Learning unknown pure quantum states
- Title
- Learning unknown pure quantum states
- Author
- 이진형
- Keywords
- TOMOGRAPHY; OPTIMIZATION; PROTOCOL
- Issue Date
- 2018-11
- Publisher
- AMER PHYSICAL SOC
- Citation
- PHYSICAL REVIEW A, v. 98, no. 5, Article no. 052302
- Abstract
- We propose a learning method for estimating unknown pure quantum states. The basic idea of our method is to learn a unitary operation (U) over cap that transforms a given unknown state vertical bar psi(tau)> to a known fiducial state vertical bar f >. Then, after completion of the learning process, we can estimate and reproduce vertical bar psi(tau)> based on the learned (U) over cap (a) under bar nd vertical bar f >. To realize this idea, we cast a random-based learning algorithm, called "single-shot measurement learning," in which the learning rule is based on an intuitive and reasonable criterion: the greater the number of success (or failure), the less (or more) changes are imposed. Remarkably, the learning process occurs by means of a single-shot measurement outcome. We demonstrate that our method works effectively, i.e., the learning is completed with a finite number, say N, of unknown-state copies. Most surprisingly, our method allows the maximum statistical accuracy to be achieved for large N, namely similar or equal to O (N-1) scales of average infidelity. It highlights a nontrivial message, that is, a random-based strategy can potentially be as accurate as other standard statistical approaches.
- URI
- https://journals.aps.org/pra/abstract/10.1103/PhysRevA.98.052302https://repository.hanyang.ac.kr/handle/20.500.11754/120670
- ISSN
- 2469-9926; 2469-9934
- DOI
- 10.1103/PhysRevA.98.052302
- Appears in Collections:
- COLLEGE OF NATURAL SCIENCES[S](자연과학대학) > PHYSICS(물리학과) > Articles
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