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Blogs - Quantum computers – myths and reality


Quantum computers – myths and reality

The general public know more about quantum computers (QC) than silicon chips. Devs, the American science fiction thriller, provides good idea about quantum computers – both how they look and even what they may be capable of doing. QCs are all over the news – Google News features new QC story almost every new feed. The UK government and UK investors love QCs perhaps believing that in the future they may compensate for the UKs lack of advanced CMOS manufacturing capabilities. However, there are

and reality about quantum computers that should be clearly understood by the general public and by the politicians who make decisions about our science and technology future. 


Myth No. 1: QCs will replace the classical (Von Neumann) computers.
Jack Krupansky addresses this myth in his article ‘What Can’t a Quantum Computer Compute?’ ‘Quantum computers offer some awesome features, but they lack most of the features of a general purpose Turing Machine which are offered by all classical computers.’ He lists 61 tasks that classical computers can and quantum computers cannot do. To start with: QC cannot compute PI to arbitrary large number of digits. Most importantly for me, QC cannot be used for solving partial differential equations – the backbone of modelling and simulation in all engineering disciplines including both CMOS and QC design.
So what are the ‘awesome’ QC features? According to Amit Katwala ‘Quantum computers … let us do things that we couldn’t even have dreamed of without them’. This covers new algorithms for artificial intelligence (AI) applications, predicting uncertain complicated systems like the financial markets, drug discovery, and perhaps like in Devs, revealing the past future relations. From military and national security point of view the QC have the potential of cracking all encryption algorithms designed so far.
Myth No. 2. Silicon quantum chips can replace the ‘real’ (CMOS) chips.
Even if the development QC on a silicon chip is succesful, the replacement will be impossible, since QC cannot do most of the things that the silicon chip are currently doing in your mobile phones, laptops, workstations and data centres. And of course silicon QC can only work at very low temperature (close to milli-kelvin regime) – can you imagine carrying your mobile phone in a helium cryostat? By the way, perhaps more than 90% of the electronic contents of the present QCs are silicon chips.
Therefore, establishing and hopefully sustaining UK leadership in quantum computers is not a remedy for the UK lack of CMOS chip manufacturing capabilities. Clearly, we need to go back to the drawing board and figure out What Needs to be Done with CMOS in the UK.


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The Quantum computer in Devs.
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