Introduction to Quantum Computing? - careerplanner1606/Quantum_Resources GitHub Wiki

Quantum computers use subatomic particles like electrons and photons as the basic unit of information for doing computations. Quantum computers are not the next generation of supercomputers; for the first time in history we have two entirely different ways of computing: our current classical computers/supercomputers and the new quantum computers. Quantum computers are programmable and can solve some problems many many times faster than the most powerful supercomputers. The power comes from the fact that the basic unit of information in a quantum computer, the qubit, can be put in a state of Superposition where it can exist in more than one distinct state (both 0 and 1). Another powerful property of the qubit is Entanglement for which the 2022 Nobel prize in Physics was awarded. Entanglement allows multiple qubits to be linked so that what happens to one determines what happens to the others. This means that calculations among entangled qubits can happen nearly instantly. The more entangled bits, the more calculations that can be done. As well, quantum systems are not just faster computers. They also solve, or show, a probability of an answer in a unique manner.

Technical leaders may wonder how they can harness or utilize this faster and different computational power, which will likely change technology and even society as much or more than the semiconductor.

How Does Quantum Computing Work?

Just like their classical counterparts, quantum computers are programmable. They use the same programming languages as classical computers; several quantum languages are libraries or extensions of Python, even if the major components, such as cache or memory, of a classical computer have not been created for quantum systems.

Quantum computers are fundamentally different in the way they compute. They use quantum mechanical properties to do some classes of tasks much faster than what can be done with normal computers. The world of quantum (subatomic particles) operates on very different laws and these particles behave very differently from what we see in our world. Quantum computing uses subatomic particles, such as electrons or photons. Quantum bits, or qubits, can exist in a state of superposition, where they can be in more than one state (i.e., 1 and 0) at the same time. Also, these qubits can be entangled so that they get into a quantum correlation where the act of measuring one determines the result of measuring the other.

We will briefly discuss these properties here.

Superposition Quantum mechanics predicts that a computer with n qubits can exist in a superposition of all 2^n of its distinct logical states. Which means that with 3 qubits, all the 2^3 states (000, 001, 101, 100, 010, 110, 011, 111) are simultaneously possible; similarly, this is valid for 4, 5, ….., n.

Entanglement In the Can Quantum-Mechanical Description of Physical Reality Be Considered Complete? paper (1935), Einstein argued that quantum mechanics could not explain its own prediction of entanglement. Hence, quantum mechanics was an incomplete theory according to him. But over the decades several scientists proved that entanglement is indeed possible. In 2022, the Nobel Prize in Physics was awarded to Alain Aspect, John Clauser and Anton Zeilinger, who demonstrated entanglement and even controlled the particles that are in entangled states, thus paving the way for a new era of quantum technologies.

Under the right conditions, qubits can be entangled, whereby the properties of the particles are related even if the particles are separated, even by vast distances. Measuring one instantly decides the state of the other, both of which leave their probable quantum state immediately upon the other being measured. This property cannot be simulated on classical computers. Quantum algorithms exploit this property to achieve speedup in several problems.

Intense research and development is underway to utilize the special properties of individual particle systems to construct quantum computers. Today, quantum computers are available over the cloud from multiple companies, and several industries are utilizing them to explore solving business problems.

Algorithmic advancements have been going hand-in-hand with progress in quantum hardware and software. We will list out some of the key milestones below. But before that, let us briefly discuss how quantum computers work. Scientists have been developing quantum algorithms for the past four decades. These are algorithms that exploit quantum mechanical properties like superposition and entanglement to solve problems. These algorithms are then implemented in the form of quantum circuits, which are written using higher level languages often using Python libraries. These programs manipulate the qubits using microwave pulses and make measurements on the qubits to obtain desired answers. To solve business problems, it is necessary to both develop new algorithms and improve the hardware and software to be able to implement the algorithms on quantum computers.

Differences Between Quantum and Classical Computers

We discussed the properties of quantum mechanics which make quantum computers work. Quantum computers manipulate quantum particles such as electrons and photons at low temperatures using microwave pulses. They are very different from classical computers.

Timeline of Quantum Computing Algorithms Milestones

Over the past few decades, several advances have been made in terms of quantum algorithms that show exponential or quadratic speedups. These algorithms have demonstrated that indeed quantum computing can solve certain problems much faster than classical computers and, in fact, they could even tackle some problems which will never be possible to implement on a classical computer.