The Pièzo de Résistance

New Atom-Scale Products on Horizon: Breakthrough Discovery Enables Nanoscale Manipulation of Piezoelectric Effect

“The piezoelectric effect has never been manipulated at this scale before, so the range of possible applications is very exciting,” explained Pooja Tyagi, a PhD researcher in Professor Patanjali Kambhampati’s laboratory. “For example, the vibrations of a material can be analyzed to calculate the pressure of the solvent they are in. With further development and research, maybe we could measure blood pressure non-invasively by injecting the dots, shining a laser on them, and analyzing their vibration to determine the pressure.”

(The title was the pun I forgot to use in my thesis defense talk, in describing our homemade diode laser systems)

In the Whole, I'm Glad I'm not in Philadelphia

Pay Up

After dutifully reporting even the smallest profits on their tax filings this year, a number — though no one knows exactly what that number is — of Philadelphia bloggers were dispatched letters informing them that they owe $300 for a privilege license, plus taxes on any profits they made.

Even if, as with Sean Barry, that profit is $11 over two years.

My blog is purely a hobby, but I’d probably get nabbed for selling a t-shirt

Nobody Can Do the Triple Lindy

Bee has a short post on the triple-slit interference experiment: Testing the foundations of quantum mechanics. Contrary to the prediction of the writers at Nature, she does not appear to be “flummoxed” by QM.

If you know one thing about quantum mechanics, it’s Born’s rule: The probability of a measurement is the square of the amplitudes of the wave-functions. It is the central axiom of quantum mechanics and what makes it quantum. If you have a superposition of states, the amplitudes are sums of these states. Taking the square to obtain the probability means you will not only get the square of each single amplitude – which would be the classical result – but you will get mixed terms. These mixed terms are what is responsible for the interference in the famous double-slit experiment and yield the well-known spectrum with multiple maxima rather than one reproducing the two slits, as you’d get were the particles classical.

The View from Up There

Earth from Above

“Earth From Above” is the result of the aerial photographer Yann Arthus-Bertrand’s five-year airborne odyssey across six continents. It’s a spectacular presentation of large scale photographs of astonishing natural landscapes. Every stunning aerial photograph tells a story about our changing planet.

Overheard in the Lab of the Day

A laser recently died a violent death (probably natural, though foul play has not been ruled out; we are interviewing a component of interest), and during the autopsy we got a whiff of the tell-tale smell of burnt insulation and saw where the circuitry had failed. One colleague wondered aloud of the viability of selling an air freshener that smelled that way. This is the same one who thought that the scent of acetone would make a good cologne.
From the geek collection

Politics and the Star Trek Effect

There are a couple of episodes of Star Trek that I can recall having some fundamental physics failures, which would lead one to believe that in the Star Trek universe, one cannot do an integral over time. The episodes that come to mind (and it’s been a while, so I may have some details wrong) are The Paradise Syndrome from ToS, and Déjà Q fom TNG. In both episodes, the Enterprise needs to transfer some energy and momentum to an object, and in each episode, they go for the Big Effort™ and lose.

In The Paradise Syndrome, Spock tries to deflect a large asteroid and fails to budge it, so he goes for broke and zaps it so hard he burns out a whole bunch of circuitry — the sci-fi equivalent of overexerting one’s self and pulling a muscle — and can subsequently only match the speed of the asteroid. It’s after this that we learn that the asteroid is two months away from the planet; a force exerted continuously for two months would transfer half a million times more momentum than their ten-second attempt, so they could have even tried a smaller force for that duration and deflected the asteroid. But that makes for boring TV. (And they could have increased their speed my throwing junk out of the rear shuttle bay, with bonus points if the projectile hit the asteroid, since the collision would slow it down. This would have been slightly more exciting than two months of pushing, but still not very much excitement) Similarly, the attempts to restore a moon’s orbit is made in fits and starts in Déjà Q, though in the plot there is at least an excuse for interruptions to their attempts, from some attacking Calamarains, but that’s after they gave up a few times. Forces cause accelerations and change momentum of an object. With the exception of the static frictional force on a surface, these don’t turn on and off only when a threshold is reached*.

\(p = int F dt\)

For a constant force this is just p = Ft. Linear in force, but also linear in time.

What’s the connection to politics? The US government seems to approach solutions to problems like the Star Trek folks do. Wait until the problem is a crisis and then try and exert a huge force to correct it, when a much gentler push would have sufficed if you had simply started earlier. We have been seeing this with Social Security for decades now — we know the system is going to go broke, and yet nothing is being done to fix it. Had we started when I first started paying into the system, the adjustments could have been relatively small. But like the transfer of momentum, the longer we wait, the force needed to achieve the desired result gets larger. The occasional nudge does only a little; it needs to be sustained.

Similarly for global warming. Our government hems and haws and does very little to actually address the problem. Even those politicians who are still doubtful (or whose palms are being greased so that they act doubtful) should be able to recognize that there is value in weaning our country from foreign energy sources, and that the kind of technology adoption involved takes decades to realize.

Of course, getting them to do something would be asking them to do their job, and we can’t have that, can we? Star Trek ignored physics because slow-and-steady makes for little drama, and TV, like sex, is all about having a climactic ending. Our elected officials have no such excuse. They are distracted by the manufactured controversy du jour, and are more concerned with not upsetting their benefactors and voter base than doing the business that’s in the best long-term interest of the country.

*which really isn’t how the frictional force behaves, but it’s a reasonable first-order approximation for its highly nonlinear behavior

Entanglement Done Right

I finally found post about quantum entanglement that does a great job of explaining entanglement, in the context of an attempt to entangle macroscopic objects: Spooky Mirror Tricks. As far as I have seen, it contains none of the “wall of shame statements” I ranted about recently. Quite the opposite.

[Entanglement] allows two particles to form a quantum object even when they are far apart.

[I]f one measures, on one particle, the quantum property through which that particle is entangled with other particles, the same property will promptly be determined for each of the particles involved.

[E]ntangled quantum particles behave similarly: there seems to be a strange connection between them. However, even this image is misleading, as there are no physical forces in play. In addition, only certain properties are ever entangled. For light quanta, for instance, this can be what is known as polarization, which can be imagined as a small pointer.If two entangled photons are prepared in a certain way, then the polarizations of both photons must point in exactly the same direction.

Now, although the two photons must obey this strict “principle of conservation,” the quantum world does not dictate the direction in which the polarizations must point in relation to their surroundings. This is a further quirk of the entangled quantum world: as long as a property isn’t measured, it isn’t fixed for the object being observed. Only when someone measures the polarization of one of the two photons does he give it a direction relative to its surroundings. The polarization of the other photon must then immediately point in the same direction, no matter how far away it is.

Voilà! It can be done! Hear ye, hear ye. Let the journalism world know that you can explain entanglement properly, without mentioning Star Trek at all.