Using Unison with Android over USB

For some time, I've been happily using Unison in conjunction with my Android phone's USB mass storage function to synchronize files between my phone and my desktop. It was simple: I'd plug in my phone with USB and enable the SD card to be used as a mass storage device, then mount it in Linux and run Unison as if the phone was a local folder (with appropriate tweaks to support the FAT filesystem).

Alas, my phone was getting on in years (or months, as it is in tech), and with support long dropped and capacity nigh exhausted, I had to upgrade. With my new phone I've been promoted to the “new hotness” that is Android 6 Marshmallow, but one of the functions that was dropped along the way was the ability to expose the SD card as mass storage over USB. Admittedly it wasn't ...

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Published in Optics Express: Free-space quantum key distribution to a moving receiver

We take our quantum key distribution system out of the laboratory and mount it in the back of a small truck. Integrating a two-axis pointing system at both sites, polarization correction, and time-of-flight compensation, we demonstrate quantum key distribution from a stationary transmitter to a receiver moving at an angular speed (relative to the transmitter) equivalent to the maximum angular speed of a typical low-Earth-orbit satellite.

J.-P. Bourgoin, B. L. Higgins, N. Gigov, C. Holloway, C. J. Pugh, S. Kaiser, M. Cranmer, and T. Jennewein
Optics Express 23, 33437–47 (2015)

Bonus: Read the IQC's news release, which covers both this and the previous paper for a general audience.

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Published in Physical Review A: Experimental quantum key distribution with simulated ground-to-satellite photon losses and processing limitations

Fundamental laws of quantum physics guarantee the security of encryption keys generated through quantum key distribution, in contrast to standard encryption techniques which rely on assumptions about an eavesdropper's computational ability. That said, special technology is necessary to facilitate quantum key distribution transmissions between parties that are more than a couple of hundred kilometers apart.

A near-term solution is to use an orbiting satellite as a trusted quantum receiver. Here we detail specifically chosen algorithms that make up an implementation of quantum key distribution, suitable for a satellite receiver platform. We examine these algorithms' computational requirements while demonstrating them experimentally as we emulate the variable channel losses that would be experienced during a satellite pass (following those we published about previously).

J.-P. Bourgoin, N. Gigov, B. L. Higgins, Z. Yan, E. Meyer-Scott, A. K. Khandani, N. Lütkenhaus, and T. Jennewein

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Removing hostile Windows updates

As a consequence of their recent effort to boost the numbers of Windows 10 installs using any means possible, however questionable, and turn their paying customers into beta testers, Microsoft have been especially hostile to their users as of late, installing nag-screens and “telemetry” code (also known as “spyware”) under the guise of important updates to existing installs of previous versions of Windows. While I would happily eschew Windows for Linux on all the machines I use, and have largely done so, the idea of avoiding Windows in totality is, sadly, not yet practical―the common-use machines I maintain in our lab required it for various reasons, and even I still keep a Wintendo partition.

There are plenty of discussions around about what to do about this. Here's a fine example. Though this is intended for my own reference, I've had success with the following:

wusa /uninstall /kb ...

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Hey look-it, I'm on the TV!

So it seems my face has now graced (or disgraced, perhaps) North American television. Some folks from DMG Productions were in the lab a while ago gathering footage for a segment on IQC for Innovations with Ed Begley, Jr. Though my supervisor fielded the actual spoken material, you can spot me in the background of various “action shots” discussing clearly very important things™ with students and colleagues.

Here's the segment in question, first broadcast on Discovery Channel, May 25, 2015.

I've similarly been on Australian TV before, so that makes two continents that have had to deal with my mug on air.

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Published in Physical Review A: Using weak values to experimentally determine “negative probabilities” in a two-photon state with Bell correlations

It's well known that quantum entangled systems can exhibit correlations that go beyond those that could be seen if Nature worked in intuitive “classical” ways. However, as Richard Feynman noted, classical theory can support exhibiting such correlations if we invoke negative probabilities to describe their properties. What he did not do was specify how these negative probabilities ought to be chosen, and without any justification, an infinite number of different combinations could be chosen that will satisfy the relevant equations.

The concept of negative probabilities seems nonsensical because they cannot actually be observed—indeed, they cannot be observed even within the framework of quantum theory due to the effects of measurement back-action. Here, we show how they can instead be inferred through the use of weak measurements, where a meter is only weakly coupled to the property of interest, thereby avoiding the back-action problem. Each individual weak measurement has ...

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