Quantum physics remains one of the most fascinating fields of science. Responsible for several leaps in modern technology, quantum physics now has in its hands one of its most important tools: quantum bits.

Computing is defined as the process of using electronic systems and devices to manipulate and process data. At its core, classical computing involves the use of bits, which can assume two states: 0 or 1, to represent and perform calculations on information. These bits operate under the rules of binary logic, and are the basis for all operations performed on devices such as computers, smartphones and servers.

Quantum computing, on the other hand, is an emerging form of computing that uses the laws of quantum mechanics to perform calculations much more complex than those possible on classical computers. Instead of bits, quantum computing uses qubits.

## Qbit: what is a quantum bit

The new quantum computer has 256 physical qubits and 10 logical qubits (Credit: Bartlomiej K. Wroblewski/Shutterstock)

A quantum bit, or qubit, is the fundamental unit of data in the field of quantum computing, playing a role analogous to that of a bit in classical computing. However, while a traditional bit represents a binary value of 0 or 1, a qubit can exhibit significantly more complex behaviors, thanks to the properties of quantum mechanics, such as superposition and quantum entanglement.

Qubits are often represented by subatomic particles, such as electrons or photons, whose properties, such as charge, photon polarization, or spin, are used to encode information. In classical computing, bits can be in one of two states: 0 or 1. In contrast, qubits can exist simultaneously in both states, a characteristic called superposition. This superposition allows a qubit to assume a combination of 0 and 1 at the same time, something impossible in traditional computing systems.

The idea of superposition is one of the most important and yet strange properties of quantum physics. Imagine that you have two qubits. In a classical computer, they could only represent one of four possible states: 00, 01, 10 or 11, at any given time. However, in a quantum computer, these two qubits can represent all of these states simultaneously, which increases the processing power exponentially as more qubits are added to the system.

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Another crucial feature of qubits is quantum entanglement, a property that allows particles to be linked in such a way that the state of one instantly influences the state of another, regardless of the distance between them. This means that if we measure one entangled particle and determine its state, we automatically know the state of the other entangled particle, no matter how far away it is. This phenomenon, which Einstein called “spooky action at a distance,” is one of the principles that drives the incredible processing power of qubits.

Qubits can interact and perform calculations simultaneously, regardless of where they are in space. This offers immense potential for quantum computing, allowing extremely complex calculations to be performed in a fraction of the time it would take on a traditional binary computer. Problems that would take years or even centuries to solve on a classical supercomputer could be solved in seconds by a properly optimized quantum computer.

If we can build quantum computers with millions of entangled qubits, the impact would be revolutionary. They could solve complex cryptographic problems in seconds, while algorithms that would take millions of years on classical supercomputers could be solved almost instantly. This revolution could impact many fields, from physics to biology, bringing incalculable advances in research, technology and digital security.