It’s unique and quite intriguing to discover that quantum mechanics can manifest itself in a form that could enhance the capabilities of traditional computer systems, which as we all know today work on binary. The application creates what is called as quantum computers and it harvests the principles of quantum mechanics to attain computing power that is beyond the scope of classical computers that we now use. The article gives a brief overview of this phenomenon of computing in layman terms, one that non-physicist computing geeks could possibly digest.

**How traditional computers work –**

All information is processed and understood by a computer using this binary language composed of bits (0 or 1). When you break a computer down, you will find a bunch of silicon chips with circuits of logic gates made up of transistors or switches which function using voltage. A high voltage represents on state of the switch equivalent to 1 and a low equivalent to 0. All forms of data be it text, music, audio, video or software are ultimately encoded and stored by the computer as binary in the computer’s memory.

**Rethinking binary and transistors –**

Abandoning the existing classical principles of computing, this new world of quantum computing follows its own rules, one that nature is based on. Nature is not classical. The natural world does not function at the macroscopic level and it is this fundamental aspect that quantum computing is built on, that is:

To reduce what we call “bits” or switches down to the smallest possible discrete unit or quantum level, computing like nature computes. This gives rise to **“qubits”** as opposed to classical bits.

**How quantum computers work –**

Logically, the quantum system uses, as mentioned earlier, what is coined as qubits as the smallest discrete units to **represent information**, which may be electrons with spins, photons with polarization, trapped ions, semiconducting circuits etc. The property of quantum mechanics comes into play as a single qubit can exist not only, in two discrete energy states, low and high (similar to 0 and 1) but it can also exist in a superposition state where in it exists in both states at once. When measured however, the superposition fades and one of the two distinct states is returned based on the probabilities of each state.

When using two qubits instead of a single qubit 4 discrete energy states exist, (2 discrete states for each qubit) and a qubit can even exist in a superposition of these states.

Similarly using n qubits, 2^{n} states are achieved which exist as combinations of 0s and 1s in parallel.

So this gives a way to represent information. The next step is to **process information**, which requires manipulation of these qubits. This is brought about by the use of special quantum logic gates and quantum algorithms such as Shor’s algorithm and Grover’s algorithm which function using the principles of quantum mechanics of superposition, entanglement and measurement. Without going into the complicated details of the quantum phenomena, the state of the qubits is manipulated by application of precise electromagnetic waves, microwaves and amplification functions as defined by the algorithms.

**Advantages of quantum computers –**

Two key factors make quantum computers a billion times more powerful than the most powerful supercomputer known to us today. These are:

- Parallelism
- Exponential increase in computing ability with the addition of each qubit

This gives quantum computers processing power that is beyond the scope of a classical computer.

**Applications of quantum computing –** Processing of billions of bytes can easily be performed by quantum computers, which can be applied in:

- Big data
- Cryptography
- Molecular Simulations
- Protein Folding
- Drug Discovery
- Genome Sequencing
- Diagnose DNA sequence
- Catalyst Analysis
- Financial Analysis
- Climate Prediction
- Graphic searches of complicated databases
- Optimisation
- Massive Software Testing

Work on quantum computers is an ongoing endeavor with tremendous potential to revolutionize the way we understand the digital world. It does not seek to replace classical computers but a sustainable quantum computer could aid classical computers in computationally intensive tasks that are restrictive, difficult and time consuming for our traditional Turing based computers.

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