Lin received his Ph.D. in 2006 from the Institute of Optics, where he worked as a graduate student in the laboratory of Govind Agrawal.

“He published 30 research papers before graduating, a record that is unlikely to be broken,” said Agrawal, the James C. Wyant Professor of Optics and professor of physics.

Following his doctoral work, Lin was a valued postdoctoral scholar in the laboratory of Oskar Painter at the California Institute of Technology. He returned to Rochester in 2011.

Lin now directs the Laboratory for Quantum, Nonlinear and Mechanical Photonics, studying the fundamental physics of light and its applications, including secure communication and advanced computing. His group has made important contributions to the burgeoning field of quantum information processing.

In 2013, he received a prestigious Faculty Early Career Development grant from the National Science Foundation, a five-year award given to��junior faculty who distinguish themselves as outstanding researchers and educators. He has published numerous papers with his Ģ����ý research students in prestigious peer-reviewed journals of pure and applied physics and optics.

Jonathan Lee, who has worked with Lin as a postdoctoral researcher for more than two years, said, “Professor Lin is one of the most admired professors I have ever met. He is brilliant, passionate, and works tirelessly in teaching and conducting cutting-edge research.”

“Qiang is an intelligent scholar, ambitious scientist, and kind person,” said Wei Jiang, a Ph.D. student in Lin’s lab.

Graduate student Xiyuan Lu said, “He sincerely cares about every student in the group. He really tries to prepare students to be all around researchers.”

The Leonard Mandel Faculty Fellow Award was established this year by the . It is given in honor of the late Leonard Mandel, a long-time Ģ����ý physicist and pioneer of quantum optics.

Mandel joined the University in 1964, and was highly regarded for his experiments that demonstrated for the first time a number of the exotic and counter-intuitive phenomena predicted by quantum optical theory.

“Len systematically tested quantum theory, producing the finest experiments in the world to test the foundations of quantum optics,” said Emil Wolf, the Wilson Professor of Optical Physics.

“His experiments were models of simplicity and elegance. It was the way you would do the experiment if you were as smart as someone like Len Mandel,” said his colleague Ian Walmsley, former director of the Institute of Optics.

Among his many achievements, Mandel trained 39 doctoral students, earned top awards in optical physics, and was elected to the National Academy of Sciences. He is remembered by colleagues and friends as an excellent teacher and a first-class researcher, and a kind, generous man. The Mandel award is funded by donations from his family, former students and admirers of his work.

“I am extremely honored to receive this award,” said Lin. “In some sense it builds a connection between me and Professor Mandel.”

For more information about Leonard Mandel and his legacy, see his obituaries in and the .

In a new paper, two astrophysicists argue that these questions may soon be resolvable scientifically, thanks to new data about the Earth and about other planets in our galaxy, and by combining the earth-based science of sustainability with the space-oriented field of astrobiology.

“We have no idea how long a technological civilization like our own can last,” says Ģ����ý astrophysicist Adam Frank.�� “Is it 200 years, 500 years or 50,000 years?�� Answering this question is at the root of all our concerns about the sustainability of human society.”

“Are we the first and only technologically-intensive civilization in the entire history of the universe?” asks Frank. “If not, shouldn’t we stand to learn something from the past successes and failures of these other species?”

, Frank and co-author Woodruff Sullivan call for creation of a new research program to answer questions about humanity’s future in the broadest astronomical context. The authors explain: “The point is to see that our current situation may, in some sense, be natural or at least a natural and generic consequence of certain evolutionary pathways.”

To frame these questions, Frank and Sullivan begin with the famous Drake equation, a straightforward formula used to estimate the number of intelligent societies in the universe. In their treatment of the equation, the authors concentrate on the average lifetime of a Species with Energy-Intensive Technology (SWEIT). Frank and Sullivan calculate that even if the chances of forming such a “high tech” species are 1 in a 1,000 trillion, there will still have been 1,000 occurrences of a history like own on planets across the “local” region of the Cosmos.

“That’s enough to start thinking about statistics,” says Frank, “like what is the average lifetime of a species that starts harvesting energy efficiently and uses it to develop high technology.”

Employing dynamical systems theory, the authors map out a strategy for modeling the trajectories of various SWEITs through their evolution. The authors show how the developmental paths should be strongly tied to interactions between the species and its host planet. As the species’ population grows and its energy harvesting intensifies, for example, the composition of the planet and its atmosphere may become altered for long timescales.

Frank and Sullivan show how habitability studies of exoplanets hold important lessons for sustaining the civilization we have developed on Earth. This “astrobiological perspective” casts sustainability as a place-specific subset of habitability, or a planet’s ability to support life. While sustainability is concerned with a particular form of life on a particular planet, astrobiology asks the bigger question: what about any form of life, on any planet, at any time?

We don’t yet know how these other life forms compare to the ones we are familiar with here on Earth. But for the purposes of modeling average lifetimes, Frank explains, it doesn’t matter.

“If they use energy to produce work, they’re generating entropy. There’s no way around that, whether their human-looking Star Trek creatures with antenna on their foreheads, or they’re nothing more than single-cell organisms with collective mega-intelligence. And that entropy will almost certainly have strong feedback effects on their planet’s habitability, as we are already beginning to see here on Earth.”

“Maybe everybody runs into this bottleneck,” says Frank, adding that this could be a universal feature of life and planets.�� “If that’s true, the question becomes whether we can learn anything by modeling the range of evolutionary pathways. Some paths will lead to collapse and others will lead to sustainability. Can we, perhaps, gain some insight into which decisions lead to which kind of path?”

As Frank and Sullivan show, studying past extinction events and using theoretical tools to model the future evolutionary trajectory of humankind—and of still unknown but plausible alien civilizations—could inform decisions that would lead to a sustainable future.

Inspired perhaps by Harry Potter’s invisibility cloak, scientists have recently developed several ways—some simple and some involving new technologies—to hide objects from view. The latest effort, developed at the URochester, not only overcomes some of the limitations of previous invisibility cloaking devices, but it uses inexpensive, readily available materials in a novel configuration.

“There’ve been many high tech approaches to cloaking and the basic idea behind these is to take light and have it pass around something as if it isn’t there, often using high-tech or exotic materials,” said John Howell, a professor of physics at the URochester. Forgoing the specialized components, Howell and graduate student Joseph Choi developed a combination of four standard lenses that keeps the object hidden as the viewer moves up to several degrees away from the optimal viewing position.

“This is the first device that we know of that can do three-dimensional, continuously multidirectional cloaking, which works for transmitting rays in the visible spectrum,” said Choi, a PhD student at Rochester’s Institute of Optics.

Many cloaking designs work fine when you look at an object straight on, but if you move your viewpoint even a little, the object becomes visible, explains Howell. Choi added that previous cloaking devices can also cause the background to shift drastically, making it obvious that the cloaking device is present.

In order to both cloak an object and leave the background undisturbed, the researchers determined the lens type and power needed, as well as the precise distance to separate the four lenses. To test their device, they placed the cloaked object in front of a grid background. As they looked through the lenses and changed their viewing angle by moving from side to side, the grid shifted accordingly as if the cloaking device was not there. ��There was no discontinuity in the grid lines behind the cloaked object, compared to the background, and the grid sizes (magnification) matched.

The Rochester Cloak can be scaled up as large as the size of the lenses, allowing fairly large objects to be cloaked. And, unlike some other devices, it’s broadband so it works for the whole visible spectrum of light, rather than only for specific frequencies.

Their simple configuration improves on other cloaking devices, but it’s not perfect. “This cloak bends light and sends it through the center of the device, so the on-axis region cannot be blocked or cloaked,” said Choi. This means that the cloaked region is shaped like a doughnut. He added that they have slightly more complicated designs that solve the problem.�� Also, the cloak has edge effects, but these can be reduced when sufficiently large lenses are used.

In a new paper submitted to the journal Optics Express and ��[UPDATE 11/19/2014: ], Howell and Choi provide a mathematical formalism for this type of cloaking that can work for angles up to 15 degrees, or more.�� They use a technique called ABCD matrices that describes how light bends when going through lenses, mirrors, or other optical elements.

While their device is not quite like Harry Potter’s invisibility cloak, Howell had some thoughts about potential applications, including using cloaking to effectively let a surgeon “look through his hands to what he is actually operating on,” he said. The same principles could be applied to a truck to allow drivers to see through blind spots on their vehicles.

Howell became interested in creating simple cloaking devices with off-the-shelf materials while working on a holiday project with his children. Together with his 14 year-old son and Choi, he recently , and also demonstrated simple cloaking with mirrors, like magicians would use, .

To build your own Rochester Cloak, follow these simple steps:

1. Purchase 2 sets of 2 lenses with different focal lengths f₁ and f₂ (4 lenses total, 2 with f₁ focal length, and 2 with f₂ focal length)
2. Separate the first 2 lenses by the sum of their focal lengths (So f₁ lens is the first lens, f₂ is the 2nd lens, and they are separated by t₁= f₁+ f₂).
3. Do the same in Step 2 for the other two lenses.
4. Separate the two sets by t₂=2 f₂ (f₁+ f₂) / (f₁— f₂) apart, so that the two f₂ lenses are t₂ apart.

NOTES:

• Achromatic lenses provide best image quality.
• Fresnel lenses can be used to reduce the total length (2t₁+t₂)
• Smaller total length should reduce edge effects and increase the range of angles.
• For an easier, but less ideal, cloak, you can try the 3 lens cloak in the paper.

A patent has been filed for this cloaking device. Please .

Anton Zeilinger, one of the world’s leading experts in the field of quantum optics, will present a free, public lecture Tuesday at the URochester. The talk, titled “From Einstein’s Spook and Schrödinger’s Cat to Quantum Communication and Quantum Computation,” is designed to convey the exciting frontiers of quantum mechanics to a general audience.

Zeilinger, a professor of experimental physics at the University of Vienna and president of the Austrian Academy of Sciences, has made tremendous contributions to our understanding of how the universe works at its most fundamental level. His innovative experiments have led to groundbreaking discoveries into such quantum phenomena as entanglement, a property that governs pairs of subatomic particles where manipulation of one particle has an instant effect on another. Most recently, Zeilinger’s research group exploited this property of two photons, the quantum of light, to create an image from a series of photons that never actually interacted with the object to be imaged. All the necessary information came from their entangled twins.

Zeilinger is well-known for pushing the boundaries of current knowledge. In the 1980s, he and his colleagues were the first to theorize—and later demonstrate in the lab—that it was possible to entangle more than two photons. ��In a recent feat, Zeilinger led a group that successfully transmitted quantum states between entangled photons across two of Spain’s Canary Islands, separated by a distance of 90 miles.

This idea of quantum teleportation has a host of practical applications, including the development of ultra-secure ways to transmit confidential information. By using what’s called a “quantum key distribution,” a message could be encrypted on one photon and decrypted from the entangled photon. If a third party tried to interfere, the quantum system would collapse and reveal the security breach.

Zeilinger was awarded the Institute of Physics’ inaugural Isaac Newton medal in 2008 for “his pioneering conceptual and experimental contributions to the foundations of quantum physics, which have become the cornerstone for the rapidly-evolving field of quantum information.” He writes about the weirdness of quantum physics, and the experiments confirming its reality, in his 2010 book Dance of the Photons: From Einstein to Quantum Teleportation.

For more on Anton Zeilinger, read his profiles in and , and an .

Reporting today in The Optical Society’s (OSA) high-impact journal��, optical and material scientists at the URochester and Swiss Federal Institute of Technology in Zurich describe a basic model circuit consisting of a silver nanowire and a single-layer flake of��molybdenum��disulfide (MoS2).

Using a laser to excite electromagnetic waves called plasmons at the surface of the wire, the researchers found that the MoS2 flake at the far end of the wire generated strong light emission. Going in the other direction, as the excited electrons relaxed, they were collected by the wire and converted back into plasmons, which emitted light of the same wavelength.

“We have found that there is pronounced nanoscale light-matter interaction between plasmons and atomically thin material that can be exploited for nanophotonic integrated circuits,” said Nick Vamivakas, assistant professor of quantum optics and quantum physics at the URochester and senior author of the paper.

Typically about a third of the remaining energy would be lost for every few microns (millionths of a meter) the plasmons traveled along the wire, explained Kenneth Goodfellow, a graduate student at Rochester’s Institute of Optics and lead author of the Optica paper.

“It was surprising to see that enough energy was left after the round-trip,” said Goodfellow.

Photonic devices can be much faster than electronic ones, but they are bulkier because devices that focus light cannot be miniaturized nearly as well as electronic circuits, said Goodfellow. The new results hold promise for guiding the transmission of light, and maintaining the intensity of the signal, in very small dimensions.

Ever since the discovery of graphene, a single layer of carbon that can be extracted from graphite with adhesive tape, scientists have been rapidly exploring the world of two-dimensional materials. These materials have unique properties not seen in their bulk form.

Like graphene, MoS2 is made up of layers that are weakly bonded to each other, so they can be easily separated. In bulk MoS2, electrons and photons interact as they would in traditional semiconductors like silicon and gallium arsenide. As MoS2 is reduced to thinner and thinner layers, the transfer of energy between electrons and photons becomes more efficient.

The key to MoS2’s desirable photonic properties is in the structure of its energy band gap. As the material’s layer count decreases, it transitions from an indirect to direct band gap, which allows electrons to easily move between energy bands by releasing photons. Graphene is inefficient at light emission because it has no band gap.

Combining electronics and photonics on the same integrated circuits could drastically improve the performance and efficiency of mobile technology. The researchers say the next step is to demonstrate their primitive circuit with light emitting diodes.

Paper: K. Goodfellow, R. Beams, C. Chakraborty, L. Novotny, A.N. Vamivakas����Optica Vol. 1, Issue 3, pp.149-152 (2014).

The new method, called compressive direct measurement, allowed the team to reconstruct a quantum state at 90 percent fidelity (a measure of accuracy) using only a quarter of the measurements required by previous methods.

“We have, for the first time, combined weak measurement and compressive sensing to demonstrate a revolutionary, fast method for measuring a high-dimensional quantum state,” said Mohammad Mirhosseini, a graduate student in the Quantum Photonics research group at the URochester and lead author of .

The research team, which also included graduate students Omar Magaña-Loaiza and Seyed Mohammad Hashemi Rafsanjani, and Professor Robert Boyd, initially tested their method on a 192-dimensional state. Finding success with that large state, they then took on a massive, 19,200-dimensional state. Their efficient technique sped up the process 350-fold and took just 20 percent of the total measurements required by traditional direct measurement to reconstruct the state.

“To reproduce our result using a direct measurement alone would require more than one year of exposure time,” said Rafsanjani. “We did the experiment in less than 48 hours.”

While recent compressive sensing techniques have been used to measure sets of complementary variables like position and momentum, Mirhosseini explains that their method allows them to measure the full wave function.

Compression is widely used in the classical world of digital media, including recorded music, video, and pictures. The MP3s on your phone, for example, are audio files that have had bits of information squeezed out to make the file smaller at the cost of losing a small amount of audio quality along the way.

In digital cameras, the more pixels you can gather from a scene, the higher the image quality and the larger the file will be. But it turns out that most of those pixels don’t convey essential information that needs to be captured from the scene. Most of them can be reconstructed later. Compressive sensing works by randomly sampling portions from all over the scene, and using those patterns to fill in the missing information.

Similarly for quantum states, it is not necessary to measure every single dimension of a multidimensional state. It takes only a handful of measurements to get a high-quality image of a quantum system.

The method introduced by Mirhosseini et al. has important potential applications in the field of quantum information science. This research field strives to make use of fundamental quantum effects for diverse applications, including secure communication, teleportation of quantum states, and ideally to perform quantum computation. This latter process holds great promise as a method that can, in principle, lead to a drastic speed-up of certain types of computation. All of these applications require the use of complicated quantum states, and the new method described here offers an efficient means to characterize these states.

Research funding was provided by the Defense Advanced Research Projects Agency’s (DARPA) Information in a Photon (InPho) program, U.S. Defense Threat Reduction Agency (DTRA), National Science Foundation (NSF), El Consejo Nacional de Ciencia y Tecnología (CONACYT) and Canadian Excellence Research Chair (CERC).

“You don’t destroy the laws of quantum mechanics that easily,” said Robert Boyd, professor of optics and of physics at Rochester and the Canada Excellence Research Chair in Quantum Nonlinear Optics at the University of Ottawa.

In their 2012 version of the famous Young two-split experiment, Ralf Menzel and his colleagues at the University of Potsdam simultaneously determined a photon’s path and observed high contrast interference fringes created by the interaction of waves from the two slits.

“This result was extremely surprising, as one of the basic tenets of quantum mechanics holds that there should be no quantum interference when it is known through which slit the particle (a photon in this case) had passed,” said Boyd.

Inspired by these intriguing results, Boyd and his colleagues replicated the Menzel experiment. Their findings were recently .

“The data of the Menzel experiment were very clean, so we weren’t surprised to obtain the same initial result,” said Boyd. “My coworkers and I asked what could explain this apparent violation of a key principle of quantum mechanics. What we found is that the resolution of the problem requires great subtly in the way that one needs to analyze the data for this type of measurement.”

Following the method of Menzel and the Potsdam researchers, Boyd’s group generated an entangled pair of photons, one called a signal and the other called an idler. By measuring the position of the idler photon, they thereby determined through which slit the signal photon had passed. They then observed that the signal photons produced an interference pattern, in agreement with the results of the Potsdam group and in apparent conflict with the duality principle.

A careful examination of the results shows that the visibility of the interference pattern is stronger in some places and weaker in others. In particular, the strongest recorded visibility was much higher than the average visibility of the entire pattern.

Wave-particle duality suggests that elementary particles, like electrons and photons, cannot be completely described as either waves or particles, because they exhibit both types of properties. In the double-slit experiment, observing a photon pass through one of the two slits is an example of a particle-like property; a particle can only pass through one or the other. When two waves converge to form an interference pattern, the photon must have passed through both slits simultaneously—a wave-like property. Trying to measure both types of properties simultaneously, however, is problematic. The interference pattern disappears as soon as it is known through which slit the photon has passed.

Boyd and his colleagues discovered that the German physicists had inadvertently sampled the sections of high visibility with greater probability than the other sections. While only a handful of photons produced high visibility interference, they used the entire set of photons to determine the predictability of knowing through which slit they had passed.

This phenomenon, called biased sampling, occurs when certain measurements of a system are selected with a higher probability than others, and that subset of measurements is mistakenly taken to be representative of the entire system. In this case, the high visibility photon subsystem was more likely to be sampled. When Boyd’s team “fairly” sampled each variable—giving each subsystem an equal opportunity to be detected and sampled—the problem went away and the results were consistent with the standard interpretation of quantum mechanics.

Boyd emphasizes that the Menzel group had interpreted its data just as anyone else would have. The results were both “strange” and “incredible,” but it took Boyd and his colleagues nearly a year and a half to figure out what was going on. He said in some ways everyone is relieved that our understanding of quantum laws has been reaffirmed.

As a quantum state collapses from a quantum superposition to a classical state or a different superposition, it will follow a path known as a quantum trajectory. For each start and end state there is an optimal or “most likely” path, but it is not as easy to predict the path or track it experimentally as a straight-line between two points would be in our everyday, classical world.

In a new, scientists from the URochester, University of California at Berkeley and Washington University in St. Louis have shown that it is possible to track these quantum trajectories and compare them to a recently developed theory for predicting the most likely path a system will take between two states.

, professor of physics at the URochester and one of the authors of the paper, and his group had developed this new theory in an earlier paper. The results published this week show good agreement between theory and experiment.

For their experiment, the and Washington University teams devised a superconducting qubit with exceptional coherence properties, permitting it to remain in a quantum superposition during the continuous monitoring. The experiment actually exploited the fact that any measurement will perturb a quantum system. This means that the optimal path will come about as a result of the continuous measurement and how the system is being driven from one quantum state to another.

, co-author and assistant professor at Washington University in St. Louis, explained that a key part of the experiment was being able to measure each of these trajectories while the system was changing, something that had not been possible until now.

Jordan compares the experiment to watching butterflies make their way one by one from a cage to nearby trees. “Each butterfly’s path is like a single run of the experiment,” said Jordan. “They are all starting from the same cage, the initial state, and ending in one of the trees, each being a different end state.” By watching the quantum equivalent of a million butterflies make the journey from cage to tree, the researchers were in effect able to predict the most likely path a butterfly took by observing which tree it landed on (known as post-selection in quantum physics measurements), despite the presence of a wind, or any disturbance that affects how it flies (which is similar to the effect measuring has on the system).

“The experiment demonstrates that for any choice of final quantum state, the most likely or ‘optimal path’ connecting them in a given time can be found and predicted,” said Jordan. “This verifies the theory and opens the way for active quantum control techniques.” He explained that only if you know the most likely path is it possible to set up the system to be in the desired state at a specific time.

The experiment was discussed in a��.

For more information on a related experiment, read .

The 1500 mile Appalachian mountain chain runs along a nearly straight line from Alabama to Newfoundland—except for a curious bend in Pennsylvania and New York State. Researchers from the College of New Jersey and the Ģ����ý now know what caused that bend—a dense, underground block of rigid, volcanic rock forced the chain to shift eastward as it was forming millions of years ago.

According to Cindy Ebinger, a professor of earth and environmental sciences at the URochester, scientists had previously known about the volcanic rock structure under the Appalachian mountain chain. “What we didn’t understand was the size of the structure or its implications for mountain-building processes,” she said.

The findings have been .

When the North American and African continental plates collided more than 300 million years ago, the North American plate began folding and thrusting upwards as it was pushed westward into the dense underground rock structure—in what is now the northeastern United States. The dense rock created a barricade, forcing the Appalachian mountain range to spring up with its characteristic bend.

The research team—which also included Margaret Benoit, an associate professor of physics at the College of New Jersey, and graduate student Melanie Crampton at the College of New Jersey—studied data collected by the Earthscope project, which is funded by the National Science Foundation. Earthscope makes use of 136 GPS receivers and an array of 400 portable seismometers deployed in the northeast United States to measure ground movement.

Benoit and Ebinger also made use of the North American Gravity Database, a compilation of open-source data from the U.S., Canada, and Mexico. The database, started two decades ago, contains measurements of the gravitational pull over the North American terrain. Most people assume that gravity has a constant value, but when gravity is experimentally measured, it changes from place to place due to variations in the density and thickness of Earth’s rock layers. Certain parts of the Earth are denser than others, causing the gravitational pull to be slightly greater in those places.

Data on the changes in gravitational pull and seismic velocity together allowed the researchers to determine the density of the underground structure and conclude that it is volcanic in origin, with dimensions of 450 kilometers by 100 kilometers. This information, along with data from the Earthscope project ultimately helped the researchers to model how the bend was formed.

Ebinger called the research project a “foundation study” that will improve scientists’ understanding of the Earth’s underlying structures. As an example, Ebinger said their findings could provide useful information in the debate over hydraulic fracturing—popularly known is hydrofracking—in New York State.

Hydrofracking is a mining technique used to extract natural gas from deep in the earth. It involves drilling horizontally into shale formations, then injecting the rock with sand, water, and a cocktail of chemicals to free the trapped gas for removal. The region just west of the Appalachian Basin—the Marcellus Shale formation—is rich in natural gas reserves and is being considered for development by drilling companies.

Research funding was provided by NASA and the National Science Foundation.