Cascaded GHZ state code based quantum gate construction method of logic quantum bits

Abstract

The invention discloses a cascaded GHZ state code based quantum gate construction method of logic quantum bits. The method comprises the steps that coded logic quantum bits based on cascaded GHZ statecodes serve as input, each coded logic quantum bit is formed by multiplying N cascaded logic quantum bits represented in the GHZ state, and each logic quantum bit represented in the GHZ state is formed by m physical quantum bits; a quantum bit gate composed of a bit flipping gate, a phase flipping gate and a control NOT gate is constructed, and bit flipping, phase flipping and control NOT operation are carried out on each input coded logic quantum bit; and coded logic quantum bits after different operations are obtained in the output end. Via the method of the invention, operations related tothe cascaded GHZ state code based coded logic quantum bits can be realized, the method is realized via basic logic gates, the method has an anti-interference capability as to certain error models, and negative influence caused by photon loss can be offset to certain extent.

Description

technical field [0001] The invention relates to a method for constructing a logical qubit quantum gate based on cascaded Greenberg-Horn-Sellinger state (GHZ state) coding, and belongs to the technical field of quantum computing. Background technique [0002] In 1982, Nobel laureate Feynman proposed the concept of "quantum computer". In 1994, Shor proposed the Shor algorithm for the prime factorization of large numbers. In 1996, Grove proposed the Grove algorithm based on unordered database search. In 2001, Long proposed an improved Grover's algorithm, namely the Dragon's algorithm. These algorithms show that quantum computers can perform computations far faster than conventional computers. In 2001, Knill, Laflamme and Milbum proposed a coding scheme and successfully completed logic calculation under linear optical conditions. However, to complete a quantum computer, there must be general-purpose logic gates and good anti-noise performance, that is, fault tolerance. Quan...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, to provide a method for constructing a logical qubit quantum gate based on cascaded GHZ state coding, and to solve the problem that the quantum computing logic unit of the logical coding cannot construct a specific quantum gate in the existing method. Gates, and general-purpose logic gates are not resistant to certain errors, using three basic quantum gates, namely bit flip gates, phase flip gates and control NOT gates

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