Ancilla models for quantum operations: for what unitaries does the ancilla state have to be physical?

作者：Jiang Zhang^*; Piani Marco; Caves Carlton M

来源：Quantum Information Processing, 2013, 12(5): 1999-2017.

DOI：10.1007/s11128-012-0500-x

• Ancilla model
• Stinespring extension
• Completely positive
• Quantum operation
• Quantum tomography

Any evolution described by a completely positive trace-preserving linear map can be imagined as arising from the interaction of the evolving system with an initially uncorrelated ancilla. The interaction is given by a joint unitary operator, acting on the system and the ancilla. Here we study the properties such a unitary operator must have in order to force the choice of a physical-that is, positive-state for the ancilla if the end result is to be a physical-that is, completely positive-evolution of the system.

• 出版日期2013-5