# Waht is Quantum Computing

Quantum computing, often known as quantum information, is an alternative computer paradigm to the more traditional "classical" computing. A unique set of ones and zeros called cubits serves as the foundation for this system. While classical computing's bits are limited to either a 1 or a 0 state, cubits can occupy both positions at once. This results in the creation of novel logic gates, which in turn allows for the development of cutting-edge algorithmic techniques.

The fact that the same work might have different complexity in conventional computing compared to what it has in quantum computing has led to high hopes, since certain previously intractable problems become amenable to solution. However, a quantum computer is equivalent to a quantum Turing machine, while a classical computer is equivalent to a Turing machine.

Quantum computers use a novel method to problem-solving. The researchers believe that by using this novel kind of computing, they will be able to begin investigating issues that will remain intractable for the foreseeable future.

IBM's Director of Research Strategy and Growth Initiatives, Dr. Talia Gershon, gives a high-level explanation of quantum computing as a combination of three factors: the superposition of spins, the entanglement of two objects, and interference, which helps to control quantum states and amplify the types of signals that are oriented towards the correct answer while cancelling the types of signals that lead to the wrong answer.

Quantum computing's humble beginnings Increased processing velocity is a direct result of the shrinking size of transistors made possible by technological progress. There is a practical limit to how tiny chips can go until they no longer function correctly, therefore you can't make them eternally small. At the nanoscale scale, the tunnelling effect causes electrons to bypass their intended pathways and instead flow freely between neighbouring atoms.

If a classical particle runs into something, it will be reflected off of it rather than able to go around it. However, since electrons are quantum particles that act like waves, it is possible for some of them to pass through the walls if they are thin enough; in this way, the signal can travel through channels where it should not. As a result, the chip becomes dysfunctional.

Paul Benioff first publicised his notion to use quantum rules in the context of computers in 1981, which led to the birth of the field of quantum computing. We're not concerned with electrical voltages, but rather absolute amounts. A bit in digital computing has just two possible values, 0 and 1. In contrast, quantum computing is governed by the principles of quantum physics, and the particle might be in coherent superposition, being in three possible states at once: 0, 1, and both 1 and 0 (two orthogonal states of a subatomic particle). Since the number of operations is not limited by the number of qubits, multiple operations can be carried out simultaneously.

The number of qubits represents the maximum number of superimposed bits. For example, if you had a three-bit register using traditional bits, you could only store one of eight potential values. However, with a vector of three qubits, the particle can take on eight values simultaneously due to quantum superposition. This means that eight parallel processes are possible with a three-qubit vector. The number of operations scales exponentially with the number of qubits, as was predicted.

To put this in perspective, the current state-of-the-art conventional supercomputer Summit can handle 200 petaflops (200 thousand billion) of floating point operations per second, whereas a quantum computer with 30 qubits would be comparable to a conventional processor of 10 teraflops.

Explain the inner workings of quantum computing. The bit is the basic building block of information in the classic computer architecture; in a binary system, it can only take on the two possible values of 0 and 1. When bits are added, they can be combined to represent more data.

In quantum computing, the smallest unit of data is called a "Qbit," and thanks to the principle of quantum superposition, Qbits can hold multiple values at once. For example, a pair of Qbits can represent the superposition of values 00, 01, 10, and 11 all at once.3 An improved capacity for overlap means more accurate data representation.

The ability to perform operations in parallel or simultaneously scales exponentially with the number of Qbits available in a quantum computer, thanks to a property known as entanglement, which allows two correlated Qbits to be manipulated to behave identically.

Issues with Quantum Computing The issue of quantum decoherence is a major roadblock to the development of practical quantum computers because it results in the breakdown of the unitary nature (and more precisely, the reversibility) of the quantum algorithm's individual operations. At low temperatures, the decoherence periods for the candidate systems, in particular the transverse relaxation time (using the nomenclature used in nuclear magnetic resonance technology and magnetic resonance imaging), are generally between nanoseconds and seconds. Any operation must be finished in significantly less time than the decoherence time because error rates are typically proportional to the ratio of operation time to decoherence time. Quantum error correction is effective if the error rate is small enough, allowing for computation periods longer than the decoherence time and, in theory, arbitrary long. It is often believed that quantum error correction would be most useful for reducing errors to below the limitation rate of 10-4.

Yale Quantum Institute physicist and expert in quantum error correction Dr. Steven Girvin says, "everyone thinks they know it when they see it, but no one in the quantum case can define it precisely." In addition, he notes that the behaviour of a quantum system might undergo unpredictable changes when fault tolerance is seen or measurements are taken.

A further major issue is scalability, particularly in light of the massive increase in qubits required for any error-correcting computation. No presently suggested system has an easily implemented architecture for a large enough number of qubits to tackle computationally interesting challenges as they stand.

The underlying hardware for quantum computing No one has yet figured out what kind of hardware would be most suited for quantum computing. There are now a number of potential possibilities, and a set of criteria has been developed for him to satisfy (Di Vincenzo's list).

A quantum computer codenamed "Bristlecone" is currently (2018) being developed by Google developers.

It's contingent on meeting certain conditions. The system must be capable of being initialised, or set to a known and tunable initial state. The qubits must be able to undergo controlled manipulations using a set of operations that constitutes a universal set of logic gates (such that any other potential logic gate may be reproduced). The quantum coherence of the system must be maintained during the experiment. After the calculation is complete, the final state of the system must be readable. Problems with greater computational costs need a system that is scalable, meaning there is a clear path to adding more qubits.