Physics is one major scientific discipline that helps us understand the universe. While classical Physics is more about the world and things we can observe, we study the matter at the atomic and subatomic level with quantum physics. Quantum physics (or quantum mechanics) is best known as probabilistic as opposed to being deterministic. Classical Physics, or any branch of science for that matter, is deterministic in the sense that we can predict the results of an experiment accurately provided we have all the available information. For instance, when throwing a ball into the air, I can, with certainty, predict the trajectory of the ball if factors such as initial speed, wind velocity, and air resistance are known. However, this certainty fades away within the realm of quantum mechanics, not due to limitations in our knowledge or measurement capabilities, but as an intrinsic quality of quantum entities.

Subatomic particles, referred to as quantum objects, include entities like protons, electrons, and atoms. While quantum mechanics’ principles theoretically extend to sizable objects, their effects become imperceptible, primarily owing to a phenomenon physicists call decoherence. Decoherence emerges from interactions with the many particles in the environment, effectively erasing quantum behavior, a process likened to the “washing out” of quantum features. If we could isolate an atom perfectly from its surroundings, we would be able to see quantum behavior; but in everyday large objects there exist a huge number of particles which renders the observation of quantum behavior practically impossible.

To begin, let’s delve into the concept of probability. In the realm of quantum mechanics (QM), a particle has the potential to exist in a linear combination or superposition of multiple states. To simplify and sidestep technical jargon, let’s consider the “color” property of a quantum object, such as an electron. While electrons don’t possess color in the conventional sense, the analogy applies to measurable physical attributes like position, velocity, or spin. When measured, the color of an electron is always either a red or a blue. Classical logic asserts that an object’s color is an unchanging, fixed property, unaffected by observation. However, QM challenges this notion, proposing that the object exists as a blend of red and blue until subjected to observation or measurement. There is a certain probability of getting red, and getting blue; however, we cannot tell which one. Let’s assume these probabilities are 50% each. This would mean if I measured the color of an electron, I would get red or blue with a 50% probability for each. The math of QM can calculate the probabilities with accuracy but dictates that the color was in a superposition state going back and forth between the two prior to observation. Suppose the measurement reveals the color red. The intriguing question then arises: “Was it red before the observation?” Although specific probabilities are linked to each color in an observation, certainty about the revealed color remains mysterious. The act of observation leads to the phenomenon termed the “collapse of the state,” signifying the transformation from a two-state mixture (superposition) to a definitive state of either red or blue.

The renowned double-slit experiment is a typical illustration demonstrating the concept of superposition. Here, we will provide a concise description of the double slit experiment without delving into technicalities. Imagine sending electrons through a double-slit configuration one at a time. Once through, the electron strikes a screen positioned beyond the slits. Each electron leaves a mark on the screen like a point particle. As we send more electrons, one at a time, a pattern gradually builds up on the screen generated by the many marks left by the electrons. The pattern is exactly a copy of what a wave would do. So, the outcome is that the electrons collectively behave as a wave – much like a water wave that would pass through both slits simultaneously and hit the screen. This is what physicists call wave-particle duality: when an electron behaves like a particle as it leaves a point mark on the screen, but the collective behavior is one of waves (not many particles). To explain the wavy pattern formed at the screen, we are compelled to accept that the electron is just like a wave passing through the two slits simultaneously. In the language of QM, the electron is in a superposition state of being at both slits at the same time. Things get even more interesting once we devise an experiment to measure which slit it “really” goes through. Experiments like this have undoubtedly confirmed that if we have the “which slit” information, the superposition state collapses: the electrons are observed to pass through one of the two slits and, moreover, they form a pattern on the screen that particles would generate. The overall inference is that until we observe which slit an electron goes through, we must treat the electron as being in a state of superposition, i.e. going through both slits simultaneously. However, an observation will make it collapse to a state of passing through only one slit.

The mathematical framework was clear: before we make an observation, a quantum particle or system is in a superposition state lacking well-defined properties that preclude assertions about its physical attributes. The particle manifests a specific property only after an observation. This quantum behavior has been confirmed countless times especially with experiments involving electron spins and photons (light particles). In summary, QM essentially argues that every tiny particle is in a mixed state consisting of all possible realities until subjected to observation. Since every entity, living or nonliving, is made up of tiny quantum particles like protons, electrons and neutrons, this should apply to any object in the universe. It is the act of observation that brings out the reality; no inherent “real property” existed prior to measurement.

During the initial stages of its development, the idea of superposition was taken with skepticism notably by the famous Albert Einstein. Einstein acknowledged that the observations are explained by this new weird mathematical framework of QM; however, he believed there is more to unravel. Einstein basically argued that a particle must always have a definite property even before the measurement. To him, the notion that a particle lacked a “real” value in the absence of observation seemed illogical. Einstein is reported to have said, “I would like to think that the Moon is still there even if I do not look at it.” This stance aligns with the concepts of “localism” and “realism,” suggesting a persistent, definite reality irrespective of observation.

At this juncture, the issue becomes more philosophical than scientific. The pivotal question emerges: did the electron have a real and definite color prior to observation? (In lieu of color, the experiments would measure physical properties like spin or position). QM will respond “no, it exists in a superposition state.” In contrast, classical logic or Einsteinian viewpoints would say “yes, of course! It has always had a definite color; we just did not know it.” This debate is deeply related to measurement theory as well. To put it from a different standpoint, measurement in classical logic discloses an object’s property, while in QM, measurement forces the object to assume one of its potential and observable properties.

In opposition to this idea of QM, Einstein and his colleagues published the renowned EPR paper titled “Can Quantum Mechanical Description of Physical Reality Be Considered Complete?” In this article, Einstein argued that even though the Math of QM is accurate, QM is insufficient in addressing the measurement problem. The authors basically argued that there is more to the story and postulated the existence of “hidden variables” (HV). According to this perspective, these hidden variables serve as the “genes” of a particle, akin to an inaccessible genetic code. Though beyond our reach, the realist viewpoint, or the HV theory, asserts their existence, containing information about a particle’s measurement outcome. Take, for instance, the spin property of an electron, which can be up or down when measured along a certain axis. If not observed, the electron exists in a superposition/mixed state of up and down according to QM principles. Only upon observation, it takes on either one of the values (up or down); and we cannot know which one. In contrast, the EPR paper proposes that the particle has a HV that actually dictates what the measurement outcome is which also means it has always had a definite, real property since its creation. This HV is currently inaccessible and beyond our human scope.

So, how can we test the EPR idea or the HV theory? In 1964, John S. Bell, an Irish Mathematician published an article demonstrating that measuring the spin of entangled particles could, in principle, serve as a decisive test for the existence of hidden variables. In the absence of hidden variables, the spin (or any property) of a particle would genuinely exist in a peculiar superposition state encompassing all potentialities. The initial experiments utilizing Bell’s ideas were carried out by John Clauser [Freedman, Stuart J.; Clauser, John F. (April 3, 1972). “Experimental Test of Local Hidden-Variable Theories”. Physical Review Letters. 28 (14): 938-941] at Columbia University in 1972. In his experiments Clauser employed photons and measured their “polarization.” Polarization is a directional physical property of light akin to the spin of an electron. His results strongly refuted the HV theory, thereby aligning with the QM perspective. In the coming years, physicist Alain Aspect carried out more sophisticated experiments that ruled out possible imperfections (loopholes) in Clauser’s initial experiments. The cumulative outcomes of these experimental studies not only enhanced the QM viewpoint but also unequivocally ruled out the hidden variables. Remarkably, J. Clauser and A. Aspect were two of the three experimental physicists honored with the Nobel Prize in Physics in 2022 for their groundbreaking investigations with entangled particles, persistently supporting quantum mechanics.

In contemplating the broader context outlined so far, we find ourselves compelled to acknowledge the inherently ambiguous nature of reality in the quantum realm. Particles exhibit properties that are in a superposition state leaving us only with uncertain claims and talking in terms of possibilities. This is equivalent to attributing wave-like properties. (For instance, a wave is extended and stretched and does not have a distinct position – it is in many places.) Yet, upon observation, the property becomes one of the possible realities and remains in that state. In other words, the wavy behavior goes away, and we now have a particle after the observation. This mind-blowing inference makes us ask what reality is. Is it a state of possibilities that only reveals itself only after we make an observation? Then, is it the act of observation that plays the critical role here? One is even tempted to say a reality exists solely through our perception. The interpretation of quantum mechanics is the topic of an ongoing debate. The experimental facts and the accurate mathematical description stay intact, but fundamental questions persist. Questions like “how does it make sense?”, “what does this all mean?” still temper with the minds of many philosophers and scientists. There are several interpretations of these quantum mechanical principles which we will only name here such as Many Worlds, Ensemble Interpretation, or Objective Collapse.

Beyond these various interpretations, a realization emerges from all this: our human understanding and knowledge remains fundamentally limited. Regardless of the advancements we make, there is a limit within the universe that puts us in a blind position. It is as if an imperceptible barrier restricts the boundary of human knowledge cautioning “no entry beyond this point.” It is as if “the keys of the unseen” is with God only (Qur’an 6:59), and that He creates every moment (Qur’an 55:29).

Another point to contemplate is the power of observation which in a sense showcases the significance of willpower. Our observations can change the reality in the quantum world. Extrapolating from this principle one may even argue that “if you really desire an outcome, visualize it, contemplate it, put in all your effort, and it will happen.” These are actually ideas that have widely been used by people in the field of self-improvement.

A third point is the wavy behavior we encounter in the quantum realm. An electron is like a wave until observation, after which point it becomes a “particle.” This prompts us to ponder: could the essence of everything be rooted in wave-like structures, suggesting a universe composed of foundational waves permeating all aspects of existence?

Note

1. Nursi, Bediuzzaman Said. 2007. Al-Mathnawi al-Nuri (Seedbed of the Light), The Light Inc. NJ. p. 68. The Turkish original is “Nazar ve niyet mahiyet-i eşyayı tağyir eder.” “Nazar,” originally from Arabic, means eyesight, vision, viewpoint, perspective. We preferred to use “observation” here to make a better connection with the article. Already done with vision and from a viewpoint, “observation” is not a false translation.

How about quantum computers? Quantum computers make use of a quantum mechanical phenomenon, so-called quantum superposition (being in different states simultaneously). Classically, voltage across a circuit element can be either positive or negative when measured by a voltmeter, but not simultaneously negative and positive. Could it somehow be possible to be in both states simultaneously?

Quantum superposition

For electrical circuits, the answer is obviously no. In microscopic scales of single atoms, or photons (i.e., single quantized packets that constitutes the light beam), however, the answer is yes. Consider an optical component, for instance, that splits an incoming light beam into two beams of equal intensity. In optics, such a device is called a 50/50-beam splitter. You can ask what happens when a single photon is sent to such a beam splitter. Since a single photon cannot be split in this simple experiment, you might expect that it would either be transmitted or reflected with equal probability . Experiments, however, show that this is not actually true in the single photon level. The single photon is indeed simultaneously reflected and transmitted.

Once microscopic quantum superposition is brought into our macroscopic world, we can imagine many interesting phenomena. Simultaneously occupying many different places and being dead and alive at the same time are only two of them. Of course such technology, especially applied to humans is highly science fiction, given current experimental and theoretical challenges. Nevertheless, quantum superposition has a strikingly interesting similarity with the spiritual states already achievable by saints, such that they can be available in more than one place at a given time or become dead and alive, in the sense that they live both in the future and in the past.

It is not known exactly why quantum superposition exists, but what we know is that it is a necessary ingredient for our complex universe to perform its vital functions in a finite amount of time. Quantum superposition principle reflects the great wisdom and power of the Omnipotent. Similar to the single photon example above, with this principle, God gives the underlying particles of the universe an immense power to achieve many tasks simultaneously. Otherwise, regarding the finite age of the universe (about 15 billion years), our physical universe and the events taking place all around us would not come into existence. The Quantum superposition principle has also inspired researchers to build unprecedentedly fast computers to solve the problems that are intractable with any classical computing method. In this article, we introduce this new strategy to computing.

Quantum computing with superposition

Having provided some background about the quantum superposition, we ask the question “How could we exploit quantum superposition for fast computing?” Below we will give a glimpse of that power. Consider a three-bit register. It can only store one out of eight numbers in the set, {0, 1, 2, 3, 4, 5, 6, 7}, in a given moment of time. For example, number 5 is stored in a three-bit register as “101.” Now suppose that these three bits are replaced by their quantum cousins, so-called qubits (short for quantum bit). You can imagine, for example, a quantum register consisting of three rubidium (Rb) atoms. These individual atoms can be prepared in the 0 and 1 logical states simultaneously by shining a laser beam for a certain amount of time. Then it is possible for three atoms combined to be prepared in a superposition of eight numbers, which is impossible classically. In other words all those eight guys physically exist in the same room, although it doesn’t allow more than one guy to fit classically. If we want to make operations on all of these numbers, we don’t need to perform serially; instead, we can achieve that in only one computational step on a single hardware. Thus, quantum superposition leads to a massive parallelism, which renders the computational complexity (i.e., a measure of how efficiently a given problem could be solved) highly reduced for various difficult problems in computer science.

For example, let’s consider RSA, a well-known algorithm (i.e., a set of instructions to solve a problem on a computer) for secure communication that was invented by Rivest, Shamir, and Adelman, hence the name, in 1977 at MIT. It is widely used in electronic commerce protocols. The details of RSA are out of scope in this article (See the FAQ section of the RSA Laboratories’ web site in Ref. [1] for a brief introduction to RSA). Here, we only want to mention its vulnerability to quantum computers if they were to exist. The security of the RSA cryptosystem relies on the difficulty of factoring large numbers, which is intractable with classical computers. Factorization for small numbers, say 15, is quite simple. When the number of digits increase up to a few 100s, for example, enormous computational resource is required. RSA Laboratories publish the RSA challenge numbers (see Ref. [2] for the list of challenge numbers and the prize) on their web site to test the security of their algorithm at various key lengths. The largest integer, RSA-640, which has 193 decimal digits (640 bits), was factorized recently by F. Bahr, et al. The next challenge number in turn is RSA-704, and the prize is $30,000. Imagine factorizing a 1000-digit number. You would probably be a considerably rich person in just a few minutes, if you had a moderate quantum computer and the RSA Laboratories kept feeding you with new challenge numbers, because the factorization of such a large number with current computational resources takes forever, perhaps even more than the estimated age of the universe. Of course, the RSA Laboratories will not let you be very rich, by simply quitting posting new challenge numbers. They would be interested in your quantum computer, though.

How does the quantum computer crack the world’s most secure cryptosystems with little effort? One can construct new algorithms for quantum computers based on above described principle of superposition. These algorithms can take the outcome of previous calculations and input them as a superposition to the next stage of the instructions, which results in a highly efficient form of computing (please consult Ref [3] to have for a simple explanation of quantum superposition for fast computation). In 1994, Peter Shor from AT&T’s Bell Labs in New Jersey just did that. He developed the world’s first quantum algorithm, which efficiently performs factorization. In 1996, Lov Grover also at Bell Labs invented the unstructured database (i.e., a disordered list such as a list of city names not in alphabetical order) search algorithm for quantum computers, so-called Grover’s algorithm.

Suppose that there is a basket with ten balls in it. You are now asked to find a specific one with your eyes closed, say red. It is known, however, beforehand that there is only one red ball in the basket. All you, or your smart digital friend, can do is just pick one randomly and see if it is red. If you are lucky enough, the first ball you pick might be red. In the worst case, however, you will be successful at your last choice. So, classically you have to repeat the process on average at half times the number of balls. If you made a quantum friend rather than classical, however, your life would be smoother. You would be able to find and manage your stuff easily, no matter how messy you are. Quantum computers speed up such unsorted database searches quadratically. You can find, say your favorite socks, in a number of trials that is about the square root of the total number of your stuff. You may think that you don’t have that much stuff. But consider identifying a specific element in a considerably large pool of unsorted data. As the number of elements in the set increases, it quickly becomes intractable to find what exactly you are looking for. In that case the significance of quadratic boost cannot be denied.

Motivated by the above mentioned factorization and unsorted database search algorithms, the power of quantum computing has inspired great attention, since their invention, among many disciplines including physicists, computer scientists, mathematicians, engineers, and material scientists.

Quantum computer today

Despite promising developments in theory, progress in the physical realization of quantum circuits, algorithms, and communication systems have been extremely challenging to date. There are many approaches for quantum information processing. Major model physical systems include nuclear spins, ions, neutral atoms, solid state nanostructures, superconductors, and optical circuits. In optics, for example, the qubit can be represented by the polarization (i.e., direction of oscillation of electric field) state of a single photon. So that the instructions described by the algorithm could be implemented by manipulating the polarization states of single photons. Unfortunately, all the models for quantum computing have their own drawbacks besides their advantages.

Given the trends, nobody knows whether or not a sufficiently scalable (i.e., large enough to harvest its potential power) quantum computer would be available in the decades to come. Nonetheless, D-Wave Systems, Inc., The Quantum Computing Company, was eager enough to unveil the “world’s first commercially viable quantum computer” (see Figure 1, and Ref [4] for the story.). D-Waves’ 16-qubit quantum computer makes use of superconducting element niobium, which operates at an extremely low temperature. It can search for molecular structures that match a target molecule, create a complicated seating plan, and fill in Sudoku puzzles. Although the device is very slow compared to an inexpensive PC, D-Wave intends to develop a 1000-qubit quantum computer.* The goal is to scale the quantum computer to about 10 thousand qubits to solve the most challenging problems outright, which are simply intractable with classical computers. The researchers, however, are not very optimistic. Prof. Lloyd of Massachusetts of Institute of Technology, a pioneering scientist in superconducting approach for quantum computing that underlies the D-Wave’s quantum computer, says “It’s too good to be true.”

Once quantum computers of reasonable power are built, the world will be unimaginably exciting and perhaps scary too. When the first commercial computer, Universal Atomic Computer I (UNIVAC I) (see Figure 2), was shipped to the United States Air Force in 1952, nobody was indeed aware of what this fat guy would lead to in our social, economical, political, and psychological life. Its descendants, however, are now inevitable parts of our lives. They are helping us in many aspects of daily life. Controlling machines, sending electronic mail, scheduling our plane tickets, communicating with our best friends, playing games, making our payments are only some of them.

In this article we only sketched the quantum superposition principle as an important ingredient for quantum computation. This is certainly not the whole story. “Entanglement” [6], for example, is another complementary resource for quantum computing and communications, as well as quantum mechanics to test its foundations.

Contrary to its classical counterparts, the power of quantum computers indeed comes directly from our granted capability of tailoring and mimicking the amazing design hidden in the microscopic world of atoms, photons or other quantum particles. Quantum computers sooner or later will bring the most science-fiction into reality. They will play a significant role especially in the development of ultra-intelligent machines and robots superior to classical ones, and communication systems whose ultimate security is guarantied by the nature’s architecture which was lay down by God. Quantum computers will reveal to us the deepest secrets of our Creator embedded in our universe, which cannot be explored using conventional computers. That day, the future will only be lacked by our limited imagination.

Acknowledgment

This article was produced in MERGEOUS [7], an online article and project development service for authors and publishers dedicated to the advancement of technologies in the merging realm of science and religion.

Omer D. Ikramoglu is a freelance writer in optics and quantum physics.

References

1. RSA Laboratories, http://www.rsa.com/rsalabs/

2. RSA Challenge Numbers, http://www.rsa.com/rsalabs/node.asp?id=2093

3. A short introduction to quantum computation by A. Barenco, A.Ekert, A. Sanpera and C.Machiavello from La Recherche, November 1996. http://cam.qubit.org/articles/intros/comp.php

4. J. R. Minkel, “First “Commercial” Quantum Computer Solves Sudoku Puzzles”, Scientific American, Feb 13 (2007).

5. UNIVAC I, http://en.wikipedia.org/wiki/UNIVAC_I

6. S. Candaroglu, “Quantum Entanglement: Illusion or Reality?” Fountain, Issue 61 (January-February 2008).

7. http://www.mergeous.com/

* At the time of writing D-Wave Systems had only 16-qubit quantum chip and they were intending to develop a 1000-qubit quantum computer by the end of 2008. Although they couldn’t meet their goal, they now have a design of a 128-qubit most powerful ever quantum chip which awaits the tests (see http://www.dwavesys.com for up to date information).