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On Quantum Computing (Undergraduate Term Paper)

Originally submitted March 25, 2020. University of Waterloo's Philosophy of Quantum Mechanics/Quantum Mechanics for Everyone (PHIL 252) with Professor Doreen Fraser.

Chosen Source: Shohini Ghose, “The Quantum Revolution”

Niels Bohr once said: “Anyone who thinks they can talk about quantum mechanics without getting dizzy hasn’t yet understood the first word of it.” (Ekert, Gottesman, Lloyd & Rieffel, 2015). In his time, quantum mechanics was a subject of great debate. Seventy years later, it remains so. Foundational principles of quantum mechanics such as superposition, quantum entanglement, and the Uncertainty Principle have continued to be strongly debated to this day. Bohr argued with great thinkers such as Einstein over the completion of quantum mechanics, and the total possibility of human understanding on the topic; which is to say that Bohr posited that quantum mechanics is, even in principle, profoundly unknowable by us (Bohr, 1948). In his view, quantum mechanics had no necessity to explain the world and the universe, and contentedly should be used as a precise tool for making predictions (IEP, n.d.).

Heisenberg’s Uncertainty Principle describes the universe’s fuzziness through the fact that we are not able to know precisely everything about quantum particles, such as both position and momentum. This is a problem which cannot be solved by better technology but is rather embedded directly in the principles of quantum mechanics (Ghose, 2020). The lacking physical reality left unconstrued by quantum mechanics greatly plagued Einstein, a realist who insisted that the imprecision of knowledge in quantum mechanics represented an unacceptable lack of understanding and theoretical completion on behalf of physicists (Born-Einstein, 1948). As Shohini Ghose states in her public lecture The Quantum Revolution, “there is nothing imprecise about the mathematics of imprecision.” The quantum revolution described by Ghose can be interpreted as having two applications—one being the increased investment and advancement in research and quantum technologies, and the second of pushing forward despite theoretical debate on the profound characteristics of topics such as The Uncertainty Principle in the scientific community. As Ghose (2020) puts it: “Uncertainty has power… [it is] not a bug, but a feature.”

Cryptography plays a key role in the current Information Age, allowing users to safely navigate the untrustworthy seas of data exchange and the internet (Mosca, 2019). Current encryption systems utilize factoring problems that are not impossible but unfeasible to hack, requiring tremendous computing power and time. Quantum computers will likely be able to solve complex mathematical problems in N steps, whereas classical computers require N steps (Mosca, 2019). The introduction and continued development of quantum computers poses a great threat to all existing security encryption systems used today. The solution: integrating quantum physics into encryption. This application of cryptography results in eavesdroppers introducing errors to key establishment and being easily detectable (Ghose, 2020). To hack the system would require defying the laws of physics, which is foreseeably impossible. In the application of quantum cryptography, measurement collapse and quantum entanglement are no longer debated hinderances, but highly useful assets. Employment of quantum cryptography has been underway for over a decade now, with one example being the Swiss government’s use of it for 2007 national elections (Ghose, 2020).

While considerable headway has been made in the developments of quantum cryptography, quantum computing technology can be described as being in its very early stages (Ghose, 2020). IBM has developed a basic, working quantum computer which is available for global experimentation and research. The technology behind quantum computers is foundationally rooted in principles of superposition and measurement collapse. These are necessary components which essentially allow qubits to operate as both zeros and ones at the same time, unlike classical computing which remains discretely binary (Ekert et al., 2015). These superconducting qubits respond to the flow of current moving around them in either a clockwise or counter-clockwise direction. Quantum computers can only operate if they are kept at a temperature nearly as cold as outer space, and if their particle systems are not directly observed or measured (Ghose, 2020). As they currently exist, quantum computers are not and perhaps never will be 100% perfect. Due to measurement collapse, quantum systems are extremely delicate, and can even be disturbed from internal atomic observation (Ekert et al., 2015). To compensate for this, physicists have introduced Quantum Error Correcting Codes and Fault-Tolerant Quantum Computation, which can require 100 or even 1000 times more qubits. Quantum information is then dispersed amongst a larger group of qubits to increase redundancy and allow errors to be spotted and corrected (Ekert et al., 2015).

As quantum computing technology continues to improve and errors are reduced, more currently existing problems will be solved, and opportunities realized. Google, for example, has built a quantum processor and confidently announced quantum supremacy over classical computing. Google’s quantum processor, despite being a very basic computer, was able to solve very complex problems that cannot be solved with classical computers or otherwise, with a clear quantum advantage (Ghose, 2020). Google’s pursuit of quantum computing is primarily tied to its interest in quantum advantages of data searching and analysis. (Ghose, 2020; Ekert et al., 2015). Quantum computing will lead to never-before-accomplished pattern analysis of massive data sets, finding patterns that could not have ever been found using ordinary computers. A potential example could be pattern-analysis of a dataset containing the complete genomes of all humans on Earth (over 7 billion or 1020 bits) (Ekert et al., 2015). This data could then be theoretically quantum encrypted and secured. As the Information Age continues, personal data is increasingly collected and the capacity to store it for indefinite periods of time becomes cheaper. The possible abuses of this data that can occur becomes increasingly dangerous with the improved capabilities of quantum computers (Ekert et al., 2015). Threats to personal privacy and the security of data may become more severe and dangerous; thus, safekeeping of this data and the necessity for broadscale implementation of quantum cryptography is paramount. Physicists working on the development of quantum computers theorize that their advancement can even be used to solve existing questions about quantum mechanics (Ekert et al., 2015). Thus, it is nearly impossible to fully understand where quantum mechanics will take us in the future, how we can benefit from it, and all the ways in which it can be abused (Mosca, 2019). Perhaps there may come a time in which deeper understandings of superposition and the measurement collapse are discovered, allowing eavesdroppers to evade detection and successfully intercept quantum encrypted connections – a thought that seems bizarre and impossible to us now.

In 1894, reflecting the popular attitude of many Victorian physicists at the time, Albert Michelson stated: “It seems probable that most of the grand underlying principles have been firmly established and that further advances are to be sought chiefly in the rigorous application of these principles to all the phenomena which come under our notice.” (Kragh, 1999, p. 3). This was soon to be revealed as completely incorrect, with scientific discoveries of x-rays, the electron, radioactivity, Einstein’s theory of relativity, and quantum mechanics itself emerging soon afterwards (Kragh, 1999). The current consensus among physicists today is generally a high confidence that quantum mechanical theory is correct and belongs on the shelf beside other successful physical theories that have been formulated in the past 120 years. It is true in many ways that the future of physics will largely involve the rigorous application of underlying principles which have already been established. Exciting future discoveries are tied to the reconciliation of quantum theory and general relativity, possible “theory of everything”, and the further development of quantum technologies that lead to greater quantum answers.

Overall, the quantum revolution has carried on not only in spite of but leveraging profound uncertainty. Physicists have developed technologies founded on the core principles of quantum mechanics, such as superposition, measurement collapse, and “spooky action at a distance” or quantum entanglement, things which were argued greatly by Einstein himself (Born-Einstein, 1948). Philosophical debates on the meaning of quantum mechanics will likely exist forever, but the application of quantum mechanics will only grow with time, exploring exciting areas such as teleportation, tunneling, sensing, and more.