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Microwave-induced cooling of a superconducting qubit

Published in:
Sci., Vol. 314, No. 5805, 8 December 2006, pp. 1589-1592.

Summary

We demonstrated microwave-induced cooling in a superconducting flux qubit. The thermal population in the first-excited state of the qubit is driven to a higher-excited state by way of a sideband transition. Subsequent relaxation into the ground state results in cooling. Effective temperatures as low as ≈3 millikelvin are achieved for bath temperatures of 30 to 400 millikelvin, a cooling factor between 10 and 100. This demonstration provides an analog to optical cooling of trapped ions and atoms and is generalizable to other solid-state quantum systems. Active cooling of qubits, applied to quantum information science, provides a means for qubit-state preparation with improved fidelity and for suppressing decoherence in multi-qubit systems.
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Summary

We demonstrated microwave-induced cooling in a superconducting flux qubit. The thermal population in the first-excited state of the qubit is driven to a higher-excited state by way of a sideband transition. Subsequent relaxation into the ground state results in cooling. Effective temperatures as low as ≈3 millikelvin are achieved for...

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Laser-induced fluorescence-cued, laser induced- breakdown spectroscopy biological-agent detection

Published in:
Appl. Opt., Vol. 45, No. 34, 1 December 2006, pp. 8806-8814.

Summary

Methods for accurately characterizing aerosols are required for detecting biological warfare agents. Currently, fluorescence-based biological agent sensors provide adequate detection sensitivity but suffer from high false-alarm rates. Combining single-particle fluorescence analysis with laser-induced breakdown spectroscopy (LIBS) provides additional discrimination and potentially reduces false-alarm rates. A transportable UV laser-induced fluorescence-cued LIBS test bed has been developed and used to evaluate the utility of LIBS for biological-agent detection. Analysis of these data indicates that LIBS adds discrimination capability to fluorescence-based biological-agent detectors. However, the data also show that LIBS signatures of biological agent simulants are affected by washing. This may limit the specificity of LIBS and narrow the scope of its applicability in biological-agent detection.
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Summary

Methods for accurately characterizing aerosols are required for detecting biological warfare agents. Currently, fluorescence-based biological agent sensors provide adequate detection sensitivity but suffer from high false-alarm rates. Combining single-particle fluorescence analysis with laser-induced breakdown spectroscopy (LIBS) provides additional discrimination and potentially reduces false-alarm rates. A transportable UV laser-induced fluorescence-cued LIBS...

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The security of OpenBSD: milk or wine?

Published in:
;login:, Vol. 31, No. 6, December 2006, pp. 26-32.

Summary

Purchase a fine wine, place it in a cellar, and wait a few years: The aging will have resulted in a delightful beverage, a product far better than the original. Purchase a gallon of milk, place it in a cellar, and wait a few years. You will be sorry. We know how the passing of time affects milk and wine, but how does aging affect the security of software? Many in the security research community have criticized software developers both for releasing software with so many vulnerabilities and for the lack of any apparent improvement in this software over time. However, critics have lacked quantitative evidence that applying effort over time will result in software with fewer vulnerabilities. In short, we don't know whether software security is destined to age like milk or has the potential to become wine. We thus investigated whether or not the rate at which vulnerabilities are reported in OpenBSD is decreasing over time.
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Summary

Purchase a fine wine, place it in a cellar, and wait a few years: The aging will have resulted in a delightful beverage, a product far better than the original. Purchase a gallon of milk, place it in a cellar, and wait a few years. You will be sorry. We...

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An efficient graph search decoder for phrase-based statistical machine translation

Published in:
Int. Workshop on Spoken Language Translation, 28 November 2006.

Summary

In this paper we describe an efficient implementation of a graph search algorithm for phrase-based statistical machine translation. Our goal was to create a decoder that could be used for both our research system and a real-time speech-to-speech machine translation demonstration system. The search algorithm is based on a Viterbi graph search with an A* heuristic. We were able to increase the speed of our decoder substantially through the use of on-the-fly beam pruning and other algorithmic enhancements. The decoder supports a variety of reordering constraints as well as arbitrary n-gram decoding. In addition, we have implemented disk based translation models and a messaging interface to communicate with other components for use in our real-time speech translation system.
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Summary

In this paper we describe an efficient implementation of a graph search algorithm for phrase-based statistical machine translation. Our goal was to create a decoder that could be used for both our research system and a real-time speech-to-speech machine translation demonstration system. The search algorithm is based on a Viterbi...

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The MIT-LL/AFRL IWSLT-2006 MT system

Published in:
Proc. Int. Workshop on Spoken Language Translation, IWSLT, 27-28 November 2006.

Summary

The MIT-LL/AFRL MT system is a statistical phrase-based translation system that implements many modern SMT training and decoding techniques. Our system was designed with the long-term goal of dealing with corrupted ASR input and limited amounts of training data for speech-to-speech MT applications. This paper will discuss the architecture of the MIT-LL/AFRL MT system, improvements over our 2005 system, and experiments with manual and ASR transcription data that were run as part of the IWSLT-2006 evaluation campaign.
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Summary

The MIT-LL/AFRL MT system is a statistical phrase-based translation system that implements many modern SMT training and decoding techniques. Our system was designed with the long-term goal of dealing with corrupted ASR input and limited amounts of training data for speech-to-speech MT applications. This paper will discuss the architecture of...

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The JHU Workshop 2006 IWSLT System

Published in:
Int. Workshop on Spoken Language Translation, IWSLT, 27-28 November 2006.

Summary

This paper describes the SMT we built during the 2006 JHU Summer Workshop for the IWSLT 2006 evaluation. Our effort focuses on two parts of the speech translation problem: 1) efficient decoding of word lattices and 2) novel applications of factored translation models to IWSLT-specific problems. In this paper, we present results from the open-track Chinese-to-English condition. Improvements of 5-10% relative BLEU are obtained over a high performing baseline. We introduce a new open-source decoder that implements the state-of-the-art in statistical machine translation.
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Summary

This paper describes the SMT we built during the 2006 JHU Summer Workshop for the IWSLT 2006 evaluation. Our effort focuses on two parts of the speech translation problem: 1) efficient decoding of word lattices and 2) novel applications of factored translation models to IWSLT-specific problems. In this paper, we...

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Low voltage electrowetting using thin fluoroploymer films

Published in:
J. Colloid and Interface Sci., Vol. 303, No. 2, 15 November 2006, pp. 517-524.

Summary

This paper investigates the nonideal electrowetting behavior of thin fluoroploymer films. Results are presented for a three phase system consisting of: (1) an aqueous water droplet containing sodium dodecyl sulfate (SDS), (2) phosphorous-doped silicon topped with SiO2 and an amorphous fluoroploymer (aFP) insulating top layer on which the droplet is situated, and (3) a dodecane oil that surrounds the droplet. The presented measurements indicate that the electrowetting equation is valid down to a 6 nm thick aFP film on a 11 nm thick SiO2. At this dielectric thickness, a remarkable contact angle change of over 100degreescan be achieved with an applied voltage less than 3 V across the system. The data also shows that for this water/surfactant/oil system, contact angle saturation is independent of the electric field, and is reached when the surface energy of the solid-water interface approaches zero.
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Summary

This paper investigates the nonideal electrowetting behavior of thin fluoroploymer films. Results are presented for a three phase system consisting of: (1) an aqueous water droplet containing sodium dodecyl sulfate (SDS), (2) phosphorous-doped silicon topped with SiO2 and an amorphous fluoroploymer (aFP) insulating top layer on which the droplet is...

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ASR-9 refractivity measurements using ground targets

Author:
Published in:
MIT Lincoln Laboratory Report ATC-328

Summary

Weather radars rely on the presence of radiowave scattering entities such as hydrometeors and insects to sense the dynamic evolution of the atmosphere. Under clear-air, low-reflectivity conditions, when no such "visible" tracers are present, air mass boundaries such as the outflow edge of a dry microburst may go undetected. Recently, a radar data processing technique was developed to estimate the near-ground atmospheric refractivity field using ground targets. Refractivity is dependent on the moist thermodynamic variables of the atmosphere and, thus, can be used to detect air mass changes and boundaries. In this study, we apply this technique for the first time to Airport Surveillance Radar-9 (ASR-9) Weather Systems Processor (WSP) data. Comparisons with measurements from a meteorological station show good consistency. The potential exists for improving the capability of the WSP to detect low-reflectivity wind-shear phenomena by adding interest information provided by the estimated refractivity field. Adequate computational power is the sole requirement for implementing this scheme; aside from that, no alteration or addition is necessary to the ASR-9 hardware. Its primary weakness is the sensitivity to vertical variation in refractivity and variance of target height. It also has a limited range of coverage (~20 km), but that is acceptable for terminal-area coverage. Further testing is needed during more appropriate meteorological conditions and at other sites to prove that dry wind-shear events can really be detected in the derived refractivity field by this class of radar, and that the technique is robust under various topographical settings.
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Summary

Weather radars rely on the presence of radiowave scattering entities such as hydrometeors and insects to sense the dynamic evolution of the atmosphere. Under clear-air, low-reflectivity conditions, when no such "visible" tracers are present, air mass boundaries such as the outflow edge of a dry microburst may go undetected. Recently...

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Contribution of photoacid generator to material roughness

Published in:
J. Vac. Sci. Technol. B, Microelectron. Process. Phenon., Vol. 24, No. 6, November/December 2006, pp. 3031-3039 (EIPBN 2006, 30 May-2 June 2006).

Summary

The authors have developed an atomic-force-microscopy-based technique to measure intrinsic material roughness after base development. This method involves performing an interrupted development of the resist film and measuring the resulting film roughness after a certain fixed film loss. Employing this technique, the authors previously established that the photoacid generator (PAG) is a major material contributor of film roughness and that PAG segregation in the resist is likely responsible for nanoscale dissolution inhomogeneities. The additional roughness imparted on a test polymer by incorporation of a series of iodonium, sulfonium, diazo, and imido PAGs was measured. The roughness was then correlated to the inhibition properties of the various PAGs. This was accomplished both through a NMR technique that measures interaction of the PAG with the polymer and by evaluating the dissolution inhibition properties of the PAG through a percolation model. Several PAGs that result in significantly lower material roughness and thus the potential for significantly reduced linewidth roughness in resist imaging have been identified.
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Summary

The authors have developed an atomic-force-microscopy-based technique to measure intrinsic material roughness after base development. This method involves performing an interrupted development of the resist film and measuring the resulting film roughness after a certain fixed film loss. Employing this technique, the authors previously established that the photoacid generator (PAG)...

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Required surveillance performance accuracy to support 3-mile and 5-mile separation in the National Airspace System

Published in:
MIT Lincoln Laboratory Report ATC-323

Summary

The Federal Aviation Administration is modernizing the Air Traffic Control system to improve flight efficiency, to increase capacity, to reduce flight delays, and to control operating costs as the demand for air travel continues to grow. Promising new surveillance technologies such as Automatic Dependent Surveillance Broadcast, (ADS-B), multisensor track fusion, and multifunction phased array radar offer the potential for increased efficiency in the National Airspace System (NAS). However, the introduction of these surveillance systems into the NAS is hampered because the FAA Order containing the surveillance requirements to support separation services assumes surveillance is provided by radar technology. The requirements are stated in terms that don't apply to new surveillance technologies. In order to take advantage of new surveillance technologies, the surveillance requirements to support separation services in the NAS must be articulated from a performance perspective that is not technology specific. This will allow the FAA to make the investment and performance trade-off analysis necessary to support the introduction of new surveillance technologies. [not complete]
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Summary

The Federal Aviation Administration is modernizing the Air Traffic Control system to improve flight efficiency, to increase capacity, to reduce flight delays, and to control operating costs as the demand for air travel continues to grow. Promising new surveillance technologies such as Automatic Dependent Surveillance Broadcast, (ADS-B), multisensor track fusion...

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