Introduction to Quantum Computing

Are our laptops or those gigantic supercomputers like to one in Oakridge National Lab, which consume electricity at a rate enough to power at least 260,000 laptops not enough for us? If yes, why? If no, why? If both, why? What gives the quantum computer an edge over the supercomputers or any ‘classical’ computer? What can a QC be made of? Why don’t I have one yet? In a lecture in the year 1981, Richard Feynman had said, “Nature isn’t classical, dammit, and if you want to make a simulation of nature, you’d better make it quantum mechanical, and by golly it’s a wonderful problem, because it doesn’t look so easy.”

As Feynman rightly predicted, this is what is now being done in the form of quantum computers, and in his talk, the speaker Arush Gupta mentioned how the study of quantum many-body systems, such as the ones found in magnetic and semiconducting materials, done by using ultracold atomic gases, calls for the need of simulations which when done classically require more number of possible states than there are protons in the universe! Richard Feynman had envisioned around 40 years ago that a possible way to simulate strongly correlated electronic systems was to send in laser beams from opposite directions to create standing waves through which atoms could tunnel, hence simulating the electrons as they too can exist in a superposition of numerous states simultaneously.

Arush also described some of the gigantic supercomputers like the one in Oakridge National lab and how they still prove to fall behind when it comes to simulating quantum systems. He went on to explain what qubits are and how they can exist in superposition states. He gave the audience an idea of how quantum algorithms work by explaining the Deutsch-Jozsa algorithm with the help of a Harry Potter analogy. Arush ended his talk by mentioning the DiVincenzo criteria, which are conditions any candidate quantum computer must satisfy. Hence the talk highlighted the need for quantum computers along with giving an insight into how quantum simulations can be implemented. Here is the link to the Tedx talk which covers some of the topics he spoke about.
Arush Gupta is a fourth year undergraduate student at IIT Bombay majoring in an interdisciplinary field. He is an amiable person and shares a passion for physics

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