# The Power of Quantum-Inspired Computing: Journey of Digital Annealer (Pt. 1)

*For most of us, the idea of quantum computing is akin to an exotic beast: Somewhere in the back of our minds, we know that it exists and that at some point in the future we might even be able to build proper machinery, which will be easily accessible and can solve real world problems that are unsolvable today. But what would you say if someone told you that it is possible to provide and utilize quantum-like capabilities and solve these problems in the here and now? Well, that would seem like this person had just claimed to have spotted Schrödinger's cat in the wild. This five-part blog will help us find out more.*

The **idea of quantum computing** has been around for quite a while. In fact, it **will turn 60 next December**, effectively nearing what would usually be described as retirement age not only for people, but also for concepts that – for all their popularity – failed to materialize over such a long period, much like, say, interstellar travel or entirely benign cyborgs. However, in stark contrast to those two, **quantum computing seems to be nearing the brink of realization**, with various experts implying that the first large-scale 'quantum device' might be built within less than ten years. Bearing this possibility in mind, it should be useful to **examine future usage scenarios for upcoming and existing machinery** that either possesses quantum capabilities or successfully emulates them.

**Quantum Computing and Quantum Computers**

So, what is quantum computing and what is it expected to achieve, once the technology is ready and equipped to be solving real world problems? As the term implies, it is **leveraging quantum phenomena to speed up computations exponentially**, a goal that – **according to Fujitsu CTO Dr. Joseph Reger** – would remain **unattainable for today's standard hardware** based on Moore's law and digital circuits even in the next million years. More prosaic explanations assert that quantum computing leverages any or all properties of quantum phenomena seen in molecules and/or subatomic particles, such as superposition (also called quantum parallelism), entanglement and tunneling:

**Superposition**is the**ability of a quantum system to be in all possible states at the same time**. It implies that N qubits are computationally equivalent to 2^{N}classical bits.**Entanglement is the property where 2 particles are connected and their behavior is correlated**irrespective of the distance between them.**Quantum Tunneling**denotes the**capacity of a subatomic particle to pass through a barrier that it could not surmount**if only the rules of classical mechanics applied.

Now imagine that we could **put any or all of these phenomena to use in compute systems**, and you get a pretty good first idea of how an actual quantum computer may work and why it would be **superior and revolutionary** compared to any other classical computing system of today. When it comes to performing certain tasks **in areas as diverse as cryptography, material science, or financial services**, it would be a game changer. Imagine using superposition in computing – it essentially means you can compute all possible states or paths at once instead of sequentially deriving results.

But **what could we achieve** with so much computing power or speed? **What kind of problems** are we talking about? Let's take the example of **drug discovery, an area where billions of dollars are spent each year** to discover new drugs or medicines for diseases. One of the **key ways** of finding alternative or better drugs is to **explore molecular similarities**. This may sound simple; however, it is a very **tedious process dealing with quintillions of possibilities** to solve or find the accurate, closest possible molecule. Using standard servers or even supercomputers, this would take millions of years, as they can only compare the molecules one by one across a seemingly infinite database. Similarly, **breaking a 600 digit encryption code** could take 20 billion years on a supercomputer – or in other words, 1.5 times the age of the universe, as Dr. Reger explained back in 2017. There are **several such problems** that involve huge computations to be performed with unprecedented accuracy in order to help us solve **massive societal challenges**. Quantum computing is expected to do just that by calculating or computing all possibilities at once, instead of one by one.

By now, you most likely have guessed that **such computers would rely on a totally different architecture** than the one we find in devices we're used to: Instead of encoding information into bits using strings of zeros and ones, **quantum machines employ a series of quantum-mechanical states to achieve a similar goal, thus creating a so-called qubit** – essentially the analogue of a classical bit, but one that carries an exponentially larger amount of information. Based on these observations, we arrive at the following provisional **working definition: A quantum computer is a computer that uses subatomic particles, such as photons, to store information in qubits and carry out complex mathematical operations that standard devices are either completely unable to perform or cannot master within a reasonable amount of time.** Unfortunately, that's also where the trouble starts. (To be continued in part 2.)

*Manju Annie Oommen*

*Dr. David Frith Snelling*

## About the Author:

Sr. Manager – Product Marketing

## About the second Author:

Fujitsu Fellow and Program Director Artificial Intelligence, CTO Office, Fujitsu

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