Introduction to Quantum Computing

Quantum Technology and Quantum Computing are coming to us right now. The potential of quantum computation will revolutionize many industries – from financial calculations and drug research to delivering real-time solution where they are not possible as of now. In this article we will give a short introduction to quantum computing and a few tips where to start to discover this exiting technology.

What is Quantum Computing and what is quantum mechanics? 

Quantum computing proposes a novel approach of computation which exploits physical properties at an atomic and sub-atomic scale. The area of physics which describes the world on this scale is called quantum mechanics and this world has weird and sometimes spooky properties which we do not observe on a macro scale. So, what are those properties?

• Wave-particle duality: electrons are particles and waves at the same time. In the famous double slit experiment electrons passing through slits are causing interference patterns on the screen (even when conducting an experiment with one electron).
• Measurement problem: in a macro world, when we observe something (for example a car from a window), it does not affect the properties of the observed object (the car does not change its speed or color). In quantum world measurements can have profound effect on the system itself.
• Heisenberg’s uncertainty principle: in the quantum world nothing is certain and fixed. Electrons are not “objects” in space but rather might be imagined as “clouds” where their existence is the most probable. Furthermore, you can either measure exactly where a particle was or how it was moving (position vs momentum).
• Superposition: electron might be at two places at once or at two states at once unless we observe it. This property is the base for Schrödinger’s cat paradox and enables quantum system to perform multiple calculations at the same time.
• Entanglement (or “Spukhafte Fernwirkung” how Einstein called it): if two particles are entangled, state of one particle affects the state of another particle regardless how far they are from each other
• Quantum tunnelling: electrons can disappear from one side of potential barrier and can appear on the other side of potential barrier – basically, they can “teleport” through walls.

Going from Bits to Qubits: Quantum Approach?

In quantum computing, we switch from bits to qubits which can hold many values (not only 0 and 1) and exploit some of the properties of quantum world described above, especially superposition and entanglement. There are still technical limitations which are expected to be overcame in the next years such as stability of quantum hardware and higher number of qubits on one device. When fully developed quantum computers are best suited to solve problems where an optimal solution from multiple number of probabilities is required. Application fields of quantum computing are potentially numerous and include unstructured database search, quantum internet, heavy computational problems like drug design and development, machine learning or finance portfolio optimization.

Where to start?

How do you start with quantum computing? There are some good and some not that good news. The good news is you don’t have to install costly equipment in your basement. Quantum computers are already available as a service in the Cloud. You can also use quantum simulators backends. If you are Python-native (as most of us in GA are), congratulations – you can use Qiskit from IBM or Cirq from Google to program on quantum computing. Sometimes, you can even integrate quantum parts into “normal” data science packages: e. g. in TensorFlow.

On the other side, to start with quantum computing, you must cover the bottom part of the iceberg. Solid university-level math and quantum mechanics foundations are necessary to proceed with quantum programming. Because you must design quantum circuits for every experiment, you should be comfortable with quantum operators and their effect to the system. A solid understanding of quantum-native algorithms is also needed to proceed with more advanced stuff. Finally, some knowledge about quantum hardware, its current state of development and limitations would be very beneficial.

Conclusion

I hope you are now as excited as we are about possibilities of quantum computing. Future is closer that we think, and we’d better be prepared! We at Ginkgo love cutting edge-technologies and challenging problems and have just recently launched our Quantum Lab. Feel free to connect!

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