Deterministic realization of collective measurements via photonic quantum walks.

ABSTRACT: Collective measurements on identically prepared quantum systems can extract more information than local measurements, thereby enhancing information-processing efficiency. Although this nonclassical phenomenon has been known for two decades, it has remained a challenging task to demonstrate the advantage of collective measurements in experiments. Here, we introduce a general recipe for performing deterministic collective measurements on two identically prepared qubits based on quantum walks. Using photonic quantum walks, we realize experimentally an optimized collective measurement with fidelity 0.9946 without post selection. As an application, we achieve the highest tomographic efficiency in qubit state tomography to date. Our work offers an effective recipe for beating the precision limit

SUBMITTER: Hou Z 

PROVIDER: S-EPMC5897416 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature