DiVincenzo D P, Bacon D, Kempe J, Burkard G, Whaley K B
IBM Research Division, T. J. Watson Research Center, Yorktown Heights, New York 10598, USA.
Nature. 2000 Nov 16;408(6810):339-42. doi: 10.1038/35042541.
Various physical implementations of quantum computers are being investigated, although the requirements that must be met to make such devices a reality in the laboratory at present involve capabilities well beyond the state of the art. Recent solid-state approaches have used quantum dots, donor-atom nuclear spins or electron spins; in these architectures, the basic two-qubit quantum gate is generated by a tunable exchange interaction between spins (a Heisenberg interaction), whereas the one-qubit gates require control over a local magnetic field. Compared to the Heisenberg operation, the one-qubit operations are significantly slower, requiring substantially greater materials and device complexity--potentially contributing to a detrimental increase in the decoherence rate. Here we introduced an explicit scheme in which the Heisenberg interaction alone suffices to implement exactly any quantum computer circuit. This capability comes at a price of a factor of three in additional qubits, and about a factor of ten in additional two-qubit operations. Even at this cost, the ability to eliminate the complexity of one-qubit operations should accelerate progress towards solid-state implementations of quantum computation.
尽管目前要在实验室中实现量子计算机还需满足远超当前技术水平的能力要求，但人们仍在研究量子计算机的各种物理实现方式。近期的固态方法采用了量子点、施主原子核自旋或电子自旋；在这些架构中，基本的双量子比特量子门是由自旋之间的可调谐交换相互作用（海森堡相互作用）产生的，而单量子比特门则需要控制局部磁场。与海森堡操作相比，单量子比特操作要慢得多，需要更高的材料和器件复杂度，这可能会导致退相干率有害地增加。在此，我们提出了一种明确的方案，其中仅靠海森堡相互作用就足以精确实现任何量子计算机电路。这种能力的代价是额外增加了三倍的量子比特，以及大约十倍的双量子比特操作。即便付出这样的代价，消除单量子比特操作复杂度的能力仍应会加速量子计算固态实现的进展。
