For more than 30 years, the world has been talking about the power of Quantum Computers and asking if it is something worth investing in. Finally, three decades later, they may have a convincing answer on the way. 

Google recently announced that its machine achieved a benchmark testing computation in only 200 seconds. What’s incredible about this is that the present world’s fastest computer might take 10,000 years to give out the same results. They have named this experiment ‘Quantum Supremacy’ — and rightfully so.

Let’s take a look at the 30-year journey to Supremacy:

The 20th Century.

• The 80s – Beginning:

Most of the groundwork for Quantum Computing was in the 80s and 90s. Paul Benioff in 1980, proposed the idea of Quantum Computing based on the 1936 paper by Alan Turing, which had details about his paper tape computer. Benioff intended to use a computer which could operate under the physical quantum principle.

In the following year, physicist Richard Feynman proved that it is impossible to represent the result of quantum mechanics with a classic universal device. But in 1984 he proposed the possibility of how a quantum computer might be able to simulate any quantum system including the physical world. This concept was on a similar line with the Benioff’s Turing computer.

David Deutsch, a physicist, was the first to formulate the description of quantum Turing Machine and also specify an algorithm to run on quantum computers. He showed that the quantum machine could reproduce physical data much faster than classical computers.

• The 90s:

When Peter Shor, a mathematician at Bell Labs introduced Shor’s algorithm in 1994, it had significant implications on cryptography. Shor’s algorithm searched for periodicities in long integers, i.e., sequences of repeated digits. Shor’s algorithm broke RSA, the public key cryptosystem, which is the basis on prime factorisation. It decrypted the RSA codes faster than a classical computer; some claim the algorithm performed the computation so quickly that it would’ve taken the classical computers literally ages.

In 1996 Peter Shor with the help of Andrew Steane devised quantum codes which offset the errors. Errors occur when qubits stop behaving in a quantum mechanical sense.

In 1995, David Wineland and Christopher Monroe from NIST demonstrated the first quantum logic gate, the C-NOT gate. 

In 1996, Lov Grover’s algorithm created an interest in building quantum computers. Grover’s algorithm was used to solve the problem of unstructured search. Grover’s algorithm used quantum superimposition to reduce the number of queries for a search to √N when there is N number of queries to be undertaken. In contrast, a classical computer took N/2 number of queries.

1998 saw the first demonstration of a quantum algorithm. It was used to solve Deutsch’s problem through Nuclear Magnetic Resonance Machine (NMR). A 2-qubit NMR machine solved the problem twice as fast than that of the classical machines. Later that year a 3-qubit NMR machine was developed.

The 80s and 90s were necessary for the world of Quantum Computing because many unusual ideas that it uses today were introduced in these decades.

The 21st Century:

• The year 2000:

In the year 2000, the first 5-qubit NMR computer was put to the test by the Technical University of Munich. Later, a working 7-qubit machine was developed Los Alamos National Laboratory.

• Demonstration of Shor’s theorem in 2001: 

IBM Almaden research centre’s team in California succeeded in factorising 15 into 5 and 3. Doesn’t seem complicated right? But, they forced billions of molecules of a liquid in a test tube to create a 7-qubit quantum computer which solves simple mathematical problems and is still used in many of the data-security cryptographic systems.

• 2006, a step towards making the Quantum Computers work on a Macroscopic level:

A new operational 12-qubit quantum system with minimum errors in quantum information (decoherence) was presented by IQC (Institute of Quantum Computing) and Perimeter Institute of Theoretical Physics. The computation was decoded by an NMR quantum information processor. The attained levels at the time gave hope that Quabtun Computers may one-day start work at visible levels.

The University of Kansas created molecules of quantum dot pairs. These have more scope in quantum computing.

• 2007 – Deutsch’s algorithm and D-wave:

This year saw Deutsch’s algorithm used for the first time in a clustered quantum computer. Later the same year the company D- wave systems claimed to have developed a 28-qubit quantum computer machine. The next year they claimed to have developed a 128-qubit computer chip. Although D-wave has announced such advancements, their claims were regarded as controversial because they use methods other than quantum logic gates.

• 2011 – Deviating from Shor’s Algorithm and devising Von Neumann Architecture:

2011 is the year Von Neumann Architecture unveiled. This is a classical computer set up with a Central Processing Unit and a memory which stores data and processing instructions. 

This year also saw the introduction of D-wave one, which shunned the Shor’s algorithm, which was much faster and used a special adiabatic algorithm to solve the problems.

• 2012 – Factorising 143 by Adiabatic Algorithm and Google buys Vesuvius:

In the year 2012, some Chinese scientists were able to factorise the number 143 using adiabatic algorithms. Whereas the maximum number of that could be factorised that year was 21, which uses Shor’s algorithm.

D-wave then introduced their 512-qubit system computer called Vesuvius, which was bought by Google.

• 2013 – Quantum Computing vs Room Temperature and High-End PCs:

Quantum computing works at low temperature because working at room temperature causes qubit decoherence. 2013’s landmark was beating the record for avoiding the decoherence. The previous record of 2 seconds was smashed by 39 minutes.

This year D-wave systems released the information that they compared the speeds of quantum computers with high-end PCs. The quantum computer ran an optimisation algorithm 3600 times faster than the high-end PCs.

• 2015 to present developments:

In 2015 D- wave unveiled 1,152-qubit D-Wave 2X quantum computer, and at the start of 2017, they surpassed it with D-wave 2000Q with 2048 qubit.

D- wave’s Quantum computers are designed specifically for quadratic unconstrained binary optimisation.

Google’s recent quantum computers are designed to solve real-world problems.

What’s next for Google’s Quantum Supremacy?

Now that Google has used its 54 qubit processor ‘Sycamore’ which achieved supremacy,

Google now has mainly two objectives, first is that they want to open their supremacy processor to collaborators, academics researchers, as well as to companies that are interested in developing algorithms. Second, it wants to build a ‘fault-tolerant’ computing machine, which will help in designing new materials. For example, lightweight batteries for cars and aeroplanes, new fertilisers for plants and other effective medicines.

Quantum computing has many applications like cryptography, machine-learning, chemistry, optimisation, communication and many more. With more engineering and scientific work to be done for necessary computation, the applications of Quantum Computing seem endless.