A Decoherence-Reduction Scheme by Waveguides in Quantum Information Processing
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Based on the result of cavity quantum electrodynamics, we suggest a method, in which the Fabry-Perot cavity or the confocal cavity is replaced by a waveguide with the size comparable to the wavelength of the photon, to reduce decoherence caused by spontaneous emission in quantum information processing, especially in the realization of quantum computation. Since a waveguide has a lowest cutoff frequency while a Fabry-Perot cavity or a confocal cavity has none, the spontaneous emission of excited atoms will be forbidden in an ideal waveguide with an appropriate size. To avoid the influence of the non-ideal conducting walls on the atom in a realistic waveguide, which will lead to decoherence, we suggest that the waveguide should be coated by a thin film of transparent insulating medium. In our method, the quantum information is represented by a multi-level atom or molecule; any two of its levels can be used to represent a qubit in principle. Our method greatly extends the choice of the material to be used in the realization of quantum computation, and it can be used in most schemes to reduce the decoherence caused by spontaneous emission.
KeywordsQuantum computation Quantum information Cavity QED Waveguide Spontaneous emission
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