Corralling photons to solve problems in seconds

Quantum physicist Chao-Yang Lu develops superfast computers that rely on the curious collisions of single particles of light.

by James Mitchell Crow

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Chao-Yang Lu is a quantum physicist at the University of Science and Technology of China in Hefei, China. Credit: Dave Tacon for Nature

In my laboratory, we develop quantum computers based on single photons, the fundamental particles of light. In 2020, our computer was the first worldwide to demonstrate ‘quantum advantage’: it completed a calculation in 200 seconds that would take a conventional supercomputer more than 2 billion years.

Today’s computers and mobile phones perform calculations using a binary code of 1s and 0s. Their silicon transistors can be only ever in either the 1 or the 0 state: on or off. But if we use fundamental particles such as photons to perform calculations, quantum effects come into play. In the quantum world, where a wave-like photon can be in two places at once, you can have 1 and 0 simultaneously. Quantum computers can take advantage of this ‘superposition’ to solve certain problems exponentially faster than classical computation can.

Here, I am looking through the control electronics part of our quantum computer. The control electronics ‘phase lock’ our photons so that they arrive in the computer together, with 15-nanometre precision. The machine performs calculations on the basis of the photons’ interactions.

When I accepted a professorship at the University of Science and Technology of China, my first quantum machine could control only six single photons. By 2020, my team had a machine that could control up to 76, and demonstrate quantum advantage. We are now up to 130 photons.

Quantum advantage used to be called quantum ‘supremacy’. It is very good that the new terminology has been adopted.

The problem that our computer solved to show quantum advantage is very abstract, a mathematical proof. My next steps are to scale the computer to control more photons — maybe 200 in the near term — and to reconfigure it for real-world applications, such as accelerating drug development by accurately predicting the interactions between candidate drugs and their targets.

Nature 610, 412 (2022)


Quantum advantage has demonstrated and measured success to process a real-world problem faster on a quantum computer than on a classic computer. QPUs (quantum processing units) are now becoming scalable enough to run some of the larger real-world problems. Quantum supremacy refers to the demonstrated and measured ability to process a problem faster on a quantum computer than on a classic computer. It’s, any problem, not a real-world problem which is a different situation that deserves a different perspective.

Quantum computers can not read any additional data once they start running a problem. They ingest each variable into a single qubit and then run the computations. So you need a quantum computer with enough qubits to be able to hold all of your data variables. For example, if you have 25,000 variables as part of your logistics problem you need a quantum computer that can then process 25,000 variables.

"Quantum computing will have a revolutionary impact on our understanding of quantum systems and will be good at solving intrinsically quantum problems. For example, it can help us solve physics problems where quantum mechanics and the interrelation of materials or properties are important. At an atomic level, quantum computing simulates nature and therefore could help us find new materials or identify new chemical compounds for drug discovery. It holds the promise of being able to take on problems that could take a normal computer billions of years to solve and do it in second," according to Mark Potter, SVP and CTO of Hewlett Packard Enterprise and director of Hewlett Packard Labs.
Oct 29, 2022
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It's very interesting how this is implemented at all. I remember the old computers, which were very slow. My city radio amateur club still uses a computer with a CRT monitor, because we use basic software. I am interested in the subject of quantum computers. Perhaps I should look for not only articles about it, but also an animated explainer video on how it all works. After all, I am a complete zero in quantum physics, it should be corrected. Thanks for the article.
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Sophieersted -

You might find the following of interest:

The smaller computers get, the more powerful they seem to become: there's more number-crunching ability in a 21st-century cellphone than you'd have found in a room-sized, specially cooled, military computer 50 years ago.

Despite such amazing advances, there are still plenty of complex problems that are beyond the reach of even the world's most powerful computers—and there's no guarantee we'll ever be able to tackle them. One problem is that the basic switching and memory units of computers, known as transistors, are now approaching the point where they'll soon be as small as individual atoms. If we want computers that are smaller and more powerful than today's, we'll soon need to do our computing in a radically different way. Entering the realm of atoms opens up powerful new possibilities in the shape of quantum computing, with processors that could work millions of times faster than the ones we use today. Sounds amazing, but the trouble is that quantum computing is hugely more complex than traditional computing and operates in the Alice in Wonderland world of quantum physics, where the "classical," sensible, everyday laws of physics no longer apply. What is quantum computing and how does it work?

However, even with the phenomenal strides we made in technology and classical computers since the onset of the computer revolution, there remain problems that classical computers just can’t solve. Many believe quantum computers are the answer.

Now that we have made the switching and memory units of computers, known as transistors, almost as small as an atom, we need to find an entirely new way of thinking about and building computers. Even though a classical computer helps us do many amazing things, “under the hood” it’s really just a calculator that uses a sequence of bits—values of 0 and 1 to represent two states (think on and off switch) to makes sense of and decisions about the data we input following a prearranged set of instructions. Quantum computers are not intended to replace classical computers, they are expected to be a different tool we will use to solve complex problems that are beyond the capabilities of a classical computer.

Basically, as we are entering a big data world in which the information we need to store grows, there is a need for more ones and zeros and transistors to process it. For the most part classical computers are limited to doing one thing at a time, so the more complex the problem, the longer it takes. A problem that requires more power and time than today’s computers can accommodate is called an intractable problem. These are the problems that quantum computers are predicted to solve.

Conventional computers have two tricks that they do really well: they can store numbers in memory and they can process stored numbers with simple mathematical operations (like add and subtract). They can do more complex things by stringing together the simple operations into a series called an algorithm (multiplying can be done as a series of additions, for example). Both of a computer's key tricks—storage and processing—are accomplished using switches called transistors, which are like microscopic versions of the switches you have on your wall for turning on and off the lights. A transistor can either be on or off, just as a light can either be lit or unlit. If it's on, we can use a transistor to store a number one (1); if it's off, it stores a number zero (0). Long strings of ones and zeros can be used to store any number, letter, or symbol using a code based on binary (so computers store an upper-case letter A as 1000001 and a lower-case one as 01100001). Each of the zeros or ones is called a binary digit (or bit) and, with a string of eight bits, you can store 255 different characters (such as A-Z, a-z, 0-9, and most common symbols). Computers calculate by using circuits called logic gates, which are made from a number of transistors connected together. Logic gates compare patterns of bits, stored in temporary memories called registers, and then turn them into new patterns of bits—and that's the computer equivalent of what our human brains would call addition, subtraction, or multiplication. In physical terms, the algorithm that performs a particular calculation takes the form of an electronic circuit made from a number of logic gates, with the output from one gate feeding in as the input to the next.

When the transistor was invented, back in 1947, the switch it replaced (which was called the vacuum tube) was about as big as one of your thumbs. Now, a state-of-the-art microprocessor (single-chip computer) packs up to 30 billion transistors onto a chip of silicon the size of your fingernail! Chips like these, which are called integrated circuits, are an incredible feat of miniaturization. Back in the 1960s, Intel co-founder Gordon Moore realized that the power of computers doubles roughly 18 months—and it's been doing so ever since. This apparently unshakeable trend is known as Moore's Law*.

When you enter the world of atomic and subatomic particles, things begin to behave in unexpected ways. In fact, these particles can exist in more than one state at a time. It’s this ability that quantum computers take advantage of.

Instead of bits, which conventional computers use, a quantum computer uses quantum bits—known as qubits. To illustrate the difference, imagine a sphere. A bit can be at either of the two poles of the sphere, but a qubit can exist at any point on the sphere. So, this means that a computer using qubits can store an enormous amount of information and uses less energy doing so than a classical computer.

As Richard P. Feynman, one of the greatest physicists of the 20th century, once put it: "Things on a very small scale behave like nothing you have any direct experience about... or like anything that you have ever seen."

If you've studied light, you may already know a bit about quantum theory. You might know that a beam of light sometimes behaves as though it's made up of particles (like a steady stream of cannonballs), and sometimes as though it's waves of energy rippling through space (a bit like waves on the sea). That's called wave-particle duality and it's one of the ideas that comes to us from quantum theory. It's hard to grasp that something can be two things at once—a particle and a wave—because it's totally alien to our everyday experience: a car is not simultaneously a bicycle and a bus. In quantum theory, however, that's just the kind of crazy thing that can happen. The most striking example of this is the baffling riddle known as Schrödinger's cat. Briefly, in the weird world of quantum theory, we can imagine a situation where something like a cat could be alive and dead at the same time!

Instead of bits, a quantum computer has quantum bits or qubits, which work in a particularly intriguing way. Where a bit can store either a zero or a 1, a qubit can store a zero, a one, both zero and one, or an infinite number of values in between—and be in multiple states (store multiple values) at the same time! If that sounds confusing, think back to light being a particle and a wave at the same time, Schrödinger's cat being alive and dead, or a car being a bicycle and a bus.

A gentler way to think of the numbers qubits store is through the physics concept of superposition (where two waves add to make a third one that contains both of the originals). If you blow on something like a flute, the pipe fills up with a standing wave: a wave made up of a fundamental frequency (the basic note you're playing) and lots of overtones or harmonics (higher-frequency multiples of the fundamental). The wave inside the pipe contains all these waves simultaneously: they're added together to make a combined wave that includes them all. Qubits use superposition to represent multiple states (multiple numeric values) simultaneously in a similar way.

Just as a quantum computer can store multiple numbers at once, so it can process them simultaneously. Instead of working in serial (doing a series of things one at a time in a sequence), it can work in parallel (doing multiple things at the same time). Only when you try to find out what state it's actually in at any given moment (by measuring it, in other words) does it "collapse" into one of its possible states—and that gives you the answer to your problem. Estimates suggest a quantum computer's ability to work in parallel would make it millions of times faster than any conventional computer if only we could build it!

In practice, there are lots of possible ways of containing atoms and changing their states using laser beams, electromagnetic fields, radio waves, and an assortment of other techniques. One method is to make qubits using quantum dots, which are nanoscopically tiny particles of semiconductors inside which individual charge carriers, electrons and holes (missing electrons), can be controlled. Another method makes qubits from what are called ion traps: you add or take away electrons from an atom to make an ion, hold it steady in a kind of laser spotlight (so it's locked in place like a nanoscopic rabbit dancing in a very bright headlight), and then flip it into different states with laser pulses. In another technique, the qubits are photons inside optical cavities (spaces between extremely tiny mirrors). Don't worry if you don't understand; not many people do. Since the entire field of quantum computing is still largely abstract and theoretical, the only thing we really need to know is that qubits are stored by atoms or other quantum-scale particles that can exist in different states and be switched between them.

We know for certain that a quantum computer could do better than a normal one is factorisation: finding two unknown prime numbers that, when multiplied together, give a third, known number.

In 1994, while working at Bell Laboratories, mathematician Peter Shor demonstrated an algorithm that a quantum computer could follow to find the "prime factors" of a large number, which would speed up the problem enormously. Shor's algorithm really excited interest in quantum computing because virtually every modern computer (and every secure, online shopping and banking website) uses public-key encryption technology based on the virtual impossibility of finding prime factors quickly (it is, in other words, essentially an "intractable" computer problem). If quantum computers could indeed factor large numbers quickly, today's online security could be rendered obsolete at a stroke. But what goes around comes around, and some researchers believe quantum technology will lead to much stronger forms of encryption. (In 2017, Chinese researchers demonstrated for the first time how quantum encryption could be used to make a very secure video call from Beijing to Vienna.)

Apart from Shor's algorithm, and a search method called Grover's algorithm, hardly any other algorithms have been discovered that would be better performed by quantum methods. Given enough time and computing power, conventional computers should still be able to solve any problem that quantum computers could solve, eventually. In other words, it remains to be proven that quantum computers are generally superior to conventional ones, especially given the difficulties of actually building them. Who knows how conventional computers might advance in the next 50 years, potentially making the idea of quantum computers irrelevant—and even absurd.

There's also the fundamental issue of how you get data in and out of a quantum computer, which is, itself, a complex computing problem. Some critics believe these issues are insurmountable; others acknowledge the problems but argue the mission is too important to abandon.

One thing is beyond dispute: quantum computing is very exciting—and you can find out just how exciting by tinkering with it for yourself, In 2019, Amazon's AWS Cloud Computing offshoot announced a service called Braket, which gives its users access to quantum computing simulators based on machines being developed by three cutting-edge companies (D-wave, IonQ, and Rigletti). Microsoft's Azure cloud platform offers a rival service called Azure Quantum, while Google's Quantum AI website offers access to its own research and resources. Take your pick—or try them all.

Suppose we keep on pushing Moore's Law—keep on making transistors smaller until they get to the point where they obey not the ordinary laws of physics (like old-style transistors) but the more bizarre laws of quantum mechanics. The question is whether computers designed this way can do things our conventional computers can't. If we can predict mathematically that they might be able to, can we actually make them work like that in practice?

By entering into this quantum area of computing where the traditional laws of physics no longer apply, we will be able to create processors that are significantly faster (a million or more times) than the ones we use today. Sounds fantastic, but the challenge is that quantum computing is also incredibly complex.

Most researchers agree that we're unlikely to see practical quantum computers appearing for some years—and more likely several decades. The conclusion reached by an influential National Academies of Sciences, Medicine and Engineering report in December 2018 was that "it is still too early to be able to predict the time horizon for a practical quantum computer" and that "many technical challenges remain to be resolved before we reach this milestone."

The pressure is on the computer industry to find ways to make computing more efficient, since we reached the limits of energy efficiency using classical methods. By 2040, according to a report by the Semiconductor Industry Association, we will no longer have the capability to power all of the machines around the world. That’s precisely why the computer industry is racing to make quantum computers work on a commercial scale. No small feat, but one that will pay extraordinary dividends.

It’s difficult to predict how quantum computing will change our world simply because there will be applications in all industries. We’re venturing into an entirely new realm of physics and there will be solutions and uses we have never even thought of yet. But when you consider how much classical computers revolutionized our world with a relatively simple use of bits and two options of 0 or 1, you can imagine the extraordinary possibilities when you have the processing power of qubits that can perform millions of calculations at the same moment.

What we do know is that it will be game-changing for every industry and will have a huge impact in the way we do business, invent new medicine and materials, safeguard our data, explore space, and predict weather events and climate change. It’s no coincidence that some of the world’s most influential companies such as IBM and Google and the world’s governments are investing in quantum computing technology. They are expecting quantum computing to change our world because it will allow us to solve problems and experience efficiencies that aren’t possible today. In another post, I dig deeper into how quantum computing will change our world.



Despite all this progress, it's early days for the whole field, and most researchers agree that we're unlikely to see practical quantum computers appearing for some years—and more likely several decades. The conclusion reached by an influential National Academies of Sciences, Medicine and Engineering report in December 2018 was that "it is still too early to be able to predict the time horizon for a practical quantum computer" and that "many technical challenges remain to be resolved before we reach this milestone."

The quantum computing devices can operate more than a degree above absolute zero, the scientists report in two papers published in the April 16, 2020, Nature. Although still chilly, that temperature is much easier to achieve than the approximately 10 millikelvin (0.01 degrees above absolute zero) temperatures typical of a popular type of quantum computer based on superconductors, materials which transmit electricity without resistance.

* Moore's Law: states that the number of transistors on a microchip doubles every two years. The law claims that we can expect the speed and capability of our computers to increase every two years because of this, yet we will pay less for them. Another tenet of Moore's Law asserts that this growth is exponential. The law is attributed to Gordon Moore, the co-founder and former CEO of Intel. Another tenet of Moore's Law says that the growth of microprocessors is exponential.

Gordon Moore did not call his observation "Moore's Law," nor did he set out to create a "law." Moore made that statement based on noticing emerging trends in chip manufacturing at Fairchild Semiconductor. Eventually, Moore's insight became a prediction, which in turn became the golden rule known as Moore's Law.

As transistors in integrated circuits become more efficient, computers become smaller and faster. Chips and transistors are microscopic structures that contain carbon and silicon molecules, which are aligned perfectly to move electricity along the circuit faster. The faster a microchip processes electrical signals, the more efficient a computer becomes. The cost of higher-powered computers has been dropping annually, partly because of lower labor costs and reduced semiconductor prices.

As Moore's Law advances, so the number of intractable problems diminishes: computers get more powerful and we can do more with them. The trouble is, transistors are just about as small as we can make them: we're getting to the point where the laws of physics seem likely to put a stop to Moore's Law. Unfortunately, there are still hugely difficult computing problems we can't tackle because even the most powerful computers find them intractable. That's one of the reasons why people are now getting interested in quantum computing.

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Instead of bits, a quantum computer has quantum bits or qubits, which work in a particularly intriguing way. Where a bit can store either a zero or a 1, a qubit can store a zero, a one, both zero and one, or an infinite number of values in between—and be in multiple states (store multiple values) at the same time! If that sounds confusing, think back to light being a particle and a wave at the same time, Schrödinger's cat being alive and dead, or a car being a bicycle and a bus.
This is where I already understand the concept of quantum computers and how they work.
I know how "traditional" computers work, because I studied circuit engineering and telecommunication systems. But quantum theory is something of a mystery to me. Thank you for such fascinating information. I had a very interesting time tonight and learned a lot of new things.
sophieersted - Here's bit on the mysteries of quantum mechanics:

Quantum physics differs significantly from classical physics. Classical physics describe the physical laws governing the behavior of ordinary size objects that we deal with everyday in our lives – objects like a baseball, a bullet, a musical instrument like a violin, water waves on a beach or in an ocean. Quantum physics describe the physical laws governing the behavior of very small objects that we have to deal with in the subatomic world – objects like an electron, a proton, a neutron, a photon (the constituents of light). This article discusses some of the largest differences between quantum physics and classical physics, and the associated wonders and mysteries of quantum physics.

In classical physics, the objects that we deal with behave either like particles (e.g., a baseball, a coin) or like waves (e.g., a water wave, an air or light wave). Furthermore, an object is either a particle or a wave. But in quantum physics, the objects that we deal with have characteristics of a particle and characteristics of a wave. In other words, the subatomic objects behave both like a particle and a wave. This new and surprising discovery occurred through a series of experiments known as the double-slit experiments from the 19th century to the first quarter of the 20th century.

The behavior of these subatomic objects like electrons behave very differently from macroscopic objects like bullets. Electrons exhibit wave-like properties (similar to what we saw with water waves as in our second experiment).

But this is not the only mystery when dealing in the subatomic world. We now discuss several more mysteries.

Now, if the electrons go through both slits at the same time, when we detect the electrons at the backstop, do we find only part of an electron? From the experiments, we found that the clicks that we hear from the counters in Fig 3 that detect the arrival of the electrons at the backstop are always the same. For example, we don’t hear any half clicks that perhaps indicate that only half of the electron arrived at that location and the other half might have arrived at another location, which may be what you would guess if the electron went through both slits. This means when you detect the electrons, you detect the whole electron, and not only part of the electron, i.e., electrons also behave like particles. This leads to:

Subatomic objects, although displaying wave-like characteristics, also display particle-like characteristics. This is known as the wave-particle duality of quantum physics., i.e., subatomic particles display both characteristics, showing behavior like a wave, and also showing behavior like a particle.

There are more mysteries of quantum physics. From the previous experiment, we saw that electrons behave with wave-like properties in the sense that they seem to go through both slits at the same time, and they don’t just go through slit 1 or slit 2.

Can we try to detect which slit the electron went through? We know that electric charges scatter light. Since electrons are charged particles, if we put a light source behind the wall, we should be able to determine the path the electron took by observing the location of the scattered light.

The act of observance can change what you are observing.

This particular mystery is my favorite.

This is understandable for the experiments discussed above because in order to observe, you need to use light. In order to give more precision to what you are observing, you have to use smaller and smaller wavelengths (or larger and larger frequencies of light), which is equivalent to imparting larger and larger momentum to the electrons and therefore results in larger and larger disturbance to the path of the electrons.

Heisenberg’s Uncertainty Principle – One cannot simultaneously measure precisely the position and momentum of any object (first proposed in 1927 by the German physicist Werner Heisenberg).

This uncertainty principle applies not just for the position and momentum of any object, it actually applies for any pair of complementary (or conjugate) variables, like time and energy of an object. Furthermore, it is an intrinsic limitation of nature, and not just due to inadequacy of the accuracy of our current experiments.

The uncertainty principle leads to one of the most significant and puzzling implications of quantum physics: Something may be created from “nothing.” We often think of a vacuum as made up of empty space. However, if we are talking about an extremely tiny interval of time, as at the moment of the Big Bang when our current universe was created, then the uncertainty principle tells us that the uncertainty in the involved energy could be very large, large enough to create electron and positron pairs, or mater and anti-matter pairs to form stars and galaxies. This is known as vacuum polarization or vacuum fluctuation. That means that things may be created from the nothingness in a vacuum. However, solving this mystery of creating something from nothing leads to another great mystery that currently we have no clue of solving, i.e., why is there not an equal amount of matter and anti-matter, instead of our observed universe which is made up of essentially only matter.

Predictability of Quantum Physics

In classical physics, if we are given the initial conditions of an object, then using the laws of physics, we can predict precisely the future behavior of an object. However, in the subatomic world, because particles have wave-like characteristics, we can no longer predict precisely the behavior of an object even if given the initial conditions.

Mathematical digression: The physical state is described by a complex wave function (complex in the mathematical sense of real versus complex numbers), which we denote as C (or the Greek letter phi ϕ). The distribution function is determined as the square of C. In the double slit experiment, when only Slit 1 is open, that function is C1. When only Slit 2 is open, that function is C2. When both slits are opened, the distribution function is the square of the sum of C1 and C2, which is not the same as the sum of C1 squared and C2 squared. When you do this square calculation, there will be cross terms involving both C1 and C2. These cross terms are the interference terms coming from the fact that the wave can go through both slits 1 and 2.

Because in quantum theory, the state of an object is described by a wave function, we can calculate only the probability distribution of the future, and unlike classical physics where we can calculate precisely the object’s future state. This leads to another mystery of quantum physics.

In the subatomic world, we can only predict the probability distribution of certain physical happenings in the future.

As we stated at the beginning of this article, on the one hand quantum physics has introduced many wonders and has revolutionized essentially all aspects of our lives. It has introduced all kinds of gadgets, like vacuum tubes, transistors, TVs, computers, video games, medical imaging, cell phones, GPS, Internet, nuclear weapons, missiles, and so on. However, on the other hand, quantum physics has also led us to many mysteries, like the wave-particle duality and the probability interpretation of quantum physics. That has led many people, including Albert Einstein, to make the remark that God does not play dice and question whether there is a more fundamental theory than quantum theory so that the uncertainties. can be removed and the theory can then be deterministic, and not probabilistic.

Interpretations of Quantum Theory

As just stated, the probabilistic interpretation of quantum theory has led many people to feel that quantum theory cannot be the ultimate theory of physics. For example, perhaps there are some hidden variables that we are not aware of and therefore we have not defined their values. In the future, if we can figure out what these hidden variables are and determine their values, then we can remove the uncertainties and our physical theory then becomes deterministic. This is known as the hidden variable theory.

In 1964, the Irish physicist John Bell proved a very simple theorem that states that all local hidden variable theories cannot make the same predictions as quantum theory.

Therefore, one can perform experiments to prove whether quantum theory or local hidden variable theory is correct.

Even though Bell’s Theorem is one of the most important and remarkable theorems in physics, it is relatively simple to prove in terms of the length of the proof and the sophistication of the required mathematics. But the proof requires some ingenious use of mathematics and logic.
In a future article, we will discuss Bell’s Theorem and the experiments that have been done which so far have shown that quantum theory is the correct theory. There we can see the differences between quantum entanglement from the wave function description of quantum theory and its implications for encryption in quantum computers.

Spooky Tunnels

Another strange feature of quantum physics is entanglement, which Albert Einstein famously called “spooky action at a distance”. This is when two particles form a connection across an unknown distance, which could be a millimetre or the width of a universe, and one of the particles can vanish from one area and reappear elsewhere.

This weird and wonderful world up-ends accepted scientific wisdom, creating obstacles to conventional thinking.

Bacterial mechanics

While entanglement may have appeared “spooky” to Einstein’s brilliant mind, subsequently the scientific community has grappled with that and other counterintuitive aspects of quantum physics.

Some have turned their backs on quantum theories that challenge accepted laws of physics.

But despite – or maybe because of – its unusual aspects, quantum physics is improving our understanding of the natural world, to a point where some of these theories can no longer be overlooked.

Quantum research has been selected by the World Economic Forum’s scientific community as one of the most important “future frontiers” in science.

And the emerging field of quantum biology could be the key to explaining the previously inexplicable.

A new study suggests living bacteria can be put into “quantum entanglement”. If bacteria are confirmed to exhibit quantum effects, it would form the first evidence of interplay between macroscopic organic matter and the subatomic quantum world.


A number of studies have linked a quantum reaction with the process of photosynthesis. Plant cells collect light particles, which release energy-gathering particles called excitons. The excitons carry the energy to the reaction centre, where it is turned into chemical energy and metabolized by the plant.

Everything happens in a billionth of a second to avoid losing heat, and with complete accuracy. Although the excitons don’t travel along one single path or another, energy still flowed in an instant to the reaction centre, but it wasn’t clear how.

In a 2007 experiment, biophysicist Greg Engel showed that excitons undergo a quantum reaction called superposition, where particles can exist in two places at once and in two states – a particle and a wave.

Engel, a professor at the University of Chicago and a World Economic Forum Young Scientist, found that excitons can travel as a wave and feel out all possible routes to the reaction centre, identifying the most efficient one to take.

He told Physics World: “The general notion that the language and mathematics of quantum information, including coherence, can be used to understand photosynthetic dynamics in ultrafast spectroscopy experiments seems to be growing in acceptance.”

How do birds migrate?

Just as humans used compasses to find their way across open seas, birds navigate using an inner, chemical compass that picks up signals from the Earth’s magnetic field. As the signal is weak, scientists are unclear how it is picked up by birds.

University of Oxford researchers studied the migratory habits of the European robin. They suggest that when a photon of sunlight hits the robin’s retina, two unpaired electrons are released. Each electron spins to align itself with the Earth’s magnetic field and guides the bird towards warmer climates.

Another University of Oxford physicist, Simon Benjamin, suggests the process is the result of quantum entanglement, which could also explain how insects accurately orient themselves. And then imagine an insect like the Monarch Butterfly flying for thousands of miles or Dung beetles associating their journey with the location and orientation of the Milky Way.

Making sense of smells

Precisely how a human nose distinguishes the multitude of smells it encounters has eluded scientists. Molecules from the air enter the nostril and interact with receptors to determine one from another, but how this happens is unclear.

Chemist Luca Turin, of Alexander Fleming Biomedical Sciences Research Centre in Athens, suggests molecules contain electrons which arrive at the other side of the receptor in the nostril through quantum tunneling. Once through, the electron sends a signal to the brain to identify the smell, performing olfaction at the subatomic level.

Theoretical physicist, author and broadcaster Jim Al-Khalili likens the implausible phenomenon of quantum tunneling to throwing a tennis ball at a solid wall and it disappearing and reappearing at the other side.

In a TedGlobal London talk, he explained: “Quantum tunneling takes place all the time; in fact, it’s the reason our sun shines. The particles fuse together, and the Sun turns hydrogen into helium through quantum tunneling.”

In his talk, Al-Khalili recalled a quote from Danish physicist Niels Bohr, a pioneer in quantum mechanics, who said about the discipline: “If you're not astonished by it, then you haven't understood it.”



The foregoing shows that it is now possible to extract information from the same photon. This is important because the major part of all information we get from the universe come from light. “Developing a new way of ‘seeing’ could have applications in quantum science,” said Prof. Serge Haroche. “A photon could share its information with an ensemble of atoms to build up an ‘entangled state’ of light or matter”.

Attempting to manipulate and control quantum systems raises important questions about the transition between quantum and classical behaviour. “Fundamentally, the goal is to understand nature better,” explained Prof. Haroche. “Applications, such as quantum communication machines, will certainly come but what they will be useful for is not yet clear. This is why research is so exciting – unpredictable things keep happening all the time.”
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Des informations étonnantes. J'ai vraiment apprécié la lecture de ce fil et la discussion des gens. En tant qu'acteur impliqué dans ces outils numérique depuis de nombreuses années, je souhaite référer calculer son salaire en fonction des heures travail léesà cet effet. Il ne se concentre pas seulement sur la discussion du sujet de fond en comble, mais offre également la possibilité de calculer vos heures de travail. J'espère que tout le monde appréciera la lecture de ce blog.
nadirabbas -

Merci beaucoup pour votre plaisir de la physique quantique. C'est généralement tout un exploit de surmonter les idées impliquées, en réalisant qu'un système peut être modifié simplement en l'observant, puis en lançant des calculs statistiques quantiques pour comprendre le résultat d'un système quatique. J'encourage vos études ultérieures dans ce domaine des miroirs, qui fonctionne un peu comme la « maison du plaisir » dans un carnaval où différents calculs de probabilité donnent naissance à différents miroirs.