The More You Know: Qubit

A Qubit, or quantum bit is the fundamental unit of quantum information, it is a mathematical concept satisfying particular properties. The Qubit is the quantum counterpart of the classical bit.

A classical bit can be in one of two different states: 0 or 1, whereas a Qubit can be in the quantum states |1\rangle|0\rangle but also in any superposition of these two. That is, the state |\psi\rangle  of a Qubit will be of the form

|\psi\rangle=\alpha|0\rangle + \beta|1\rangle,

where \alpha and \beta are complex number satisfying

|\alpha|^2+|\beta|^2=1.

The states |1\rangle and |0\rangle form the so-called computational basis \{|1\rangle,|0\rangle\}. Then, as a mathematical concept, a Qubit is a vector normalized to length 1 in a 2D complex vector field.

Just as it’s classical analogue, a Qubit can have many physical realizations: The polarization of a photon, the spin of an electron or a nucleus, the localization of a charge, among other two-state quantum systems.

Go to the Dictionary of Quantum Information and Quantum Computation.


 All text copyright © Marco Vinicio Sebastian Cerezo de la Roca.

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The More You Know: Qubit by Marco Vinicio Sebastian Cerezo de la Roca is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

 

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About marcocerezo

My name is Marco Cerezo, I have a degree in physics from the Universidad Nacional de la Plata (UNLP) in Buenos Aires, Argentina, and I'm a Ph.D student. Although I study in Argentina, I was born and raised in Guatemala, so I consider myself "chapín" at heart. From an early age I discovered how exciting, interesting and fun physics can be, so I decided to devote myself to study this passionate field. This blog is dedicated to all those who want to dig a little into the mysteries and beauty of physics. And in particular, to all those who are interested in studying Quantum Computation and Quantum Information. ---------------------------------------------------------------------------------------------------------- Mi nombre es Marco Cerezo, Licenciado en Física egresado de la Universidad Nacional de la Plata (UNLP) en Buenos Aires, Argentina. Actualmente estoy haciendo mi Doctorado en física. Aunque estudio en Argentina, nací y crecí en Guatemala por lo que me considero chapín de corazón. Desde muy temprana edad descubrí lo apasionante, interesante y divertida que es la física por lo que decidí dedicarme a su estudio. Este blog es está dedicado a todos aquellos que quieren indagar un poco en los misterios y la belleza de la física; y en particular, a aquellos que quieran aprender sobre Computación e Información Cuántica.
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