Tag Archives: quantum communications

Entanglement and biological systems

I think it was about five years ago thatI wrote a paper on something I called ‘cognitive entanglement’ (mentioned in my July 20,2012 posting) so the latest from Northwestern University (Chicago, Illinois, US) reignited my interest in entanglement. A December 5, 2017 news item on ScienceDaily describes the latest ‘entanglement’ research,

Nearly 75 years ago, Nobel Prize-winning physicist Erwin Schrödinger wondered if the mysterious world of quantum mechanics played a role in biology. A recent finding by Northwestern University’s Prem Kumar adds further evidence that the answer might be yes.

Kumar and his team have, for the first time, created quantum entanglement from a biological system. This finding could advance scientists’ fundamental understanding of biology and potentially open doors to exploit biological tools to enable new functions by harnessing quantum mechanics.

A December 5, 2017 Northwestern University news release (also on EurekAlert), which originated the news item, provides more detail,

“Can we apply quantum tools to learn about biology?” said Kumar, professor of electrical engineering and computer science in Northwestern’s McCormick School of Engineering and of physics and astronomy in the Weinberg College of Arts and Sciences. “People have asked this question for many, many years — dating back to the dawn of quantum mechanics. The reason we are interested in these new quantum states is because they allow applications that are otherwise impossible.”

Partially supported by the [US] Defense Advanced Research Projects Agency [DARPA], the research was published Dec. 5 [2017] in Nature Communications.

Quantum entanglement is one of quantum mechanics’ most mystifying phenomena. When two particles — such as atoms, photons, or electrons — are entangled, they experience an inexplicable link that is maintained even if the particles are on opposite sides of the universe. While entangled, the particles’ behavior is tied one another. If one particle is found spinning in one direction, for example, then the other particle instantaneously changes its spin in a corresponding manner dictated by the entanglement. Researchers, including Kumar, have been interested in harnessing quantum entanglement for several applications, including quantum communications. Because the particles can communicate without wires or cables, they could be used to send secure messages or help build an extremely fast “quantum Internet.”

“Researchers have been trying to entangle a larger and larger set of atoms or photons to develop substrates on which to design and build a quantum machine,” Kumar said. “My laboratory is asking if we can build these machines on a biological substrate.”

In the study, Kumar’s team used green fluorescent proteins, which are responsible for bioluminescence and commonly used in biomedical research. The team attempted to entangle the photons generated from the fluorescing molecules within the algae’s barrel-shaped protein structure by exposing them to spontaneous four-wave mixing, a process in which multiple wavelengths interact with one another to produce new wavelengths.

Through a series of these experiments, Kumar and his team successfully demonstrated a type of entanglement, called polarization entanglement, between photon pairs. The same feature used to make glasses for viewing 3D movies, polarization is the orientation of oscillations in light waves. A wave can oscillate vertically, horizontally, or at different angles. In Kumar’s entangled pairs, the photons’ polarizations are entangled, meaning that the oscillation directions of light waves are linked. Kumar also noticed that the barrel-shaped structure surrounding the fluorescing molecules protected the entanglement from being disrupted.

“When I measured the vertical polarization of one particle, we knew it would be the same in the other,” he said. “If we measured the horizontal polarization of one particle, we could predict the horizontal polarization in the other particle. We created an entangled state that correlated in all possibilities simultaneously.”

Now that they have demonstrated that it’s possible to create quantum entanglement from biological particles, next Kumar and his team plan to make a biological substrate of entangled particles, which could be used to build a quantum machine. Then, they will seek to understand if a biological substrate works more efficiently than a synthetic one.

Here’s an image accompanying the news release,

Featured in the cuvette on the left, green fluorescent proteins responsible for bioluninescence in jellyfish. Courtesy: Northwestern University

Here’s a link to and a citation for the paper,

Generation of photonic entanglement in green fluorescent proteins by Siyuan Shi, Prem Kumar & Kim Fook Lee. Nature Communications 8, Article number: 1934 (2017) doi:10.1038/s41467-017-02027-9 Published online: 05 December 2017

This paper is open access.

What is Dr. Who’s sonic screwdriver?

Dr. Who, a British Broadcasting Corporation science fiction television programme, has an enormous following worldwide. I am not one of those followers as you might have guessed from the headline, which means I didn’t understand this pop culture reference, from the April 23, 2012 news item on Nanowerk,

For fans of the hit series Doctor Who, the Sonic Screwdriver will be a familiar device. But now an international team of EU-funded researchers has taken equipment designed for magnetic resonance imaging (MRI)-guided focused ultrasound surgery and demonstrated a real Sonic Screwdriver, lifting and spinning a free-floating 10 cm-diameter rubber disk with an ultrasound beam.

I’m going to concentrate on the project first since this EU (European Union) funded project has a somewhat confusing configuration, which I’ll try to tease apart later in this posting. From the news item,

Dr Mike MacDonald, of the Institute for Medical Science and Technology (IMSAT) in the [University of Dundee, Scotland] United Kingdom, comments: ‘This experiment not only confirms a fundamental physics theory but also demonstrates a new level of control over ultrasound beams which can also be applied to non-invasive ultrasound surgery, targeted drug delivery and ultrasonic manipulation of cells.’

The theory the team were testing had not previously been proved in a single experiment; it is valid for both sound and light, and is used in fields like quantum communications and biophotonics. The theory states that the ratio of angular momentum to energy in a vortex beam is equal to the ratio of the number of intertwined helices to the frequency of the beam.

Dr Christine Demore from IMSAT comments: ‘For the first time, our experimental results confirm directly the validity of this fundamental theory. Previously this ratio could only be assumed from theory as the angular momentum and power in a beam had only ever been measured independently.’

The ultrasound beam generated by the researchers resembles the ‘double-helix’ structure of DNA but with many more twisted strands, or helices. This vortex beam generates a rotating, angular component of momentum that can exert torque on an object. In the recent publication, they showed how they could generate vortex beams with many intertwined helices, using a 1 000-element ultrasound transducer array as an acoustic hologram. These beams are so powerful they can levitate and spin the 90 g-disk made of ultrasonic absorber in water.

Here’s a 30 secs. video of the ‘sonic screwdriver’,

Ray Walters in his April 20, 2012 article  for Geek.com offers a description using measurements that are more commonly used in Canada and the US for what we’re seeing in the video [I have removed a link from the following passage],

Depicted in the video above, the “Sonotweezers” [aka, sonic screwdriver] project as it’s officially known, uses an ultrasound beam that is structured like a strand of DNA. The difference being that there are many more twisted strands that can be used to bring torque to bear on objects for movement. The team has used its device to levitate and spin a 3.17 ounce, 10cm diameter rubber disk that was suspended in water.

To make this happen, the research team used a 1000-element ultrasound transducer array to create what’s called an acoustic hologram.

The project known as ‘Sonotweezers’ at the University of Dundee,  is part of a larger European Union project, Nanoporation, which is investigating drug delivery to cancer cell using MRI (magnetic resonance imaging) and guided focused ultrasound. The larger project includes a couple of Israeli teams, neither of which seem to be involved with the Sonotweezers/sonic screwdriver project. I gather some of the funding for the Sonotweezers project comes from the UK’s Engineering and Physical Sciences Ressearch Council (EPSRC). You can find out more about the Scottish team at the University of Dundee, Sonotweezers, and EPSRC in the April 19, 2012 press release on the University of Dundee website.