Quantum Hamiltonian Complexity: Through the Computational Len

Tuesday, October 30, 2012

Abstract:
Quantum Hamiltonian complexity studies questions at the intersection of condensed matter physics and complexity theory. In this talk I will focus on three basic questions:

1. Do `typical' quantum states that occur in Nature have succinct (polynomial) description?

2. Can quantum systems at room temperature exhibit exponential complexity?

3. Is the scientific method sufficiently powerful to comprehend general quantum systems?

Each of these issues is best studied through the computational lens as a question about computation. The resulting questions lie at the core of computational complexity theory. The first asks about the structure of solutions to the quantum analog of SAT. The second asks whether there is a quantum analog of the PCP theorem. And the third can be formulated as a question about interactive proof systems with BQP provers.

The computational lens is a major theme for the new Simons Institute at Berkeley, and I will briefly describe a special semester-long program on Quantum Hamiltonian Complexity that we are organizing at the Simons Institute in Spring 2014.

Bio:
Prof. Vazirani’s research focuses on algorithms and complexity, the computational foundations of randomness, and novel models of computation. His 1993 paper with Ethan Bernstein helped launch the field of quantum complexity theory. He is the author of two books, “An introduction to computational learning theory” with Michael Kearns, and “Algorithms” with Sanjoy Dasgupta and Christos Papadimitriou. He is a fellow of the ACM and recipient (with Arora and Rao) of the 2012 Fulkerson Prize for his work on graph separators.

Exploring Big and Not so Big Data

Tuesday, December 4, 2012

Abstract:
The explosion in the volume of digital data currently available has created new opportunities in many different domains, from spurring scientific discoveries to enabling smarter cities that provide a better quality of life for its citizens. Unfortunately, the infrastructure to analyze, visualize, and integrate information has not kept pace with our collective ability to gather data, leading to an unprecedented situation: data exploration is now the bottleneck to discovery. In this talk, I will describe some of the efforts we are conducting at the Visualization and Data Analysis Center at NYU Poly that aim to address this challenge.

Bio:
Prof. Freire’s recent research focuses on Web-scale data integration, big-data analysis and visualization, and provenance management. Prof. Freire is an active member of the database and Web research communities. She has co-authored over 120 technical papers, and holds 8 U.S. patents. She is a recipient of an NSF CAREER Award and an IBM Faculty Award. Prof. Freire also holds an appointment in the Courant Institute for Mathematical Sciences. Prior to joining NYU, Prof. Freire was on faculty at the University of Utah, and before this, a member of technical staff at Bell Laboratories (Lucent Technologies).

Applications of Computing to Energy and Health

Tuesday, January 29, 2013

Abstract:
Much of the fundamental research in computer science has been driven by the needs of those attempting to utilize computing for various applications, such as energy and health. Dr. Patel will talk about a new generation of electricity and water sensing systems that are capable of providing consumption data down to the individual appliance or device from single sensing points. He will also describe how microphones found on mobile phones can enable new health sensing applications. These projects follow the theme of finding usable signals in unusual places in order to enable scale. Dr. Patel's remarks will underscore advances in energy and health through the convergence of sensing, machine learning, and human-computer interaction.

Bio:
Prof. Patel’s research interests are in the areas of human-computer interaction, ubiquitous computing, sensor-enabled embedded systems, and user interface technology. His particular focus is on developing easy-to-deploy sensing technologies and approaches for activity recognition and energy monitoring applications. In 2009, Prof. Patel received a TR-35 award and in 2010 he was named top innovator of the year by Seattle Business Magazine. In 2011, Prof. Patel was named a MacArthur Foundation Fellow. He also received a 2011 Microsoft Research Faculty Fellowship and, in 2012, an Alfred P. Sloan Foundation Fellowship.

Advances in Subretinal Implants

Tuesday, April 30, 2013

Abstract:
In the last decade, about 100 people world-wide have received several kinds of electronic implants to restore visual function lost to retinal degenerations.

Background:
Essentially three concepts are being pursued (Ref. 1): a) epiretinal electrode arrays that are controlled by a camera outside the body and a computer that translates the video image into pulses that are sent directly to the retina’s output cells, the ganglion cells and their nerve fibers, and b) the subretinal approach aiming at replacing the photoreceptors by photodiodes at the input side of the degenerated retina, and stimulating bipolar cells, as photoreceptors would normally do; this approach utilizes the natural processing network of the inner retina, and places the stimulation electrodes at the place of the former photoreceptors; c) the suprachoroidal approach, where the electrode array is placed behind the choroid, with some distance to retinal input neurons. Presently three approaches are available to patients, the ARGUS II System (Second Sight, Sylamar USA, 60 epiretinal electrodes, approx. 50 Patients, postmarketing surveillance starting), the Alpha-IMS study (Retina Implant AG, Tübingen/Reutlingen, Germany, 1500 subretinal electrodes, 36 patients) and the study of Bionic Vision Australia (24 suprachoroidal electrodes in 3 patients). Many other groups are also working hard to develop implants for artificial vision in blind people. In the first part of the lecture, the peculiar properties of the various approaches will be discussed from a physiological and clinical viewpoint.

The subretinal approach:
To restore useful visual sensations to patients blind from photoreceptor dystrophies, an externally powered photosensitive microphotodiode array with 1500 pixels (Alpha-IMS implant of Retina Implant AG, Reutlingen , Germany) was implanted in the subretinal space, as will be reported in the second part of the lecture (Ref.2). A multicentre trial is presently being performed (www.clinicaltrials.gov, NCT01024803) that includes centres in Tuebingen, London, Oxford, Dresden, Budapest and Hongkong. So far 36 patients have undergone the procedure. Here we report on the pilot trial and the first module of the main trial (Ref.3). All the subjects had successful implantation of the chip and were able to perceive light after implantation of the photodiode chip. The visual experiences ranged from perception of light where there was none before surgery, to the ability to see individual letters 4 cm high at a working distance of 40 cm. Motion detection was possible up to angular speed up to 35 deg/s, grating acuity up to 3.3 cycles per degree. In some cases visual acuity measurement with Landolt C-rings was possible up to Snellen visual acuity of 20/546. Additionally, the identification, localization and discrimination of objects improved significantly in most patients. In repeated tests over a nine month period, several subjects were able to read letters spontaneously, controlled in four alternative forced choice tests. Control tests were performed each time with the implant's power source switched off.

Conclusion:
The study has shown proof of concept that a photodiode chip placed in the subretinal space can provide useful vision for many subjects. Selection of patients based on experiences with preoperative OCT analysis, fluorescence angiography and autofluorescence helps to identify patients optimally suited for rehabilitation measures by means of subretinal electronic implants. From these developments and ongoing clinical studies it can be predicted that electronic implants will finally be available for the blind for restitution of visual abilities that are truly useful in daily life.

References:

1. Zrenner E, Artificial vision: solar cells for the blind. Nature Photonics 2012, 6: 344–345

2. Zrenner E, Bartz-Schmidt KU, Benav H, Besch D, Bruckmann A, Gabel VP, Gekeler F, Greppmaier U, Harscher A, Kibbel S, Koch J, Kusnyerik A, Peters T, Stingl K, Sachs H, Stett A, Szurman P, Wilhelm B, Wilke R. Subretinal electronic chips allow blind patients to read letters and combine them to words. Proc Biol Sci. 2011; 278:1489-97

3. Stingl K, Bartz-Schmidt KU, Besch D, Braun A, Bruckmann A, Gekeler F, Greppmaier U, Hipp S, Hörtdörfer G, Kernstock C, Koitschev A, Kusnyerik A, Sachs H, Schatz A, Stingl KT, Peters T, Wilhelm B and Zrenner E. Artificial vision with wirelessly powered subretinal electronic implant alpha-IMS. Proc. R. Soc. B 2013, 280, published online, 20 February 2013

Bio:
Prof. Dr. med. Eberhart Zrenner trained as an engineer before studying medicine and has become one of the foremost retinal electrophysiologists and psychophysicists. His research interests include retinal physiology and pathophysiology, neuro-ophthalmology, ophthalmic toxicology, retina implants and methods of non-invasive function testing. He is Principal Investigator of several clinical studies and has developed a subretinal active microphotodiode array (MPDA) to replace degenerated photoreceptors in blind people. He serves for the German Research Council on several projects and is the recipient of several international awards, author of more than 200 publications and coordinator of several European grants.