Origin of Quantum Computing
Starting from around 1935 scientists were struggling to accept the idea that classical science might not be able to explain everything. The idea of quantum mechanics potentially breaking the fundamental laws of physics like the speed of light barrier was jarring.
A few years after Heisenberg published the paper on uncertainity principle, Einstein, Rosen and Podolsky published an article questioning the Quantum Mechanical description of Reality.
“Can Quantum-Mechanical Description of Physical Reality be Considered Complete?” was the article published in Physical Review and quoted below is the conclusion.
While we have thus shown that the wave function does not provide a complete description of the physical reality, we left open the question of whether or not such a description exists. We believe, however, that such a theory is possible.
Considering the fact that Einstein is considered the third founder of Quantum Theory, for which he won the 1921 Nobel Prize — him being associated with an article questioning the validity of that theory was too catchy a story for newspapers to pass on without taking advantage.
This story, which quoted Podolsky, understandably irritated Einstein, who wrote back to the Times clarifying that the relevant information was given to them without authority.
Einstein’s own argument
In his own publications and correspondence, Einstein used a different argument to insist that quantum mechanics is an incomplete theory. He explicitly de-emphasized EPR’s attribution of “elements of reality” to the position and momentum of particle B, saying that “I couldn’t care less” whether the resulting states of particle B allowed one to predict the position and momentum with certainty.
For Einstein, the crucial part of the argument was the demonstration of nonlocality, that the choice of measurement done in particle A, either position or momentum, would lead to two different quantum states of particle B. He argued that, because of locality, the real state of particle B couldn’t depend on which kind of measurement was done in A, and therefore the quantum states cannot be in one-to-one correspondence with the real states.
Source: Wikipedia
Shortly after on 28th October 1935, Schrödinger discussed the same matter in the Discussion of Probability Relations between separated systems and referred to the phenomenon as “entanglement” and how it was not possible to describe the same with classical lines of thought.
It took 28 long years for any significant update on the subject; on 4th November 1964 Bell was able to theoretically prove that no classical explanation was possible for the Einstein-Podolski-Rosen or EPR pairs.
This was followed by another fairly long break of about 16 years. On 20th December 1982 Alain Aspect along with Jean Dalibard and Gérard Roger was able to experimentally prove that Bell’s predictions were correct. At this point all the doubts had been clarified and it was accepted that there was no classical explanation for this phenomenon.
Around the same time efforts were already underway to utilise this brand new information about the understanding of physical reality.
Notably on 15th January 1982, Nick Herbert published a paper introducing First Laser Amplified Superluminal Hookup or FLASH, or in simpler words, faster than light communication using the non-classical properties of EPR pairs and quantum mechanics — this was immediately proven wrong by W. K. Wootters & W. H. Zurek on 28th October 1982 using what has since then been known as The no cloning theorem — this theorem states that a single unknown quantum state cannot be duplicated.
This was the situation and presence of quantum mechanics when Richard Feynman shed light on his ideas about simulating physics on computers. He said that it is very difficult to simulate quantum mechanics since it requires 2n time for n particles on a classical computer. If there were a quantum computer, it would be faster. Basically the idea was to use quantum mechanics for simulating quantum mechanics. This would result in a few key findings in the coming decade that laid down the groundwork for all the Quantum Computing research and advancements that are being done today.
