With CVitae.org, we're trying to create a community for academics, with functions and a layout that's tailored to this user base. That's why you find the resume editor, research group functions, and discussion, publication, and scheduling tools all integrated. We're hoping that through open source, we can make such a site. I hope you'll find this site useful -- let Ilya or me know if you find problems or think of improvements.
Physics and applications of quantum dots in photonic crystals, Dirk Englund, Andrei Faraon, Ilya Fushman, Bryan Ellis, and Jelena Vuckovic,, Invited book chapter in Single Semiconductor Quantum Dots, edited by Peter Michler, to be published by Springer Book series NanoScience and Technology (2008)
We're working on photonic crystal lasers, which are interesting because they're extremely fast, have low threshold (require little power to turn on), and are extremely compact. In addition, many different frequency channels can be packed onto the same chip and combined onto a common fiber, which makes them particularly interesting for telecommunications and signal interconnects. In this project section, we discuss our research on photonic crystal lasers in the context of the general PC laser field, and in the broader context of lasers and modulators for telecommunications and possible future interconnects. We also describe our lasers in greater detail than was possible in the papers (below), and give additional data.
Anyone working with photonic crystals, or any photonic nanostructures for that matter, knows that fabricated structures never come out as well as the simulated design. What's to blame? Material losses? Fabrication inaccuracies? In this articles, we analyze the optical properties of photonic nanostructures.
The project attempted to explain the unusually large obliquity of the planet Uranus. The commonly accepted reason for Uranus' obliquity is (as far as I can tell) that a great collision took place with a near earth-sized planet. This planet would have struck Uranus near one of its poles, imparting the angular momentum that's required for the large tilt.
There are some problems with this explanation, though..
The ATACS series of software is the fraud detection software most widely used by phone companies around the world. This program was a first in that it can learn customer fraud patterns as it is in operation at the phone company. I'm co-inventor of U.S. Patent 6,597,775 for adaptive fraud detection software.
This project investigated the optical properties of ZBLAN, a type of low-loss glass, produced in microgravity. This project is possible through a NASA program that has allowed us to perform our experiment aboard the KC-135, a research plane that provides multiple half-minute phases of micro-gravity. During these periods of weightlessness, we produced microspheres of ZBLAN, a new type of glass whose transmission properties are significantly better than standard optical fiber glass (silica).e of typical silica-based fibers. Here's a happy picture before I got sick.
The goal here was to develop a non-intrusive way to observe single bio-molecules. To avoid fluorescent tags, which always alter the behavior the molecule in some way, we rely on absorption spectroscopy. However, the absorptoin of a single molecule is extremely small and difficult to measure. The way around it is to put the molecule inside an optical cavity, which confines the probe light and amplifies its interaction with the molecule. The paper shows that it should be possible to observe single molecules with a high-Q (low-loss) optical cavity. In this project, we were not able to reach the single-molecule, but we were able to observe ~10,000-100,000 molecules in a high-Q, liquid resonance cavity.
The idea of a quantum computer was first proposed by Richard Feynman in 1981 as a way to solve intractable quantum mechanical problems[1]. Since then, quantum computers were proven to be inherently superior at solving certain problem than their classical counterparts[2,3]. In addition, communication across quantum channels offers absolute security because it is impossible to eavesdrop on a transmission without disturbing it [4,5] To date, quantum computers have solved only trivial problems, and secure communication is limited to about 200 km [6]. Continued progress in computing and signal amplification in communication will require scalable systems that can perform basic quantum information processing functions. We have recently developed a technique to coherently probe an atomic system -- a semiconductor quantum dot -- that is strongly coupled to a photonic crystal nanocavity. The article is published in Nature[7].
This research was aimed at developing an apertureless Scanning Near-field Magneto-Optic Microscope (apertureless SNMOM) with pico-second temporal and sub-wavelength spatial resolution. This device would aid in understanding the spin dynamics in small domains of ferromagnetic ultra-thin films. Our aperturless SNMOM achieves high spatial resolution by local light scattering from a nanometer-sized tip. It will measure the local magnetic field from the Faraday-rotation of polarized light passing through the sample.
In the last part of this series, we saw that any classical cryptography approach can, with enough computing power, be broken. Quantum key distribution (QKD), on the other hand, can guarantee unconditionally secure information -- try as she might, eavesdropper Eve Bob without disturbing it and giving away her evil intentions. In this installment, we will look at some current implementation of quantum key distribution.
Unbreakable Codes: the path to quantum cryptography
Part 1: From classical encryption to the first quantum algorithm
In WWII, the U.S. Marine Corps enlisted Navajo indians to pass secret messages in the Pacific war theater. These code talkers proved extremely effective, keeping American communication secure through the war's end (as opposed to communication by axis powers). Secure communication has always been vital for states. The rapid rise of the internet and electronic banking has also made it crucial for individuals.
To keep pace with ever-more sophisticated eavesdroppers and hackers, increasingly advanced cryptographic methods are required. Cryptography relies on a set of keys which is shared between the sender and receiver. These keys may just be an uncommon language. But a Navajo indian (or Henry Kissinger clones, for that matter) at everyone's computer would not be practical. Nowadays code talkers are replaced by numerical encryption, most commonly public-key RSA protocols[1].
Quantum computers promise to solve mathematical problems that cannot be solved efficiently on conventional computers. Many of these problems have important practical applications in the areas of quantum physics simulation, cryptography, and combinatorial optimization. The challenge today is to implement a quantum computer and demonstrate scalable operation. This paper reviews one of the most promising schemes, Linear Optics Quantum Computation (LOQC), a recent proposal that requires only ordinary (linear) optical elements. We pay particular attention to recent theoretical and experimental developments that have significantly eased the complexity and experimental requirements of the original proposal, and list remaining technical challenges.
We take a look back today at one of the landmark papers in plasmonics applied to switching in the telecom wavelength. 15-nm-long and 8-um wide gold stripes are embedded in a polymer where they are heated by electrical contacts.  The stripes are arranged into Mach-Zender interferometers, measning that a small phase shift along one of the arms of this interferometer results in a large modulation intensity.  One of the interestesting things about this type of device is that it works in a large range of wavelengths and powers -- in this paper, the group demonstrates opeartion at 1.55um (interesting for telecom applications) and for powers from 10mW to 100mW.   Since modulation happens through rather slow thermal changes, the device is slow -- teh group measures response times of 1ms.  This drawback unfortunately makes this devices rather uninteresting for signal processing, The group speculates, however, that by taking advantage of a faster thermooptic coefficient in other materials, teh speed could be increased significantly -- although we’d still like to see thsi approach the speed of tens of GHz required in telecom today..  
This is a question that has confounded science since its beginnings. In about 400 B.C., the Greek philosopher Democritus surmised that all matter consisted of indivisible units he called atomos. Up until the late 19th century, scientists thought they had found these fundamental building pieces of matter in what we now call the chemical elements (hydrogen, helium, iron, and so on). But with the discovery of radioactivity, this simple picture was cast into doubt.
When asked what energy source will be the most important in a world 15 years from now, most respondents (27%) in a recent survey named solar energy[1]. This is not surprising. The sun is by far the most abundant source of power in the solar system. Nearly all energy forms used on Earth are, either directly or indirectly, based on solar energy, the most prominent being fossil fuels, biomass, wind, hydro energy, tidal, and solar energy. The latter can be directly converted into electricity in several ways. So it would appear that direct harnessing of solar power should be one of the biggest hopes as an alternative energy source. However, extrapolating from current growth estimates, one arrives at a much more modest role for solar energy in the future -- probably still in single-digit percentiles in 20 years. It appears the only way that solar power can live up to its expectations is through some dramatic break-through that will dramatically increase its growth rate. In this paper, we assume that this breakthrough happens by some break-through in research. A break-through appears rather likely -- several approaches are currently underway to dramatically increase the solar capture efficiency, most notably concentrators, semiconductor heterostructures, and quantum wires and quantum dots for multiple exciton generation to capture a larger fraction of the solar spectrum. In this paper, we focus on photovoltaic (PV) power generation (although century-old thermal power generation is seeing remarkable revival in recent years).
[1] A.C. Charania, J.R. Olds, A Unified Economic View of Space Solar Power, 51st International
Astronautical Congress (6 Oct. 2000)
With all the talk about carbon dioxide, maybe we're losing sight of the environmental problems caused by combustion of most fuels. For the first time in years, Los Angeles again topped the list of most polluted cities in the United States -- would cars running on ethanol make such metro areas cleaner? A recent study [1] shows that to the contrary, ethanol-based vehicles actually may pose a larger risk than today's octane-burning ones. The study considered the pollution resulting from smog processes -- the chemical reactions that happen after the emissions have left the car. When considered in this larger picture, it turns out that ethanol may actually lead to more respiratory illnesses. Furthermore, ethanol is only slightly better in reducing CO2 emissions than gasoline [2]-- and arguably worse if one also considers the environmental damage from farming. But it's clearly politically savvy to tout the benefits of ethanol -- mak'n them farm jobs and fight'n them terrists -- but mostly it's just hot smoke in your face.
The C5680 is one of the most common streak cameras, and is pretty good at most tasks. When coupled to a spectrometer, it can resolve a spectrum with high spectral accuracy, approaching 2ps. Even though it a 'common' tool, it still costs nearly $200k -- a pretty large investment. But what are the alternatives, and how close do they come to the proven functionality of the Hamamatsu streak camera?
This article is meant to give an introduction to the technology of Photonic Crystals (PC's) and how they can be applied to quantum information processing on the chip. Photonic crystals offer a highly versatile platform for manipulation of light and an unprecedented degree of control over light matter interaction on a chip. [2] The development of this technology has come along in two main avenues. The first is the development of tools for controlling light on a chip with a focus on systems level integration for optical communication and optical signal processing. The second is the development of tools for strong interactions between light and matter, where the focus has been on single elements of an optical network that can be used to enhance quantum effects, such as getting more light out of emitters. We review work along both of these avenues and show that they can come together to realize a quantum information processing device in solid state. There are many challenges which need to be overcome in order to realize useful devices. Luckily, developments in PC's for optics and communication can be directly transferred to quantum information processing devices at a system level, which is where this research will head in the next years. On the quantum side, a breakthrough in material science and manipulation of "atoms" inside these chips will be needed in order to realize a quantum memory and stable quantum bits.
Chris McGuinness
fas
harvard
2007.APL.Englund.efficient THz PC laser.pdf (
e of typical silica-based fibers. Here's a happy picture before I got sick.
be inherently superior at solving certain problem than their classical counterparts[2,3]. In addition, communication across quantum channels offers absolute security because it is impossible to eavesdrop on a transmission without disturbing it [4,5] To date, quantum computers have solved only trivial problems, and secure communication is limited to about 200 km [6]. Continued progress in computing and signal amplification in communication will require scalable systems that can perform basic quantum information processing functions. We have recently developed a technique to coherently probe an atomic system -- a semiconductor quantum dot -- that is strongly coupled to a photonic crystal nanocavity. The article is published in Nature[7]. 
combinatorial optimization. The challenge today is to implement a quantum computer and demonstrate scalable operation. This paper reviews one of the most promising schemes, Linear Optics Quantum Computation (LOQC), a recent proposal that requires only ordinary (linear) optical elements. We pay particular attention to recent theoretical and experimental developments that have significantly eased the complexity and experimental requirements of the original proposal, and list remaining technical challenges. 
either directly or indirectly, based on solar energy, the most prominent being fossil fuels, biomass, wind, hydro energy, tidal, and solar energy. The latter can be directly converted into electricity in several ways. So it would appear that direct harnessing of solar power should be one of the biggest hopes as an alternative energy source. However, extrapolating from current growth estimates, one arrives at a much more modest role for solar energy in the future -- probably still in single-digit percentiles in 20 years. It appears the only way that solar power can live up to its expectations is through some dramatic break-through that will dramatically increase its growth rate. In this paper, we assume that this breakthrough happens by some break-through in research. A break-through appears rather likely -- several approaches are currently underway to dramatically increase the solar capture efficiency, most notably concentrators, semiconductor heterostructures, and quantum wires and quantum dots for multiple exciton generation to capture a larger fraction of the solar spectrum. In this paper, we focus on photovoltaic (PV) power generation (although century-old thermal power generation is seeing remarkable revival in recent years). 
at most tasks. When coupled to a spectrometer, it can resolve a spectrum with high spectral accuracy, approaching 2ps. Even though it a 'common' tool, it still costs nearly $200k -- a pretty large investment. But what are the alternatives, and how close do they come to the proven functionality of the Hamamatsu streak camera? 
 "J. Steinbeck's novel 'The Moon is Down'")