Quantum Bit

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What Does Quantum Bit Mean?

A quantum bit (qubit) is the smallest unit of quantum information, which is the quantum analog of the regular computer bit, used in the field of quantum computing. A quantum bit can exist in superposition, which means that it can exist in multiple states at once. Compared to a regular bit, which can exist in one of two states, 1 or 0, the quantum bit can exist as a 1, 0 or 1 and 0 at the same time. This allows for very fast computing and the ability to do multitudes of calculations at once, theoretically.

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Techopedia Explains Quantum Bit

The ability of a qubit to exist in a superposition state means that a quantum computer is not limited to two states and is therefore able to hold more information, giving quantum computers the potential to be millions of times more powerful than today’s supercomputers. A qubit may represent anything very small, of quantum level, such as atoms, photons and electrons, which, when made to work together, can act like processors and memory.

The inherent parallelism of a quantum computer is due to the superposition of qubits, and according to physicist David Deutsch, this parallelism will allow a quantum computer to process millions of calculations during the time it takes a standard desktop PC to do a single calculation. Therefore, a 30-qubit computer could theoretically equal the power of a modern supercomputer that runs at 10 teraflops, whereas a modern desktop PC runs at only a few gigaflops.

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Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.