Quantum computing – Hype or Reality?

Quantum computing is receiving lot of attention in the recent times. Google announced Quantum Supremacy late last year by claiming that they could execute a task in their Sycamore quantum computer in 200 seconds, that would take the world’s best supercomputer 10,000 years to complete, although the magnitude of this claim is disputed by the likes of IBM stating that an ideal simulation of the same task can be performed on a classical system in 2.5 days and with far greater fidelity[1]. Cloud service providers like Amazon and Microsoft are offering quantum services through their cloud offerings. Governments are allocating funds for the development of quantum systems and training people in this new technology. A consortium led by Cambridge-based quantum computing software developer Riverlane has been awarded a grant to deploy a highly innovative quantum operating system. Has quantum computing emerged out of the research labs to public domain?

What’s Quantum Computing

Quantum computing is a computing based on the quantum state of subatomic particles. It differs fundamentally from classic computers, which operate using binary bits. Quantum computing uses quantum bits, or qubits.

Qubit can exist in superposition of 0 and 1 at the same time. As a result, quantum computers can achieve higher information density and handle very complex operations at speeds exponentially higher than conventional computers. One qubit can represent a range of values, which is known as ‘Superpositioning’. Superpositioning grants quantum computers speed and parallelism, since each individual qubit can represent a quantitative solution to a problem.

Qubits can also be linked together (known as “entanglement”). Each entangled qubit adds two additional dimensions to the system. Combined with superposition, quantum computers are capable of processing a massive number of possible outcomes at once.

Benefits of Quantum computing

Quantum computing promises dramatic speed improvements that it could solve complex problems in hours and days, whereas the current super computers would take hundreds of years to solve.

Quantum computing promises huge impact on areas such as logistics, military affairs, pharmaceuticals (drug design and discovery), aerospace, financial modelling, chemicals (polymer design), Artificial Intelligence, Cybersecurity etc. The fields of Chemistry, Medicine and Pharmacology would shift to the next level with this dramatic leap in computing power--perhaps providing real solutions to climate change, food production and drug discovery. If usable quantum computing were accessible, the field of cryptography would dramatically change, encryption codes could be broken quickly and perhaps crushing Blockchain technology. Following table details the potential areas, where quantum computing can make a difference. 

Who is making it?

Building the hardware for a quantum computer is a formidable challenge. Qubits in their nature are very fragile and can lose the information encoded in them very quickly. The major challenge is to keep the qubits completely isolated from the environment while allowing high precision control and readout of the qubit state. To effectively decouple qubits from any noise source, and therefore sustain longer coherence times, these systems are typically cooled to extremely low temperatures using liquid helium. This puts a heavy burden on the size of the system and results in high running costs. Classical computers can be used to simulate quantum behaviours however it is not efficient. Quantum computers offer speed advantage over a classical computer.

There are many different ways to realise qubits, e.g. trapped ions, superconducting rings, photons and many others. Each architecture has its advantages and drawbacks and it is not yet clear which qubit material is the most scalable one. qubits’ delicate quantum state lasts for mere fractions of a second and can easily be disrupted by even the slightest vibration or tiny change in temperature—phenomena known as “noise” in quantum-speak. The problem quantum engineers now face is that as the number of qubits and gates increases, so does the error rate. A program on a quantum computer must be completed before the quantum state becomes garbage. And if the error rate is too high, quantum computers lose their advantage over classical ones.

There are many sources of error in a quantum circuit. The most crucial one is the error that accumulates in a computation each time the circuit performs a gate operation. At the moment, the best two-qubit quantum gates have an error rate of around 0.5%[2], meaning that there’s about one error for every 200 operations. This is astronomically higher than the error rate in a standard classical circuit, where there’s about one error every 10^17  operations. To demonstrate quantum supremacy, engineers are going to have to bring the error rate for two-qubit gates down to around 0.1%.

There are many companies and research institutes working hard to create the next generation of quantum computers

Canada headquartered, D-Wave is the world’s first commercial supplier of quantum computers and its systems are being used by organisations such as NEC, Volkswagen, DENSO, Lockheed Martin, USRA, USC, Los Alamos National Laboratory and Oak Ridge National Laboratory. D-Wave also offers cloud based services.

IBM has been one of the pioneers in the field of quantum computing. In January 2019, IBM unveiled the IBM Q System One, the world's first integrated universal approximate quantum computing system designed for scientific and commercial use.

Amazon introduced its service Amazon Braket in late 2019, which is designed to let its users get some hands-on experience with qubits and quantum circuits. It allows to build and test circuits in a simulated environment and then run them on an actual quantum computer.

Microsoft has gone further by launching a programming language Q# (pronounced Q sharp) that can work with Visual Studio and run on your laptop.  It can provide an excellent tool for simulation of quantum algorithms and developing the software bridge between classical and quantum computing.

Closing Remarks

We are entering a fascinating period in the development of quantum computers. Quantum computers represent a paradigm shift in computation. You would need to build a fault-tolerant quantum computer with more qubits so that you can generalise it better, execute it for longer periods of time, and hence be able to run more complex algorithms.

Quantum systems are scaling up in both size and reliability and are getting close to showing a real advantage over classical computers. Moore’s law been applicable over the years from the 1960s and newer generation computers become smaller in size and higher in computing power. This dream run is going to end in this decade. One possible solution for the inevitable failure of Moore’s law is quantum computing.

As this technology is still in such an early phase and its true impact is not even fully understood yet. This makes this field even more fascinating to follow. Clearly, new quantum hardware and cloud-platforms are becoming accessible now beyond the laboratory or high-cost infrastructure.  Workforce development is critical.  Software engineers, algorithm designers, data scientists, mathematicians and physicists are already in great demand.  University courses and company training for quantum computing needs to increase. Also, adequate attention is needed at board level as it is going to be a disruptive technology.

To summarise, quantum computers exist, and access to them via the cloud is affordable, university- and industry-developed education is increasing, and government funding was approved to further research and focus needed on workforce development.

Reference:

1. https://www.quantamagazine.org/quantum-supremacy-is-coming-heres-what-you-should-know-20190718/.
2.  https://www.ibm.com/quantum-computing/learn/what-is-ibm-q
3. Nielsen, M.A. and Chuang, I.L. (2000). Quantum Computation and Quantum Information. Cambridge University Press.
4. https://www.dwavesys.com/
5. https://www.forbes.com/sites/cognitiveworld/2019/02/24/why-quantum-computings-time-is-now/#424401be58d4
6. https://www.nasdaq.com/articles/quantum-computing%3A-how-to-invest-in-it-and-which-companies-are-leading-the-way-2020-02-11

[1] https://www.ibm.com/blogs/research/2019/10/on-quantum-supremacy/

[2] https://www.quantamagazine.org/quantum-supremacy-is-coming-heres-what-you-should-know-20190718/