Quantum computing

The Next Computing Evolution On The Horizon!

It has been almost 47 years from the release of the world’s first commercial microprocessor on a silicon-chip, the Intel 4004, a 4-bit CPU comprising of only 2300 transistors. Since then, the silicon-chip technology got advanced & cost effective and brought us to the current state of computing where we have a plethora of silicon-chip based digital computers all around us starting from our utmost convenient & personal device, the mobile phone, to the purpose-built, state-of-the-art superco- mputers used for handling more complex computational tasks needed in fields such as Space Exploration, Weather Reporting & Scientific Studies. Even a typical desktop personal computer we use today has processors which contain more than half a billion transistors providing speeds measured in gigaflops.However, it is obvious that our thirst for computational needs has not been fulfilled yet and will not be forever. On the other hand, transistor, the building block of our digital computer processors, reaching its atomic level miniaturization which is a fundamental barrier

D-Wave Quantum Processor

atomic level miniaturization which is a fundamental barrier, is reaching to its limits. The Moore’s Law, that states the number of transistors incorporated in a chip will approximately double every two years, will become invalid by around 2025 according to most of the semiconductor-industry forecasters including Gordon Moore. This leaves us in the necessity of a technology that can surpass the computing abilities of the current digital silicon-chip technology in order to fulfill the computational needs of the future. Even though there are several such computing technologies emerging, Quantum Computing takes an upper hand. Despite the fact that Quantum Computing is still in its infancy, by reviewing the present developments, it is evident that Quantum Computing would be the future of computing.

D-Wave Quantum System with Visible 512-Qubit Chip

What’s Quantum Computing?

In Quantum Computing, we make use of the unusual phenomena such as superposition and entanglement that matter exhibit at below atomic level or quantum level. In contrast to the conventional transistor-based digital computers which uses binary digits; “bits” (0 or 1), always in one of its two definite states, quantum computers are based on quantum bits known as “qubits”, which can be in a superposition of states allowing them to work on million computations simultaneously and making them inherently parallel and powerful. For instance, a 30-qubit quantum computer would be equal to the processing power of a conventional computer that could run at 10 teraflops (trillions of floating-point operations per second) while a typical desktop computer runs at speeds measured in gigaflops (billions of floating-point operations per second).

The beginning –

The basic model for a quantum computer was first described by an American physicist Richard Feynman in 1981. However, the first theorization of quantum computing was taken place in 1981 by a physicist at the Argonne National Laboratory, Paul Benioff. In his theory, he described quantum mechanical Hamiltonian models of computers. In his speech “Quantum mechanical Hamiltonian models of discrete processes that erase their own histories: Application to Turing machines” he gave at the conference “Physics of Computation” held at MIT in May 1981, he theorized about creating a quantum Turing machine based on Turing Computability Theory which is also the base of the most conventional digital computers we use. In 1985, David Deutsch, at the University of Oxford, described the first universal quantum computer as it is possible to simulate any other quantum computer with at most a polynomial slowdown.

The first experimental demonstration of a quantum algorithm, a working 2-qubit NMR quantum computer used to solve Deutsch’s problem was demonstrated by Jonathan A. Jones and Michele Mosca at the University of Oxford and shortly after, by Isaac L. Chuang at IBM’s Almaden Research Center and Mark Kubinec at the University of California, Berkeley together with coworkers at Stanford University and MIT. Since then, scientists have already built basic quantum computers that can perform certain calculations but a practical quantum computer that can be utilized in our everyday computing is yet to be developed.

D-Wave Quantum System

Current status –

As of the time of writing this article, even though the development of actual quantum computers is still in its infancy, experiments have been carried out in which quantum computational operations were executed on a very small number of quantum bits and both practical and theoretical research continues as an effort to develop quantum computers for civilian, business, quantumtrade, environmental and national security purposes such as cryptanalysis. Companies such as IBM, Google, D-Wave Systems, Intel, Microsoft are in developing their own versions of quantum computers. Among them, D-Wave Systems, the world’s first company to sell quantum computers, currently have released the “D-Wave 2000Q” in January 2017, a 2048-qubit annealing-based quantum computer. IBM has given the access to the general public to their prototype quantum-processors via their “IBM Q Experience” online cloud platform. Currently, it has two 5-qubit Processors & one 16-qubit processor, that can be used to run algorithms and experiments. They also provide an online internet forum for discussing quantum computing relevant topics, a set of tutorials on how to program the IBM Q devices and other educational material about quantum computing. As of today, IBM reports that there are over 80,000 users of the IBM Q Experience who have collectively run over 3 million experiments. Among those users, many of them are active researchers who have collectively published at least 71 academic papers using the platform. University professors are also integrating examples and experiments based on the IBM Q Experience, into their educational curricula.Recently, Google unveiled the world’s largest quantum computer processor to-date, the “Bristlecone”, a 72-qubit gate-based superconducting system that blows the previous best, IBM’s 50-qubit processor, out of the water. They created this 72-qubit processor by scaling their previous 9-qubit system.

Inside a D-wave System

Quantum Supremacy & the future of Quantum Computing –

Quantum supremacy is the moment when a quantum computer can carry out a task beyond the means of today’s best classical supercomputers. In a Google Blogspot, they mention that if a quantum processor can be operated with low enough error, it would be able to outperform a classical supercomputer on a well-defined computer science problem; an achievement known as quantum supremacy. Some experts believe this will happen at around 100-qubits, where a quantum system would theoretically be more powerful than all the supercomputers on the planet. When it comes to quantum supremacy, size is not everything. However, Google researchers point out, although no one has achieved this goal yet, the calculated quantum supremacy can be comfortably demonstrated with 49 qubits, a circuit depth exceeding 40, and a two-qubit error below 0.5% and they believe the experimental demonstration of a quantum processor outperforming a supercomputer would be a watershed moment for the quantum computing field which remains as one of the key objectives.

Even though there are still a few challenges standing in the way of quantum systems, making them not feasible for anything except laboratory work, the quantum computing taking the place of silicon-chip based digital computers that we use every day, is not too far away. 

Exposition Magazine Issue 14

Piyumika Peiris


Department of Industrial Management

University of Kelaniya

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