How Do Quantum Computers Work?
By: Piyumi Rathnayaka
Tags: Quantum Superposition, Quantum Computer, Qubit, Quantum Computing, Quantum Entanglement

“The purpose of quantum computing based compassionate artificial intelligence is to develop integrated systems that can preserve and enhance human values of peace, love, happiness and freedom.”

― Amit Ray

What is a quantum computer?

All computers rely on bits, the smallest unit of information encoded as an “on” “off” state, more commonly referred to as 1 or 0 by some physical medium or other means. Quantum computing is a new generation computer based on quantum mechanics, a branch of physics that studies atomic and subatomic particles. So, these supercomputers perform speeds and calculations that the average computer can’t handle. A quantum computer uses something called qubits. Quantum partners can perform multiple operations at once. These machines store more than one state per unit of data and operate on more efficient algorithms.

And the incredible processing power enables quantum computers to solve complex tasks and search through unsorted data.

Traditional computers perform logical operations using the exact location of a physical state. These are usually binary, and their functionality is based on one of the two locations. Quantum computers perform calculations before measuring the position of an object. Such a “quantum bit” provides greater flexibility than the binary system. This concept is heavily being used in the field of cryptography. To build a working quantum computer, you need to keep an object in a high position. Unfortunately, once a superposition meets with materials that are part of a measured system, it loses its quantum state and becomes a boring old classical bit. Devices must be able to protect quantum conditions aesthetically and should be easy to read. Quantum dominance describes the ability of quantum computers to surpass their classical counterparts.

What is a qubit ?

Qubit is a quantum bit, which is the binary number of quantum computers. Just like the basic unit of information in classical computers, quantum computers use qubits.

Qubit is a two level quantum mechanics system, the simplest quantum system that exemplifies the uniqueness of quantum mechanics. Elemental particles such as electrons or photons, can be used in a quantum computer, and their charge or polarization acts as a 0 or 1 representation. The basis of quantum computing is the nature and behavior of these particles.

The two most relevant areas of quantum physics that are also used in Quantum Computing are the principles of Superposition and Entanglement.

Superposition in quantum computing

Consider the qubit as an electron in a magnetic field. The rotation of an electron is either aligned with the field or opposite to the field and is known as the rotating state. Changing the rotation of electrons from one state to another can be achieved by using a laser-like energy pulse. Let’s say we use 1 unit of laser energy, but what if we use only half of the laser energy and completely isolate the particle from all external influences? According to the quantum law, the particle would enter a superstructure of states, behaving as if it’s in both states at the same time. Every qubit used can take a super position in both 0s and 1s.

The number of computations that a quantum computer could undertake is 2^n, where n is the number of qubits used.

According to that point, this amazing number, 2¹⁰⁰⁰ is atomically and infinitely larger than the number of atoms in the known universe.

Quantum entanglement describes how these particles interact with each other.

Entanglement in quantum computing

The interacted particles retain a type of connection and become entangled with each other in pairs, in a process known as correlation. If two qubits are in conflict, the measurement of one qubit will immediately “break” the value of the other. Not only that, but if we measure a qubit in an entangled state, we can get the value of the other qubit. There is no need to measure a second qubit as the same effect occurs even if the two entangled qubits are far apart. Knowing the rotational position of one entangled particle (up or down) allows one to know that one’s partner is rotating in the opposite direction.

Even more astonishing is that due to the superposition phenomenon, it is measured that the particle rotates in both directions simultaneously. This is the same even if the particular particle does not have a single rotational direction before being measured.

The rotational position of the measured particle is determined during the measurement and is communicated to the correlated particle, thereby assuming the opposite direction of rotation to the simultaneously measured particle.

Quantum entanglement allows qubits that are separated at incredible distances to instantly interact with each other.

Applicable use cases in quantum computing

Quantum computers already exist to perform certain functions, all of which require very rigorous calculations that classical computers cannot handle. There are four main applications which are mentioned in the following figure.

Conclusion

You would have understood that quantum computers can be faster than classical computers. And this can be done, by activating a number of online quantum amplifiers at the same time. Unfortunately, so far, only specific algorithms exist. On the other hand, quantum cryptography is available with controllable quantum bits. It is a secure cryptographic proposition that can be proved in some sense.

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