Quantum Computing: Limits, Options And Applications
(Forbes.com) Semiconductor companies have used various techniques to keep Moore’s Law alive in recent years. Some in the computer industry are moving away from central processing units (CPUs) to more powerful and purpose-built graphical processing units (GPUs). All of this raises a few questions: How long can we continue to improve? Do we have to do something fundamentally different? How do so-called quantum computers figure into this process?
Kazuhiro Gomi, a Forbes Technology Council member writes, “We are not looking at an either/or scenario”. Quantum will not displace classical computing. Rather, it should be utilized as an accelerator to take up specific kinds of tasks or applications. Classical systems will be used for a long time to run task scheduling and also human-machine interface. Both have strengths, weaknesses and best use cases.
One approach involves the use of quantum gates, a basic quantum circuit that operates on a number of qubits. While sensitive to noise and gate error, quantum gates are suited to discovering hidden patterns. Yet, they are unlikely to be commercially available for many decades (which gives cryptographers time to develop post-quantum encryption algorithms).
Another quantum gate-based approach is emerging with different characteristics. Using the quantum approximate optimization algorithm (QAOA), this system is relatively robust against noise and gate error and suited for combinatorial optimization.
Then there is the so-called Ising model, named after the physicist Ernst Ising, who was a pioneer in explaining phase transitions between magnetic states. This model has several variants, one of which is similar to QAOA-based simulation in its merits, limits and roadmap; but instead of using gate-based quantum processors, it builds a network of artificial “spins” using coherent Ising machines.
It is important to note that there is more than one quantum computing model, each with pros and cons, timetables for realization and optimal applications.