mechanics has many applications, and it has been verified many times with a great degree of accuracy over the last century, we are still unable to explain what wave functions actually are: are they simply a handy mathematical tool, or are they something real?

“Our experiment is one of the first allowing us to directly observe one of the fundamental parameters of photon’s wave function – its phase – bringing us a step closer to understanding what the wave function really is,” explains Jachura.

The Warsaw physicists used quantum holography to reconstruct wave function of an individual photon. Researchers hope that in the future they will be able to use a similar method to recreate wave functions of more complex quantum objects, such as certain atoms. Will quantum holography find applications beyond the lab to a similar extent as classical holography, which is routinely used in security (holograms are difficult to counterfeit), entertainment, transport (in scanners measuring the dimensions of cargo), microscopic imaging and optical data storing and processing technologies?

“It’s difficult to answer this question today. All of us – I mean physicists – must first get our heads around this new tool. It’s likely that real applications of quantum holography won’t appear for a few decades yet, but if there’s one thing we can be sure of it’s that they will be surprising,” summarises Prof. Banaszek.

Here’s a link to and a citation for the paper,

Hologram of a single photon by Radosław Chrapkiewicz, Michał Jachura, Konrad Banaszek, & Wojciech Wasilewski.  Nature Photonics (2016) doi:10.1038/nphoton.2016.129 Published online 18 July 2016

This paper is behind a paywall.

Light-captured energetics (harvesting light for optoelectronics)

Comparing graphene to a tiger is unusual but that’s what researcher Sanfeng Wu does—eventually—in a May 13, 2016 University of Washington news release (also on EurekAlert) about his work,

In the quest to harvest light for electronics, the focal point is the moment when photons — light particles — encounter electrons, those negatively-charged subatomic particles that form the basis of our modern electronic lives. If conditions are right when electrons and photons meet, an exchange of energy can occur. Maximizing that transfer of energy is the key to making efficient light-captured energetics possible.

“This is the ideal, but finding high efficiency is very difficult,” said University of Washington physics doctoral student Sanfeng Wu. “Researchers have been looking for materials that will let them do this — one way is to make each absorbed photon transfer all of its energy to many electrons, instead of just one electron in traditional devices.”

In traditional light-harvesting methods, energy from one photon only excites one electron or none depending on the absorber’s energy gap, transferring just a small portion of light energy into electricity. The remaining energy is lost as heat. But in a paper released May 13 in Science Advances, Wu, UW associate professor Xiaodong Xu and colleagues at four other institutions describe one promising approach to coax photons into stimulating multiple electrons. Their method exploits some surprising quantum-level interactions to give one photon multiple potential electron partners. Wu and Xu, who has appointments in the UW’s Department of Materials Science & Engineering and the Department of Physics, made this surprising discovery using graphene.

There has been intense research on graphene’s electrical properties but the researchers’ discovery adds a new property to be investigated (from the news release),

“Graphene is a substance with many exciting properties,” said Wu, the paper’s lead author. “For our purposes, it shows a very efficient interaction with light.”

Graphene is a two-dimensional hexagonal lattice of carbon atoms bonded to one another, and electrons are able to move easily within graphene. The researchers took a single layer of graphene — just one sheet of carbon atoms thick — and sandwiched it between two thin layers of a material called boron-nitride.

Boron-nitride is a material that has excited a great deal of interest in the last 12 to 18 months (from the news release),

“Boron-nitride has a lattice structure that is very similar to graphene, but has very different chemical properties,” said Wu. “Electrons do not flow easily within boron-nitride; it essentially acts as an insulator.”

Xu and Wu discovered that when the graphene layer’s lattice is aligned with the layers of boron-nitride, a type of “superlattice” is created with properties allowing efficient optoelectronics that researchers had sought. These properties rely on quantum mechanics, the occasionally baffling rules that govern interactions between all known particles of matter. Wu and Xu detected unique quantum regions within the superlattice known as Van Hove singularities.

Here’s an animated .gif illustrating the superlattice in action,

The Moire superlattice they created by aligning graphene and boron-nitride. Credit: Sanfeng Wu.

The Moire superlattice they created by aligning graphene and boron-nitride. Credit: Sanfeng Wu.

The news release goes on to describe the Van Hove singularities within the superlattice and to mention the ‘tiger’,

“These are regions of huge electron density of states, and they were not accessed in either the graphene or boron-nitride alone,” said Wu. “We only created these high electron density regions in an accessible way when both layers were aligned together.”

When Xu and Wu directed energetic photons toward the superlattice, they discovered that those Van Hove singularities were sites where one energized photon could transfer its energy to multiple electrons that are subsequently collected by electrodes— not just one electron or none with the remaining energy lost as heat. By a conservative estimate, Xu and Wu report that within this superlattice one photon could “kick” as many as five electrons to flow as current.

With the discovery of collecting multiple electrons upon the absorption of one photon, researchers may be able to create highly efficient devices that could harvest light with a large energy profit. Future work would need to uncover how to organize the excited electrons into electrical current for optimizing the energy-converting efficiency and remove some of the more cumbersome properties of their superlattice, such as the need for a magnetic field. But they believe this efficient process between photons and electrons represents major progress.

“Graphene is a tiger with great potential for optoelectronics, but locked in a cage,” said Wu. “The singularities in this superlattice are a key to unlocking that cage and releasing graphene’s potential for light harvesting application.”

H/t to a May 13, 2016 news item on phys.org.

Here’s a link to and a citation for the paper,

Multiple hot-carrier collection in photo-excited graphene Moiré superlattices by Sanfeng Wu, Lei Wang, You Lai, Wen-Yu Shan, Grant Aivazian, Xian Zhang, Takashi Taniguchi, Kenji Watanabe, Di Xiao, Cory Dean, James Hone, Zhiqiang Li, and Xiaodong Xu. Science Advances 13 May 2016: Vol. 2, no. 5, e1600002 DOI: 10.1126/sciadv.1600002

This paper is open access.

A new state for water molecules

ORNL researchers discovered that water in beryl displays some unique and unexpected characteristics. (Photo by Jeff Scovil)

ORNL researchers discovered that water in beryl displays some unique and unexpected characteristics. (Photo by Jeff Scovil)

That striking image from the Oak Ridge National Laboratory (ORNL; US) depicting a new state for water molecules looks like mixed media: photography and drawing/illustration. Thankfully, an April 22, 2016 news item on ScienceDaily provides a text description,

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.

In a paper published in Physical Review Letters, researchers at the Department of Energy’s Oak Ridge National Laboratory [ORNL] describe a new tunneling state of water molecules confined in hexagonal ultra-small channels — 5 angstrom across — of the mineral beryl. An angstrom is 1/10-billionth of a meter, and individual atoms are typically about 1 angstrom in diameter.

The discovery, made possible with experiments at ORNL’s Spallation Neutron Source and the Rutherford Appleton Laboratory in the United Kingdom, demonstrates features of water under ultra confinement in rocks, soil and cell walls, which scientists predict will be of interest across many disciplines.

An April 22, 2016 ORNL news release (also on EurekAlert), which originated the news item, offers more detail,

“At low temperatures, this tunneling water exhibits quantum motion through the separating potential walls, which is forbidden in the classical world,” said lead author Alexander Kolesnikov of ORNL’s Chemical and Engineering Materials Division. “This means that the oxygen and hydrogen atoms of the water molecule are ‘delocalized’ and therefore simultaneously present in all six symmetrically equivalent positions in the channel at the same time. It’s one of those phenomena that only occur in quantum mechanics and has no parallel in our everyday experience.”

The existence of the tunneling state of water shown in ORNL’s study should help scientists better describe the thermodynamic properties and behavior of water in highly confined environments such as water diffusion and transport in the channels of cell membranes, in carbon nanotubes and along grain boundaries and at mineral interfaces in a host of geological environments.

ORNL co-author Lawrence Anovitz noted that the discovery is apt to spark discussions among materials, biological, geological and computational scientists as they attempt to explain the mechanism behind this phenomenon and understand how it applies to their materials.

“This discovery represents a new fundamental understanding of the behavior of water and the way water utilizes energy,” Anovitz said. “It’s also interesting to think that those water molecules in your aquamarine or emerald ring – blue and green varieties of beryl – are undergoing the same quantum tunneling we’ve seen in our experiments.”

While previous studies have observed tunneling of atomic hydrogen in other systems, the ORNL discovery that water exhibits such tunneling behavior is unprecedented. The neutron scattering and computational chemistry experiments showed that, in the tunneling state, the water molecules are delocalized around a ring so the water molecule assumes an unusual double top-like shape.

“The average kinetic energy of the water protons directly obtained from the neutron experiment is a measure of their motion at almost absolute zero temperature and is about 30 percent less than it is in bulk liquid or solid water,” Kolesnikov said. “This is in complete disagreement with accepted models based on the energies of its vibrational modes.”

Here’s a link to and a citation for the paper,

Quantum Tunneling of Water in Beryl: A New State of the Water Molecule by Alexander I. Kolesnikov, George F. Reiter, Narayani Choudhury, Timothy R. Prisk, Eugene Mamontov, Andrey Podlesnyak, George Ehlers, Andrew G. Seel, David J. Wesolowski, and Lawrence M. Anovitz.
Phys. Rev. Lett. 116, 167802 – Published 22 April 2016

This paper is behind a paywall.