If curiosity kills the cat, the solution is to pretend not to care.

http://www.nature.com/news/entangled-photons-make-a-picture-from-a-paradox-1.15781

Normally, you have to collect particles that come from the object to image it, says Anton Zeilinger, a physicist at the Austrian Academy of Sciences in Vienna who led the work. “Now, for the first time, you don’t have to do that."

One advantage of this imaging technique is that the two photons need not be of the same energy, Zeilinger says, meaning that the light that touches the object can be of a different colour than the light that is detected. For example, a quantum imager could probe delicate biological samples by sending low-energy photons through them while building up the image using visible-range photons and a conventional camera. (!)

According to the laws of quantum physics, if no one detects which path a photon took, the particle effectively has taken both routes, and a photon pair is created in each path at once, says Gabriela Barreto Lemos, a physicist at Austrian Academy of Sciences and a co-author on the latest paper.

In the first path, one photon in the pair passes through the object to be imaged, and the other does not. The photon that passed through the object is then recombined with its other ‘possible self’ — which travelled down the second path and not through the object — and is thrown away. The remaining photon from the second path is also reunited with itself from the first path and directed towards a camera, where it is used to build the image, despite having never interacted with the object.

The researchers imaged a cut-out of a cat, a few millimetres wide, as well as other shapes etched into silicon. The team probed the cat cut-out using a wavelength of light which they knew could not be detected by their camera. "That's important, it's the proof that it's working," says Zeilinger.

http://www.nature.com/news/entangled-photons-make-a-picture-from-a-paradox-1.15781

Information is central to quantum mechanics. In particular, quantum interference occurs only if there exists no information to distinguish between the superposed states. The mere possibility of obtaining information that could distinguish between overlapping states inhibits quantum interference. Here we introduce and experimentally demonstrate a quantum imaging concept based on induced coherence without induced emission.

The experiment is fundamentally different from previous quantum imaging techniques, such as interaction-free imaging or ghost imaging, because now the photons used to illuminate the object do not have to be detected at all and no coincidence detection is necessary. This enables the probe wavelength to be chosen in a range for which suitable detectors are not available. To illustrate this, we show images of objects that are either opaque or invisible to the detected photons.

Paper: http://www.nature.com/nature/journal/v512/n7515/full/nature13586.html

From 2014-08-31

Quantum Life disentangled

"In this talk titled; how physics can revolutionize biology, Professor Jim Al-Khalili explores how the mysteries of quantum theory might be observable at the biological level.

"Although many examples can be found in the scientific literature dating back half a century, there is still no widespread acceptance that quantum mechanics -- that baffling yet powerful theory of the subatomic world -- might play an important role in biological processes. Biology is, at its most basic, chemistry, and chemistry is built on the rules of quantum mechanics in the way atoms and molecules behave and fit together.

As Jim explains, biologists have until recently been dismissive of counter-intuitive aspects of the theory and feel it to be unnecessary, preferring their traditional ball-and-stick models of the molecular structures of life. Likewise, physicists have been reluctant to venture into the messy and complex world of the living cell - why should they when they can test their theories far more cleanly in the controlled environment of the physics lab?

But now, experimental techniques in biology have become so sophisticated that the time is ripe for testing ideas familiar to quantum physicists. Can quantum phenomena in the subatomic world impact the biological level and be present in living cells or processes - from the way proteins fold or genes mutate and the way plants harness light in photosynthesis to the way some birds navigate using the Earth's magnetic field? All appear to utilize what Jim terms "the weirdness of the quantum world".

The discourse explores multiple theories of quantum mechanics, from superposition to quantum tunneling, and reveals why "the most powerful theory in the whole of science" remains incredibly mysterious."

Al-Khalili begins his talk with a quote from the famous physicist Niels Bohr; "If you are not astonished by quantum mechanics then you have not understood it." In this clip, a small part from the full lecture, he does his best to make clear just why quantum mechanics is so astonishing by digging into the famous double slit experiment. No matter how many times you've come across it, this experiment, the most stunning experiment in all of science, never loses the power to stop you in your tracks by flooding your brain with a torrent of question marks.



Did this talk fire up your appetite for anything and everything that meets at the intersection between quantum physics and biology? Here are some good places to start if you want to go a bit deeper;

• The Dawn of Quantum Biology
• In this paper, the authors take a look at a variety of organisms which may be harnessing some of the unique features of quantum mechanics to gain a biological advantage. Including the aviation system used by Robins which is something Al-Khalili also touched upon in his talk.
• With his 1944 book; What is Life? Erwin Schrödinger was one of the founding fathers of this emerging science. You can read it in full here.

The Bose-Einstein condensation of matter

In school we all learned that there are 3 states of matter; solid, liquid and gas. It turns out that we have been lied to. Most people will have heard of plasma which is sometimes called the 4th state of matter but there are many more. Have you ever heard of the Bose-Einstein Condensate phase of matter? Prepare yourself for some truly mindblowing stuff.

 More info: Wikipedia - Bose-Einstein condensate

 This clip was taken from a two part BBC series called absolute zero. Part 1 is called "The conquest of cold" and part 2 "The race for absolute zero". PBS has cut down that material to a single episode called absolute zero (1h40, HD) but I would recommend watching the longer BBC version.

How long is a piece of string?

How long is a piece of string? It sounds like a ridiculous question... but it isn't. This hour long journey to find out the length of a certain piece of string will blow your mind. This trip takes you from the classical to the quantum and leaves you with more questions than answers. Easily one of the best episodes from BBC's Horizon. I know that an hour of your time is a lot to ask for, but believe me, it's worth it.