Wu L-A, Lidar D A
Chemical Physics Theory Group, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada.
Phys Rev Lett. 2002 May 20;88(20):207902. doi: 10.1103/PhysRevLett.88.207902. Epub 2002 May 6.
A decoherence-free subspace (DFS) isolates quantum information from deleterious environmental interactions. We give explicit sequences of strong and fast ["bang-bang" (BB)] pulses that create the conditions allowing for the existence of DFSs that support scalable, universal quantum computation. One such example is the creation of the conditions for collective decoherence, wherein all system particles are coupled in an identical manner to their environment. The BB pulses needed for this are generated using only the Heisenberg exchange interaction. In conjunction with previous results, this shows that Heisenberg exchange is by itself an enabler of universal fault-tolerant quantum computation on DFSs.
无退相干子空间（DFS）将量子信息与有害的环境相互作用隔离开来。我们给出了强且快速的["砰砰"（BB）]脉冲的明确序列，这些脉冲创造了允许存在支持可扩展通用量子计算的DFS的条件。一个这样的例子是创造集体退相干的条件，其中所有系统粒子以相同方式与其环境耦合。为此所需的BB脉冲仅使用海森堡交换相互作用来生成。结合先前的结果，这表明海森堡交换本身就是在DFS上进行通用容错量子计算的一个促成因素。
