What is Quantum Computing and How does it work?

 Post Author - TYIT Dharini Iyer

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        The electronic calculator was created by humans. Since then, the world of computing has advanced by leaps and bounds! In the field of information processing, the last several years have been particularly transformative; what were previously considered science fiction fantasies are now technological reality. Traditional computing has become tremendously quicker and more sophisticated, allowing for smaller and more versatile systems. And while we've accomplished great things with the traditional computing environment, it, too, has its limitations... 

WHY DO WE NEED MORE POWERFUL COMPUTERS? 

        "Why would we need any more powerful machines?" some people wonder. The issues we're trying to address right now are extremely difficult and aren't well-suited to the architecture of traditional computing. So, we can think of quantum computing as a novel set of tools, a new set of resources for scientists, researchers, computer scientists, and programmers to create and enhance some of these capabilities so that we can alter the world far more effectively than we can with classical computers. Moore's Law, which states that a computer's power doubles every 18 months, was predicted to cease years ago by physicists. 

        Moore's Law is already showing signs of slowing down. So, what exactly is the concern? Standard silicon technology simply cannot sustain with the exponential growth in computer power. Heat and leakage are the two primary concerns. The challenge is that today's Pentium chips have a layer that is almost 20 atoms wide. It's all over when that layer gets down to around five atoms across. The chip will melt due to the extreme heat created. You can actually cook an egg on top of a chip before it starts to dissolve. Then there's the issue of leaking. You have no idea where the electron is currently. The quantum hypothesis now reigns supreme. You don't know where that electron is anymore, according to the Heisenberg Uncertainty Principle, which means it may be outside the wire, outside the Pentium chip, or within the Pentium chip. As a result, the rules of thermodynamics and quantum physics force an ultimate limit on the amount of computational power that silicon can provide. 


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WHAT EXACTLY DO QUANTUM COMPUTERS DO? 

        A quantum computer is a technology, a technical gadget, that could theoretically harness the full power of quantum physics to do computations that a regular computer would be incapable of. For example, Google's quantum computer recently performed a computation in less than four minutes that would have taken 10,000 years for the world's most powerful conventional computer. 

SO HOW IS QUANTUM COMPUTING DIFFERENT FROM CLASSICAL COMPUTERS? 

        All computers rely on the basic ability to store and modify data. Individual bits, which store information as binary 0 and 1 states, are manipulated by modern computers. When we see the letter "A," for example, our computers perceive a precise series of zeroes and ones. A Qubit (quantum bit) is a unit of quantum information in quantum computing, analogous to a classical computer bit. Whereas traditional bits can only carry one binary value, such as a 0 or 1, a qubit may contain both values at the same time in what is known as a superposition state. One way to approach Quantum computing could be the concept of parallel universes! Yes, parallel worlds like the ones in Spiderman: No way home, Stranger Things or even Interstellar! Imagine a quantum computer that exists in two different worlds at the same time. It could do twice as many calculations as a classical computer existing in one world would be able to do. This allows quantum computers to look at many different variables simultaneously, and solve them in parallel. 

BUT IS QUANTUM COMPUTING THE FLAWLESS FUTURE WE LOOK FORWARD TO? 

    Now, quantum computing in some sense is the ultimate computer, but there are enormous problems with quantum computing. 

➢ Decoherence: Let's say we have two atoms and they vibrate in unison-This is called coherence. Assume it gets contaminated by disturbances from the outside world, say your colleague coughs or there’s a gush of wind from the window, and then all of a sudden, they're no longer in synchronization. Once you lose the coherence the computer is useless. In order to have a quantum mechanical state you have to isolate that system from all of its environment, because if it interacts with the environment, the quantum mechanical magic sort of washes away, and that's the problem with a quantum computer. 

➢ Temperature: Typically, qubits operate at 20 millikelvin, or about -273 degrees Celsius – temperatures that are even colder than outer space. A very low temperature is necessary to keep them stable. Otherwise, the super positional states (0 and 1) will quickly vanish into decoherence before any useful calculations can be done. 

APPLICATIONS OF QUANTUM COMPUTING 
        So, you may ask why do we go through all this trouble? The answer is the promise of quantum computing is exponential speed-ups over classical computing for a particular set of problems. And that's very important and exciting to researchers who are working on human-scale problems ranging from things like developing drugs for cancer or better modelling the molecular interactions of cancer and how it attacks cells and things like that, to big data analysis, looking for patterns and inferences and drawing insight from large amounts of data, or doing things like better modelling financial services markets and better managing risk and so on. So, these are all kinds of applications that aren't particularly well-suited by today's type of computers.



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