entanglement Archives

February 25, 2014December 23, 2015 by Jason Major

Does Free Will Exist? Ancient Quasars May Hold the Clue.

Artist’s interpretation of ULAS J1120+0641, a very distant quasar. Credit: ESO/M. Kornmesser

Do you believe in free will? Are people able to decide their own destinies, whether it’s on what continent they’ll live, who or if they’ll marry, or just where they’ll get lunch today? Or are we just the unwitting pawns of some greater cosmic mechanism at work, ticking away the seconds and steering everyone and everything toward an inevitable, predetermined fate?

Philosophical debates aside, MIT researchers are actually looking to move past this age-old argument in their experiments once and for all, using some of the most distant and brilliant objects in the Universe.

Rather than ponder the ancient musings of Plato and Aristotle, researchers at MIT were trying to determine how to get past a more recent conundrum in physics: Bell’s Theorem. Proposed by Irish physicist John Bell in 1964, the principle attempts to come to terms with the behavior of “entangled” quantum particles separated by great distances but somehow affected simultaneously and instantaneously by the measurement of one or the other — previously referred to by Einstein as “spooky action at a distance.”

The problem with such spookiness in the quantum universe is that it seems to violate some very basic tenets of what we know about the macroscopic universe, such as information traveling faster than light. (A big no-no in physics.)

(Note: actual information is not transferred via quantum entanglement, but rather it’s the transfer of state between particles that can occur at thousands of times the speed of light.)

Then again, testing against Bell’s Theorem has resulted in its own weirdness (even as quantum research goes.) While some of the intrinsic “loopholes” in Bell’s Theorem have been sealed up, one odd suggestion remains on the table: what if a quantum-induced absence of free will (i.e., hidden variables) is conspiring to affect how researchers calibrate their detectors and collect data, somehow steering them toward a conclusion biased against classical physics?

“It sounds creepy, but people realized that’s a logical possibility that hasn’t been closed yet,” said David Kaiser, Germeshausen Professor of the History of Science and senior lecturer in the Department of Physics at MIT in Cambridge, Mass. “Before we make the leap to say the equations of quantum theory tell us the world is inescapably crazy and bizarre, have we closed every conceivable logical loophole, even if they may not seem plausible in the world we know today?”

What are Quasars — A color composite image of the quasar in HE0450-2958 obtained using the VISIR instrument on the Very Large Telescope and the Hubble Space Telescope. Image Credit: ESO

So in order to clear the air of any possible predestination by entangled interlopers, Kaiser and MIT postdoc Andrew Friedman, along with Jason Gallicchio of the University of Chicago, propose to look into the distant, early Universe for sufficiently unprejudiced parties: ancient quasars that have never, ever been in contact.

According to a news release from MIT:

…an experiment would go something like this: A laboratory setup would consist of a particle generator, such as a radioactive atom that spits out pairs of entangled particles. One detector measures a property of particle A, while another detector does the same for particle B. A split second after the particles are generated, but just before the detectors are set, scientists would use telescopic observations of distant quasars to determine which properties each detector will measure of a respective particle. In other words, quasar A determines the settings to detect particle A, and quasar B sets the detector for particle B.

By using the light from objects that came into existence just shortly after the Big Bang to calibrate their detectors, the team hopes to remove any possibility of entanglement… and determine what’s really in charge of the Universe.

“I think it’s fair to say this is the final frontier, logically speaking, that stands between this enormously impressive accumulated experimental evidence and the interpretation of that evidence saying the world is governed by quantum mechanics,” said Kaiser.

Then again, perhaps that’s exactly what they’re supposed to do…

The paper was published this week in the journal Physical Review Letters.

Source: MIT Media Relations

Want to read more about the admittedly complex subject of entanglement and hidden variables (which may or may not really have anything to do with where you eat lunch?) Click here.

April 12, 2013December 23, 2015 by John Williams

Spooky Experiment on ISS Could Pioneer New Quantum Communications Network

The cameras mounted in the ISS's cupola could serve as the platform for the first-ever quantum optics experiment in space.

With its 180 degree views of Earth and space, the ISS’s cupola is the perfect place for photography. But Austrian researchers want to use the unique and panoramic platform to test the limits of “spooky action at distance” in hopes of creating a new quantum communications network.

In a new study published April 9, 2012 in the New Journal of Physics, a group of Austrian researchers propose equipping the camera that is already aboard the ISS — the Nikon 400 mm NightPOD camera — with an optical receiver that would be key to performing the first-ever quantum optics experiment in space. The NightPOD camera faces the ground in the cupola and can track ground targets for up to 70 seconds allowing researchers to bounce a secret encryption key across longer distances than currently possible with optical fiber networks on Earth.

“During a few months a year, the ISS passes five to six times in a row in the correct orientation for us to do our experiments. We envision setting up the experiment for a whole week and therefore having more than enough links to the ISS available,” said co-author of the study Professor Rupert Ursin from the Austrian Academy of Sciences.

Albert Einstein first coined the phrase ‘spooky action at a distance’ during his philosophical battles with Neils Bohr in the 1930s to explain his frustration with the inadequacies of the new theory called quantum mechanics. Quantum mechanics explains actions on the tiniest scales in the domain of atoms and elemental particles. While classical physics explains motion, matter and energy on the level that we can see, 19th century scientists observed phenomena in both the macro and micro world that could not easily explained using classical physics.

In particular, Einstein was dissatisfied with the idea of entanglement. Entanglement occurs when two particles are so deeply connected that they share the same existence; meaning that they share the same mathematical relationships of position, spin, momentum and polarization. This could happen when two particles are created at the same point and instant in spacetime. Over time, as the two particles become widely separated in space, even by light-years, quantum mechanics suggests that a measurement of one would immediately impact the other. Einstein was quick to point out that this violated the universal speed limit set out by special relativity. It was this paradox Einstein referred to as spooky action.

CERN physicist John Bell partially resolved this mystery in 1964 by coming up with the idea of non-local phenomena. While entanglement allows one particle to be instantaneously influenced by its exact counterpart, the flow of classical information does not travel faster than light.

The orbital pass of the ISS over an optical ground station could be used for quantum communication from inside the Cupola Module, as long as the OGS is not more than 36° off the NADIR direction. Credit: T Scheidl, E Wille and R Ursin.

The ISS experiment proposes using a “Bell experiment” to test the theoretical contradiction between predictions in quantum and classical physics. For the Bell experiment, a pair of entangled photons would be generated on the ground; one would be sent from the ground station to the modified camera aboard the ISS, while the other would be measured locally on the ground for later comparison. So far, researchers sent a secret key to receivers just a few hundred kilometers apart.

“According to quantum physics, entanglement is independent of distance. Our proposed Bell-type experiment will show that particles are entangled, over large distances — around 500 km — for the very first time in an experiment,” says Ursin. “Our experiments will also enable us to test potential effects gravity may have on quantum entanglement.”

The researchers point out that making the minor alteration to a camera already aboard the ISS will save time and money needed to build a series of satellites to test researchers’ ideas.

January 23, 2013December 23, 2015 by Jason Major

Don’t Tell Bones: Are We One Step Closer to “Beaming Up?”

It’s a crazy way to travel, spreading a man’s molecules all over the Universe…

While we’re still a very long way off from instantly transporting from ship to planet à la Star Trek, scientists are still relentlessly working on the type of quantum technologies that could one day make this sci-fi staple a possibility. Just recently, researchers at the University of Cambridge in the UK have reported ways to simplify the instantaneous transmission of quantum information using less “entanglement,” thereby making the process more efficient — as well as less error-prone.

(Because nobody wants a transporter mishap.)

In a paper titled Generalized teleportation and entanglement recycling, Cambridge researchers Sergii Strelchuk, Michal Horodecki and Jonathan Oppenheim investigate a couple of previously-developed protocols for quantum teleportation.

“Teleportation lies at the very heart of quantum information theory, being the pivotal primitive in a variety of tasks. Teleportation protocols are a way of sending an unknown quantum state from one party to another using a resource in the form of an entangled state shared between two parties, Alice and Bob, in advance. First, Alice performs a measurement on the state she wants to teleport and her part of the resource state, then she communicates the classical information to Bob. He applies the unitary operation conditioned on that information to obtain the teleported state.” (Strelchuk et al.)

In order for the teleportation to work, the process relies on entanglement — the remote connection between particles or individual bits of information regardless of the physical space separating them. This was what Einstein referred to as “spooky action at a distance.” But getting particles or information packets entangled is no simple task.

“Teleportation crucially depends on entanglement, which can be thought as a ‘fuel’ powering it,” Strelchuk said in an article on ABC Science. “This fuel… is hard to generate, store and replenish. Finding a way to use it sparingly, or, ideally, recycling it, makes teleportation potentially more usable.”

Read: Beam Me Up, Obama: Conspiracy Theory Claims President Teleported to Mars

Considering the sheer amount of information that makes up the also-difficult-to-determine state of a single object (in the case of a human, even simplistically speaking, about 10^28 kilobytes worth of data) you’re obviously going to want to keep the amount of entanglement fuel needed at a minimum.

Of course, we’re not saying we can teleport red-shirted security officers anywhere yet. But if.

Still, with a more efficient method to reduce — and even recycle — entanglement, Strelchuk and his team are bringing us a little closer to making quantum computing a reality. And it may very well take the power of a quantum computer to even make the physical teleportation of large-scale objects possible… once the technology becomes available.

“We are very excited to show that recycling works in theory, and hope that it will find future applications in areas such as quantum computation,” said Strelchuk. “Building a quantum computer is one of the great challenges of modern physics, and it is hoped that the new teleportation protocol will lead to advances in this area.”

(I’m sure Dr. McCoy would still remain skeptical.)

You can find the team’s full paper here (chock full of maths!) and read the article on ABC Science by Stephen Pincock here.