# Development of software for quantum computers

Software development on quantum computers is a different process from conventional software development. The handling of quantum bits, also called QuBits or Qbits, requires a multidimensional perspective in software development. Since 2013, our research department has been working more intensively on quantum computers and their programming. The original reason for this was an analysis order from a well-known airline. We are also strongly represented in the travel industry as a software development service company. Our customers include airlines, GDS providers such as Amadeus and large online travel platforms such as Invia (e.g. www.ab-in-den-urlaub.de). All these providers would like to offer round trips with several stopovers on their websites. There was an idea to give travellers the opportunity to put the following filters on their websites:

- It should be possible for the trip to end where it began
- The shortest (and cheapest) routes between stopovers should be made selectable

This, however, would lead to a massive overloading of entire data centers. The computational effort for the solution of these combinatorial optimization calculations for multiple passengers at the same time would not be feasible with conventional server architects in an acceptable time (https://en.wikipedia.org/wiki/Travelling_salesman_problem_salesman_problem). By using quantum computers our customers from the travel industry could probably offer round trips on their websites. But also other industries, e.g. insurances and space travel, face similar challenges. Therefore, our R&D department has been dealing with quantum engineering for quite some time. Quantum engineering refers to the application of the findings resulting from quantum mechanics research.

## What is a quantum computer?

Before we deal with **software development for quantum computers** (e.g. with the Microsoft programming language Q), we would like to explain the topics “quantum computers” and “quantum engineering” in more detail. This website about software development on quantum computers is regularly updated.

Introduction to the structure and functionality of quantum computers with QuBits. QBits replace bits and therefore mark the end of digital technology. Algorithms for classical computers according to the Von Neumann architecture (VNA) calculate with bits and have the binary states 0 and 1. Algorithms for quantum computers calculate with *quantum bits* (QuBits) and have several state variants, e.g. orthogonal states or infinitely many superposition states.

Algorithms, as they are used daily in the digital world, do not work with quantum computers.

Algorithms that can be applied to quantum computers have not been researched yet.

It is likely that it will be possible to program quantum computers on the basis of Deutsch-Josza algorithms (which are based on quantum interference effects) or Grover algorithms which make use of superposition (e.g. for database access).

IBM itself searches for the right algorithms using a kind of open innovation management strategy and provides a quantum simulation platform for everyone (URL below).

The programming of quantum computers is new, so that every mathematical-oriented newcomer now has good chances of getting started.

It can be assumed that quantum computers will replace the currently popular trends in the field of artificial intelligence, such as artificial neural networks (KNNs), in foreseeable future.

While numerous companies of all sizes are currently jumping on the bandwagon of digitization and digital transformation, the end of technical digitization is already in sight.

Digital networking will be replaced by quantum networking.

The quantum pioneers Anton Zeilinger and Jian-Wei Pan are already working on a satellite-based China-Europe quantum network (among other things in response to the US-American NSA activities), which should make it impossible to intercept data without being noticed.

## IBM’s quantum simulation for everyone

In the “Quantum Experience” project, IBM is making a quantum computer available to the masses. With 5 QuBits, this computer can probably calculate not more than the prime factors of the number 15 – of which we all know the results (3 and 5) (IBM Quantum Computing). It is rather about the algorithms that lead to these results – the computing power is not important in the first step.

The provision of a quantum computer or a quantum computer simulation by Big Blue is a friendly gesture towards the scientific community.

Nevertheless, IBM is not pursuing pure charity – this applies to all companies that offer similar open innovation platforms. According to the current state of the art, quantum computers are in theory only suitable for very few applications.

With “Quantum Experience”, IBM will probably not only try to find new ideas for quantum applications by involving society, but will also try to attract interesting new employees. The licensing agreements allow these conclusions to be drawn (IBM Quantum Experience Licence Agreement).

## Quantum computer – simplified description and field of application

Quantum computers are a bit like the Indian deity “Shiva”, who can handle several things simultaneously with her many arms.

Depending on their form, quantum computers make use of the three quantum properties (wave-particle duality, superposition and entanglement) which are difficult for humans to envisage.

While a bit in digital technology can only have two states (0 and 1/stream on and stream off), a quantum bit (short: QuBit) can have several states. Figuratively speaking, a bit can point either to the North Pole or to the South Pole, but a quantum bit can point simultaneously to both poles (and to numerous other places on earth).

Quote Brigitte Bardot:

*“The unpleasant thing about computers is that they can only say yes or no, but not maybe.”*

Quantum computers, however, are now very much in a position to say “maybe” after all.

A quantum computer would thus be the ideal solution to the problem of the traveling salesman.

There is a traveler who would like to plan a round trip across several cities and finally arrive back at his starting point again. This would result in 12 possible routes he can choose from with just four cities to visit, – but with 15 cities on his agenda however, there are already 87 billion possible routes for the traveler to choose from! This is the reason why airlines or Internet travel portals hardly offer any possibilities for roundtrip bookings, by the way.

Quantum computers are specialists for solving tasks that can be easily fixed on a small scale – but on a larger scale they can have gigantic dimensions (“quantum speedup”). The quantum speedup is a solution recipe for quantum computers where their computing time does not increase exponentially as the problem increases.

At present, there is a lack of creative solutions with regard to possible meaningful applications with different algorithms for quantum computers. However, quantum engineering is still in its beginnings and certainly won’t be inferior to the development curve of microelectronics.

The experts are currently divided into two opposing groups.

One side regards quantum computers merely as solutions for certain areas of application and thus only suitable for a few research areas or economic sectors.

The other group of experts estimates that the areas of application will develop in a similar way to classical computers (Von Neumann principle) and that everyone will have a quantum computer at home sooner ot later.

In the beginning, quantum computers will be less versatile than classical computers. In all probability, the performance lies in solving optimization and pattern recognition challenges (see above). As mentioned above, quantum computers could replace neuronal networks in the field of image or text recognition in the future.

## Quantum computer – data center environment

Quantums are losing their properties at the time of the intended or unintended measurement possibility.

In the double-slit experiment, the location or velocity of a quantum is defined at the time of the measurement (not both together, – Heisenberg’s uncertainty relation).

In the example of Schrödinger’s cat, the cat in the box would have to be completely shielded from the outside world; at the moment when the body heat or the heartbeat of the cat could be measured with measuring instruments, the quanta would lose their properties and the cat would be either dead or alive, but no longer “both” at the same time.

A quantum computer cannot be isolated from the outside world for long. The current world record is 30 milliseconds (in which the light travels at least for 9kms). For this reason, quantum computers are operated in a vacuum to prevent collisions with air molecules, which in turn can transport information to the outside; quantum computers are also operated near absolute zero (-273 °C) to prevent treacherous heat radiation.

## Quantum Computers – Algorithms to Consider

Up to now, it is only the functionality of two algorithms, that is highly probable, and which would be suitable for solving problems relevant to quantum computers. On the one hand the Shor algorithm (because factorization problems have a period) and on the other hand the Grover algorithm (e.g. with a Hadamard gate).

However, there are other quantum algorithms that could theoretically work on quantum computers. Stephen Jordan of the National Institute of Standards & Technology has summarized them all (about 50) and calls them his “Zoo of Quantum Algorithms” (Joint Center for Quantum Information and Computer Science).

Currently, there are not too many problems for which quantum computers are suitable. The factorization problem may be very complex, but there are still other tens of thousands of problems that are much more critical. These problems do not have the mathematical structure that Peter Shor used for the Shor algorithm.

There are currently no indicators at all stating that these problems could be solved, neither by quantum nor by classical computers.

From this perspective, IBM’s idea of opening the door to quantum computers for society in order to find fields of application is comprehensible and intelligent.

## Other manufacturers of quantum computers

Besides the manufacturer D-Wave, my colleague John Martinis from the University of California is also developing a quantum computer (for Google).

It currently works with 512 QuBits and is as fast as a modern PC.

This year the computer will be extended to 1000 QuBits and will be about 1000x faster.

## The inevitable way to quantum computing

Based on Moor’s law, the transistors of conventional processors will merely have the size of atoms/molecules in a few years’ time and will per se find their way into quantum engineering.

Even today, many people already work with devices based on quantum mechanical effects (e.g. USB sticks). Although quantum mechanics has not been researched yet, the transition to quantum engineering has taken place since quantum mechanics offers reliable features on the basis of which new products can be developed.

## Quantum computers and data security

At the time of the Snowden unveilings, the German magazine “Fokus” described the quantum computer as a “US monster computer”.

The magazine’s fear is exaggerated and the article does not justify this lurid headline.

There are already multiple mathematical encryption methods which will be unsolvable for quantum computers (e.g. random ellipse calculations).

The encryption algorithms contain no hidden periodicity that quantum computers could exploit.

Johannes Buchmann from the Technical University of Darmstadt is working on making these encryption algorithms fit for everyday Internet use. The quantum computer will be the end of current cryptographic methods, but certainly not the end of cryptography itself.

## Companies in Silicon Valley want to know everything about everyone

The fact that we should encrypt all our data is confirmed by the conversation between Seth Lloyds, physicist at MIT and the billionaires from Silicon Valley, e.g. Larry Page from Google.

There is a regular dinner between the researchers and the billionaires. Lloyd showed Larry Page how he could make the Google search engine more secure. Google was highly interested in Lloyd’s quantum knowledge, but less in his quantum encryption plans. Lloyd got a rejection the next day from Larry Page “we can’t buy that”. Lloyd replied “of course you can! You just spent more than a billion on Youtube. In privacy sensitive Europe you can score with it!” But Page replied “our business model is based on knowing everything about everyone; we can’t invest in a business model that prevents us from knowing everything about everyone”.

It is obvious that not only governments have a keen interest in getting information on all aspects of mankind.

Against this background and the fact that pattern recognition in mass data with classical computers and processes is becoming increasingly difficult, it is advisable to accept IBM’s offer to gain initial experience with the quantum computer. This not only addresses computer scientists, but also all people who (want to) come into contact with “Big Data” – regardless of whether they are scientists of the humanities, economics, law or nature.

## Outlook to 2030 …and a little beyond

In the medium term, powerful quantum computers with different quantum service offers will be available.

These services will be, for example, search services that will be able to search and analyze incredibly large amounts of data.

There will be quantum algorithms in genome databases for professional medical applications as well as for standard recruitment companies (e.g. IQ potential) or for consumers (e.g. partner selection, doctors, drugs).

Weather services will be able to provide numerous (micro-)climate simulations and mark the variant with the highest probability of occurrence. People surprised by the weather would be found in places without Internet connection only.

Quantum services will also carry out and optimise the complex planning of conductor paths and transistor circuits on microcontrollers. In its very own sense, the quantum computer will be able to construct and improve itself on its own.

In this respect, the accumulation of know-how in quantum engineering cannot be wrong – even if it is guaranteed that in this century artificially created or artificially expanded (bio-)intelligences will surpass not only the best human intellect, but also intuition.