In a separate experiment, and the final state afterĮncoding and decoding inferred by adding the results. Is proportional to the diffusion constant DĪs well as to the square of the coherence order n :įour product operators in the sum of Eq. The effective decoherence time of this process The magnetization after allowing molecular diffusionĪs a result of random spin displacement Δ z,Īre not returned to their original values but are randomly modified byįor a gaussian displacement profile with a width Where n is the coherence order of the density matrix element and With a phase varying linearly along the z direction according to This modifies the magnetization in the sample This is achieved by turning on an external field gradient To mimic the effect of a slowly varying random field. Induced by diffusion in a constant field gradient This implementation used the random molecular motion To obtain a clean demonstration of error correction,Ī simple error model was implemented precisely in the case of alanine. Insurmountable obstacles to realizing a quantum computer. Thus decoherence and imprecision are no longer considered Provided the error rate is below a threshold Of decoherence a quantum computation can be as longĪs desired with arbitrarily accurate answers, It is now known that for physically reasonable models Were found to protect quantum information againstĬorruption due to imperfect control and decoherence. This judgment was demonstrated to be overly pessimistic when quantum error-correction Physically impossible due to the extreme fragility of quantum Searching and simulations of quantumĮxploiting the power of quantum computation was thought to be (thereby breaking public key cryptography), combinatorial These problems include factoring large numbers Than any known algorithm for their classical counterparts. To solve some problems much more efficiently Quantum computers exploit the superposition principle
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