Quantum digitaltoanalog conversion algorithm using decoherence
Abstract
We consider the problem of mapping digital data encoded on a quantum register to analog amplitudes in parallel. It is shown to be unlikely that a fully unitary polynomialtime quantum algorithm exists for this problem; NP becomes a subset of BQP if it exists. In the practical point of view, we propose a nonunitary lineartime algorithm using quantum decoherence. It tacitly uses an exponentially large physical resource, which is typically a huge number of identical molecules. Quantumness of correlation appearing in the process of the algorithm is also discussed.
 Publication:

Quantum Information Processing
 Pub Date:
 August 2015
 DOI:
 10.1007/s111280151033x
 arXiv:
 arXiv:1409.0088
 Bibcode:
 2015QuIP...14.2729S
 Keywords:

 Digitaltoanalog conversion;
 Quantum algorithm;
 Bulkensemble computation;
 Quantum Physics;
 Computer Science  Data Structures and Algorithms;
 81P68;
 C.1.3
 EPrint:
 22 pages, no figure, v2: minor revision, style changed, minor changes of proofs in section 2, v3: revision with more detailed explanations, style changed, supplementary material added, v4: minor revision, v5: typos corrected, to appear in QIP