Quantum computing: Unlocking the unknown

TO THE POINT

Quantum computing is a fascinating field of computer science that has the potential to disrupt and revolutionize the way computers are used today. The combination of quantum mechanics and computing have enabled us to explore the world of the very small and unlock the power of atoms. Through this, it can create complex machines and solve problems that were once thought to be impossible. By understanding the principles of quantum mechanics and computing, humankind can take a step closer to realizing the capabilities of this revolutionary technology. Quantum computing is an innovative field that has the power—and has already started— to shake up the world.

Quantum computing is a revolutionary technology that integrates quantum physics properties into a computer. This technology could revolutionize industries by solving complex problems at a faster rate than traditional computing methods. Businesses in various sectors, including finance, healthcare, and transportation, are exploring the numerous benefits of quantum computing to gain a competitive edge and drive innovation. This technology is poised to create a significant impact on the future.

Let’s explore how quantum physics meeting computing will shake up the world, promising a new reality that’s already starting to take form.

It’s time to bust the myth: A computer is nothing more than a calculator.

This may sound like an oversimplification, but the first goal of a computer is to perform calculations, and the second is to store results. From browsing files on your computer to video games, a computer always goes through the same process: addition calculations. At the heart of your computer is a microprocessor called the central processing unit (CPU); calculations occur here and the results are stored in storage hardware that you can access depending on their nature (e.g., cache for immediate results from the CPU, RAM for fast results, memory for medium or long-time results like pictures, photos, etc.).

Contrary to traditional computers, quantum computing uses quantum interactions to perform calculations that are underpinned by two fundamental principles. These are:

• Quantum superposition
• Quantum entanglement

Quantum superposition is often understood through Schrödinger’s cat (Figure 1):

                                                             Figure 1: Schrödinger’s cat 

Imagine that a cat is confined in a steel container together with the following devices (which must be protected from the cat's direct access): An atom, a detector and a death mechanism composed by a hammer and a poison bottle. The radioactive atom includes two states:

• State A: The atom is stable and does not trigger the detector; the cat is alive.
• State B: The atom is unstable, triggers the detector and the death mechanism breaks a poison bottle with a hammer; the cat is dead.

Through quantum superposition, an atom can be in both state A and state B, meaning the cat can be both dead and alive. This thought experiment highlights the limitation of quantum mechanisms at a human level, as a cat cannot be both dead and alive. However, atoms can simultaneously be in two different states. It’s important to state that this superposition state only occurs when atoms aren’t observed or measured. When they’re measured, the superposition state collapses and atoms can only be in a deterministic state (here, state A or B). Hence, quantum superposition represents the probability of an atom being measured in a certain state.

Quantum entanglement allows two (or more) atoms to have a hidden link between each other, meaning when one atom is modified, entangled atoms are also impacted (Figure 2).

                                             Figure 2: Quantum entanglement principle

If two entangled atoms are in superposition (either state A or B), one atom’s measurement affects the other entangled atom, even if the other atom was not yet measured. In fact, a group of entangled atoms cannot be described independently of the others’ state.

How does quantum mechanics apply to computers?

In 1981, American theoretical physicist Richard Feynman is reported to have said: “Nature is quantum, […]! So, if we want to simulate it, we need a quantum computer.”

In a classical computer, information is stored in bits, which have a value of either 0 or 1. However, within a quantum computer, information is stored in qubits, which also have a value of either 0, 1 or a superposition of the two.

                                                  Figure 3: Classical bits vs qubits states 

Hence, when a qubit is in a state of superposition it can represent multiple values at the same time. Combined with quantum entanglement, quantum computers can simultaneously perform operations on multiple values. This is known as parallelism, and it’s one of the main reasons why quantum computers can solve certain specific problems much faster than classical computers.

However, qubits and their entanglement pairs are highly sensitive to the environment, and they are easily disturbed by the surrounding noise. So, it remains a breakthrough challenge to maintain more and more qubits entangled in superposition state over the time.

What benefits can quantum computing bring to the modern world?

Quantum computing provides improvements to many domains of present-day life, creating opportunity from which society can gain tangible benefits. Some examples include:

Database search
One of the most famous applications of quantum computing is database search. For datasets with N elements, a quantum computer will take √N operations to find an element, compared to N operations in a classic computer. Consider a bank that needs to retrieve an element from a dataset of 100 billion transactions. A quantum computer will take four milliseconds to do this while it would take a good microprocessor 20 minutes. Developments in quantum computing will revolutionize the next generation of databases, impacting the future database leaders.  

Refactor internet encryption
Using quantum computing maliciously can disrupt communication, as processes can break down encryption protocols in minutes. This was the case with RSA (Rivest–Shamir–Adleman) a public-key cryptosystem that’s widely used for secure data transmission. In response, the global internet authority prepared a new encryption protocol to prevent this incoming threat. Without this new encryption protocol, all secured communication through the internet would be jeopardized, including especially sensitive information like credentials, payment information, privacy data, etc. 

Computational biology
One of the most significant components to understand in biology is protein folding. By understanding and predicting how proteins fold, researchers can determine its properties and try to make advances in medicine. And since proteins are intrinsically composed of atoms, they are therefore subject to laws of quantum physics. Thus, quantum computing promises to improve predictions in protein folding, which could further the development of new treatments. 

Drug design and discovery
When it comes to bringing new medicines to market, the research investment required is a considerable constraint. As a result of research costs, rare diseases are too often ignored by pharmaceutical companies. Quantum computing can help change this by simulating a body at a subatomic level, creating an “identical twin” or “digital replica.” This “twin” would then act as a proxy on which to run simulations with several medications and identify those that are most effective. Furthermore, this “digital twin” can also be used to personalize medicines for tailored patient treatments. 

New internet
Another theoretical application of quantum computing with the potential for significant impact is an internet where information is not emitted through electrical wires but directly teleported. While it might sound like science fiction, thanks to quantum entanglement, it’s hypothetically possible to use entangled qubits to share information all around the world. By improving all services provided through the internet, it could ultimately reduce the latency of global communications.   

All these applications demonstrate that quantum computers’ calculation capacity is a game changer across industries, with the potential to create the next industrial revolution.

Additional Resources

Mermin, N. David. Quantum Computer Science. New York: Cambridge University Press, 2007.

Michele, Cini. Elements of Classical and Quantum Physics. Cham: Springer International Publishing AG, 2018.

Tanenbaum, Andrew S. and Todd Austin. Structured Computer Organization. 6th ed. Boston: Pearson, 2012.

CONCLUSION

Quantum computing creates avenues which previously didn’t exist, but there are still some obstacles to overcome. For instance, to truly leverage the benefits, quantum engineers will need to continue making major technical improvements that differ significantly from those in classic computing. This is because as more qubits are added, there is more quantum entanglement that requires more calculations. To mitigate instability and reduce number of calculation errors, quantum engineers will need to keep addressing technical difficulties in quantum hardware production.

Lastly, it’s important to highlight that quantum computers are not positioned to replace our daily electronic computers. While quantum computers require exponentially fewer steps, classical computers are still faster for simple calculations. But in the use cases where the goal is complex database search or the development of new medical interventions, for example, quantum computing is the computing of choice and will undoubtedly change our world.