Author: Madhu Reddy

A new protocol for estimating unknown optical processes, called unitary operations, with precision enhanced by the unique properties of quantum mechanics has been demonstrated by scientists and engineers from the University of Bristol, UK, and the Centre for Quantum Technologies in Singapore.

The work, published in the June issue of Optica, could lead to both dramatically better sensors for medical research and new approaches to benchmark the performance of ultra-powerful quantum computers.
History tells us the ability to measure parameters and sense phenomena with increasing precision leads to dramatic advances in identifying new phenomena in science and improving the performance of technology: famous examples include X-ray imaging, magnetic resonance imaging (MRI), interferometry and the scanning-tunnelling microscope.
Scientists are understanding how to engineer and control quantum systems to vastly expand the limits of measurement and sensing is growing rapidly. This area, known as quantum metrology, promises to open up radically alternative methods to the current state-of-the-art in sensing.
In this new study, the researchers re-directed the sensing power of quantum mechanics back on itself to characterise, with increased precision, unknown quantum processes that can include individual components used to build quantum computers. This ability is becoming more and more important as quantum technologies move closer to real applications.
Dr Xiao-Qi Zhou of Bristol’s School of Physics said: “A really exciting problem is characterizing unknown quantum processes using a technique called quantum process tomography. You can think of this as a problem where a quantum object, maybe a photonic circuit of optics or an atomic system, is locked in a box. We can send quantum states in and we can measure the quantum states that come out. Our challenge is to correctly identify what is in the box. This is a difficult problem in quantum mechanics and it is a highly active area of research because its solution is needed to enable us to test quantum computers as they grow in size and complexity.”
One major shortcoming of quantum process tomography is that precision using standard techniques is limited by a type of noise known as ‘shot noise’. By borrowing techniques from quantum metrology, the researchers were able to demonstrate precision beyond the shot noise limit. They expect their protocol can also be applied to build more sophisticated sensors that identify molecules and chemicals more precisely by observing how they interact with quantum states of light.

Co-author Rebecca Whittaker, a PhD student in Bristol’s Centre for Quantum Photonics said: “The optical process we measured here can be used to manipulate quantum bits of information in a quantum computer but they can also occur in nature. For example, our setup could be used to measure how the polarisation of light is rotated by a sample. We could then infer properties of that sample with better precision.
“Increasing measurement precision is particularly important for probing light-sensitive samples where we want to get as much information as we can before our probe light damages or causes alterations to the sample. We feel this will have a big impact on the tools used in medical research.”
The researchers’ protocol relies on generating multiple photons in an entangled state and this study demonstrates that they can reconstruct rotations which act on the polarisation of light.

References:http://phys.org/

Our homes are a tangled mess of wires and chargers. But that might be about to change. Work is under way to use the Wi-Fi signals that surround us to power our gadgets.

In Seattle, six households have taken part in an experiment in which modified electrical devices were put in their homes along with a Wi-Fi router. Over 24 hours, the devices were powered solely by the router’s signal, which also continued to provide wireless internet access to the home.

How was this possible? The energy of the radio waves the router sent out was converted into direct current voltage with a component called a rectifier, much as solar panels convert light energy into electrical energy. That voltage was then boosted to a useful level by a DC-DC converter (arxiv.org/abs/1505.06815).

The system powered temperature sensors and battery-less low-resolution cameras, and charged standard batteries.

The hard part is getting the router to constantly push out enough energy, says team member Vamsi Talla from the University of Washington in Seattle.

When someone is browsing the web, the Wi-Fi signal is active and can be used to power devices. However, when not browsing the signal goes quiet.

“With Wi-Fi for communications, you only want to transmit when you have data to send,” Talla says. “But for power delivery, you want to transmit something all the time. There’s a clear mismatch.”

To get around this, the team designed software that broadcasts meaningless data across several Wi-Fi channels when no one is using the internet.

Small devices could use this as part of an internet of things, says Ben Potter at the University of Reading, UK. “Where we’re heading is to have more sensors in everything around us,” he says. “Innovations with microchips mean they can run with less power. For that type of application, this is interesting technology.”

The problem is that Wi-Fi is never going to provide a very powerful signal. Wi-Fi is tightly regulated in many countries – the US Federal Communications Commission (FCC), for example, limits the power of a Wi-Fi broadcast to 1 watt. An iPhone charger delivers at least 5 watts – and has no other demands on its output.

One company with a solution is Ossia in Bellevue, Washington. It has a system called Cota that gets around the FCC regulations by designing a wireless hub that transmits waves at a Wi-Fi frequency but doesn’t send a communications signal.

The Cota set-up can produce up to 20 watts, but would only deliver 1 watt to a single phone. CEO Hatem Zeine says that’s enough to charge an iPhone 5 several times over in a single day if it has constant access to the signal.

“Unlike Wi-Fi, our power signal is unmodulated,” says Zeine. “It’s a continuous wave, there’s no message in it.”

A receiver chip on the device being charged tells the hub which of Cota’s thousands of antennas it is receiving signals from. Those antennas alone are kept active and the system is able to ignore other objects in the room, such as a human body.

Eric Woods, an IT infrastructure researcher at consultancy firm Navigant in London, thinks there will be demand for this type of technology for the many sensors that will fill the smart homes and cities of the future.

Sensors powered by Wi-Fi could be used to monitor air quality or the status of systems across a city, says Woods. “Removing the need to think about batteries takes away one of the barriers to the exploitation of those technologies,” he says.

References:http://www.newscientist.com/

A lot of users are using outdated mobile devices that fail to reach adequate speeds on mobile networks. This is shown by measurements shared by the users of Netradar, a free mobile application that measures mobile connections and devices. The impartial Netradar application is developed and run globally by Aalto University in Finland. The full list of the 150 most popular smart phones and tablets and their average and median top 10 maximum download speeds is here.

Android phones like Sony Ericsson Xperia Acro S and Xperia S, Samsung Galaxy Xcover and S Plus, LG Optimus L7, Nokia X, ZTE Blade III, Huawei Ideos X5 or HTC Desire S or Android tablets like Samsung Galaxy Tab 7 are among the slowest mobile devices. The iPhone 4 and iPad 2 are clearly slower than newer Apple devices and often contribute to the speed bottleneck. Out of the most popular smart phones based on the Windows Phone, the Nokia 610 and ZTE Tania have very limited download speeds. Old Symbian phones are also limited in performance.
At the moment, the mobile device market is very polarized. Out of the 150 most commonly used mobile phones, half are 4G/LTE devices that can reach at least 95 Mbit download speeds over mobile networks. Yet, about one fourth of the popular devices cannot reach 10 Mbit. A 10 Mbit download speed enables reasonably fast Internet services and smooth HD video streams. The remaining one fourth can give up to 20 Mbit download speeds, the upper limit of 3G networks.
“Quite often ordinary smart phone users fail to reach proper speeds. A device that was bought and considered fast few years ago, but also brand new devices, can contribute to the speed bottleneck. People often expect that it is the operator’s fault if the Internet connection is bad, but the device can also be the problem”, says professor Jukka Manner, who leads the Netradar development team at Aalto University in Finland.
“If a consumer wants to use fast mobile Internet, almost any LTE device is up to the job, provided that LTE is available in the area and there is no speed limitation in the data plan. The fastest mobile Internet speeds are all achieved using LTE”, continues professor Manner.
The results are based on speed measurements shared by mobile phone users using Netradar, a free mobile application to measure mobile connections and devices, available for all smart phones and tablets. When using the application, users are presented with data about the quality of their connectivity. Simultaneously, this data is uploaded anonymously to the Netradar database.
The free Netradar app measures devices and mobile network quality in terms of download and upload speed, latency and signal strength, network problems and the performance of individual brands of smartphones and tablets. Mobile device users can download the Netradar app for Android, iOS, Windows Phone, Blackberry, Nokia X, Meego, Symbian and Jolla/Sailfish. Maps of mobile Internet speeds measured all around the world are displayed at www.netradar.org . Netradar mobile network maps can also be viewed at http://www.internetsociety.org/netradar .
So far, the Netradar app has been installed over 220,000 times. The database currently holds almost 6 million measurements from all around the globe.

References:http://phys.org/

Fujitsu Laboratories Ltd. today announced that it has developed technology for web applications that run on smart devices or wearables, and that delivers the same level of security as thin clients while offering an exceptional degree of operability. In recent years, there have been increasing expectations that the use of smart devices and wearables in a variety of front-line scenarios will lead to greater efficiency in business operations. When a high degree of confidentiality is required for the data used by these devices, such as patient data or confidential company data, thin client environments, which leave no trace of the data on the devices, are ideal from a security perspective. Generally, thin clients are environments in which screen data is frequently sent and received. As a result, depending on the status of the mobile network or the processing performance on the device side, lags of up to about a second can occur, and operations that are unique to smart devices, such as swiping are effected.

Fujitsu Laboratories has now developed new virtualization technology for web applications, developed for smart devices, that automatically separates the user interface processing (UI processing) from the data processing. With this technology, data processing is executed in the cloud, and the UI processing is executed on the smart device side. As a result, new web applications running on smart devices or wearables can have a work application execution environment that is as secure as a thin client environment while achieving outstanding operability.
In recent years, the trend of using smart devices for work in a variety of settings is becoming more common. Moreover, as smart glasses and other wearables come into practical use, there are high expectations that linking wearables with smart devices will lead to greater efficiencies in business operations for people in the field (figure 1).

Technological Issues

Web applications developed for smart devices, such as cameras and sounds, for example, may use data that have been stored on the devices themselves. In addition, once data received from the cloud are stored on the devices, they may execute business logic. When a high degree of confidentiality is desired for the data used by these devices, such as in the case of patient data or confidential company data, thin client environments, which leave no trace of the data on the devices, are ideal from a security perspective. The problem with thin client environments, however, is that, depending on the status of the mobile network or the processing performance on the device side, lags of up to about a second can occur, and affect smart device operations, such as swiping (figure 2).

The Newly Developed Technology

Fujitsu Laboratories has now developed a technology that places the source code of the developed web applications on a server. When web applications are executed on a smart device, they are automatically interpreted. This technology enables processing to be distributed with data processing handled by the server, and UI processing handled by the smart device (figures 3 and 4). The features of this technology are described below.

1. Distributed web applications

A newly developed virtualization engine, run on both the device and the server, performs tasks including the transfer of UI processing and execution of processing content. In addition, a conventional web application library is replaced with a proprietarily developed web application library that supports virtualization. When the engine executes a web application, the source code is analyzed, and, by estimating the source code’s UI processing, it separates that part of the source code written in an API related to the UI defined in the library (web application library), and that is required in web application execution. Having been notified by the device executing the web application, the server sends the UI processing part of the source code and the specific web application library that supports virtualization to the smart device. By executing data processing of everything in the source code except the separated UI processing on the server side, and by executing in a distributed way on the smart device the transferred UI processing, this technology is able to maintain security while achieving a high level of operability. Because these are dynamically processed when a web application is executed, there is no need for redesign or redevelopment work for the distributed processing.

2. Distributed processing in accordance with operations

Fujitsu Laboratories also developed a feature that analyzes on the smart device the user’s operations, processing times, and frequency of operations, and dynamically transfers to the server the processes within the UI processing that have little impact on operability. The result is a secure system that also maintains a high level of operability.

The use of this newly developed virtualization technology enables smart devices to be utilized in business operations when using web applications in a mobile environment. This can be achieved with both security and the high level of operability characteristic of smart devices. In addition, by applying the technology to web applications that communicate with smart glasses and other wearables that are increasingly coming into practical use, thin client environments can be newly expanded to web applications that run on smart devices and wearables, such as for use in work that deals with large amounts of data for which a high level of confidentiality is needed.

Fujitsu Laboratories will work to improve the virtualization technology’s multiplex execution performance on servers and make its operations analysis highly accurate with the goal of practical implementation in fiscal 2016. In addition, rather than just applications for servers or storage equipment, Fujitsu Laboratories will proceed with developing technologies for distributed execution tailored to devices, network equipment, and servers in accordance with execution conditions or the network environment in order to create hyperconnected clouds, in which a variety of clouds are linked together, such as for an Internet of Things environment.

References:http://phys.org/