The Applications of Quantum Entanglement

9 min read

If you tickle one…both will laugh, applications of quantum entanglement.

The Red Thread of Fate

Quantum mechanics (QM; also known as quantum physics, quantum theory, the wave mechanical model, or matrix mechanics) is a fundamental theory in physics, which describes nature at the smallest scales of energy levels of atoms and subatomic particles.

One of QM’s most mystifying phenomena is quantum entanglement (Qe). According to this phenomenon, 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 the opposite sides of the universe, a million light-years away. So, entangled means that the behavior of these particles is tied to one another. For example, if one particle is found spinning in one direction, then the other particle instantaneously and immediately changes its spin in a corresponding manner dictated by the entanglement. In fact, an observer measuring one particle could perfectly predict the corresponding measurements of a second observer looking at the other particle far away. In entanglement, one constituent (system or particle) cannot be fully described without considering the other(s). So far Qe has been demonstrated experimentally with photons, neutrinos, electrons, molecules as large as buckyballs and even small diamonds. Measurements of physical properties such as position, momentum, spin, and polarisation, performed on entangled particles have been found to be entangled.

Quantum Weirdness May Seem to Outrun Light- Here’s Why It Can’t

But how fast is “instantaneously and immediately” in Qe? According to a research done by a team of Chinese physicists, the lower limit to the speed associated with Qe is at least 3 trillion meters per second or four orders of magnitude faster than the speed of light. And this means that during Qe the transmission of “non-classical information” between two particles happens instantaneously, while the revelation of Qe at the two observers (classical information), in the different universes, does not happen instantaneously. Simply because it depends on the speed of light.

So, in this magical quantum world, QM yes is weird that even Albert Einstein and his colleagues in 1935 claimed that Qe must be “incomplete” inasmuch it was too “spooky” to be real. The trouble is that QM seems to defy the common-sense notions of causality, locality, and realism. For example:

1) You know that the moon exists even when you’re not looking at it — that’s realism. But, according to the theoretical physicist, John Wheeler reality is made of information which is created by observation, and that means that the moon exists only when it is observed.

2) Regarding causality (cause and effect), we know and take it for granted that “if you flick a light switch on, the bulb will illuminate”. But Qe is independent of time and space. In fact in QM, the distinction between cause and effect is not made at the most fundamental level, so time symmetric systems can be viewed as causal or retro-causal. Retrocausality is a concept where the effect precedes its cause in time. And that means that “if I illuminate a bulb, a flick of light will be switched on”.

3) Moreover, thanks to a hard limit on the speed of light, if you flick a switch on now, the related effect could not occur instantly a million light-years away according to the locality. But in Qe information transfer “breaks” the speed of light.

In conclusion, these 3 principles of causality, locality, and realism break down in the quantum realm, with Qe being the most famous spooky example. Eventually, in 1964 physicist John Stewart Bell proved that QM was, in fact, a complete and workable theory. His results, now called Bell’s Theorem, effectively proved Qe is as real as the moon, so today the bizarre behaviors of quantum systems are being harnessed for use in a variety of real-world applications.

“The Red Thread of Fate”

Leaving for a while the quantum world behind us and traveling back to our “ordinary world”, Qe could actually remind someone the East Asian belief: “The Red Thread of Fate”. According to an ancient myth: “The gods tie an invisible red cord around the ankles or the little fingers of those that are destined to meet one another in a certain situation or help each other in a certain way. The two people connected by the red thread are destined partners, regardless of place, time, or circumstances”…like in Qe. Moreover, this magical cord between the two parts/partners may stretch or tangle, but will never break…maintaining the “human entanglement” forever.

This myth is similar to the Western concept of soul mates or destined partners, a concept that can be used to express the seeming fate or destiny of an event, friendship, or happening. Fate and destiny have traditionally been seen as a “power” divinely inspired, that “orders” the course of events and defining events as “inevitable”. This is a concept based on the belief that there is a fixed natural order in this universe.

Moreover, determinism is a philosophical concept often confused with fate and destiny, that indicates that everything that happens is determined by things that have already happened (causality: the relationship between cause and effect). But determinism differs from fate and destiny in that it is never conceived as being of a spiritual, religious, or of astrological notion, in fact, determinism is simply “caused”. In any case, “caused determinism” or “given fate by the gods”, both imply that reality is some kind of deterministic programmed animation, idea that the famous double slit experiment (the cornerstone of modern physics) has ruled out, that is initiating the era of the free will.

In fact, going back again to our quantum world, according to some physicists reality is made of information in the form of symbolism, that is something like a geometric code. And like any language, this geometric code has some rules (determinism) but also some syntactical freedom (free will), that requires some notion of a chooser to choose the free steps in the language. Consequently, that might indicate, that if you tickle one particle in one universe then both entangled particles in the two different universes will definitely and instantly laugh but one particle might also sneeze in free will…! Who knows? The battle between determinism and free will is to be continued among physicists while trying to understand the deepest secrets of this wonderful quantum and the ordinary world we call life.

But here are some of the most intriguing real-world applications of Qe in our “ordinary world”:

Uncrackable Codes (Quantum Communication)

Quantum Internet.

In traditional cryptography, a sender uses one key to encode information, and a recipient uses the shared key between the two parties to decode the message. However, in this process, it’s difficult to remove the risk of a third party trying to learn information about the key being established and compromising the cryptography. But, potentially this can be fixed by using unbreakable quantum key distribution (QKD). In QKD, information about the key is sent via photons that have been randomly polarized. This restricts the photon so that it vibrates in only one plane — for example, up and down, or left to right. The recipient can use polarized filters to decipher the key and then use a chosen algorithm to securely encrypt a message. The secret data still gets sent over normal communication channels, but no one can decode the message unless they have the exact quantum key. That’s tricky because quantum rules dictate that “reading” the polarized photons will always change their states, and any attempt at eavesdropping will alert the communicators to a security breach. The biggest problem with current QKD technology is that you can only send a photon about 100 kilometers down a fiber-optic cable before it’s too dim to be received. After that, you’ve got to decrypt and retransmit it, which calls for a high-security installation and some expensive kit. The first bank transfer using entangled QKD went ahead in Austria in 2004.

Today companies such as BBN Technologies, Toshiba, ID Quantique and much more use QKD to design ultra-secure networks. Quantum cryptography market by segmentation, major players, size, market dynamics & forecast 2024 can be found here.

Quantum Computers (Quantum Computing)

Quantum computing is the use of quantum phenomena such as superposition and Qe to perform computation. The field of quantum computing is actually a sub-field of quantum information science, which includes quantum cryptography and quantum communication. A standard computer encodes information as a string of binary digits, or bits. Quantum computers supercharge processing power because they use quantum bits, or qubits, which exist in a superposition of states, and until they are measured these qubits can be both “1” and “0” at the same time. This field is still in development, but there have been steps in the right direction. As of April 2019, no large scalable quantum hardware has been demonstrated. Right now there is an increasing amount of investment in quantum computing by governments, established companies, and start-ups. Demonstration of quantum supremacy is actively pursued both in academic and industrial research. The quantum computer market is expected to grow from $ 93 million in 2019 to $ 283 million by 2024.

Quantum computing is used also for material simulation in various industries, such as healthcare, automotive, entertainment, banking and finance, and defense. Companies such as D-Wave Systems Inc. (Canada), 1QB Information Technologies Inc. (Canada), and QxBranch, LLC (US) are working toward providing a platform to enhance the availability, usability, and accessibility of quantum computers in the material simulation applications. QxBranch LLC (US) has launched quantum-computing simulator for the Commonwealth Bank of Australia; a quantum simulator differs from a computer. Simulators are designed to solve one equation, solving a different equation would require building a new system, whereas a computer can solve many different equations. Such developments are expected to drive the growth of the quantum computing market for the simulation application. Moreover, Atos SE (France) launched the highest-performing quantum simulator named Atos Quantum Learning Machine’ (Atos QLM).

Quantum computing could have a potential impact on fintech with processing and settlement of transactions, with faster data processing, with risk and performance modeling and better security. JP Morgan and Barclays have been dabbling with IBM’s quantum computing tools, according to Wired, looking to the future for practical applications. While quantum computers aren’t yet perfect, if they turn out to work like fintech giants hope that would mean lower energy costs and vastly improved performance in everything.

Quantum computers could also help the world cope with climate change, one of the world’s most complex and hard-to-predict phenomena. In fact, Exxon Mobil partnered with IBM to explore applications including predictive environmental modeling and carbon-capture technology. Daimler Mercedes-Benz is also using quantum computing to test new types of battery chemistry to improve electric vehicles. And the Dubai Electricity and Water Authority is working with Microsoft to optimize its energy grid management.

Pharmaceutical giant Biogen teamed up with consultancy Accenture and startup 1QBit on a quantum computing experiment in 2017 aimed at molecular modeling, one of the more complex disciplines in medicine. The goal: finding candidate drugs to treat neurodegenerative diseases. Microsoft is collaborating with Case Western Reserve University to improve the accuracy of MRI machines, which help detect cancer. Finally, large chemical companies are actively investing in quantum computing.

Improved Microscopes (Quantum Entanglement Microscopy)

In 2013 a team of researchers at Japan’s Hokkaido University developed the world’s first entanglement-enhanced microscope, using a technique known as differential interference contrast microscopy. This type of microscope fires two beams of photons at a substance and measures the interference pattern created by the reflected beams. Using entangled photons greatly increases the amount of information the microscope can gather, as measuring one entangled photon gives information about its partner. The Hokkaido team managed to image an engraved “Q” that stood just 17 nanometers above the background with unprecedented sharpness. Quantum entanglement microscope is a form of confocal-type differential interference contrast microscope. Information regarding the size of the global microscopy industry can be found here.

Similar techniques could be used to improve the resolution of astronomy tools called interferometers, used in the hunt for extrasolar planets, to probe nearby stars and to search for ripples in space-time called gravitational waves.

Biological Compasses (Quantum Biology)

How can birds be able to perceive and follow something as faint as the Earth’s magnetic field while migrating?….And the most plausible explanation is: “with the effect of the magnetic field on entangled molecules of a chemical in birds’ eyes called Cry4, or cryptochrome”, via the entangled radical pair mechanism. Cryptochromes were in fact proposed as the “magnetic molecules” that could harbor magnetically sensitive radical-pairs.

When a photon, a light particle, hits a molecule of cryptochrome in a bird’s eye, it knocks loose an electron that may then become associated with a second molecule. The two Cry 4 molecules then both have an odd number of electrons, and they become a radical pair. Since both of these radicals were created simultaneously—by that loosened electron — the radical pair becomes entangled. This entangled state is extremely temporary, and it won’t survive beyond 100 microseconds. But during that brief time, the radical pair will be in either one of two states. Scientists believe that the Earth’s magnetic field affects the amount of time the molecules spend in either state, and any changes to the duration of these states somehow tell the bird where he/she is. The radical pair theory is really the best explanation for birds’ navigation systems we have so far.

Moreover, the human body is a constant flux of thousands of chemical/biological interactions and processes connecting molecules, cells, organs, and fluids, throughout the brain, body, and nervous system. Up until recently, it was thought that all these interactions operated in a linear sequence, passing on information much like a runner passing the baton to the next runner. However, the latest findings in quantum biology and biophysics have discovered that there is, in fact, a tremendous degree of coherence within all living systems with Qe playing probably a very important role inside all of us. In fact, it is possible that protein quaternary architecture may have evolved to enable sustained quantum entanglement and coherence. Quantum biology is just an emerging field and most of the current research is theoretical and subject to questions that require further experimentation.


Love. Quantum physics. Completely unrelated, and yet strangely parallel.

The red thread of fate, fate, destiny and determinism are umpteenth examples of ancient believes, myths and philosophies that our ancestors have left behind for us, knowing somehow that one day we will be more “technologically capable” of having a better understanding of life while “navigating” in the intersection between the quantum and the ordinary world. In the end, the quantum world is more about the “mind” rather than the “matter”, while the ordinary world it should be more about “love” rather than the “matter”, but in the intersection of these two apparently different worlds is where mind, matter, and love collide. And probably in that intersection, all major technological advancements have somehow started. As William Blake said — “What is now proved was once only imagined”.

Marina Alamanou Marina has a PhD in molecular and cellular biology and has strong experience in academia, startups and multinationals. She loves science and the sea.

3 Replies to “The Applications of Quantum Entanglement”

  1. An in-depth and effortless dive into the world of quantum entanglement, supporting its increasingly irrefutable existence through the deep-researched methods by which quantum mechanics are applied in a real world setting. I really appreciate the presentation as it flowed through the East Asian belief of the Red Thread of Fate, likening it to the Western concept of soulmate-ship, also illustrating how this topic is just another drop in the bucket that is the debate over free will and determinism. Thanks Marina

  2. Hi Michael, the effortless dive is just the result of story telling about myths and ancient beliefs. Our brain is just a story processor, and it takes more than two brains to have an effortless dive. So, thanks to you also 🙂

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